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Byrne KE, Poirier Y, Xu J, Gerry A, Foley MJ, Jackson IL, Sawant A, Jiang K. Technical note: A small animal irradiation platform for investigating the dependence of the FLASH effect on electron beam parameters. Med Phys 2024; 51:1421-1432. [PMID: 38207016 DOI: 10.1002/mp.16909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 10/30/2023] [Accepted: 12/12/2023] [Indexed: 01/13/2024] Open
Abstract
BACKGROUND The recent rediscovery of the FLASH effect, a normal tissue sparing phenomenon observed in ultra-high dose rate (UHDR) irradiations, has instigated a surge of research endeavors aiming to close the gap between experimental observation and clinical treatment. However, the dependences of the FLASH effect and its underpinning mechanisms on beam parameters are not well known, and large-scale in vivo studies using murine models of human cancer are needed for these investigations. PURPOSE To commission a high-throughput, variable dose rate platform providing uniform electron fields (≥15 cm diameter) at conventional (CONV) and UHDRs for in vivo investigations of the FLASH effect and its dependences on pulsed electron beam parameters. METHODS A murine whole-thoracic lung irradiation (WTLI) platform was constructed using a 1.3 cm thick Cerrobend collimator forming a 15 × 1.6 cm2 slit. Control of dose and dose rate were realized by adjusting the number of monitor units and couch vertical position, respectively. Achievable doses and dose rates were investigated using Gafchromic EBT-XD film at 1 cm depth in solid water and lung-density phantoms. Percent depth dose (PDD) and dose profiles at CONV and various UHDRs were also measured at depths from 0 to 2 cm. A radiation survey was performed to assess radioactivation of the Cerrobend collimator by the UHDR electron beam in comparison to a precision-machined copper alternative. RESULTS This platform allows for the simultaneous thoracic irradiation of at least three mice. A linear relationship between dose and number of monitor units at a given UHDR was established to guide the selection of dose, and an inverse-square relationship between dose rate and source distance was established to guide the selection of dose rate between 20 and 120 Gy·s-1 . At depths of 0.5 to 1.5 cm, the depth range relevant to murine lung irradiation, measured PDDs varied within ±1.5%. Similar lateral dose profiles were observed at CONV and UHDRs with the dose penumbrae widening from 0.3 mm at 0 cm depth to 5.1 mm at 2.0 cm. The presence of lung-density plastic slabs had minimal effect on dose distributions as compared to measurements made with only solid water slabs. Instantaneous dose rate measurements of the activated copper collimator were up to two orders of magnitude higher than that of the Cerrobend collimator. CONCLUSIONS A high-throughput, variable dose rate platform has been developed and commissioned for murine WTLI electron FLASH radiotherapy. The wide field of our UHDR-enabled linac allows for the simultaneous WTLI of at least three mice, and for the average dose rate to be modified by changing the source distance, without affecting dose distribution. The platform exhibits uniform, and comparable dose distributions at CONV and UHDRs up to 120 Gy·s-1 , owing to matched and flattened 16 MeV CONV and UHDR electron beams. Considering radioactivation and exposure to staff, Cerrobend collimators are recommended above copper alternatives for electron FLASH research. This platform enables high-throughput animal irradiation, which is preferred for experiments using a large number of animals, which are required to effectively determine UHDR treatment efficacies.
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Affiliation(s)
- Kevin E Byrne
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of Physics, School of Natural Sciences, University of Galway, Galway, Ireland
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Junliang Xu
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Andrew Gerry
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Mark J Foley
- Department of Physics, School of Natural Sciences, University of Galway, Galway, Ireland
| | - Isabel Lauren Jackson
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kai Jiang
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Hoang T, Sutera P, Nguyen T, Chang J, Jagtap S, Song Y, Shetty AC, Chowdhury DD, Chan A, Carrieri FA, Hathout L, Ennis R, Jabbour SK, Parikh R, Molitoris J, Song DY, DeWeese T, Marchionni L, Ren L, Sawant A, Simone N, Lafargue A, Van Der Eecken K, Bunz F, Ost P, Tran PT, Deek MP. TP53 structure-function relationships in metastatic castrate-sensitive prostate cancer and the impact of APR-246 treatment. Prostate 2024; 84:87-99. [PMID: 37812042 DOI: 10.1002/pros.24629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/13/2023] [Accepted: 09/18/2023] [Indexed: 10/10/2023]
Abstract
PURPOSE Despite well-informed work in several malignancies, the phenotypic effects of TP53 mutations in metastatic castration-sensitive prostate cancer (mCSPC) progression and metastasis are not clear. We characterized the structure-function and clinical impact of TP53 mutations in mCSPC. PATIENTS AND METHODS We performed an international retrospective review of men with mCSPC who underwent next-generation sequencing and were stratified according to TP53 mutational status and metastatic burden. Clinical outcomes included radiographic progression-free survival (rPFS) and overall survival (OS) evaluated with Kaplan-Meier and multivariable Cox regression. We also utilized isogenic cancer cell lines to assess the effect of TP53 mutations and APR-246 treatment on migration, invasion, colony formation in vitro, and tumor growth in vivo. Preclinical experimental observations were compared using t-tests and ANOVA. RESULTS Dominant-negative (DN) TP53 mutations were enriched in patients with synchronous (vs. metachronous) (20.7% vs. 6.3%, p < 0.01) and polymetastatic (vs. oligometastatic) (14.4% vs. 7.9%, p < 0.01) disease. On multivariable analysis, DN mutations were associated with worse rPFS (hazards ratio [HR] = 1.97, 95% confidence interval [CI]: 1.31-2.98) and overall survival [OS] (HR = 2.05, 95% CI: 1.14-3.68) compared to TP53 wild type (WT). In vitro, 22Rv1 TP53 R175H cells possessed stronger migration, invasion, colony formation ability, and cellular movement pathway enrichment in RNA sequencing analysis compared to 22Rv1 TP53 WT cells. Treatment with APR-246 reversed the effects of TP53 mutations in vitro and inhibited 22Rv1 TP53 R175H tumor growth in vivo in a dosage-dependent manner. CONCLUSIONS DN TP53 mutations correlated with worse prognosis in prostate cancer patients and higher metastatic potential, which could be counteracted by APR-246 treatment suggesting a potential future therapeutic avenue.
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Affiliation(s)
- Tung Hoang
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Biochemistry and Molecular Biology, Johns Hopkins University School of Public Health, Baltimore, Maryland, USA
| | - Philip Sutera
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Triet Nguyen
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Biochemistry and Molecular Biology, Johns Hopkins University School of Public Health, Baltimore, Maryland, USA
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Jinhee Chang
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Shreya Jagtap
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Yang Song
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Amol C Shetty
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Dipanwita D Chowdhury
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Aaron Chan
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Francesca A Carrieri
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Lara Hathout
- Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
| | - Ronald Ennis
- Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
| | - Salma K Jabbour
- Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
| | - Rahul Parikh
- Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
| | - Jason Molitoris
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Daniel Y Song
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Urology, James Buchanan Urological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Theodore DeWeese
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Urology, James Buchanan Urological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Lei Ren
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Amit Sawant
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Nicole Simone
- Department of Radiation Oncology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Audrey Lafargue
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
| | - Kim Van Der Eecken
- Department of Pathology, Ghent University Hospital, Cancer Research Institute (CRIG), Ghent, Belgium
| | - Fred Bunz
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Urology, James Buchanan Urological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Piet Ost
- Department of Radiation Oncology, Iridium Network, Antwerp, Belgium
- Department of Human Structure and Repair, Ghent University, Ghent, Belgium
| | - Phuoc T Tran
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Radiation Oncology, Division of Translational Radiation Sciences, University of Maryland Baltimore, School of Medicine, Baltimore, Maryland, USA
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Department of Urology, James Buchanan Urological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Matthew P Deek
- Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey, USA
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Tu KJ, Zhang H, Rodrigues D, Molitoris JK, Sawant A, Shukla HD. Abstract 1104: Gene expression profile analysis of hyperthermia-induced radiosensitivity in breast cancer. Cancer Res 2023. [DOI: 10.1158/1538-7445.am2023-1104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Abstract
Hyperthermia treatment of tumors (43-47°C) is used to sensitize breast cancer tumors to radiotherapy. Thermoradiotherapy significantly increases complete response rate and provides a treatment modality for more aggressive forms of the disease for which treatment options are generally more limited. However, the cellular mechanism underlying hyperthermia-induced radiosensitivity remains unclear. To better understand this phenomenon, we analyzed microarray data from four cell lines following treatment at 45°C for 30 minutes (Gene Expression Omnibus GSE48398). Three of the cell lines, MDA231 (37ºC, n=6; 45ºC, n=3), MDA486 (37ºC, n=6; 45ºC, n=3), and MCF7 (37ºC, n=6; 45ºC, n=6), were malignant breast cancer cell lines. The fourth cell line, MCF10A (37ºC, n=3; 45ºC, n=3), was from non-malignant mammary epithelial tissue. We identified 164 DEGs (adjP < 0.05, Fold change > 2) shared between the four cell lines and 182 DEGS shared by the three cancerous cell lines. Genes involved in radiosensitivity regulation as identified by dbCRSR, a database of radioresistance genes, were significantly dysregulated (Chi-squared test, p = 0.04). Gene ontology analysis using Cytoscape (v3.8.2) found 53 significantly enriched GO terms from an analysis off the DEGs (Benjamini-Hochberg adjP < 0.05). In particular, DEGs were enriched in processes involving G2 cell cycle arrest, apoptosis, and DNA damage checkpoints (adjP<0.005). We identified nine significantly enriched KEGG pathways, which included the ErbB (adjP=0.02), p53 (adjP=0.03), and PD-1 (adjP=0.02) cancer signaling pathways. We constructed a STRING protein-protein interaction network and then identified the 20 DEGs which had the greatest number of interactions. Identification of key genes in regulating hyperthermia-induced radiosensitivity were identified out of these 20 genes using two criteria: 1) overlap with two cancer signaling pathways and 2) involvement in radiosensitivity regulation. PTEN, a tumor suppressor overexpressed by up to 3.2-fold in vitro following hyperthermia, was identified as a key gene that may regulate hyperthermia-induced radiosensitivity in breast cancer. Distinct patterns of gene expression existed between breast cancer cells treated with hyperthermia and non-treated cells. Our data suggest that hyperthermia may exert its effects through arresting cells in the G2 phase, a particularly radiosensitive section of the cell cycle. Understanding the genes and pathways responsible for the heat-induced sensitization of breast cancer will allow us to exploit genetic alterations in tumors and develop non-invasive thermoradiotherapy regimens that more specifically target the tumor. Our study provides the basis for further investigation of genes regulating heat-induced radiosensitization and its molecular mechanism in breast cancer.
Citation Format: Kevin Jili Tu, Hong Zhang, Dario Rodrigues, Jason K. Molitoris, Amit Sawant, Hem D. Shukla. Gene expression profile analysis of hyperthermia-induced radiosensitivity in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1104.
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Affiliation(s)
- Kevin Jili Tu
- 1University of Maryland School of Medicine, Baltimore, MD
| | - Hong Zhang
- 1University of Maryland School of Medicine, Baltimore, MD
| | | | | | - Amit Sawant
- 1University of Maryland School of Medicine, Baltimore, MD
| | - Hem D. Shukla
- 1University of Maryland School of Medicine, Baltimore, MD
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Parsons D, Joo M, Iqbal Z, Godley A, Kim N, Spangler A, Albuquerque K, Sawant A, Zhao B, Gu X, Rahimi A. Stability and reproducibility comparisons between deep inspiration breath-hold techniques for left-sided breast cancer patients: A prospective study. J Appl Clin Med Phys 2023; 24:e13906. [PMID: 36691339 PMCID: PMC10161105 DOI: 10.1002/acm2.13906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/06/2022] [Accepted: 12/23/2022] [Indexed: 01/25/2023] Open
Abstract
PURPOSE Deep inspiration breath-hold (DIBH) is crucial in reducing the lung and cardiac dose for treatment of left-sided breast cancer. We compared the stability and reproducibility of two DIBH techniques: Active Breathing Coordinator (ABC) and VisionRT (VRT). MATERIALS AND METHODS We examined intra- and inter-fraction positional variation of the left lung. Eight left-sided breast cancer patients were monitored with electronic portal imaging during breath-hold (BH) at every fraction. For each patient, half of the fractions were treated using ABC and the other half with VRT, with an equal amount starting with either ABC or VRT. The lung in each portal image was delineated, and the variation of its area was evaluated. Intrafraction stability was evaluated as the mean coefficient of variation (CV) of the lung area for the supraclavicular (SCV) and left lateral (LLat) field over the course of treatment. Reproducibility was the CV for the first image of each fraction. Daily session time and total imaging monitor units (MU) used in patient positioning were recorded. RESULTS The mean intrafraction stability across all patients for the LLat field was 1.3 ± 0.7% and 1.5 ± 0.9% for VRT and ABC, respectively. Similarly, this was 1.5 ± 0.7% and 1.6 ± 0.8% for VRT and ABC, respectively, for the SCV field. The mean interfraction reproducibility for the LLat field was 11.0 ± 3.4% and 14.9 ± 6.0% for VRT and ABC, respectively. Similarly, this was 13.0 ± 2.5% and 14.8 ± 9% for VRT and ABC, respectively, for the SCV. No difference was observed in the number of verification images required for either technique. CONCLUSIONS The stability and reproducibility were found to be comparable between ABC and VRT. ABC can have larger interfractional variation with less feedback to the treating therapist compared to VRT as shown in the increase in geometric misses at the matchline.
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Affiliation(s)
- David Parsons
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Mindy Joo
- Department of Radiation Oncology, Inova Fairfax Hospital, Falls Church, Virginia, USA
| | - Zohaib Iqbal
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Andrew Godley
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Nathan Kim
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ann Spangler
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kevin Albuquerque
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Bo Zhao
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Xuejun Gu
- Department of Radiation Oncology, Stanford University, Palo Alto, California, USA
| | - Asal Rahimi
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Modiri A, Koduri S, Savla B, Ahmady A, Marter J, Vicente E, Sawant A, Jeudy J, Mohindra P. Changes in CT Attenuation Values of Pericardium Months after Radiotherapy as Surrogates for Later Major Cardiotoxicity. Int J Radiat Oncol Biol Phys 2022. [DOI: 10.1016/j.ijrobp.2022.07.2209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Kalavagunta C, Xu H, Zhang B, Mossahebi S, MacFarlane M, Jiang K, Lee SW, Chen S, Sawant A, Gopal A, Yi B. Is a weekly qualitative picket fence test sufficient? A proposed alternate EPID-based weekly MLC QA program. J Appl Clin Med Phys 2022; 23:e13699. [PMID: 35856943 PMCID: PMC9359020 DOI: 10.1002/acm2.13699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 05/18/2022] [Accepted: 05/30/2022] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Well-designed routine multileaf collimator (MLC) quality assurance (QA) is important to assure external-beam radiation treatment delivery accuracy. This study evaluates the clinical necessity of a comprehensive weekly (C-Weekly) MLC QA program compared to the American Association of Physics in Medicinerecommended weekly picket fence test (PF-Weekly), based on our seven-year experience with weekly MLC QA. METHODS The C-Weekly MLC QA program used in this study includes 5 tests to analyze: (1) absolute MLC leaf position; (2) interdigitation MLC leaf position; (3) picket fence MLC leaf positions at static gantry angle; (4) minimum leaf-gap setting; and (5) volumetric-modulated arc therapy delivery. A total of 20,226 QA images from 16,855 tests (3,371 tests × 5) for 11 linacs at 5 photon clinical sites from May 2014 to June 2021 were analyzed. Failure mode and effects analysis was performed with 5 failure modes related to the 5 tests. For each failure mode, a risk probability number (RPN) was calculated for a C-Weekly and a PF-Weekly MLC QA program. The probability of occurrence was evaluated from statistical analyses of the C-Weekly MLC QA. RESULTS The total number of failures for these 16,855 tests was 143 (0.9%): 39 (27.3%) for absolute MLC leaf position, 13 (9.1%) for interdigitation position, 9 (6.3%) for static gantry picket fence, 2 (1.4%) for minimum leaf-gap setting, and 80 (55.9%) for VMAT delivery. RPN scores for PF-Weekly MLC QA ranged from 60 to 192 and from 48 to 96 for C-Weekly MLC QA. CONCLUSION RPNs for the 5 failure modes of MLC QA tests were quantitatively determined and analyzed. A comprehensive weekly MLC QA is imperative to lower the RPNs of the 5 failure modes to the desired level (<125); those from the PF-Weekly MLC QA program were found to be higher (>125). This supports the clinical necessity for comprehensive weekly MLC QA.
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Affiliation(s)
- Chaitanya Kalavagunta
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Huijun Xu
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Baoshe Zhang
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Sina Mossahebi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Michael MacFarlane
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kai Jiang
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Sung-Woo Lee
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Shifeng Chen
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Arun Gopal
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - ByongYong Yi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Vicente EM, Modiri A, Kipritidis J, Yu KC, Sun K, Cammin J, Gopal A, Xu J, Mossahebi S, Hagan A, Yan Y, Owen DR, Mohindra P, Matuszak MM, Timmerman RD, Sawant A. Combining Serial and Parallel Functionality in Functional Lung Avoidance Radiation Therapy. Int J Radiat Oncol Biol Phys 2022; 113:456-468. [PMID: 35279324 DOI: 10.1016/j.ijrobp.2022.01.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 01/10/2022] [Accepted: 01/26/2022] [Indexed: 10/18/2022]
Abstract
PURPOSE Functional lung avoidance (FLA) radiation therapy (RT) aims to minimize post-RT pulmonary toxicity by preferentially avoiding dose to high-functioning lung (HFL) regions. A common limitation is that FLA approaches do not consider the conducting architecture for gas exchange. We previously proposed the functionally weighted airway sparing (FWAS) method to spare airways connected to HFL regions, showing that it is possible to substantially reduce risk of radiation-induced airway injury. Here, we compare the performance of FLA and FWAS and propose a novel method combining both approaches. METHODS We used breath-hold computed tomography (BHCT) and simulation 4-dimensional computed tomography (4DCT) from 12 lung stereotactic ablative radiation therapy patients. Four planning strategies were examined: (1) Conventional: no sparing other than clinical dose-volume constraints; (2) FLA: using a 4DCT-based ventilation map to delineate the HFL, plans were optimized to reduce mean dose and V13.50 in HFL; (3) FWAS: we autosegemented 11 to 13 generations of individual airways from each patient's BHCT and assigned priorities based on the relative contribution of each airway to total ventilation. We used these priorities in the optimization along with airway dose constraints, estimated as a function of airway diameter and 5% probability of collapse; and (4) FLA + FWAS: we combined information from the 2 strategies. We prioritized clinical dose constraints for organs at risk and planning target volume in all plans. We performed the evaluation in terms of ventilation preservation accounting for radiation-induced damage to both lung parenchyma and airways. RESULTS We observed average ventilation preservation for FLA, FWAS, and FLA + FWAS as 3%, 8.5%, and 14.5% higher, respectively, than for Conventional plans for patients with ventilation preservation in Conventional plans <90%. Generalized estimated equations showed that all improvements were statistically significant (P ≤ .036). We observed no clinically relevant improvements in outcomes of the sparing techniques in patients with ventilation preservation in Conventional plans ≥90%. CONCLUSIONS These initial results suggest that it is crucial to consider the parallel and the serial nature of the lung to improve post-radiation therapy lung function and, consequently, quality of life for patients.
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Affiliation(s)
| | - Arezoo Modiri
- University of Maryland School of Medicine, Baltimore, Maryland
| | | | | | - Kai Sun
- University of Maryland School of Medicine, Baltimore, Maryland
| | - Jochen Cammin
- University of Maryland School of Medicine, Baltimore, Maryland
| | - Arun Gopal
- University of Maryland School of Medicine, Baltimore, Maryland
| | - Jingzhu Xu
- University of Maryland School of Medicine, Baltimore, Maryland
| | - Sina Mossahebi
- University of Maryland School of Medicine, Baltimore, Maryland
| | - Aaron Hagan
- University of Maryland School of Medicine, Baltimore, Maryland
| | - Yulong Yan
- UT Southwestern Medical Center, Dallas, Texas
| | | | | | | | | | - Amit Sawant
- University of Maryland School of Medicine, Baltimore, Maryland
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Poirier Y, Xu J, Mossahebi S, Therriault‐Proulx F, Sawant A. Technical note: Characterization and practical applications of a novel plastic scintillator for on‐line dosimetry for ultra‐high dose rate (FLASH). Med Phys 2022; 49:4682-4692. [DOI: 10.1002/mp.15671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 03/23/2022] [Accepted: 03/30/2022] [Indexed: 11/06/2022] Open
Affiliation(s)
- Yannick Poirier
- University of Maryland School of Medicine Baltimore MD 21201
- McGill University Montreal QC H3A 2T5 Canada
| | - Junliang Xu
- University of Maryland School of Medicine Baltimore MD 21201
| | - Sina Mossahebi
- University of Maryland School of Medicine Baltimore MD 21201
| | | | - Amit Sawant
- University of Maryland School of Medicine Baltimore MD 21201
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Tu K, Lee S, Roy S, Sawant A, Shukla H. Dysregulated Epigenetics of Chordoma: Prognostic Markers and Therapeutic Targets. Curr Cancer Drug Targets 2022; 22:678-690. [PMID: 35440334 DOI: 10.2174/1568009622666220419122716] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 11/22/2022]
Abstract
Chordoma is a rare, slow-growing sarcoma that is locally aggressive, and typically resistant to conventional chemo- and radiotherapies. Despite its low incidence, chordoma remains a clinical challenge because therapeutic options for chordoma are limited, and little is known about the molecular mechanisms involved in resistance to therapies. Furthermore, there are currently no established predictive or prognostic biomarkers to follow disease progression or treatment. Whole-genome sequencing of chordoma tissues has demonstrated a low-frequency mutation rate compared to other cancers. This has generated interest in the role of epigenetic events in chordoma pathogenesis. In this review, we discuss the current understanding of the epigenetic drivers of chordoma and their potential applications in prognosis and the development of new therapies.
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Affiliation(s)
- Kevin Tu
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland school of Medicine, Baltimore, MD, USA.,Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, College Park, MD, USA
| | - Sang Lee
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States
| | - Sanjit Roy
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland school of Medicine, Baltimore, MD, USA
| | - Amit Sawant
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland school of Medicine, Baltimore, MD, USA
| | - Hem Shukla
- Division of Translational Radiation Sciences, Department of Radiation Oncology, University of Maryland school of Medicine, Baltimore, MD, USA
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10
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Perstin A, Poirier Y, Sawant A, Tambasco M. Quantifying the DNA-damaging effects of FLASH irradiation with plasmid DNA. Int J Radiat Oncol Biol Phys 2022; 113:437-447. [PMID: 35124135 DOI: 10.1016/j.ijrobp.2022.01.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 01/19/2022] [Accepted: 01/26/2022] [Indexed: 11/15/2022]
Abstract
PURPOSE To investigate a plasmid DNA nicking assay approach for isolating and quantifying the DNA damaging effects of ultra-high dose rate (i.e., FLASH) irradiation relative to conventional dose rate irradiation. METHODS We constructed and irradiated phantoms containing plasmid DNA to nominal doses of 20 Gy and 30 Gy using 16 MeV electrons at conventional (0.167 Gy/s) and FLASH (46.6 Gy/s and 93.2 Gy/s) dose rates. We delivered conventional dose rates using a standard clinical Varian iX linac and FLASH dose rates (FDR) using a modified Varian 21EX C-series linac. We ran the irradiated DNA and controls (0 Gy) through an agarose gel electrophoresis procedure that sorted and localized the DNA into bands associated with single strand breaks (SSBs), double strand breaks (DSBs), and undamaged DNA. We quantitatively analyzed the gel images to compute the relative yields of SSBs and DSBs, and applied a mathematical model of plasmid DNA damage as a function of dose to compute relative biological effectiveness (RBE) of SSB and DSB (RBESSBandRBEDSB) damage for a given endpoint and FDR. RESULTS Both RBESSBandRBEDSB were less than unity with the FDR irradiations, indicating FLASH sparing. With regard to the more deleterious DNA DSB damage, RBEDSBs of FLASH beams at dose rates of 46.6 Gy/s and 93.2 Gy/s relative to the conventional 16 MeV beam dose rate were 0.54 ± 0.15 and 0.55 ± 0.17, respectively. CONCLUSION We have demonstrated the feasibility of using a DNA-based phantom to isolate and assess the FLASH sparing effect on DNA. We also found that FLASH irradiation causes less damage to DNA compared to a conventional dose rate. This result supports the notion that the protective effect of FLASH irradiation occurs at least partially via fundamental biochemical processes.
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Affiliation(s)
- Alan Perstin
- Physics Graduate Student, San Diego State University
| | - Yannick Poirier
- Assistant Professor, Oncology, Department of Radiation Oncology, University of Maryland
| | - Amit Sawant
- Professor and Vice Chair, Department of Radiation Oncology, University of Maryland
| | - Mauro Tambasco
- Associate Professor/Medical Physicist, Associate Program Director, Medical Physics Residency, Associate Director, Medical Physics , Department of Physics, San Diego State University.
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11
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Mossahebi S, Poirier Y, Gerry A, Repetto C, Vujaskovic Z, Jackson I, Sawant A. FLASH in the Clinic Track (Oral Presentations) DOSIMETRIC EVALUATION OF A NOVEL COLLIMATOR DESIGN FOR CONCURRENT MURINE HEMITHORAX IRRADIATIONS USING PROTON FLASH-RT. Phys Med 2022. [DOI: 10.1016/s1120-1797(22)01554-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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12
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Guerrieri P, Jacob NK, Maxim PG, Sawant A, Van Nest SJ, Mohindra P, Dominello MM, Burmeister JW, Joiner MC. Three discipline collaborative radiation therapy (3DCRT) special debate: FLASH radiotherapy needs ongoing basic and animal research before implementing it to a large clinical scale. J Appl Clin Med Phys 2022; 23:e13547. [PMID: 35104025 PMCID: PMC8992943 DOI: 10.1002/acm2.13547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 01/20/2022] [Indexed: 11/15/2022] Open
Affiliation(s)
- Patrizia Guerrieri
- Department of Radiation Oncology, Bon Secours Mercy Health, Youngstown, Ohio, USA
| | | | - Peter G Maxim
- Department of Radiation Oncology, University of California, Irvine, California, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA.,Maryland Proton Treatment Center, Baltimore, Maryland, USA
| | - Samantha J Van Nest
- Department of Radiation Oncology, Weill Cornell Medicine, New York, New York, USA
| | - Pranshu Mohindra
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA.,Maryland Proton Treatment Center, Baltimore, Maryland, USA
| | | | - Jay W Burmeister
- Department of Oncology, Wayne State University, Detroit, Michigan, USA.,Gershenson Radiation Oncology Center, Barbara Ann Karmanos Cancer Institute, Detroit, Michigan, USA
| | - Michael C Joiner
- Department of Oncology, Wayne State University, Detroit, Michigan, USA
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Tu KJ, Roy SK, Bhandary B, Sawant A, Shukla HD. Abstract PO-126: Loss of HIF1A decreases resistance to radiation and invasiveness in pancreatic ductal adenocarcinoma. Cancer Res 2021. [DOI: 10.1158/1538-7445.panca21-po-126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is the fourth most lethal cancer in the United States with an estimated 60,430 new cases and 48,220 deaths in 2021. PDACs are characterized by extensive desmoplastic stroma and severe hypovascularity, resulting in an intra-tumoral hypoxic microenvironment. In response to hypoxic stress, cancer cells set off many adaptive responses including metabolism regulation, cell survival, and inflammation through the stabilization and activation of the hypoxia-inducible factor (HIF) family of transcription factors. In this study, we used the gene-editing tool CRISPR-cas9 to knock out HIF1A and investigate whether HIF1A affects the radioresistant and invasive characteristics of PDACs in a KPC cell line model. To first observe how HIF1A affects PDAC radioresistance, we performed a clonogenic survival assay with increasing doses of radiation on both wild-type and HIF1A knockout (KO) cells treated and untreated with CoCl2-induced hypoxia conditions (100 uM and 200 uM CoCl2). Our data showed that under hypoxia, KO cells exhibited significant cell death when treated with 6, 8, and 10 Gy of radiation as compared to wild-type KPC cells, emphasizing the role of HIF1A in radiation resistance. In addition, to understand the role of HIF1A in regulating the invasive behavior of PDACs, we performed a cell proliferation assay on wild-type and KO KPC cells. HIF1A KO cells treated with CoCl2 exhibited significantly reduced proliferation compared to wild-type cells also treated with CoCl2 (p<0.01), though no significant difference was observed between untreated HIF1A KO and untreated wild-type cells (p>0.05). Because western blot demonstrated increased HIF1A expression in wild-type cells following CoCl2 treatment, our results provided evidence for the role of HIF1A activation in promoting PDAC invasiveness. Through western blot, we also confirmed the association between HIF1A expression with p53 degradation in PDAC. We used COREMINE, a literature mining tool, to map a direct interaction between HIF1A with KRAS in PDACs (p=0.000016). We propose HIF1A as a switch to activate KRAS and degrade p53 under hypoxic conditions in PDAC proliferation. Thus, modulating the HIF1A switch may be an important mechanism to reduce the tumor-promoting microenvironment and inhibit cancer growth.
Citation Format: Kevin J. Tu, Sanjit K. Roy, Binny Bhandary, Amit Sawant, Hem D. Shukla. Loss of HIF1A decreases resistance to radiation and invasiveness in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-126.
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Affiliation(s)
- Kevin J. Tu
- 1University of Maryland School of Medicine, Baltimore, MD,
| | - Sanjit K. Roy
- 1University of Maryland School of Medicine, Baltimore, MD,
| | | | - Amit Sawant
- 1University of Maryland School of Medicine, Baltimore, MD,
| | - Hem D. Shukla
- 1University of Maryland School of Medicine, Baltimore, MD,
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Kinkopf P, Modiri A, Yu KC, Yan Y, Mohindra P, Timmerman R, Sawant A, Vicente E. Virtual bronchoscopy-guided lung SAbR: dosimetric implications of using AAA versus Acuros XB to calculate dose in airways. Biomed Phys Eng Express 2021; 7. [PMID: 34488197 DOI: 10.1088/2057-1976/ac240c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/06/2021] [Indexed: 11/12/2022]
Abstract
In previous works, we showed that incorporating individual airways as organs-at-risk (OARs) in the treatment of lung stereotactic ablative radiotherapy (SAbR) patients potentially mitigates post-SAbR radiation injury. However, the performance of common clinical dose calculation algorithms in airways has not been thoroughly studied. Airways are of particular concern because their small size and the density differences they create have the potential to hinder dose calculation accuracy. To address this gap in knowledge, here we investigate dosimetric accuracy in airways of two commonly used dose calculation algorithms, the anisotropic analytical algorithm (AAA) and Acuros-XB (AXB), recreating clinical treatment plans on a cohort of four SAbR patients. A virtual bronchoscopy software was used to delineate 856 airways on a high-resolution breath-hold CT (BHCT) image acquired for each patient. The planning target volumes (PTVs) and standard thoracic OARs were contoured on an average CT (AVG) image over the breathing cycle. Conformal and intensity-modulated radiation therapy plans were recreated on the BHCT image and on the AVG image, for a total of four plan types per patient. Dose calculations were performed using AAA and AXB, and the differences in maximum and mean dose in each structure were calculated. The median differences in maximum dose among all airways were ≤0.3Gy in magnitude for all four plan types. With airways grouped by dose-to-structure or diameter, median dose differences were still ≤0.5Gy in magnitude, with no clear dependence on airway size. These results, along with our previous airway radiosensitivity works, suggest that dose differences between AAA and AXB correspond to an airway collapse variation ≤0.7% in magnitude. This variation in airway injury risk can be considered as not clinically relevant, and the use of either AAA or AXB is therefore appropriate when including patient airways as individual OARs so as to reduce risk of radiation-induced lung toxicity.
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Affiliation(s)
- P Kinkopf
- University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - A Modiri
- University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Kun-Chang Yu
- Broncus Medical, Inc., San Jose, CA, United States of America
| | - Y Yan
- UT Southwestern Medical Center, Dallas, TX, United States of America
| | - P Mohindra
- University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - R Timmerman
- UT Southwestern Medical Center, Dallas, TX, United States of America
| | - A Sawant
- University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - E Vicente
- University of Maryland School of Medicine, Baltimore, MD, United States of America
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15
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Poirier Y, Mossahebi S, Becker SJ, Koger B, Xu J, Lamichhane N, Maxim PG, Sawant A. Radiation shielding and safety implications following linac conversion to an electron FLASH-RT unit. Med Phys 2021; 48:5396-5405. [PMID: 34287938 DOI: 10.1002/mp.15105] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/03/2021] [Accepted: 07/12/2021] [Indexed: 11/05/2022] Open
Abstract
PURPOSE Due to their finite range, electrons are typically ignored when calculating shielding requirements in megavoltage energy linear accelerator vaults. However, the assumption that 16 MeV electrons need not be considered does not hold when operated at FLASH-RT dose rates (~200× clinical dose rate), where dose rate from bremsstrahlung photons is an order of magnitude higher than that from an 18 MV beam for which shielding was designed. We investigate the shielding and radiation protection impact of converting a Varian 21EX linac to FLASH-RT dose rates. METHODS We performed a radiation survey in all occupied areas using a Fluke Biomedical Inovision 451P survey meter and a Wide Energy Neutron Detection Instrument (Wendi)-2 FHT 762 neutron detector. The dose rate from activated linac components following a 1.8-min FLASH-RT delivery was also measured. RESULTS When operated at a gantry angle of 180° such as during biology experiments, the 16 MeV FLASH-RT electrons deliver ~10 µSv/h in the controlled areas and 780 µSv/h in the uncontrolled areas, which is above the 20 µSv in any 1-h USNRC limit. However, to exceed 20 µSv, the unit must be operated continuously for 92 s, which corresponds in this bunker and FLASH-RT beam to a 3180 Gy workload at isocenter, which would be unfeasible to deliver within that timeframe due to experimental logistics. While beam steering and dosimetry activities can require workloads of that magnitude, during these activities, the gantry is positioned at 0° and the dose rate in the uncontrolled area becomes undetectable. Likewise, neutron activation of linac components can reach 25 µSv/h near the isocenter following FLASH-RT delivery, but dissipates within minutes, and total doses within an hour are below 20 µSv. CONCLUSION Bremsstrahlung photons created by a 16 MeV FLASH-RT electron beam resulted in consequential dose rates in controlled and uncontrolled areas, and from activated linac components in the vault. While our linac vault shielding proved sufficient, other investigators would be prudent to confirm the adequacy of their radiation safety program, particularly if operating in vaults designed for 6 MV.
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Affiliation(s)
- Yannick Poirier
- University of Maryland School of Medicine, Baltimore, MD, USA.,McGill University, Montreal, QC, Canada
| | - Sina Mossahebi
- University of Maryland School of Medicine, Baltimore, MD, USA
| | | | | | - Junliang Xu
- University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Peter G Maxim
- University of California Irvine, School of Medicine, Irvine, CA, USA
| | - Amit Sawant
- University of Maryland School of Medicine, Baltimore, MD, USA
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16
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Keall PJ, Sawant A, Berbeco RI, Booth JT, Cho B, Cerviño LI, Cirino E, Dieterich S, Fast MF, Greer PB, Munck Af Rosenschöld P, Parikh PJ, Poulsen PR, Santanam L, Sherouse GW, Shi J, Stathakis S. AAPM Task Group 264: The safe clinical implementation of MLC tracking in radiotherapy. Med Phys 2021; 48:e44-e64. [PMID: 33260251 DOI: 10.1002/mp.14625] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/11/2020] [Accepted: 11/18/2020] [Indexed: 12/25/2022] Open
Abstract
The era of real-time radiotherapy is upon us. Robotic and gimbaled linac tracking are clinically established technologies with the clinical realization of couch tracking in development. Multileaf collimators (MLCs) are a standard equipment for most cancer radiotherapy systems, and therefore MLC tracking is a potentially widely available technology. MLC tracking has been the subject of theoretical and experimental research for decades and was first implemented for patient treatments in 2013. The AAPM Task Group 264 Safe Clinical Implementation of MLC Tracking in Radiotherapy Report was charged to proactively provide the broader radiation oncology community with (a) clinical implementation guidelines including hardware, software, and clinical indications for use, (b) commissioning and quality assurance recommendations based on early user experience, as well as guidelines on Failure Mode and Effects Analysis, and (c) a discussion of potential future developments. The deliverables from this report include: an explanation of MLC tracking and its historical development; terms and definitions relevant to MLC tracking; the clinical benefit of, clinical experience with and clinical implementation guidelines for MLC tracking; quality assurance guidelines, including example quality assurance worksheets; a clinical decision pathway, future outlook and overall recommendations.
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Affiliation(s)
- Paul J Keall
- ACRF Image X Institute, The University of Sydney Faculty of Medicine and Health, Sydney, NSW, 2006, Australia
| | - Amit Sawant
- Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Ross I Berbeco
- Radiation Oncology, Brigham and Women's Hospital, Boston, MA, 02115, USA
| | - Jeremy T Booth
- Radiation Oncology, Royal North Shore Hospital, St Leonards, 2065, NSW, Australia.,Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, 2006, Australia
| | - Byungchul Cho
- Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 138-736, Republic of Korea
| | - Laura I Cerviño
- Radiation Medicine & Applied Sciences, Radiation Oncology PET/CT Center, UC San Diego, LA Jolla, CA, 92093-0865, USA.,Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, 10065-6007, USA
| | - Eileen Cirino
- Lahey Health and Medical Center, Burlington, MA, 01805, USA
| | - Sonja Dieterich
- Department of Radiation Oncology, UC Davis Medical Center, Sacramento, CA, 95618, USA
| | - Martin F Fast
- Department of Radiotherapy, University Medical Center Utrecht, 3584 CX, Utrecht, The Netherlands
| | - Peter B Greer
- Calvary Mater Newcastle, Newcastle, NSW, 2310, Australia
| | - Per Munck Af Rosenschöld
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Parag J Parikh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Radiation Oncology, Henry Ford Hospital, Detroit, MI, 48202, USA
| | - Per Rugaard Poulsen
- Department of Oncology and Danish Center for Particle Therapy, Aarhus University Hospital, 8200, Aarhus, Denmark
| | - Lakshmi Santanam
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, 10065-6007, USA
| | | | - Jie Shi
- Sun Nuclear Corp, Melbourne, FL, 32940, USA
| | - Sotirios Stathakis
- University of Texas Health San Antonio Cancer Center, San Antonio, TX, 78229, USA
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17
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Ranjbar M, Sabouri P, Mossahebi S, Sawant A, Mohindra P, Lasio G, Topoleski LDT. Validation of a CT-based motion model with in-situ fluoroscopy for lung surface deformation estimation. Phys Med Biol 2021; 66:045035. [PMID: 33207334 PMCID: PMC7906954 DOI: 10.1088/1361-6560/abcbcf] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Many surrogate-based motion models (SMMs), proposed to guide motion management in radiotherapy, are constructed by correlating motion of an external surrogate and internal anatomy during CT-simulation. Changes in this correlation define model break down. We validate a methodology that incorporates fluoroscopic images (FL) acquired during treatment for SMM construction and update. Under a prospective IRB, 4DCT scans, VisionRT surfaces, and orthogonal FLs were collected from five lung cancer patients. VisionRT surfaces and two FL time-series were acquired pre- and post-treatment. A simulated annealing optimization scheme was used to estimate optimal lung deformations by maximizing the mutual information between digitally reconstructed radiographs (DRRs) of the SMM-estimated 3D images and FLs. Our SMM used partial-least-regression and was trained using the optimal deformations and VisionRT surfaces from the first breathing-cycle. SMM performance was evaluated using the mutual information score between reference FLs and the corresponding SMM or phase-assigned 4DCT DRRs. The Hausdorff distance for contoured landmarks was used to evaluate target position estimation error. For four out of five patients, two principal components approximated lung surface deformations with submillimeter accuracy. Analysis of the mutual information score between more than 4,000 pairs of FL and DRR demonstrated that our model led to more similarity between the FL and DRR images compared to 4DCT and DRR images from a model based on an a priori correlation model. Our SMM consistently displayed lower mean and 95th percentile Hausdorff distances. For one patient, 95th percentile Hausdorff distance was reduced by 11mm. Patient-averaged reductions in mean and 95th percentile Hausdorff distances were 3.6mm and 7mm for right-lung, and 3.1mm and 4mm for left-lung targets. FL data were used to evaluate model performance and investigate the feasibility of model update. Despite variability in breathing, use of post-treatment FL preserved model fidelity and consistently outperformed 4DCT for position estimation.
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Affiliation(s)
- M Ranjbar
- Department of Mechanical Engineering, University of Maryland, Baltimore County, Baltimore, MD, United States of America. These authors have contributed equally. Author to whom any correspondence should be addressed
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Lele N, Kripa MK, Panda M, Das SK, Nivas AH, Divakaran N, Naik-Gaonkar S, Sawant A, Pattnaik AK, Samal RN, Thangaradjou T, Saravanakumar A, Rodrigues BF, Murthy TVR. Seasonal variation in photosynthetic rates and satellite-based GPP estimation over mangrove forest. Environ Monit Assess 2021; 193:61. [PMID: 33443643 DOI: 10.1007/s10661-021-08846-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
In view of increasing anthropogenic influences and global changes, quantification of carbon assimilation through photosynthesis has gained tremendous significance. Precise estimation of Gross Primary Productivity (GPP) is essential for several ecosystem models and is typically done using coarser scale satellite data. The mangrove ecosystem, which offers significant protection to the coastal environment, is one of the critical habitats from a global change point of view. Light use efficiency (LUE) was measured using diurnal in situ photosynthetic rate observations for 13 dominant mangrove species for 3 seasons at each of the three mangrove dominant test-sites situated along the east and west coast of India. Variations in photosynthetic rates among these species were studied for 3 seasons that indicated varying responses of mangrove ecosystem at each site. Among all species, Rhizophora mucronata and Sonneratia apetala indicated higher values at two of the test-sites. IRS Resourcesat-2 LISS-IV datasets were used for the estimation of GPP. Mean GPP for all the sites varied from 1.2 to 7.7 g C m-2 day-1 with maximum value of 14.4 g C m-2 day-1. Mean values of GPP varied across the sites, based on its maximum LUE values and available photosynthetically active radiation (PAR). The results provide GPP values at much better spatial resolution for a threatened habitat like mangroves that typically survive in a narrow habitat along the coasts.
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Affiliation(s)
- N Lele
- Agriculture and Land Ecosystem Division (AED-BPSG-EPSA), Space Applications Centre (ISRO), Ahmedabad, Gujarat, India.
| | - M K Kripa
- Agriculture and Land Ecosystem Division (AED-BPSG-EPSA), Space Applications Centre (ISRO), Ahmedabad, Gujarat, India
| | - M Panda
- Chilika Development Authority, Bhubaneshwar, Odisha, India
| | - S K Das
- Chilika Development Authority, Bhubaneshwar, Odisha, India
| | - A Hari Nivas
- Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, Tamil Nadu, India
| | - N Divakaran
- Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, Tamil Nadu, India
| | | | - A Sawant
- Botany Department, Goa University, Taleigao, Goa, India
| | - A K Pattnaik
- Chilika Development Authority, Bhubaneshwar, Odisha, India
| | - R N Samal
- Chilika Development Authority, Bhubaneshwar, Odisha, India
| | - T Thangaradjou
- Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, Tamil Nadu, India
| | - A Saravanakumar
- Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, Tamil Nadu, India
| | - B F Rodrigues
- Botany Department, Goa University, Taleigao, Goa, India
| | - T V R Murthy
- Agriculture and Land Ecosystem Division (AED-BPSG-EPSA), Space Applications Centre (ISRO), Ahmedabad, Gujarat, India
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19
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Patel NV, Yu NY, Koroulakis A, Diwanji T, Sawant A, Sio TT, Mohindra P. Proton therapy for thoracic malignancies: a review of oncologic outcomes. Expert Rev Anticancer Ther 2021; 21:177-191. [PMID: 33118427 DOI: 10.1080/14737140.2021.1844567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Introduction: Radiotherapy is an integral component in the treatment of the majority of thoracic malignancies. By taking advantage of the steep dose fall-off characteristic of protons combined with modern optimization and delivery techniques, proton beam therapy (PBT) has emerged as a potential tool to improve oncologic outcomes while reducing toxicities from treatment.Areas covered: We review the physical properties and treatment techniques that form the basis of PBT as applicable for thoracic malignancies, including a brief discussion on the recent advances that show promise to enhance treatment planning and delivery. The dosimetric advantages and clinical outcomes of PBT are critically reviewed for each of the major thoracic malignancies, including lung cancer, esophageal cancer, mesothelioma, thymic cancer, and primary mediastinal lymphoma.Expert opinion: Despite clear dosimetric benefits with PBT in thoracic radiotherapy, the improvement in clinical outcomes remains to be seen. Nevertheless, with the incorporation of newer techniques, PBT remains a promising modality and ongoing randomized studies will clarify its role to determine which patients with thoracic malignancies receive the most benefit. Re-irradiation, advanced disease requiring high cardio-pulmonary irradiation volume and younger patients will likely derive maximum benefit with modern PBT.
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Affiliation(s)
- Nirav V Patel
- Department of Radiation Oncology, University of Miami Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Nathan Y Yu
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Antony Koroulakis
- Department of Radiation Oncology, University of Maryland School of Medicine and Maryland Proton Treatment Center, Baltimore, MD, USA
| | - Tejan Diwanji
- Department of Radiation Oncology, University of Miami Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine and Maryland Proton Treatment Center, Baltimore, MD, USA
| | - Terence T Sio
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, AZ, USA
| | - Pranshu Mohindra
- Department of Radiation Oncology, University of Maryland School of Medicine and Maryland Proton Treatment Center, Baltimore, MD, USA
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Diwanji T, Sawant A, Sio TT, Patel NV, Mohindra P. Proton stereotactic body radiation therapy for non-small cell lung cancer. Ann Transl Med 2020; 8:1198. [PMID: 33241047 PMCID: PMC7576051 DOI: 10.21037/atm-20-2975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Tejan Diwanji
- Department of Radiation Oncology, University of Miami Miller School of Medicine, Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA.,Maryland Proton Treatment Center Baltimore, MD, USA
| | - Terence T Sio
- Department of Radiation Oncology, Mayo Clinic, Phoenix, Arizona, USA
| | - Nirav V Patel
- Department of Radiation Oncology, University of Miami Miller School of Medicine, Sylvester Comprehensive Cancer Center, Miami, FL, USA
| | - Pranshu Mohindra
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA.,Maryland Proton Treatment Center Baltimore, MD, USA
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Vicente E, Modiri A, Kipritidis J, Hagan A, Yu K, Wibowo H, Yan Y, Owen DR, Matuszak MM, Mohindra P, Timmerman R, Sawant A. Functionally weighted airway sparing (FWAS): a functional avoidance method for preserving post-treatment ventilation in lung radiotherapy. Phys Med Biol 2020; 65:165010. [PMID: 32575096 DOI: 10.1088/1361-6560/ab9f5d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Recent changes to the guidelines for screening and early diagnosis of lung cancer have increased the interest in preserving post-radiotherapy lung function. Current investigational approaches are based on spatially mapping functional regions and generating regional avoidance plans that preferentially spare highly ventilated/perfused lung. A potentially critical, yet overlooked, aspect of functional avoidance is radiation injury to peripheral airways, which serve as gas conduits to and from functional lung regions. Dose redistribution based solely on regional function may cause irreparable damage to the 'supply chain'. To address this deficiency, we propose the functionally weighted airway sparing (FWAS) method. FWAS (i) maps the bronchial pathways to each functional sub-lobar lung volume; (ii) assigns a weighting factor to each airway based on the relative contribution of the sub-volume to overall lung function; and (iii) creates a treatment plan that aims to preserve these functional pathways. To evaluate it, we used four cases from a retrospective cohort of SAbR patients treated for lung cancer. Each patient's airways were auto-segmented from a diagnostic-quality breath-hold CT using a research virtual bronchoscopy software. A ventilation map was generated from the planning 4DCT to map regional lung function. For each terminal airway, as resolved by the segmentation software, the total ventilation within the sub-lobar volume supported by that airway was estimated and used as a function-based weighting factor. Upstream airways were weighted based on the cumulative volumetric ventilation supported by corresponding downstream airways. Using a previously developed model for airway radiosensitivity, dose constraints were determined for each airway corresponding to a <5% probability of airway collapse. Airway dose constraints, ventilation scores, and clinical dose constraints were input to a swarm optimization-based inverse planning engine to create a 3D conformal SAbR plan (CRT). The FWAS plans were compared to the patients' prescribed CRT clinical plans and the inverse-optimized clinical plans. Depending on the size and location of the tumour, the FWAS plan showed superior preservation of ventilation due to airflow preservation through open pathways (i.e. cumulative ventilation score from the sub-lobar volumes of open pathways). Improvements ranged between 3% and 23%, when comparing to the prescribed clinical plans, and between 3% and 35%, when comparing to the inverse-optimized clinical plans. The three plans satisfied clinical requirements for PTV coverage and OAR dose constraints. These initial results suggest that by sparing pathways to high-functioning lung subregions it is possible to reduce post-SAbR loss of respiratory function.
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Affiliation(s)
- E Vicente
- University of Maryland School of Medicine, Baltimore, MD, United States of America
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Rechner LA, Modiri A, Stick LB, Maraldo MV, Aznar MC, Rice SR, Sawant A, Bentzen SM, Vogelius IR, Specht L. Biological optimization for mediastinal lymphoma radiotherapy - a preliminary study. Acta Oncol 2020; 59:879-887. [PMID: 32216586 PMCID: PMC7446040 DOI: 10.1080/0284186x.2020.1733654] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 02/18/2020] [Indexed: 11/30/2022]
Abstract
Purpose: In current radiotherapy (RT) planning and delivery, population-based dose-volume constraints are used to limit the risk of toxicity from incidental irradiation of organs at risks (OARs). However, weighing tradeoffs between target coverage and doses to OARs (or prioritizing different OARs) in a quantitative way for each patient is challenging. We introduce a novel RT planning approach for patients with mediastinal Hodgkin lymphoma (HL) that aims to maximize overall outcome for each patient by optimizing on tumor control and mortality from late effects simultaneously.Material and Methods: We retrospectively analyzed 34 HL patients treated with conformal RT (3DCRT). We used published data to model recurrence and radiation-induced mortality from coronary heart disease and secondary lung and breast cancers. Patient-specific doses to the heart, lung, breast, and target were incorporated in the models as well as age, sex, and cardiac risk factors (CRFs). A preliminary plan of candidate beams was created for each patient in a commercial treatment planning system. From these candidate beams, outcome-optimized (O-OPT) plans for each patient were created with an in-house optimization code that minimized the individual risk of recurrence and mortality from late effects. O-OPT plans were compared to VMAT plans and clinical 3DCRT plans.Results: O-OPT plans generally had the lowest risk, followed by the clinical 3DCRT plans, then the VMAT plans with the highest risk with median (maximum) total risk values of 4.9 (11.1), 5.1 (17.7), and 7.6 (20.3)%, respectively (no CRFs). Compared to clinical 3DCRT plans, O-OPT planning reduced the total risk by at least 1% for 9/34 cases assuming no CRFs and 11/34 cases assuming presence of CRFs.Conclusions: We developed an individualized, outcome-optimized planning technique for HL. Some of the resulting plans were substantially different from clinical plans. The results varied depending on how risk models were defined or prioritized.
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Affiliation(s)
- Laura Ann Rechner
- Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Niels Bohr Institute, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Arezoo Modiri
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Line Bjerregaard Stick
- Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Niels Bohr Institute, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Maja V. Maraldo
- Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Marianne C. Aznar
- Manchester Cancer Research Centre, Division of Cancer Sciences, The University of Manchester, Manchester, UK
- Clinical Trial Service Unit, Nuffield Department of Population Health, University of Oxford, UK
| | | | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Søren M. Bentzen
- Greenebaum Comprehensive Cancer Center, Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ivan Richter Vogelius
- Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Lena Specht
- Department of Oncology, Section of Radiotherapy, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Mahmood J, Pandita R, Zhang A, Kamlapurkar S, Saeed A, Chen M, Staats PN, Shukla HD, Anvari A, Sawant A, Vujaskovic Z. RhoA/ROCK pathway inhibitor ameliorates erectile dysfunction induced by radiation therapy in rats. Radiother Oncol 2020; 150:174-180. [PMID: 32565390 DOI: 10.1016/j.radonc.2020.06.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 10/24/2022]
Abstract
OBJECTIVES Prostate cancer (PCa) treatment with radiation therapy (RT) has an excellent cure rate. However, Radiation-induced Erectile Dysfunction (RiED) is a common and irreversible toxicity impacting quality of life, and there is no FDA approved specific drug for RiED. We previously showed that prostate RT increased RhoA/ROCK signaling in the cavernous nerve (CN) and penile tissues, which may lead to RiED in rats. In this study, we investigated whether RhoA/ROCK pathway inhibition by a specific inhibitor called Hydroxyfasudil (HF) can improve RiED in our well-established rat model. MATERIALS/METHODS Male Sprague-Dawley rats were randomized to the following groups: sham-RT, HF-only, RT-only, and RT + HF. Rats were either exposed to a single dose of 25 Gy prostate-confined RT or a sham procedure. 10 mg/kg HF or normal saline was injected intraperitoneally. Erectile function was evaluated by intracavernosal pressure (ICP) and mean arterial pressure (MAP) measurements at week 14 post-RT. Cavernous nerve (CN) injury was evaluated by transmission electron microscopy (TEM), and penile tissue fibrosis by Masson trichrome staining (MT). RESULTS We have found that the HF treatment prior to RT showed significant (p < 0.001) improvement in ICP/MAP ratio, area under the curve, and maximum ICP value, compared to RT-alone rats. Furthermore, RT + HF treated rats exhibited increased CN myelination and decreased axonal atrophy, comparted to RT-only. HF treatment showed significantly decreased penile tissue fibrosis (p < 0.05) compared to RT-alone treated rats. CONCLUSION Our results provide the first preclinical evidence that targeting RhoA/ROCK pathway by HF may provide a novel therapeutic option for the treatment of RiED.
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Affiliation(s)
- Javed Mahmood
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA.
| | - Ravina Pandita
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
| | - Angel Zhang
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
| | - Shriya Kamlapurkar
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
| | - Ali Saeed
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
| | - Minjie Chen
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
| | - Paul N Staats
- Department of Pathology, University of Maryland School of Medicine, Baltimore, USA
| | - Hem D Shukla
- Department of Neurology and Neurosurgery, Johns Hopkins University, School of Medicine, Baltimore, USA
| | - Akbar Anvari
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
| | - Amit Sawant
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
| | - Zeljko Vujaskovic
- Division of Translational Radiation Sciences (DTRS), Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, USA
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Cundell T, Guilfoyle D, Kreil TR, Sawant A. Controls to Minimize Disruption of the Pharmaceutical Supply Chain During the COVID-19 Pandemic. PDA J Pharm Sci Technol 2020; 74:468-494. [PMID: 32467176 DOI: 10.5731/pdajpst.2020.012021] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This article reviews currently available scientific literature related to the epidemiology, infectivity, survival, and susceptibility to disinfectants of Coronaviruses, in the context of the controls established to meet good manufacturing practice (GMP) regulations and guidance, and the public health guidance issued specifically to combat the COVID-19 pandemic. The possible impact of the COVID-19 pandemic on the pharmaceutical supply chain is assessed and recommendations are listed for risk mitigation steps to minimize supply disruption to pharmaceutical drug products. Areas addressed include a brief history of the COVID-19 viral pandemic, a description of the virus, the regulatory response to the pandemic, the screening of employees, the persistence of the virus on inanimate surfaces, cleaning and disinfection of manufacturing facilities, the use of GMP-mandated personal protective equipment to counter the spread of the disease, the role of air changes in viral clearance, and approaches to risk assessment and mitigation. Biological medicinal products have a great record of safety, yet the cell cultures used for production can be susceptible to viruses, and contamination events have occurred. Studies on SARS-CoV-2 for it ability to replicate in various mammalian cell lines used for biopharmaceutical manufacturing suggests that the virus poses a low risk and any contamination would be detected by currently used adventitious virus testing. The consequences of the potential virus exposure of manufacturing processes as well as the effectiveness of mitigation efforts are discussed. The pharmaceutical supply chain is complex, traversing many geographies and companies that range from large multinationals to mid- and small-size operations. This paper recommends practices that can be adopted by all companies, irrespective of their size, geographic location, or position in the supply chain.
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Affiliation(s)
- T Cundell
- Microbiological Consulting, LLC, Scarsdale, NY;
| | | | | | - A Sawant
- Merck & Co. Inc., Kenilworth, NJ
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Anvari A, Modiri A, Pandita R, Mahmood J, Sawant A. Online dose delivery verification in small animal image‐guided radiotherapy. Med Phys 2020; 47:1871-1879. [DOI: 10.1002/mp.14070] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 01/27/2020] [Accepted: 01/28/2020] [Indexed: 11/11/2022] Open
Affiliation(s)
- Akbar Anvari
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201USA
- Department of Radiation Oncology Perelman Center for Advanced Medicine University of Pennsylvania Philadelphia PA 19104USA
| | - Arezoo Modiri
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201USA
| | - Ravina Pandita
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201USA
| | - Javed Mahmood
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201USA
| | - Amit Sawant
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201USA
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Poirier Y, Johnstone CD, Anvari A, Brodin NP, Santos MD, Bazalova-Carter M, Sawant A. A failure modes and effects analysis quality management framework for image-guided small animal irradiators: A change in paradigm for radiation biology. Med Phys 2020; 47:2013-2022. [PMID: 31986221 DOI: 10.1002/mp.14049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/17/2019] [Accepted: 01/10/2020] [Indexed: 12/28/2022] Open
Abstract
PURPOSE Image-guided small animal irradiators (IGSAI) are increasingly being adopted in radiation biology research. These animal irradiators, designed to deliver radiation with submillimeter accuracy, exhibit complexity similar to that of clinical radiation delivery systems, including image guidance, robotic stage motion, and treatment planning systems. However, physics expertise and resources are scarcer in radiation biology, which makes implementation of conventional prescriptive QA infeasible. In this study, we apply the failure modes and effect analysis (FMEA) popularized by the AAPM task group 100 (TG-100) report to IGSAI and radiation biological research. METHODS Radiation biological research requires a change in paradigm where small errors to large populations of animals are more severe than grievous errors that only affect individuals. To this end, we created a new adverse effects severity table adapted to radiation biology research based on the original AAPM TG-100 severity table. We also produced a process tree which outlines the main components of radiation biology studies performed on an IGSAI, adapted from the original clinical IMRT process tree from TG-100. Using this process tree, we created and distributed a preliminary survey to eight expert IGSAI operators in four institutions. Operators rated proposed failure modes for occurrence, severity, and lack of detectability, and were invited to share their own experienced failure modes. Risk probability numbers (RPN) were calculated and used to identify the failure modes which most urgently require intervention. RESULTS Surveyed operators indicated a number of high (RPN >125) failure modes specific to small animal irradiators. Errors due to equipment breakdown, such as loss of anesthesia or thermal control, received relatively low RPN (12-48) while errors related to the delivery of radiation dose received relatively high RPN (72-360). Errors identified could either be improved by manufacturer intervention (e.g., electronic interlocks for filter/collimator) or physics oversight (errors related to tube calibration or treatment planning system commissioning). Operators identified a number of failure modes including collision between the collimator and the stage, misalignment between imaging and treatment isocenter, inaccurate robotic stage homing/translation, and incorrect SSD applied to hand calculations. These were all relatively highly rated (90-192), indicating a possible bias in operators towards reporting high RPN failure modes. CONCLUSIONS The first FMEA specific to radiation biology research was applied to image-guided small animal irradiators following the TG-100 methodology. A new adverse effects severity table and a process tree recognizing the need for a new paradigm were produced, which will be of great use to future investigators wishing to pursue FMEA in radiation biology research. Future work will focus on expanding scope of user surveys to users of all commercial IGSAI and collaborating with manufacturers to increase the breadth of surveyed expert operators.
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Affiliation(s)
- Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Christopher Daniel Johnstone
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada
| | - Akbar Anvari
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - N Patrik Brodin
- Department of Radiation Oncology, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY, USA
| | - Morgane Dos Santos
- Service de Recherche en Radiobiologie et en Médecine régénérative, Laboratoire de Radiobiologie des expositions Accidentelles, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Roses, France
| | | | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
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Vicente E, Modiri A, Yu KC, Wibowo H, Yan Y, Timmerman R, Sawant A. Accounting for respiratory motion in small serial structures during radiotherapy planning: proof of concept in virtual bronchoscopy-guided lung functional avoidance radiotherapy. Phys Med Biol 2019; 64:225011. [PMID: 31665703 DOI: 10.1088/1361-6560/ab52a1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Respiratory motion management techniques in radiotherapy (RT) planning are primarily focused on maintaining tumor target coverage. An inadequately addressed need is accounting for motion in dosimetric estimations in smaller serial structures. Accurate dose estimations in such structures are more sensitive to motion because respiration can cause them to move completely in or out of a high dose-gradient field. In this work, we study three motion management strategies (m1-m3) to find an accurate method to estimate the dosimetry in airways. To validate these methods, we generated a 'ground truth' digital breathing model based on a 4DCT scan from a lung stereotactic ablative radiotherapy (SAbR) patient. We simulated 225 breathing cycles with ±10% perturbations in amplitude, respiratory period, and time per respiratory phase. A high-resolution breath-hold CT (BHCT) was also acquired and used with a research virtual bronchoscopy software to autosegment 239 airways. Contours for planning target volume (PTV) and organs at risk (OARs) were defined on the maximum intensity projection of the 4DCT (CTMIP) and transferred to the average of the 10 4DCT phases (CTAVG). To design the motion management methods, the RT plan was recreated using different images and structure definitions. Methods m1 and m2 recreated the plan using the CTAVG image. In method m1, airways were deformed to the CTAVG. In m2, airways were deformed to each of the 4DCT phases, and union structures were transferred onto the CTAVG. In m3, the RT plan was recreated on each of the 10 phases, and the dose distribution from each phase was deformed to the BHCT and summed. Dose errors (mean [min, max]) in airways were: m1: 21% (0.001%, 93%); m2: 45% (0.1%, 179%); and m3: 4% (0.006%, 14%). Our work suggests that accurate dose estimation in moving small serial structures requires customized motion management techniques (like m3 in this work) rather than current clinical and investigational approaches.
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Affiliation(s)
- Esther Vicente
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, United States of America. Author to whom correspondence should be addressed
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Ranjbar M, Sabouri P, Mossahebi S, Leiser D, Foote M, Zhang J, Lasio G, Joshi S, Sawant A. Development and prospective in-patient proof-of-concept validation of a surface photogrammetry + CT-based volumetric motion model for lung radiotherapy. Med Phys 2019; 46:5407-5420. [PMID: 31518437 DOI: 10.1002/mp.13824] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/22/2019] [Accepted: 08/28/2019] [Indexed: 12/25/2022] Open
Abstract
PURPOSE We develop and validate a motion model that uses real-time surface photogrammetry acquired concurrently with four-dimensional computed tomography (4DCT) to estimate respiration-induced changes within the entire irradiated volume, over arbitrarily many respiratory cycles. METHODS A research, couch-mounted, VisionRT (VRT) system was used to acquire optical surface data (15 Hz, ROI = 15 × 20 cm2 ) from the thoraco-abdominal surface of a consented lung SBRT patient, concurrently with their standard-of-care 4DCT. The end-exhalation phase from the 4DCT was regarded as reference and for each remaining phase, deformation vector fields (DVFs) with respect to the reference phase were computed. To reduce dimensionality, the first two principal components (PCs) of the matrix of nine DVFs were calculated. In parallel, ten phase-averaged VRT surfaces were created. Surface DVFs and corresponding PCs were computed. A principal least squares regression was used to relate the PCs of surface DVF to those of volume DVFs, establishing a relationship between time-varying surface and the underlying time-varying volume. Proof-of-concept validation was performed during each treatment fraction by concurrently acquiring 30 s time series of real-time surface data and "ground truth" kV fluoroscopic data (FL). A ray-tracing algorithm was used to create a digitally reconstructed fluorograph (DRF), and motion trajectories of high-contrast, soft-tissue, anatomical features in the DRF were compared with those from kV FL. RESULTS For five of the six fluoroscopic acquisition sessions, the model out-performed 4DCT in predicting contour Dice coefficient with respect to fluoroscopy-derived contours. Similarly, the model exhibited a marked improvement over 4DCT for patch positions on the diaphragm. Model patch position errors varied from 5 to -15 mm while 4DCT errors ranged between 5 and -22.4 mm. For one fluoroscopic acquisition, a marked change in the a priori internal-external correlation resulted in model errors comparable to those of 4DCT. CONCLUSIONS We described the development and a proof-of-concept validation for a volumetric motion model that uses surface photogrammetry to correlate the time-varying thoraco-abdominal surface to the time-varying internal thoraco-abdominal volume. These early results indicate that the proposed approach can result in a marked improvement over 4DCT. While limited by the duration of the fluoroscopic acquisitions as well as the resolution of the acquired images, the DRF-based proof-of-concept technique developed here is model-agnostic, and therefore, has the potential to be used as an in-patient validation tool for other volumetric motion models.
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Affiliation(s)
- M Ranjbar
- Department of Radiation Oncology, University of Maryland School of Medicine, 22 S Greene Street, Baltimore, MD, 21201, USA
| | - P Sabouri
- Department of Radiation Oncology, University of Maryland School of Medicine, 22 S Greene Street, Baltimore, MD, 21201, USA
| | - S Mossahebi
- Department of Radiation Oncology, University of Maryland School of Medicine, 22 S Greene Street, Baltimore, MD, 21201, USA
| | - D Leiser
- Department of Radiation Oncology, University of Maryland School of Medicine, 22 S Greene Street, Baltimore, MD, 21201, USA
| | - M Foote
- Department of Biomedical Engineering, Scientific Computing and Imaging Institute, University of Utah, 72 South Central Campus Drive, Room 3750, Salt Lake City, UT, 84112, USA
| | - J Zhang
- Department of Radiation Oncology, University of Maryland School of Medicine, 22 S Greene Street, Baltimore, MD, 21201, USA
| | - G Lasio
- Department of Radiation Oncology, University of Maryland School of Medicine, 22 S Greene Street, Baltimore, MD, 21201, USA
| | - S Joshi
- Department of Biomedical Engineering, Scientific Computing and Imaging Institute, University of Utah, 72 South Central Campus Drive, Room 3750, Salt Lake City, UT, 84112, USA
| | - A Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, 22 S Greene Street, Baltimore, MD, 21201, USA
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Modiri A, Rechner L, Stick L, Maraldo M, Rice S, Sawant A, Bentzen S, Vogelius I, Specht L. Is Underdosing the Target a Risk Worth Taking? Outcome Risk Modeling in Lymphoma Radiotherapy. Int J Radiat Oncol Biol Phys 2019. [DOI: 10.1016/j.ijrobp.2019.06.205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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30
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Taylor K, Sawant A, Mobeen K, Etherington C, Whitaker P, Clifton I, Peckham D. WS11-4 Current clinical practice in the management of cystic fibrosis-related bone disease in a regional UK adult cystic fibrosis centre. J Cyst Fibros 2019. [DOI: 10.1016/s1569-1993(19)30182-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Stick LB, Vogelius IR, Modiri A, Rice SR, Maraldo MV, Sawant A, Bentzen SM. Inverse radiotherapy planning based on bioeffect modelling for locally advanced left-sided breast cancer. Radiother Oncol 2019; 136:9-14. [PMID: 31015135 DOI: 10.1016/j.radonc.2019.03.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 02/10/2019] [Accepted: 03/19/2019] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND PURPOSE Treatment planning of radiotherapy (RT) for left-sided breast cancer is a challenging case. Several competing concerns are incorporated at present through protocol-defined dose-volume constraints, e.g. cardiac exposure and target coverage. Such constraints are limited by neglecting patient-specific risk factors (RFs). We propose an alternative RT planning method based solely on bioeffect models to minimize the estimated risks of breast cancer recurrence (BCR) and radiation-induced mortality endpoints considering patient-specific factors. METHODS AND MATERIALS Thirty-nine patients with left-sided breast cancer treated with comprehensive post-lumpectomy loco-regional conformal RT were included. An in-house particle swarm optimization (PSO) engine was used to choose fields from a large set of predefined fields and optimize monitor units to minimize the total risk of BCR and mortality caused by radiation-induced ischaemic heart disease (IHD), secondary lung cancer (SLC) and secondary breast cancer (SBC). Risk models included patient age, smoking status and cardiac risk and were developed using published multi-institutional data. RESULTS For the clinical plans the normal tissue complication probability, i.e. summed risk of IHD, SLC and SBC, was <3.7% and the risk of BCR was <6.1% for all patients. Median total decrease in mortality or recurrence achieved with individualized PSO plans was 0.4% (range, 0.06-2.0%)/0.5% (range, 0.11-2.2%) without/with risk factors. CONCLUSIONS Inverse RT plan optimization using bioeffect probability models allows individualization according to patient-specific risk factors. The modelled benefit when compared to clinical plans is, however, modest in most patients, demonstrating that current clinical plans are close to optimal. Larger gains may be achievable with morbidity endpoints rather than mortality.
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Affiliation(s)
- Line Bjerregaard Stick
- Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Denmark; Niels Bohr Institute, Faculty of Science, University of Copenhagen, Denmark.
| | | | - Arezoo Modiri
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, United States
| | | | - Maja Vestmø Maraldo
- Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Denmark
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, United States
| | - Søren M Bentzen
- Greenebaum Comprehensive Cancer Center and Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, United States
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Ranjbar M, Sabouri P, Repetto C, Sawant A. A novel deformable lung phantom with programably variable external and internal correlation. Med Phys 2019; 46:1995-2005. [PMID: 30919974 DOI: 10.1002/mp.13507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 03/06/2019] [Accepted: 03/06/2019] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Lung motion phantoms used to validate radiotherapy motion management strategies have fairly simplistic designs that do not adequately capture complex phenomena observed in human respiration such as external and internal deformation, variable hysteresis and variable correlation between different parts of the thoracic anatomy. These limitations make reliable evaluation of sophisticated motion management techniques quite challenging. In this work, we present the design and implementation of a programmable, externally and internally deformable lung motion phantom that allows for a reproducible change in external-internal and internal-internal correlation of embedded markers. METHODS An in-house-designed lung module, made from natural latex foam was inserted inside the outer shell of a commercially available lung phantom (RSD, Long Beach, CA, USA). Radiopaque markers were placed on the external surface and embedded into the lung module. Two independently programmable high-precision linear motion actuators were used to generate primarily anterior-posterior (AP) and primarily superior-inferior (SI) motion in a reproducible fashion in order to enable (a) variable correlation between the displacement of interior volume and the exterior surface, (b) independent changes in the amplitude of the AP and SI motions, and (c) variable hysteresis. The ability of the phantom to produce complex and variable motion accurately and reproducibly was evaluated by programming the two actuators with mathematical and patient-recorded lung tumor motion traces, and recording the trajectories of various markers using kV fluoroscopy. As an example application, the phantom was used to evaluate the performance of lung motion models constructed from kV fluoroscopy and 4DCT images. RESULTS The phantom exhibited a high degree of reproducibility and marker motion ranges were reproducible to within 0.5 mm. Variable correlation was observed between the displacements of internal-internal and internal-external markers. The SI and AP components of motion of a specific marker had a correlation parameter that varied from -11 to 17. Monitoring a region of interest on the phantom's surface to estimate internal marker motion led to considerably lower uncertainties than when a single point was monitored. CONCLUSIONS We successfully designed and implemented a programmable, externally and internally deformable lung motion phantom that allows for a reproducible change in external-internal and internal-internal correlation of embedded markers.
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Affiliation(s)
- Maida Ranjbar
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Pouya Sabouri
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Carlo Repetto
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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Rechner L, Modiri A, Stick L, Maraldo M, Rice S, Sawant A, Bentzen S, Vogelius I. EP-1812 Outcome-optimized radiotherapy planning using risk modeling for lymphoma – a preliminary study. Radiother Oncol 2019. [DOI: 10.1016/s0167-8140(19)32232-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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34
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Caillet V, O'Brien R, Moore D, Poulsen P, Pommer T, Colvill E, Sawant A, Booth J, Keall P. Technical Note: In silico and experimental evaluation of two leaf-fitting algorithms for MLC tracking based on exposure error and plan complexity. Med Phys 2019; 46:1814-1820. [PMID: 30719723 DOI: 10.1002/mp.13425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 01/13/2019] [Accepted: 01/14/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Multileaf collimator (MLC) tracking is being clinically pioneered to continuously compensate for thoracic and pelvic motion during radiotherapy. The purpose of this work was to characterize the performance of two MLC leaf-fitting algorithms, direct optimization and piecewise optimization, for real-time motion compensation with different plan complexity and tumor trajectories. METHODS To test the algorithms, both in silico and phantom experiments were performed. The phantom experiments were performed on a Trilogy Varian linac and a HexaMotion programmable motion platform. High and low modulation VMAT plans for lung and prostate cancer cases were used along with eight patient-measured organ-specific trajectories. For both MLC leaf-fitting algorithms, the plans were run with their corresponding patient trajectories. To compare algorithms, the average exposure errors, i.e., the difference in shape between ideal and fitted MLC leaves by the algorithm, plan complexity and system latency of each experiment were calculated. RESULTS Comparison of exposure errors for the in silico and phantom experiments showed minor differences between the two algorithms. The average exposure errors for in silico experiments with low/high plan complexity were 0.66/0.88 cm2 for direct optimization and 0.66/0.88 cm2 for piecewise optimization, respectively. The average exposure errors for the phantom experiments with low/high plan complexity were 0.73/1.02 cm2 for direct and 0.73/1.02 cm2 for piecewise optimization, respectively. The measured latency for the direct optimization was 226 ± 10 ms and for the piecewise algorithm was 228 ± 10 ms. In silico and phantom exposure errors quantified for each treatment plan demonstrated that the exposure errors from the high plan complexity (0.96 cm2 mean, 2.88 cm2 95% percentile) were all significantly different from the low plan complexity (0.70 cm2 mean, 2.18 cm2 95% percentile) (P < 0.001, two-tailed, Mann-Whitney statistical test). CONCLUSIONS The comparison between the two leaf-fitting algorithms demonstrated no significant differences in exposure errors, neither in silico nor with phantom experiments. This study revealed that plan complexity impacts the overall exposure errors significantly more than the difference between the algorithms.
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Affiliation(s)
- Vincent Caillet
- Northern Sydney Cancer Centre, Sydney, NSW, Australia.,ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Ricky O'Brien
- ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Douglas Moore
- Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, AZ, USA
| | | | - Tobias Pommer
- Unit of Radiotherapy Physics and Engineering, Karolinska University Hospital, Solna, Sweden
| | - Emma Colvill
- Northern Sydney Cancer Centre, Sydney, NSW, Australia.,ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Jeremy Booth
- Northern Sydney Cancer Centre, Sydney, NSW, Australia.,ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Paul Keall
- ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
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Mohindra P, Sawant A, Griffin RJ, Lamichhane N, Vlashi E, Xu‐Welliver M, Dominello M, Joiner MC, Burmeister J. Three discipline collaborative radiation therapy (3DCRT) special debate: I would treat all early-stage NSCLC patients with SBRT. J Appl Clin Med Phys 2019; 20:7-13. [PMID: 30793828 PMCID: PMC6414141 DOI: 10.1002/acm2.12545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 01/24/2019] [Accepted: 01/24/2019] [Indexed: 11/27/2022] Open
Affiliation(s)
- Pranshu Mohindra
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Amit Sawant
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Robert J. Griffin
- Department of Radiation OncologyUniversity of Arkansas for Medical SciencesLittle RockARUSA
| | - Narottam Lamichhane
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMDUSA
| | - Erina Vlashi
- Department of Radiation OncologyUniversity of California‐Los AngelesLos AngelesCAUSA
| | - Meng Xu‐Welliver
- Department of Radiation OncologyThe James Cancer CenterOhio State UniversityColumbusOHUSA
| | - Michael Dominello
- Department of OncologyWayne State University School of MedicineDetroitMIUSA
| | - Michael C. Joiner
- Department of OncologyWayne State University School of MedicineDetroitMIUSA
| | - Jay Burmeister
- Department of OncologyWayne State University School of MedicineDetroitMIUSA
- Gershenson Radiation Oncology CenterBarbara Ann Karmanos Cancer InstituteDetroitMIUSA
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Cohen J, Anvari A, Samanta S, Poirier Y, Soman S, Alexander A, Ranjbar M, Pavlovic R, Zodda A, Jackson IL, Mahmood J, Vujaskovic Z, Sawant A. Mild hyperthermia as a localized radiosensitizer for deep-seated tumors: investigation in an orthotopic prostate cancer model in mice. Br J Radiol 2019; 92:20180759. [PMID: 30673305 PMCID: PMC6541201 DOI: 10.1259/bjr.20180759] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 01/02/2019] [Accepted: 01/16/2019] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE: Non-ablative or mild hyperthermia (HT) has been shown in preclinical (and clinical) studies as a localized radiosensitizer that enhances the tumoricidal effects of radiation. Most preclinical in vivo HT studies use subcutaneous tumor models which do not adequately represent clinical conditions (e.g. proximity of normal/critical organs) or replicate the tumor microenvironment-both of which are important factors for eventual clinical translation. The purpose of this work is to demonstrate proof-of-concept of locoregional radiosensitization with superficially applied, radiofrequency (RF)-induced HT in an orthotopic mouse model of prostate cancer. METHODS: In a 4-arm study, 40 athymic male nude mice were inoculated in the prostate with luciferase-transfected human prostate cancer cells (PC3). Tumor volumes were allowed to reach 150-250 mm3 (as measured by ultrasound) following which, mice were randomized into (i) control (no intervention); (ii) HT alone; (iii) RT alone; and (iv) HT + RT. RF-induced HT was administered (Groups ii and iv) using the Oncotherm LAB EHY-100 device to achieve a target temperature of 41 °C in the prostate. RT was administered ~30 min following HT, using an image-guided small animal radiotherapy research platform. In each case, a dual arc plan was used to deliver 12 Gy to the target in a single fraction. One animal from each cohort was euthanized on Day 10 or 11 after treatment for caspase-9 and caspase-3 Western blot analysis. RESULTS: The inoculation success rate was 89%. Mean tumor size at randomization (~16 days post-inoculation) was ~189 mm3 . Following the administration of RT and HT, mean tumor doubling times in days were: control = 4.2; HT = 4.5; RT = 30.4; and HT + RT = 33.4. A significant difference (p = 0.036) was noted between normalized nadir volumes for the RT alone (0.76) and the HT + RT (0.40) groups. Increased caspase-3 expression was seen in the combination treatment group compared to the other treatment groups. CONCLUSION: These early results demonstrate the successful use of external mild HT as a localized radiosensitizer for deep-seated tumors. ADVANCES IN KNOWLEDGE: We successfully demonstrated the feasibility of administering external mild HT in an orthotopic tumor model and demonstrated preclinical proof-of-concept of HT-based localized radiosensitization in prostate cancer radiotherapy.
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Affiliation(s)
- Justin Cohen
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Akbar Anvari
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Santanu Samanta
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sandrine Soman
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Allen Alexander
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Maida Ranjbar
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ramilda Pavlovic
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrew Zodda
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Isabel L Jackson
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Javed Mahmood
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zeljko Vujaskovic
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
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Anvari A, Poirier Y, Sawant A. A comprehensive geometric quality assurance framework for preclinical microirradiators. Med Phys 2019; 46:1840-1851. [PMID: 30656713 DOI: 10.1002/mp.13387] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/21/2018] [Accepted: 01/07/2019] [Indexed: 11/12/2022] Open
Abstract
PURPOSE The mechanical and geometric accuracy of small animal image-guided radiotherapy (SA-IGRT) systems is critical and is affected by a number of system-related factors. Because of the small dimensions involved in preclinical radiotherapy research, such factors can individually and/or cumulatively contribute to significant errors in the small animal radiation research. In this study, we developed and implemented a comprehensive quality assurance (QA) framework for characterizing the mechanical and geometric constancy and accuracy of the small animal radiation research platform (SARRP) system. METHODS We quantified the accuracy of gantry and stage rotation isocentricity and positional stage translations. We determined the accuracy and symmetry of field sizes formed by collimators. We evaluated collimator assembly system performance by characterization of collimator axis alignment along the beam axis during gantry rotation. Furthermore, we quantified the end-to-end precision and accuracy of image-guided delivery by examining the congruence of intended (e.g., imaging) and actual delivery (measured during experiment) isocenters. RESULTS The fine and broad beams showed different central axes. The center of the beam was offset toward the cathode (0.22 ± 0.05 mm) when switching the beam from a fine to a broad focus. Larger (custom-made) collimators were more symmetrically centered than smaller (standard) collimators. The field formed by a 1-mm circular collimator was found to deviate from the circular shape, measuring 1.55 mm and 1.25 mm in the X and Y directions, respectively. The 40-mm collimator showed a field that was 1.65 (4.13%) and 1.3 (3.25%) mm smaller than nominal values in the X and Y directions, respectively, and the 30-mm collimator field was smaller by 0.75 mm (2.5%) in the X direction. Results showed that fields formed by other collimators were accurate in both directions and had ≤2% error. The size of the gantry rotation isocenter was 1.45 ± 0.15 mm. While the gantry rotated, lateral and longitudinal isocenter displacements ranged from 0 to -0.34 and -0.44 to 0.33 mm, respectively. Maximum lateral and longitudinal displacements were found at obliques gantry angles of -135° and 45°, respectively. The stage translational accuracies were 0.015, 0.010, and 0 mm in the X, Y, and Z directions, respectively. The size of the stage rotation runout was 2.73 ± 0.3 mm. Maximum displacements of the stage rotational axis were -0.38 (X direction) and -0.26 (Y direction) mm at stage angles of -45° and -135°, respectively. We found that displacements of intended and actual delivery isocenters were 0.24 ± 0.10, 0.12 ± 0.62, and 0.12 ± 0.42 mm in the X, Y, and Z directions, respectively. CONCLUSION We used the SARRP built-in electronic portal imaging device (EPID) to perform most of the geometric QA tests, demonstrating the utility of the EPID for characterizing the geometric accuracy and precision of the SA-IGRT system. However, in principle, the methodology and tests developed here are applicable to any digital imaging detector available in SA-IGRT systems or film. The flexibility of film allows these tests to be adapted for QA of non-IGRT, cabinet irradiators, which make up many of preclinical small animal irradiators.
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Affiliation(s)
- Akbar Anvari
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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Samanta S, Creed M, Anvari A, Mahmood J, Kingsbury T, Sawant A. Novel Strategy to Develop Orthotopic Prostate Tumor using Androgen Dependent LNCaP Transduced with miR133b. Int J Radiat Oncol Biol Phys 2018. [DOI: 10.1016/j.ijrobp.2018.07.680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Modiri A, Rice S, Schonewolf C, Berman A, Feigenberg S, Simone C, Bentzen S, Sawant A. Modeling Patient-specific Risk Factors for Central Lung Tumor SBRT Planning. Int J Radiat Oncol Biol Phys 2018. [DOI: 10.1016/j.ijrobp.2018.06.109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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40
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Samanta S, Modiri A, Rozario T, Yu J, Yan Y, Timmerman R, Sawant A. Virtual Bronchoscopy-Guided Dose Response Modeling of Airways to Mitigate Radiation-Induced Airway Injury in Lung SAbR. Int J Radiat Oncol Biol Phys 2018. [DOI: 10.1016/j.ijrobp.2018.06.110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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41
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Modiri A, Stick LB, Rice SR, Rechner LA, Vogelius IR, Bentzen SM, Sawant A. Individualized estimates of overall survival in radiation therapy plan optimization — A concept study. Med Phys 2018; 45:5332-5342. [DOI: 10.1002/mp.13211] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/23/2018] [Accepted: 09/13/2018] [Indexed: 12/14/2022] Open
Affiliation(s)
- Arezoo Modiri
- School of Medicine University of Maryland Baltimore MD USA
| | | | | | | | | | | | - Amit Sawant
- School of Medicine University of Maryland Baltimore MD USA
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Hamzeei M, Modiri A, Kazemzadeh N, Hagan A, Sawant A. Inverse-planned deliverable 4D-IMRT for lung SBRT. Med Phys 2018; 45:5145-5160. [PMID: 30153339 DOI: 10.1002/mp.13157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 08/13/2018] [Accepted: 08/13/2018] [Indexed: 12/31/2022] Open
Abstract
PURPOSE We present a particle swarm optimization (PSO)-based technique to create deliverable four-dimensional (4D = 3D + time) intensity-modulated radiation therapy (IMRT) plans for lung stereotactic body radiotherapy (SBRT). The 4D planning concept uses respiratory motion as an additional degree of freedom to achieve further sparing of organs at risk (OARs). The 4D-IMRT plan involves the delivery of an order of magnitude more IMRT apertures (~15,000-20,000), with potentially large interaperture variations in the delivered fluence, compared to conventional (i.e., 3D) IMRT. In order to deliver the 4D plan in an efficient manner, we present an optimization-based aperture sequencing technique. METHOD A graphic processing unit (GPU)-enabled PSO-based inverse planning engine, developed and integrated with a research version of the Eclipse (Varian, Palo Alto, CA) treatment planning system (TPS), was employed to create 4D-IMRT plans as follows. Four-dimensional computed tomography scans (4DCTs) and beam configurations from clinical treatment plans of seven lung cancer patients were retrospectively collected, and in each case, the PSO engine iteratively adjusted aperture monitor unit (MU) weights for all beam apertures across all respiratory phases to optimize OAR dose sparing while maintaining planning target volume (PTV) coverage. We calculated the transition times from each aperture to all other apertures for each beam, taking into account the maximum leaf velocity of the multileaf collimator (MLC), and developed a mixed integer optimization technique for aperture sequencing. The goal of sequencing was to maximize delivery efficiency (i.e., minimize the time required to deliver the dose map) by accounting for leaf velocity, aperture MUs, and duration of each respiratory phase. The efficiency of the proposed delivery method was compared with that of a greedy algorithm which chose only from neighboring apertures for the subsequent steps in the sequence. RESULTS 4D-IMRT-optimized plans achieved PTV coverage comparable to clinical plans while improving OAR sparing by an average of 39.7% for D max heart, 20.5% for D max esophagus, 25.6% for D max spinal cord, and 2.1% for V 13 lung (with D max standing for maximum dose and V 13 standing for volume receiving ≥ 13 Gy). Our mixed integer optimization-based aperture sequencing enabled the delivery to be performed in fewer cycles compared to the greedy method. This reduction was 89 ± 79 cycles corresponding to an improvement of 15.94 ± 8.01%, when considering respiratory cycle duration of 4 s, and 55 ± 33 cycles corresponding to an improvement of 15.14 ± 4.45%, when considering respiratory cycle duration of 6 s. CONCLUSION PSO-based 4D-IMRT represents an attractive technique to further improve OAR sparing in lung SBRT. Efficient delivery of a large number of sparse apertures (control points) introduces a challenge in 4D-IMRT treatment planning and delivery. Through judicious optimization of the aperture sequence across all phases, such delivery can be performed on a clinically feasible time scale.
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Affiliation(s)
- Mahdi Hamzeei
- School of Medicine, University of Maryland, 685 W Baltimore St., Baltimore, MD, 21201, USA
| | - Arezoo Modiri
- School of Medicine, University of Maryland, 685 W Baltimore St., Baltimore, MD, 21201, USA
| | - Narges Kazemzadeh
- School of Medicine, University of Maryland, 685 W Baltimore St., Baltimore, MD, 21201, USA
| | - Aaron Hagan
- School of Medicine, University of Maryland, 685 W Baltimore St., Baltimore, MD, 21201, USA
| | - Amit Sawant
- School of Medicine, University of Maryland, 685 W Baltimore St., Baltimore, MD, 21201, USA
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Anvari A, Poirier Y, Sawant A. Kilovoltage transit and exit dosimetry for a small animal image-guided radiotherapy system using built-in EPID. Med Phys 2018; 45:4642-4651. [DOI: 10.1002/mp.13134] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 08/08/2018] [Accepted: 08/08/2018] [Indexed: 11/06/2022] Open
Affiliation(s)
- Akbar Anvari
- Department of Radiation Oncology; University of Maryland School of Medicine; Baltimore MD 21201 USA
| | - Yannick Poirier
- Department of Radiation Oncology; University of Maryland School of Medicine; Baltimore MD 21201 USA
| | - Amit Sawant
- Department of Radiation Oncology; University of Maryland School of Medicine; Baltimore MD 21201 USA
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Simone CB, Sawant A. Margins and Uncertainties in Radiation Oncology. Semin Radiat Oncol 2018; 28:169-170. [PMID: 29933875 DOI: 10.1016/j.semradonc.2018.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Charles B Simone
- Department of Radiation Oncology University of Maryland, School of Medicine Baltimore, MD.
| | - Amit Sawant
- Department of Radiation Oncology University of Maryland, School of Medicine Baltimore, MD
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Spoletini G, Sawant A, Etherington C, Watts S, Clifton I, Whitaker P, Peckham D. P124 Bicarbonate and oxygen saturation predict the need for fitness to fly test in patients with cystic fibrosis. J Cyst Fibros 2018. [DOI: 10.1016/s1569-1993(18)30420-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Anvari A, Poirier Y, Sawant A. Development and implementation of
EPID
‐based quality assurance tests for the small animal radiation research platform (
SARRP
). Med Phys 2018; 45:3246-3257. [DOI: 10.1002/mp.12939] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/13/2018] [Accepted: 04/10/2018] [Indexed: 11/10/2022] Open
Affiliation(s)
- Akbar Anvari
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
| | - Yannick Poirier
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
| | - Amit Sawant
- Department of Radiation Oncology University of Maryland School of Medicine Baltimore MD 21201 USA
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Kazemzadeh N, Modiri A, Samanta S, Yan Y, Bland R, Rozario T, Wibowo H, Iyengar P, Ahn C, Timmerman R, Sawant A. Virtual Bronchoscopy-Guided Treatment Planning to Map and Mitigate Radiation-Induced Airway Injury in Lung SAbR. Int J Radiat Oncol Biol Phys 2018; 102:210-218. [PMID: 29891202 DOI: 10.1016/j.ijrobp.2018.04.060] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 04/16/2018] [Accepted: 04/23/2018] [Indexed: 12/25/2022]
Abstract
PURPOSE Radiation injury to the bronchial tree is an important yet poorly understood potential side effect in lung stereotactic ablative radiation therapy (SAbR). We investigate the integration of virtual bronchoscopy in radiation therapy planning to quantify dosage to individual airways. We develop a risk model of airway collapse and develop treatment plans that reduce the risk of radiation-induced airway injury. METHODS AND MATERIALS Pre- and post-SAbR diagnostic-quality computerized tomography (CT) scans were retrospectively collected from 26 lung cancer patients. From each scan, the bronchial tree was segmented using a virtual bronchoscopy system and registered deformably to the planning CT. Univariate and stepwise multivariate Cox regressions were performed, examining factors such as age, comorbidities, smoking pack years, airway diameter, and maximum point dosage (Dmax). Logistic regression was utilized to formulate a risk function of segmental collapse based on Dmax and diameter. The risk function was incorporated into the objective function along with clinical dosage volume constraints for planning target volume (PTV) and organs at risk (OARs). RESULTS Univariate analysis showed that segmental diameter (P = .014) and Dmax (P = .007) were significantly correlated with airway segment collapse. Multivariate stepwise Cox regression showed that diameter (P = .015), Dmax (P < .0001), and pack/years of smoking (P = .02) were significant independent factors associated with collapse. Risk management-based plans enabled significant dosage reduction to individual airway segments while fulfilling clinical dosimetric objectives. CONCLUSION To our knowledge, this is the first systematic investigation of functional avoidance in lung SAbR based on mapping and minimizing doses to individual bronchial segments. Our early results show that it is possible to substantially lower airway dosage. Such dosage reduction may potentially reduce the risk of radiation-induced airway injury, while satisfying clinically prescribed dosimetric objectives.
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Affiliation(s)
| | - Arezoo Modiri
- University of Maryland, School of Medicine, Baltimore, Maryland
| | - Santanu Samanta
- University of Maryland, School of Medicine, Baltimore, Maryland
| | - Yulong Yan
- UT Southwestern Medical Center, Dallas, Texas
| | - Ross Bland
- UT Southwestern Medical Center, Dallas, Texas
| | | | | | | | - Chul Ahn
- UT Southwestern Medical Center, Dallas, Texas
| | | | - Amit Sawant
- University of Maryland, School of Medicine, Baltimore, Maryland.
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Sawant A, Yamamoto T, Cai J. Treatment planning based on lung functional avoidance is not ready for clinical deployment. Med Phys 2018; 45:2353-2356. [PMID: 29570812 DOI: 10.1002/mp.12881] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 03/15/2018] [Indexed: 12/25/2022] Open
Affiliation(s)
- Amit Sawant
- Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, 21201
| | - Tokihiro Yamamoto
- Department of Radiation Oncology, University of California Davis School of Medicine, Sacramento, California, 95817
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Hagan A, Sawant A, Folkerts M, Modiri A. Multi-GPU configuration of 4D intensity modulated radiation therapy inverse planning using global optimization. Phys Med Biol 2018; 63:025028. [PMID: 29176059 DOI: 10.1088/1361-6560/aa9c96] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We report on the design, implementation and characterization of a multi-graphic processing unit (GPU) computational platform for higher-order optimization in radiotherapy treatment planning. In collaboration with a commercial vendor (Varian Medical Systems, Palo Alto, CA), a research prototype GPU-enabled Eclipse (V13.6) workstation was configured. The hardware consisted of dual 8-core Xeon processors, 256 GB RAM and four NVIDIA Tesla K80 general purpose GPUs. We demonstrate the utility of this platform for large radiotherapy optimization problems through the development and characterization of a parallelized particle swarm optimization (PSO) four dimensional (4D) intensity modulated radiation therapy (IMRT) technique. The PSO engine was coupled to the Eclipse treatment planning system via a vendor-provided scripting interface. Specific challenges addressed in this implementation were (i) data management and (ii) non-uniform memory access (NUMA). For the former, we alternated between parameters over which the computation process was parallelized. For the latter, we reduced the amount of data required to be transferred over the NUMA bridge. The datasets examined in this study were approximately 300 GB in size, including 4D computed tomography images, anatomical structure contours and dose deposition matrices. For evaluation, we created a 4D-IMRT treatment plan for one lung cancer patient and analyzed computation speed while varying several parameters (number of respiratory phases, GPUs, PSO particles, and data matrix sizes). The optimized 4D-IMRT plan enhanced sparing of organs at risk by an average reduction of [Formula: see text] in maximum dose, compared to the clinical optimized IMRT plan, where the internal target volume was used. We validated our computation time analyses in two additional cases. The computation speed in our implementation did not monotonically increase with the number of GPUs. The optimal number of GPUs (five, in our study) is directly related to the hardware specifications. The optimization process took 35 min using 50 PSO particles, 25 iterations and 5 GPUs.
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Affiliation(s)
- Aaron Hagan
- University of Maryland, School of Medicine, Baltimore, MD, United States of America
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Sziklavari Z, Sun K, Sawant A, Haas V. P-177RESCUE TREATMENT WITH IMMEDIATE PHRENIC NERVE RECONSTRUCTION WITH SURAL NERVE GRAFT TRANSPOSITION. Interact Cardiovasc Thorac Surg 2017. [DOI: 10.1093/icvts/ivx280.177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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