1
|
Effectiveness of Flattening-Filter-Free versus Flattened Beams in V79 and Glioblastoma Patient-Derived Stem-like Cells. Int J Mol Sci 2023; 24:ijms24021107. [PMID: 36674623 PMCID: PMC9861147 DOI: 10.3390/ijms24021107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/31/2022] [Accepted: 01/03/2023] [Indexed: 01/09/2023] Open
Abstract
Literature data on the administration of conventional high-dose beams with (FF) or without flattening filters (FFF) show conflicting results on biological effects at the cellular level. To contribute to this field, we irradiated V79 Chinese hamster lung fibroblasts and two patient-derived glioblastoma stem-like cell lines (GSCs-named #1 and #83) using a clinical 10 MV accelerator with FF (at 4 Gy/min) and FFF (at two dose rates 4 and 24 Gy/min). Cell killing and DNA damage induction, determined using the γ-H2AX assay, and gene expression were studied. No significant differences in the early survival of V79 cells were observed as a function of dose rates and FF or FFF beams, while a trend of reduction in late survival was observed at the highest dose rate with the FFF beam. GSCs showed similar survival levels as a function of dose rates, both delivered in the FFF regimen. The amount of DNA damage measured for both dose rates after 2 h was much higher in line #1 than in line #83, with statistically significant differences between the two dose rates only in line #83. The gene expression analysis of the two GSC lines indicates gene signatures mimicking the prognosis of glioblastoma (GBM) patients derived from a public database. Overall, the results support the current use of FFF and highlight the possibility of identifying patients with candidate gene signatures that could benefit from irradiation with FFF beams at a high dose rate.
Collapse
|
2
|
Marques A, Belchior A, Silva F, Marques F, Campello MPC, Pinheiro T, Santos P, Santos L, Matos APA, Paulo A. Dose Rate Effects on the Selective Radiosensitization of Prostate Cells by GRPR-Targeted Gold Nanoparticles. Int J Mol Sci 2022; 23:ijms23095279. [PMID: 35563666 PMCID: PMC9105611 DOI: 10.3390/ijms23095279] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/02/2022] [Accepted: 05/05/2022] [Indexed: 12/14/2022] Open
Abstract
For a while, gold nanoparticles (AuNPs) have been recognized as potential radiosensitizers in cancer radiation therapy, mainly due to their physical properties, making them appealing for medical applications. Nevertheless, the performance of AuNPs as radiosensitizers still raises important questions that need further investigation. Searching for selective prostate (PCa) radiosensitizing agents, we studied the radiosensitization capability of the target-specific AuNP-BBN in cancer versus non-cancerous prostate cells, including the evaluation of dose rate effects in comparison with non-targeted counterparts (AuNP-TDOTA). PCa cells were found to exhibit increased AuNP uptake when compared to non-tumoral ones, leading to a significant loss of cellular proliferation ability and complex DNA damage, evidenced by the occurrence of multiple micronucleus per binucleated cell, in the case of PC3 cells irradiated with 2 Gy of γ-rays, after incubation with AuNP-BBN. Remarkably, the treatment of the PC3 cells with AuNP-BBN led to a much stronger influence of the dose rate on the cellular survival upon γ-photon irradiation, as well as on their genomic instability. Overall, AuNP-BBN emerged in this study as a very promising nanotool for the efficient and selective radiosensitization of human prostate cancer PC3 cells, therefore deserving further preclinical evaluation in adequate animal models for prostate cancer radiotherapy.
Collapse
Affiliation(s)
- Ana Marques
- Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal;
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; (F.M.); (M.P.C.C.); (P.S.); (A.P.)
| | - Ana Belchior
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; (F.M.); (M.P.C.C.); (P.S.); (A.P.)
- Correspondence: (A.B.); (F.S.)
| | - Francisco Silva
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; (F.M.); (M.P.C.C.); (P.S.); (A.P.)
- Correspondence: (A.B.); (F.S.)
| | - Fernanda Marques
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; (F.M.); (M.P.C.C.); (P.S.); (A.P.)
- Departamento de Engenharia e Ciências Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal;
| | - Maria Paula Cabral Campello
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; (F.M.); (M.P.C.C.); (P.S.); (A.P.)
- Departamento de Engenharia e Ciências Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal;
| | - Teresa Pinheiro
- Departamento de Engenharia e Ciências Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal;
- Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal
| | - Pedro Santos
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; (F.M.); (M.P.C.C.); (P.S.); (A.P.)
| | - Luis Santos
- Laboratório de Metrologia, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal;
| | - António P. A. Matos
- Centro de Investigação Interdisciplinar Egas Moniz, Campus Universitário, Quinta da Granja, Monte de Caparica, 2829-511 Caparica, Portugal;
| | - António Paulo
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; (F.M.); (M.P.C.C.); (P.S.); (A.P.)
- Departamento de Engenharia e Ciências Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal;
| |
Collapse
|
3
|
Nikolakopoulou A, Peppa V, Alexiou A, Pissakas G, Terzoudi G, Karaiskos P. Comparison and Evaluation of Different Radiotherapy Techniques Using Biodosimetry Based on Cytogenetics. Cancers (Basel) 2021; 14:cancers14010146. [PMID: 35008308 PMCID: PMC8749890 DOI: 10.3390/cancers14010146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 12/25/2022] Open
Abstract
Simple Summary Cell killing and tumor response in cancer patients depends not only on the absorbed radiation dose but also on the dose rate and delivery time. In this study, a biodosimetry assay based on the frequency of dicentrics chromosomes scored in peripheral blood lymphocytes from prostate cancer patients and PC3 human prostate cancer cell line was used to investigate the radiobiological impact of the relative prolonged dose delivery time and/or decreased dose rate met in advanced modulated radiotherapy techniques (VMAT and IMRT) compared to conventional non-modulated (3D-CRT) in prostate patient plan irradiations. The results showed a small but statistically significant decrease in the number of dicentrics following radiation with the modulated techniques, suggesting a corresponding decrease on the radiation dose efficiency. The biodosimetry assay could be used as an alternative to the laborious conventional clonogenic assay, while both lymphocytes and cancer cell line could effectively be used for estimation of the biological absorbed dose. Abstract While rapid technological advances in radiotherapy techniques have led to a more precise delivery of radiation dose and to a decreased risk of side effects, there is still a need to evaluate the efficacy of the new techniques estimating the biological dose and to investigate the radiobiological impact of the protracted radiotherapy treatment duration. The aim of this study is to compare, at a cytogenetic level, advanced radiotherapy techniques VMAT and IMRT with the conventional 3D-CRT, using biological dosimetry. A dicentric biodosimetry assay based on the frequency of dicentrics chromosomes scored in peripheral blood lymphocytes from prostate cancer patients and PC3 human prostate cancer cell line was used. For each patient blood sample and each subpopulation of the cultured cell line, three different irradiations were performed using the 3D-CRT, IMRT, and VMAT technique. The absorbed dose was estimated with the biodosimetry method based on the induced dicentric chromosomes. The results showed a statistically significant underestimation of the biological absorbed dose of ~6% for the IMRT and VMAT compared to 3D-CRT irradiations for peripheral blood lymphocytes, whereas IMRT and VMAT results were comparable without a statistically significant difference, although slightly lower values were observed for VMAT compared to IMRT irradiation. Similar results were obtained using the PC3 cell line. The observed biological dose underestimation could be associated with the relative decreased dose rate and increase irradiation time met in modulated techniques compared to the conventional 3D-CRT irradiations.
Collapse
Affiliation(s)
- Aggeliki Nikolakopoulou
- Laboratory of Health Physics, Radiobiology & Cytogenetics, Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, National Centre for Scientific Research ‘‘Demokritos’’, 15310 Athens, Greece; (A.N.); (G.T.)
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece;
| | - Vasiliki Peppa
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece;
- Radiotherapy Department, General Hospital of Athens Alexandra, 11528 Athens, Greece; (A.A.); (G.P.)
| | - Antigoni Alexiou
- Radiotherapy Department, General Hospital of Athens Alexandra, 11528 Athens, Greece; (A.A.); (G.P.)
| | - George Pissakas
- Radiotherapy Department, General Hospital of Athens Alexandra, 11528 Athens, Greece; (A.A.); (G.P.)
| | - Georgia Terzoudi
- Laboratory of Health Physics, Radiobiology & Cytogenetics, Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, National Centre for Scientific Research ‘‘Demokritos’’, 15310 Athens, Greece; (A.N.); (G.T.)
| | - Pantelis Karaiskos
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece;
- Correspondence:
| |
Collapse
|
4
|
Kouris P, Moutsatsos A, Pappas EP, Beli I, Pantelakos P, Karaiskos P, Pantelis E. Assessing the dose rate delivery of helical TomoTherapy prostate and head & neck treatments. Biomed Phys Eng Express 2021; 8. [PMID: 34755680 DOI: 10.1088/2057-1976/ac37cb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 11/09/2021] [Indexed: 11/11/2022]
Abstract
The dose rate distributions delivered to 55 prostate and head & neck (H&N) cancer patients treated with a helical TomoTherapy (HT) system were resolved and assessed with regard to pitch and field width defined during treatment planning. Statistical analysis of the studied cases showed that the median treatment delivery time was 4.4 min and 6.3 min for the prostate and H&N cases, respectively. Dose rate volume histogram data for the studied cases showed that the 25% and 12% of the volume of the planning target volumes of the prostate and H&N cases are irradiated with a dose rate of greater or equal to 1 Gy min-1. Quartile dose rate (QDR) data confirmed that in HT, where the target is irradiated in slices, most of the dose is delivered to each voxel of the target when it travels within the beam. Analysis of the planning data from all cases showed that this lasts for 68 s (median value). QDRs results showed that using the 2.5 cm field width, 75% of the prescribed dose is delivered to target voxels with a median dose rate of at least 3.2 Gy min-1and 4.5 Gy min-1, for the prostate and H&N cases, respectively. Systematically higher dose rates were observed for the H&N cases due to the shallower depths of the lesions in this anatomical site. Delivered dose rates were also found to increase with field width and pitch setting, due to the higher output of the system which, in general, results in accordingly decreased total treatment time. The biological effect of the dose rate findings of this work needs to be further investigated using in-vitro studies and clinical treatment data.
Collapse
Affiliation(s)
- P Kouris
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, 75 Mikras Asias, 11527 Athens, Greece
| | - A Moutsatsos
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, 75 Mikras Asias, 11527 Athens, Greece.,Radiotherapy and Radiosurgery Department, Latropolis Clinic, 54-56 Ethnikis Antistaseos, 15231 Athens, Greece
| | - E P Pappas
- Radiotherapy and Radiosurgery Department, Latropolis Clinic, 54-56 Ethnikis Antistaseos, 15231 Athens, Greece
| | - I Beli
- Radiotherapy and Radiosurgery Department, Latropolis Clinic, 54-56 Ethnikis Antistaseos, 15231 Athens, Greece
| | - P Pantelakos
- Radiotherapy and Radiosurgery Department, Latropolis Clinic, 54-56 Ethnikis Antistaseos, 15231 Athens, Greece
| | - P Karaiskos
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, 75 Mikras Asias, 11527 Athens, Greece
| | - E Pantelis
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, 75 Mikras Asias, 11527 Athens, Greece.,Radiotherapy and Radiosurgery Department, Latropolis Clinic, 54-56 Ethnikis Antistaseos, 15231 Athens, Greece
| |
Collapse
|
5
|
A Diamond-Based Dose-per-Pulse X-ray Detector for Radiation Therapy. MATERIALS 2021; 14:ma14185203. [PMID: 34576426 PMCID: PMC8466252 DOI: 10.3390/ma14185203] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/03/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022]
Abstract
One of the goals of modern dynamic radiotherapy treatments is to deliver high-dose values in the shortest irradiation time possible. In such a context, fast X-ray detectors and reliable front-end readout electronics for beam diagnostics are crucial to meet the necessary quality assurance requirements of care plans. This work describes a diamond-based detection system able to acquire and process the dose delivered by every single pulse sourced by a linear accelerator (LINAC) generating 6-MV X-ray beams. The proposed system is able to measure the intensity of X-ray pulses in a limited integration period around each pulse, thus reducing the inaccuracy induced by unnecessarily long acquisition times. Detector sensitivity under 6-MV X-photons in the 0.1–10 Gy dose range was measured to be 302.2 nC/Gy at a bias voltage of 10 V. Pulse-by-pulse measurements returned a charge-per-pulse value of 84.68 pC, in excellent agreement with the value estimated (but not directly measured) with a commercial electrometer operating in a continuous integration mode. Significantly, by intrinsically holding the acquired signal, the proposed system enables signal processing even in the millisecond period between two consecutive pulses, thus allowing for effective real-time dose-per-pulse monitoring.
Collapse
|
6
|
Varnava M, Sumida I, Oda M, Kurosu K, Isohashi F, Seo Y, Otani K, Ogawa K. Dosimetric comparison between volumetric modulated arc therapy planning techniques for prostate cancer in the presence of intrafractional organ deformation. JOURNAL OF RADIATION RESEARCH 2021; 62:309-318. [PMID: 33341880 PMCID: PMC7948894 DOI: 10.1093/jrr/rraa123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 09/24/2020] [Accepted: 09/30/2020] [Indexed: 06/12/2023]
Abstract
The purpose of this study was to compare single-arc (SA) and double-arc (DA) treatment plans, which are planning techniques often used in prostate cancer volumetric modulated arc therapy (VMAT), in the presence of intrafractional deformation (ID) to determine which technique is superior in terms of target dose coverage and sparing of the organs at risk (OARs). SA and DA plans were created for 27 patients with localized prostate cancer. ID was introduced to the clinical target volume (CTV), rectum and bladder to obtain blurred dose distributions using an in-house software. ID was based on the motion probability function of each structure voxel and the intrafractional motion of the respective organs. From the resultant blurred dose distributions of SA and DA plans, various parameters, including the tumor control probability, normal tissue complication probability, homogeneity index, conformity index, modulation complexity score for VMAT, dose-volume indices and monitor units (MUs), were evaluated to compare the two techniques. Statistical analysis showed that most CTV and rectum parameters were significantly larger for SA plans than for DA plans (P < 0.05). Furthermore, SA plans had fewer MUs and were less complex (P < 0.05). The significant differences observed had no clinical significance, indicating that both plans are comparable in terms of target and OAR dosimetry when ID is considered. The use of SA plans is recommended for prostate cancer VMAT because they can be delivered in shorter treatment times than DA plans, and therefore benefit the patients.
Collapse
Affiliation(s)
- Maria Varnava
- Corresponding author. Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 (D10) Yamadaoka, Suita, Osaka, 565-0871, Japan. Tel: +81-6-6879-3482; Fax: +81-6-6879-3489;
| | - Iori Sumida
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 (D10) Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Michio Oda
- Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keita Kurosu
- Department of Medical Technology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Fumiaki Isohashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 (D10) Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yuji Seo
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 (D10) Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keisuke Otani
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 (D10) Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 (D10) Yamadaoka, Suita, Osaka, 565-0871, Japan
| |
Collapse
|
7
|
Chen BB, Huang SM, Xiao WW, Sun WZ, Liu MZ, Lu TX, Deng XW, Han F. Prospective matched study on comparison of volumetric-modulated arc therapy and intensity-modulated radiotherapy for nasopharyngeal carcinoma: dosimetry, delivery efficiency and outcomes. J Cancer 2018; 9:978-986. [PMID: 29581777 PMCID: PMC5868165 DOI: 10.7150/jca.22843] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 01/29/2018] [Indexed: 01/04/2023] Open
Abstract
Background: The purpose of this study is to assess the feasibility of volumetric-modulated arc therapy (VMAT) for nasopharyngeal carcinoma (NPC) patients by comparing the physical dosimetry, delivery efficiency and clinical outcomes with intensity-modulated radiotherapy (IMRT). Methods: A prospective matched study was performed for patients with newly diagnosed NPC who underwent VMAT or IMRT. The patients in two groups were equally matched in terms of gender, age, tumor stage and chemotherapy. The target coverage, homogeneity index (HI) and conformity index (CI) of the planning target volume (PTV), organs at risk (OARs) sparing, average treatment time and clinical outcomes were analyzed. Results: From June 2013 to August 2015, a total of 80 patients were enrolled in this study, with 40 patients in each group. The coverage of PTV was similar for both groups. D2 was observed slight difference only in early stage disease (T1-2) (VMAT vs. IMRT, 7494±109 cGy vs. 7564±92 cGy; p=0.06). The HI of VMAT group was better than that of IMRT group (p=0.001), whereas CI was slightly worse (p=0.061). The maximum doses received by the brain stem, spinal cord, and optic nerve of VMAT were higher than those of IMRT (p<0.05). But the irradiation volumes in healthy tissue were generally lower for VMAT group, with significant differences in V20, V25 and V45 (p<0.05). With regard to the delivery efficiency compared with IMRT (1160 ± 204s), a 69% reduction in treatment time was achieved by VMAT (363 ± 162s). Both groups had 5 cases of nasopharyngeal residual lesions after radiotherapy. The 2-year estimated local relapse-free survival, regional relapse-free survival and locoregional relapse-free survival, distant metastasis-free survival, disease-free survival and overall survival were similar between two groups, with the corresponding rates of 100%, 97.4%, 97.4%, 90.0%, 90.0% and 92.4% in VMAT group, and 100%, 100%, 100%, 95.0%, 95.0% and 97.5% in IMRT group, respectively. Conclusions: Both VMAT and IMRT can meet the clinical requirements for the treatment of NPC. The short-term tumor regression rates and 2-year survival rates with the two techniques are comparable. The faster treatment time benefits of VMAT will enable more patients to receive precision radiotherapy.
Collapse
Affiliation(s)
- Bin-Bin Chen
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China.,Department of Medical Oncology, The Fifth Affiliated Hospital of Sun Yat-sen University, Zhuhai, People's Republic of China
| | - Shao-Min Huang
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China
| | - Wei-Wei Xiao
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China
| | - Wen-Zhao Sun
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China
| | - Ming-Zhu Liu
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China
| | - Tai-Xiang Lu
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China
| | - Xiao-Wu Deng
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China
| | - Fei Han
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, People's Republic of China
| |
Collapse
|
8
|
Njeh CF, Salmon HW, Schiller C. The Impact of Dose Rate on the Accuracy of Step-and-Shoot Intensity-modulated Radiation Therapy Quality Assurance Using Varian 2300CD. J Med Phys 2018; 42:206-212. [PMID: 29296034 PMCID: PMC5744448 DOI: 10.4103/jmp.jmp_18_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Introduction Intensity-modulated radiation therapy (IMRT) delivery using "step-and-shoot" technique on Varian C-Series linear accelerator (linac) is influenced by the communication frequency between the multileaf collimator and linac controllers. Hence, the dose delivery accuracy is affected by the dose rate. Aim Our aim was to quantify the impact of using two dose rates on plan quality assurance (QA). Materials and Methods Twenty IMRT patients were selected for this study. The plan QA was measured at two different dose rates. A gamma analysis was performed, and the degree of plan modulation on the QA pass rate was also evaluated in terms of average monitor unit per segment (MU/segment) and the total number of segments. Results The mean percentage gamma pass rate of 94.9% and 93.5% for 300 MU/min and 600 MU/min dose rate, respectively, was observed. There was a significant (P = 0.001) decrease in percentage gamma pass rate when the dose rate was increased from 300 MU/min to 600 MU/min. There was a weak, but significant association between the percentage pass rate at both dose rate and total number of segments. The total number of MU was significantly correlated to the total number of segments (r = 0.59). We found a positive correlation between the percentage pass rate and mean MU/segment, r = 0.52 and r = 0.57 for 300 MU/min and 600 MU/min, respectively. Conclusion IMRT delivery using step-and-shoot technique on Varian 2300CD is impacted by the dose rate and the total amount of segments.
Collapse
Affiliation(s)
- Christopher F Njeh
- Diagnostic and Treatment Center, Marshfield Clinic, Weston, WI.,Department of Radiation Oncology, Franciscan St. Francis Health, Indianapolis, IN 46237, USA
| | - Howard W Salmon
- Department of Radiation Oncology, Franciscan St. Francis Health, Indianapolis, IN 46237, USA
| | - Claire Schiller
- Diagnostic and Treatment Center, Marshfield Clinic, Weston, WI
| |
Collapse
|
9
|
Thompson HF, Butterworth KT, McMahon SJ, Ghita M, Hounsell AR, Prise KM. The Impact of Hypoxia on Out-of-Field Cell Survival after Exposure to Modulated Radiation Fields. Radiat Res 2017; 188:636-644. [PMID: 29019742 DOI: 10.1667/rr14836.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Advanced radiotherapy techniques such as intensity modulated radiation therapy achieve highly conformal dose distributions within target tumor volumes through the sequential delivery of multiple spatially and temporally modulated radiation fields and have been shown to influence radiobiological response. The goals of this study were to determine the effect of hypoxia on the cell survival responses of different cell models (H460, DU145, A549, MDA231 and FADU) to modulated fields and to characterize the time dependency of signaling under oxic conditions, following reoxygenation and after prolonged hypoxia. Hypoxia was induced by incubating cells at 95% nitrogen and 5% carbon dioxide for 4 h prior to irradiation. The out-of-field response in MDA231 cells was oxygen dependent and therefore selected for co-culture studies to determine the signaling kinetics at different time intervals after irradiation under oxic and hypoxic conditions. Under both oxic and hypoxic conditions, significant increases in cell survival were observed in-field with significant decreases in survival observed out-of-field (P < 0.05), which were dependent on intercellular communication. The in-field response of MDA231 cells showed no significant time dependency up to 24 h postirradiation, while out-of-field survival decreased significantly during the first 6 h postirradiation (P < 0.05). While in-field responses were oxygen dependent, out-of-field effects were observed to be independent of oxygen, with similar or greater cell killing under hypoxic conditions. This study provides further understanding of intercellular signaling under hypoxic conditions and highlights the need for further refinement of established radiobiological models for future applications in advanced radiotherapies.
Collapse
Affiliation(s)
- Hannah F Thompson
- a Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom; and
| | - Karl T Butterworth
- a Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom; and
| | - Stephen J McMahon
- a Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom; and
| | - Mihaela Ghita
- a Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom; and
| | - Alan R Hounsell
- b Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast, Northern Ireland, United Kingdom
| | - Kevin M Prise
- a Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom; and
| |
Collapse
|
10
|
Müller BS, Wilkens JJ. Prioritized efficiency optimization for intensity modulated proton therapy. Phys Med Biol 2016; 61:8249-8265. [DOI: 10.1088/0031-9155/61/23/8249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
11
|
Mackeprang PH, Volken W, Terribilini D, Frauchiger D, Zaugg K, Aebersold DM, Fix MK, Manser P. Assessing dose rate distributions in VMAT plans. Phys Med Biol 2016; 61:3208-21. [PMID: 27025897 DOI: 10.1088/0031-9155/61/8/3208] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Dose rate is an essential factor in radiobiology. As modern radiotherapy delivery techniques such as volumetric modulated arc therapy (VMAT) introduce dynamic modulation of the dose rate, it is important to assess the changes in dose rate. Both the rate of monitor units per minute (MU rate) and collimation are varied over the course of a fraction, leading to different dose rates in every voxel of the calculation volume at any point in time during dose delivery. Given the radiotherapy plan and machine specific limitations, a VMAT treatment plan can be split into arc sectors between Digital Imaging and Communications in Medicine control points (CPs) of constant and known MU rate. By calculating dose distributions in each of these arc sectors independently and multiplying them with the MU rate, the dose rate in every single voxel at every time point during the fraction can be calculated. Independently calculated and then summed dose distributions per arc sector were compared to the whole arc dose calculation for validation. Dose measurements and video analysis were performed to validate the calculated datasets. A clinical head and neck, cranial and liver case were analyzed using the tool developed. Measurement validation of synthetic test cases showed linac agreement to precalculated arc sector times within ±0.4 s and doses ±0.1 MU (one standard deviation). Two methods for the visualization of dose rate datasets were developed: the first method plots a two-dimensional (2D) histogram of the number of voxels receiving a given dose rate over the course of the arc treatment delivery. In similarity to treatment planning system display of dose, the second method displays the dose rate as color wash on top of the corresponding computed tomography image, allowing the user to scroll through the variation over time. Examining clinical cases showed dose rates spread over a continuous spectrum, with mean dose rates hardly exceeding 100 cGy min(-1) for conventional fractionation. A tool to analyze dose rate distributions in VMAT plans with sub-second accuracy was successfully developed and validated. Dose rates encountered in clinical VMAT test cases show a continuous spectrum with a mean less than or near 100 cGy min(-1) for conventional fractionation.
Collapse
Affiliation(s)
- P-H Mackeprang
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Dasu A, Toma-Dasu I. Will intrafraction repair have negative consequences on extreme hypofractionation in prostate radiation therapy? Br J Radiol 2015; 88:20150588. [DOI: 10.1259/bjr.20150588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
|
13
|
Abstract
RapidArc™ is a radiation technique that delivers highly conformal dose distributions through the complete rotation (360°) and speed variation of the linear accelerator gantry. This technique, called volumetric modulated arc therapy (VMAT), compared with conventional radiotherapy techniques, can achieve high-target volume coverage and sparing damage to normal tissues. RapidArc delivers precise dose distribution and conformity similar to or greater than intensity-modulated radiation therapy in a short time, generally a few minutes, to which image-guided radiation therapy is added. RapidArc has become a currently used technology in many centers, which use RapidArc technology to treat a large number of patients. Large and small hospitals use it to treat the most challenging cases, but more and more frequently for the most common cancers. The clinical use of RapidArc and VMAT technology is constantly growing. At present, a limited number of clinical data are published, mostly concerning planning and feasibility studies. Clinical outcome data are increasing for a few tumor sites, even if only a little. The purpose of this work is to discuss the current status of VMAT techniques in clinical use through a review of the published data of planning systems and clinical outcomes in several tumor sites. The study consisted of a systematic review based on analysis of manuscripts retrieved from the PubMed, BioMed Central, and Scopus databases by searching for the keywords “RapidArc”, “Volumetric modulated arc radiotherapy”, and “Intensity-modulated radiotherapy”.
Collapse
Affiliation(s)
- Erminia Infusino
- Department of Radiotherapy, Campus Bio-Medico University Hospital, Rome, Italy
| |
Collapse
|
14
|
Impact of flattening-filter-free radiation on the clonogenic survival of astrocytic cell lines. Strahlenther Onkol 2015; 191:590-6. [DOI: 10.1007/s00066-015-0823-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 01/28/2015] [Indexed: 11/25/2022]
|
15
|
Shields L, Vega-Carrascal I, Singleton S, Lyng FM, McClean B. Cell Survival and DNA Damage in Normal Prostate Cells Irradiated Out-of-Field. Radiat Res 2014; 182:499-506. [DOI: 10.1667/rr13777.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
16
|
Hyland WB, McMahon SJ, Butterworth KT, Cole AJ, King RB, Redmond KM, Prise KM, Hounsell AR, McGarry CK. Investigation into the radiobiological consequences of pre-treatment verification imaging with megavoltage X-rays in radiotherapy. Br J Radiol 2014; 87:20130781. [PMID: 24472729 PMCID: PMC4067021 DOI: 10.1259/bjr.20130781] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 01/22/2014] [Accepted: 01/23/2014] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The aim of this study was to investigate the effect of pre-treatment verification imaging with megavoltage X-rays on cancer and normal cell survival in vitro and to compare the findings with theoretically modelled data. Since the dose received from pre-treatment imaging can be significant, the incorporation of this dose at the planning stage of treatment has been suggested. METHODS The impact of imaging dose incorporation on cell survival was investigated by clonogenic assay of irradiated DU-145 prostate cancer, H460 non-small-cell lung cancer and AGO-1522b normal tissue fibroblast cells. Clinically relevant imaging-to-treatment times of 7.5 and 15 min were chosen for this study. The theoretical magnitude of the loss of radiobiological efficacy due to sublethal damage repair was investigated using the Lea-Catcheside dose protraction factor model. RESULTS For the cell lines investigated, the experimental data showed that imaging dose incorporation had no significant impact on cell survival. These findings were in close agreement with theoretical results. CONCLUSION For the conditions investigated, the results suggest that allowance for the imaging dose at the planning stage of treatment should not adversely affect treatment efficacy. ADVANCES IN KNOWLEDGE There is a paucity of data in the literature on imaging effects in radiotherapy. This article presents a systematic study of imaging dose effects on cancer and normal cell survival, providing both theoretical and experimental evidence for clinically relevant imaging doses and imaging-to-treatment times. The data provide a firm foundation for further study into this highly relevant area of research.
Collapse
Affiliation(s)
- W B Hyland
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Cole AJ, McGarry CK, Butterworth KT, McMahon SJ, Hounsell AR, Prise KM, O’Sullivan JM. Investigating the influence of respiratory motion on the radiation induced bystander effect in modulated radiotherapy. Phys Med Biol 2013; 58:8311-22. [DOI: 10.1088/0031-9155/58/23/8311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
18
|
Elith CA, Dempsey SE, Warren-Forward HM. A retrospective planning analysis comparing intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) using two optimization algorithms for the treatment of early-stage prostate cancer. J Med Radiat Sci 2013; 60:84-92. [PMID: 26229615 PMCID: PMC4175809 DOI: 10.1002/jmrs.22] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 07/20/2013] [Accepted: 07/22/2013] [Indexed: 01/21/2023] Open
Abstract
INTRODUCTION The primary aim of this study is to compare intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) for the radical treatment of prostate cancer using version 10.0 (v10.0) of Varian Medical Systems, RapidArc radiation oncology system. Particular focus was placed on plan quality and the implications on departmental resources. The secondary objective was to compare the results in v10.0 to the preceding version 8.6 (v8.6). METHODS Twenty prostate cancer cases were retrospectively planned using v10.0 of Varian's Eclipse and RapidArc software. Three planning techniques were performed: a 5-field IMRT, VMAT using one arc (VMAT-1A), and VMAT with two arcs (VMAT-2A). Plan quality was assessed by examining homogeneity, conformity, the number of monitor units (MUs) utilized, and dose to the organs at risk (OAR). Resource implications were assessed by examining planning and treatment times. The results obtained using v10.0 were also compared to those previously reported by our group for v8.6. RESULTS In v10.0, each technique was able to produce a dose distribution that achieved the departmental planning guidelines. The IMRT plans were produced faster than VMAT plans and displayed improved homogeneity. The VMAT plans provided better conformity to the target volume, improved dose to the OAR, and required fewer MUs. Treatments using VMAT-1A were significantly faster than both IMRT and VMAT-2A. Comparison between versions 8.6 and 10.0 revealed that in the newer version, VMAT planning was significantly faster and the quality of the VMAT dose distributions produced were of a better quality. CONCLUSION VMAT (v10.0) using one or two arcs provides an acceptable alternative to IMRT for the treatment of prostate cancer. VMAT-1A has the greatest impact on reducing treatment time.
Collapse
Affiliation(s)
- Craig A Elith
- British Columbia Cancer Agency, Fraser Valley Centre Surrey, BC, Canada ; School of Health Sciences, University of Newcastle Newcastle, NSW, Australia
| | - Shane E Dempsey
- School of Health Sciences, University of Newcastle Newcastle, NSW, Australia
| | | |
Collapse
|
19
|
A Retrospective Planning Analysis Comparing Volumetric-Modulated Arc Therapy (VMAT) to Intensity-Modulated Radiation Therapy (IMRT) for Radiotherapy Treatment of Prostate Cancer. J Med Imaging Radiat Sci 2013; 44:79-86. [DOI: 10.1016/j.jmir.2012.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 06/21/2012] [Accepted: 06/21/2012] [Indexed: 11/20/2022]
|
20
|
Inverse planned constant dose rate volumetric modulated arc therapy (VMAT) as an efficient alternative to five-field intensity modulated radiation therapy (IMRT) for prostate. JOURNAL OF RADIOTHERAPY IN PRACTICE 2013. [DOI: 10.1017/s1460396913000083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractPurposeThe aim of this work was to determine if volumetric modulated arc therapy (VMAT) plans, created for constant dose-rate (cdrVMAT) delivery are a viable alternative to step and shoot five-field intensity modulated radiation therapy (IMRT).Materials and methodsThe cdrVMAT plans, inverse planned on a treatment planning system with no solution to account for couch top or rails, were created for delivery on a linear accelerator with no variable dose rate control system. A series of five-field IMRT and cdrVMAT plans were created using dual partial arcs (gantry rotating between 260° and 100°) with 4° control points for ten prostate patients with the average rectal constraint incrementally increased. Pareto fronts were compared for the planning target volume homogeneity and average rectal dose between the two techniques for each patient. Also investigated were tumour control probability and normal tissue complication probability values for each technique. The delivery parameters [monitor units (MU) and time] and delivery accuracy of the IMRT and VMAT plans were also compared.ResultsPareto fronts showed that the dual partial arc plans were superior to the five-field IMRT plans, particularly for the clinically acceptable plans where average rectal doses were less for rotational plans (p = 0·009) with no statistical difference in target homogeneity. The cdrVMAT plans had significantly more MU (p = 0·005) but the average delivery time was significantly less than the IMRT plans by 42%. All clinically acceptable cdrVMAT plans were accurate in their delivery (gamma 99·2 ± 1·1%, 3%3 mm criteria).ConclusionsAccurate delivery of dual partial arc cdrVMAT avoiding the couch top and rails has been demonstrated.
Collapse
|
21
|
King RB, Hyland WB, Cole AJ, Butterworth KT, McMahon SJ, Redmond KM, Trainer C, Prise KM, McGarry CK, Hounsell AR. Anin vitrostudy of the radiobiological effects of flattening filter free radiotherapy treatments. Phys Med Biol 2013; 58:N83-94. [DOI: 10.1088/0031-9155/58/5/n83] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
22
|
Cole AJ, McGarry CK, Butterworth KT, Prise KM, O'Sullivan JM, Hounsell AR. Development of a novel experimental model to investigate radiobiological implications of respiratory motion in advanced radiotherapy. Phys Med Biol 2012; 57:N411-20. [DOI: 10.1088/0031-9155/57/22/n411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
23
|
McGarry CK, Butterworth KT, Trainor C, McMahon SJ, O'Sullivan JM, Prise KM, Hounsell AR. In-vitro investigation of out-of-field cell survival following the delivery of conformal, intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans. Phys Med Biol 2012; 57:6635-45. [PMID: 23022685 DOI: 10.1088/0031-9155/57/20/6635] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The aim of this work is to determine the out-of-field survival of cells irradiated with either the primary field or scattered radiation in the presence and absence of intercellular communication following delivery of conformal, IMRT and VMAT treatment plans. Single beam, conformal, IMRT and VMAT plans were created to deliver 3 Gy to half the area of a T80 flask containing either DU-145 or AGO-1522 cells allowing intercellular communication between the in- and out-of-field cell populations. The same plans were delivered to a similar custom made phantom used to hold two T25 culture flasks, one flask in-field and one out-of-field to allow comparison of cell survival responses when intercellular communication is physically inhibited. Plans were created for the delivery of 8 Gy to the more radio-resistant DU-145 cells only in the presence and absence of intercellular communication. Cell survival was determined by clonogenic assay. In both cell lines, the out-of-field survival was not statistically different between delivery techniques for either cell line or dose. There was however, a statistically significant difference between survival out-of-field when intercellular communication was intact (single T80 culture flask) or inhibited (multiple T25 culture flasks) to in-field for all plans. No statistically significant difference was observed in-field with or without cellular communication to out-of-field for all plans. These data demonstrate out-of-field effects as important determinants of cell survival following exposure to modulated irradiation fields when cellular communication between differentially irradiated cell populations is present. This data is further evidence that refinement of existing radiobiological models to include indirect cell killing effects is required.
Collapse
Affiliation(s)
- Conor K McGarry
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, UK.
| | | | | | | | | | | | | |
Collapse
|
24
|
Dzierma Y, Licht N, Nuesken F, Ruebe C. Beam properties and stability of a flattening-filter free 7 MV beam-an overview. Med Phys 2012; 39:2595-602. [PMID: 22559630 DOI: 10.1118/1.3703835] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Several works have recently focused on flattening-filter-free (FFF) beams of linear accelerators of various companies (in particular, Varian and Elekta), but no overview as yet exists for the flattening-filter free 7XU beam (Siemens Artiste). METHODS Dosimetric properties of the 7XU beam were measured in May and September 2011. We present depth dose curves and beam profiles, output factors, and MLC transmission and assess the stability of the measurements. The 7XU beam was commissioned in the Pinnacle[superscript three] treatment planning system (TPS), and modeling results including the spectrum are presented. RESULTS The percent depth dose curve of the 7XU beam is similar to the flat 6X beam line, with a slightly smaller surface dose. The beam profiles show the characteristic shape of flattening-filter free beams, with deviations between measurements of generally less than 1%. The output factors of the 7XU beam decrease more slowly than for the 6X beam. The MLC transmission is comparable but slightly less for the 7XU beam. The 7XU beam can be adequately modeled by the Pinnacle[superscript three] TPS, with successful dosimetric verification. The spectrum of the 7XU beam has lower photon fluence up to approximately 2.5 MeV and higher fluence beyond, with a slightly higher mean energy. CONCLUSIONS The 7XU beam has been commissioned for clinical use after successful modeling, stability checks, and dosimetric verification.
Collapse
Affiliation(s)
- Yvonne Dzierma
- Department of Radiation Oncology, Saarland University Medical Center, Saarland, Germany.
| | | | | | | |
Collapse
|
25
|
Bewes JM, Suchowerska N, Cartwright L, Ebert MA, McKenzie DR. Optimization of temporal dose modulation: Comparison of theory and experiment. Med Phys 2012; 39:3181-8. [DOI: 10.1118/1.4712223] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
26
|
Claridge Mackonis E, Suchowerska N, Naseri P, McKenzie DR. Optimisation of exposure conditions for in vitro radiobiology experiments. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2012; 35:151-7. [PMID: 22454298 DOI: 10.1007/s13246-012-0132-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 02/28/2012] [Indexed: 11/27/2022]
Abstract
Despite the long history of using cell cultures in vitro for radiobiological studies, there is to date no study specifically addressing the dosimetric implications of flask selection and exposure environment in clonogenic assays. The consequent variability in dosimetry between laboratories impedes the comparison of results. In this study we compare the dose to cells adherent to the base of three types of commonly used culture flasks or plates. The cells are exposed to a 6MV clinical photon beam using either an open or a half blocked field. The depth of medium in each flask is varied with the medium surrounding the flask either water or air. The results show that the dose to the cells is more affected by the scattering conditions surrounding the flasks than by the level of filling within the flask. It is recommended that water or a water equivalent phantom material is used to surround the flasks or plates to approximate full scatter conditions at the cell layer. However for modulated fields, surrounding the 24 well plates with water-equivalent material is inadequate because of the large volume of air surrounding individual wells. Our results stress the importance of measuring the dose for new experimental configurations.
Collapse
|
27
|
Paul S, Roy PK. The effect of stochastic fluctuation in radiation dose-rate on cell survival following fractionated radiation therapy. Phys Med Biol 2012; 57:1561-73. [PMID: 22391148 DOI: 10.1088/0031-9155/57/6/1561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In radiobiological models, it is often assumed that the radiation dose rate remains constant during the course of radiation delivery. However, instantaneous radiation dose rate undergoes random (stochastic) temporal fluctuation. The effect of stochastic dose rate in fractionated radiation therapy is unknown and there has been no analytical formulation of stochastic dose-rate fluctuation effect in fractionated radiation therapy which we endeavor to pursue here. We have obtained the quantitative expression of cellular survival fraction considering stochastic temporal fluctuation or noise in dose rate. We have shown that the constant dose-rate approximation overestimates the survival fraction compared to that under stochastic dose rate in a fractionated radiation therapy situation and this overestimation effect increases appreciably with the increase in the fluctuation level in dose rate. However, for a given level of fluctuation in dose rate, overestimation of survival fraction also depends on the value of cellular radiation sensitivity parameter β and the repair rate of DNA lesion. This overestimation effect is higher for the cells which have a higher value of β parameter or have a lower repair rate. Our study draws attention to stochastic temporal fluctuation in the radiation dose rate and its potential contribution to cell survival following fractionated radiotherapy.
Collapse
Affiliation(s)
- Subhadip Paul
- National Brain Research Centre, Manesar, Gurgaon, Haryana 122050, India
| | | |
Collapse
|
28
|
Bratengeier K, Gainey MB, Flentje M. Fast IMRT by increasing the beam number and reducing the number of segments. Radiat Oncol 2011; 6:170. [PMID: 22152490 PMCID: PMC3377925 DOI: 10.1186/1748-717x-6-170] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 12/09/2011] [Indexed: 11/10/2022] Open
Abstract
PURPOSE The purpose of this work is to develop fast deliverable step and shoot IMRT technique. A reduction in the number of segments should theoretically be possible, whilst simultaneously maintaining plan quality, provided that the reduction is accompanied by an increased number of gantry angles. A benefit of this method is that the segment shaping could be performed during gantry motion, thereby reducing the delivery time. The aim was to find classes of such solutions whose plan quality can compete with conventional IMRT. MATERIALS/METHODS A planning study was performed. Step and shoot IMRT plans were created using direct machine parameter optimization (DMPO) as a reference. DMPO plans were compared to an IMRT variant having only one segment per angle ("2-Step Fast"). 2-Step Fast is based on a geometrical analysis of the topology of the planning target volume (PTV) and the organs at risk (OAR). A prostate/rectum case, spine metastasis/spinal cord, breast/lung and an artificial PTV/OAR combination of the ESTRO-Quasimodo phantom were used for the study. The composite objective value (COV), a quality score, and plan delivery time were compared. The delivery time for the DMPO reference plan and the 2-Step Fast IMRT technique was measured and calculated for two different linacs, a twelve year old Siemens Primus™ ("old" linac) and two Elekta Synergy™ "S" linacs ("new" linacs). RESULTS 2-Step Fast had comparable or better quality than the reference DMPO plan. The number of segments was smaller than for the reference plan, the number of gantry angles was between 23 and 34. For the modern linac the delivery time was always smaller than that for the reference plan. The calculated (measured) values showed a mean delivery time reduction of 21% (21%) for the new linac, and of 7% (3%) for the old linac compared to the respective DMPO reference plans. For the old linac, the data handling time per beam was the limiting factor for the treatment time reduction. CONCLUSIONS 2-Step Fast plans are suited to reduce the delivery time, especially if the data handling time per beam is short. The plan quality can be retained or even increased for fewer segments provided more gantry angles are used.
Collapse
Affiliation(s)
- Klaus Bratengeier
- University of Würzburg, Department of Radiation Oncology, Josef-Schneider-Str, 11, 97080 Würzburg, Germany.
| | | | | |
Collapse
|
29
|
Kuperman VY, Spradlin GS. Use of radiation protraction to escalate biologically effective dose to the treatment target. Med Phys 2011; 38:6553-60. [DOI: 10.1118/1.3656053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
30
|
Lohse I, Lang S, Hrbacek J, Scheidegger S, Bodis S, Macedo NS, Feng J, Lütolf UM, Zaugg K. Effect of high dose per pulse flattening filter-free beams on cancer cell survival. Radiother Oncol 2011; 101:226-32. [DOI: 10.1016/j.radonc.2011.05.072] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 05/22/2011] [Accepted: 05/26/2011] [Indexed: 11/25/2022]
|
31
|
Sun J, Chew TY, Meyer J. Two-step intensity modulated arc therapy (2-step IMAT) with segment weight and width optimization. Radiat Oncol 2011; 6:57. [PMID: 21631957 PMCID: PMC3130662 DOI: 10.1186/1748-717x-6-57] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 06/02/2011] [Indexed: 11/30/2022] Open
Abstract
Background 2-step intensity modulated arc therapy (IMAT) is a simplified IMAT technique which delivers the treatment over typically two continuous gantry rotations. The aim of this work was to implement the technique into a computerized treatment planning system and to develop an approach to optimize the segment weights and widths. Methods 2-step IMAT was implemented into the Prism treatment planning system. A graphical user interface was developed to generate the plan segments automatically based on the anatomy in the beam's-eye-view. The segment weights and widths of 2-step IMAT plans were subsequently determined in Matlab using a dose-volume based optimization process. The implementation was tested on a geometric phantom with a horseshoe shaped target volume and then applied to a clinical paraspinal tumour case. Results The phantom study verified the correctness of the implementation and showed a considerable improvement over a non-modulated arc. Further improvements in the target dose uniformity after the optimization of 2-step IMAT plans were observed for both the phantom and clinical cases. For the clinical case, optimizing the segment weights and widths reduced the maximum dose from 114% of the prescribed dose to 107% and increased the minimum dose from 87% to 97%. This resulted in an improvement in the homogeneity index of the target dose for the clinical case from 1.31 to 1.11. Additionally, the high dose volume V105 was reduced from 57% to 7% while the maximum dose in the organ-at-risk was decreased by 2%. Conclusions The intuitive and automatic planning process implemented in this study increases the prospect of the practical use of 2-step IMAT. This work has shown that 2-step IMAT is a viable technique able to achieve highly conformal plans for concave target volumes with the optimization of the segment weights and widths. Future work will include planning comparisons of the 2-step IMAT implementation with fixed gantry intensity modulated radiotherapy (IMRT) and commercial IMAT implementations.
Collapse
Affiliation(s)
- Jidi Sun
- Department of Physics & Astronomy, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | | | | |
Collapse
|
32
|
Acharya S, Bhat NN, Joseph P, Sanjeev G, Sreedevi B, Narayana Y. Dose rate effect on micronuclei induction in human blood lymphocytes exposed to single pulse and multiple pulses of electrons. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2011; 50:253-263. [PMID: 21259020 DOI: 10.1007/s00411-011-0353-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 01/07/2011] [Indexed: 05/30/2023]
Abstract
The effects of single pulses and multiple pulses of 7 MV electrons on micronuclei (MN) induction in cytokinesis-blocked human peripheral blood lymphocytes (PBLs) were investigated over a wide range of dose rates per pulse (instantaneous dose rate). PBLs were exposed to graded doses of 2, 3, 4, 6, and 8 Gy of single electron pulses of varying pulse widths at different dose rates per pulse, ranging from 1 × 10(6) Gy s(-1) to 3.2 × 10(8) Gy s(-1). Different dose rates per pulse were achieved by changing the dose per electron pulse by adjusting the beam current and pulse width. MN yields per unit absorbed dose after irradiation with single electron pulses were compared with those of multiple pulses of electrons. A significant decrease in the MN yield with increasing dose rates per pulse was observed, when dose was delivered by a single electron pulse. However, no reduction in the MN yield was observed when dose was delivered by multiple pulses of electrons. The decrease in the yield at high dose rates per pulse suggests possible radical recombination, which leads to decreased biological damage. Cellular response to the presence of very large numbers of chromosomal breaks may also alter the damage.
Collapse
Affiliation(s)
- Santhosh Acharya
- Department of Engineering Physics, Alva's Institute of Engineering and Technology, Moodbidri, 574225, India
| | | | | | | | | | | |
Collapse
|
33
|
McGarry CK, Butterworth KT, Trainor C, O'Sullivan JM, Prise KM, Hounsell AR. Temporal characterization and in vitro comparison of cell survival following the delivery of 3D-conformal, intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Phys Med Biol 2011; 56:2445-57. [PMID: 21427488 DOI: 10.1088/0031-9155/56/8/008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A phantom was designed and implemented for the delivery of treatment plans to cells in vitro. Single beam, 3D-conformal radiotherapy (3D-CRT) plans, inverse planned five-field intensity-modulated radiation therapy (IMRT), nine-field IMRT, single-arc volumetric modulated arc therapy (VMAT) and dual-arc VMAT plans were created on a CT scan of the phantom to deliver 3 Gy to the cell layer and verified using a Farmer chamber, 2D ionization chamber array and gafchromic film. Each plan was delivered to a 2D ionization chamber array to assess the temporal characteristics of the plan including delivery time and 'cell's eye view' for the central ionization chamber. The effective fraction time, defined as the percentage of the fraction time where any dose is delivered to each point examined, was also assessed across 120 ionization chambers. Each plan was delivered to human prostate cancer DU-145 cells and normal primary AGO-1522b fibroblast cells. Uniform beams were delivered to each cell line with the delivery time varying from 0.5 to 20.54 min. Effective fraction time was found to increase with a decreasing number of beams or arcs. For a uniform beam delivery, AGO-1552b cells exhibited a statistically significant trend towards increased survival with increased delivery time. This trend was not repeated when the different modulated clinical delivery methods were used. Less sensitive DU-145 cells did not exhibit a significant trend towards increased survival with increased delivery time for either the uniform or clinical deliveries. These results confirm that dose rate effects are most prevalent in more radiosensitive cells. Cell survival data generated from uniform beam deliveries over a range of dose rates and delivery times may not always be accurate in predicting response to more complex delivery techniques, such as IMRT and VMAT.
Collapse
Affiliation(s)
- Conor K McGarry
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, UK.
| | | | | | | | | | | |
Collapse
|
34
|
Butterworth KT, McGarry CK, Trainor C, O'Sullivan JM, Hounsell AR, Prise KM. Out-of-field cell survival following exposure to intensity-modulated radiation fields. Int J Radiat Oncol Biol Phys 2011; 79:1516-22. [PMID: 21277116 DOI: 10.1016/j.ijrobp.2010.11.034] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 11/02/2010] [Accepted: 11/04/2010] [Indexed: 10/18/2022]
Abstract
PURPOSE To determine the in-field and out-of-field cell survival of cells irradiated with either primary field or scattered radiation in the presence and absence of intercellular communication. METHODS AND MATERIALS Cell survival was determined by clonogenic assay in human prostate cancer (DU145) and primary fibroblast (AGO1552) cells following exposure to different field configurations delivered using a 6-MV photon beam produced with a Varian linear accelerator. RESULTS Nonuniform dose distributions were delivered using a multileaf collimator (MLC) in which half of the cell population was shielded. Clonogenic survival in the shielded region was significantly lower than that predicted from the linear quadratic model. In both cell lines, the out-of-field responses appeared to saturate at 40%-50% survival at a scattered dose of 0.70 Gy in DU-145 cells and 0.24 Gy in AGO1522 cells. There was an approximately eightfold difference in the initial slopes of the out-of-field response compared with the α-component of the uniform field response. In contrast, cells in the exposed part of the field showed increased survival. These observations were abrogated by direct physical inhibition of cellular communication and by the addition of the inducible nitric oxide synthase inhibitor aminoguanidine known to inhibit intercellular bystander effects. Additional studies showed the proportion of cells irradiated and dose delivered to the shielded and exposed regions of the field to impact on response. CONCLUSIONS These data demonstrate out-of-field effects as important determinants of cell survival following exposure to modulated irradiation fields with cellular communication between differentially irradiated cell populations playing an important role. Validation of these observations in additional cell models may facilitate the refinement of existing radiobiological models and the observations considered important determinants of cell survival.
Collapse
Affiliation(s)
- Karl T Butterworth
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom.
| | | | | | | | | | | |
Collapse
|
35
|
Bratengeier K, Gainey M, Sauer OA, Richter A, Flentje M. Fast intensity-modulated arc therapy based on 2-step beam segmentation. Med Phys 2010; 38:151-65. [DOI: 10.1118/1.3523602] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
36
|
Ebert MA, Suchowerska N, Jackson MA, McKenzie DR. A mathematical framework for separating the direct and bystander components of cellular radiation response. Acta Oncol 2010; 49:1334-43. [PMID: 20507257 DOI: 10.3109/0284186x.2010.487874] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
UNLABELLED A mathematical model for fractional tumor cell survival was developed incorporating components of cell killing due to direct radiation interactions and bystander signals resulting from non-local dose deposition. MATERIAL AND METHODS Three possible mechanisms for signal production were tested by fitting predictions to available experimental results for tumor cells (non-small cell lung cancer NCI-H460 and melanoma MM576) exposed to gradient x-ray fields. The parameter fitting allowed estimation of the contribution of bystander signaling to cell death (20-50% for all models). Separation of the two components of cell killing allowed determination of the α and β parameters of the linear-quadratic model both with and without the presence of bystander signaling. RESULTS AND DISCUSSION For both cell lines, cell death from bystander signaling and direct radiation interactions were comparable. For NCI-H460 cells, the values for α and β were 0.18 Gy⁻¹ and 0.10 Gy⁻² respectively when direct and bystander effects were combined, and 0.053 Gy⁻¹ and 0.061 Gy⁻² respectively when the signaling component was removed. For MM576, the corresponding respective values were 0.09 Gy⁻¹ and 0.011 Gy⁻² for the combined response, and 0.014 Gy⁻¹ and 0.002 Gy⁻² for the isolated direct radiation response. The bystander component in cell death was found to be significant and should not be ignored. Further experimental evidence is required to determine how these results translate to the in vivo situation where tumor control probability (TCP) models that currently assume cellular independence may need to be revised.
Collapse
Affiliation(s)
- Martin A Ebert
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Western Australia, Australia.
| | | | | | | |
Collapse
|
37
|
Suchowerska N, Ebert MA, McKenzie DR, Jackson M. A review of in vitro experimental evidence for the effect of spatial and temporal modulation of radiation dose on response. Acta Oncol 2010; 49:1344-53. [PMID: 20553097 DOI: 10.3109/0284186x.2010.489570] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Intensity modulated radiation therapy introduces strong spatial and temporal modulation of the dose delivery that may have therapeutic benefits, as yet unrealized. MATERIAL AND METHODS Experimental evidence for spatial and temporal modulation affecting the cell survival following in vitro irradiation has been derived using clonogenic assays. RESULTS AND DISCUSSION The experimental results show that the survival status of a cell is strongly influenced by the spatial dose modulation. The classical bystander effect of decreased survival has now been supplemented by observations of increased survival, which may result from the same or different signaling mechanisms. Temporal dose modulation experiments show that dose protraction significantly increases cell survival. An appropriate choice of temporal dose modulation pattern enables cell death to be maximized or minimized for a constant dose and delivery time. CONCLUSION Bystander effects challenge the assumption that outcome is solely dependent on local dose. Intra-fractional temporal modulation via protracted treatments and time varying dose delivery both affect the cell survival. The presence of bystander and temporal effects emphasize the need for a mathematical framework which incorporates their influence on cell survival.
Collapse
Affiliation(s)
- Natalka Suchowerska
- Department of Radiation Oncology, Royal Prince Alfred Hospital, New South Wales, Australia.
| | | | | | | |
Collapse
|
38
|
Rao M, Yang W, Chen F, Sheng K, Ye J, Mehta V, Shepard D, Cao D. Comparison of Elekta VMAT with helical tomotherapy and fixed field IMRT: plan quality, delivery efficiency and accuracy. Med Phys 2010; 37:1350-9. [PMID: 20384272 DOI: 10.1118/1.3326965] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PURPOSE Helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) are arc-based approaches to IMRT delivery. The objective of this study is to compare VMAT to both HT and fixed field IMRT in terms of plan quality, delivery efficiency, and accuracy. METHODS Eighteen cases including six prostate, six head-and-neck, and six lung cases were selected for this study. IMRT plans were developed using direct machine parameter optimization in the Pinnacle3 treatment planning system. HT plans were developed using a Hi-Art II planning station. VMAT plans were generated using both the Pinnacle3 SmartArc IMRT module and a home-grown arc sequencing algorithm. VMAT and HT plans were delivered using Elekta's PreciseBeam VMAT linac control system (Elekta AB, Stockholm, Sweden) and a TomoTherapy Hi-Art II system (TomoTherapy Inc., Madison, WI), respectively. Treatment plan quality assurance (QA) for VMAT was performed using the IBA MatriXX system while an ion chamber and films were used for HT plan QA. RESULTS The results demonstrate that both VMAT and HT are capable of providing more uniform target doses and improved normal tissue sparing as compared with fixed field IMRT. In terms of delivery efficiency, VMAT plan deliveries on average took 2.2 min for prostate and lung cases and 4.6 min for head-and-neck cases. These values increased to 4.7 and 7.0 min for HT plans. CONCLUSIONS Both VMAT and HT plans can be delivered accurately based on their own QA standards. Overall, VMAT was able to provide approximately a 40% reduction in treatment time while maintaining comparable plan quality to that of HT.
Collapse
Affiliation(s)
- Min Rao
- Department of Radiation Oncology, Swedish Cancer Institute, 1221 Madison St., Seattle, Washington 98104, USA
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Dose rate effect of pulsed electron beam on micronucleus frequency in human peripheral blood lymphocytes. Arh Hig Rada Toksikol 2010; 61:77-83. [PMID: 20338871 DOI: 10.2478/10004-1254-61-2010-1982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The micronucleus assay in human peripheral blood lymphocytes is a sensitive indicator of radiation damage and could serve as a biological dosimeter in evaluating suspected overexposure to ionising radiation. Micronucleus (MN) frequency as a measure of chromosomal damage has also extensively been employed to quantify the effects of radiation dose rate on biological systems. Here we studied the effects of 8 MeV pulsed electron beam emitted by Microtron electron accelerator on MN induction at dose rates between 35 Gy min-1 and 352.5 Gy min-1. These dose rates were achieved by varying the pulse repetition rate (PRR). Fricke dosimeter was employed to measure the absorbed dose at different PRR and to ensure uniform dose distribution of the electron beam. To study the dose rate effect, blood samples were irradiated to an absorbed dose of (4.7+/-0.2) Gy at different rates and cytogenetic damage was quantified using the micronucleus assay. The obtained MN frequency showed no dose rate dependence within the studied dose rate range. Our earlier dose effect study using 8 MeV electrons revealed that the response of MN was linear-quadratic. Therefore, in the event of an accident, dose estimation can be made using linear-quadratic dose response parameters, without adding dose rate as a correction factor.
Collapse
|
40
|
Butterworth KT, McGarry CK, O'Sullivan JM, Hounsell AR, Prise KM. A study of the biological effects of modulated 6 MV radiation fields. Phys Med Biol 2010; 55:1607-18. [PMID: 20164535 PMCID: PMC2855955 DOI: 10.1088/0031-9155/55/6/005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The delivery of spatially modulated radiation fields has been shown to impact on in vitro cell survival responses. To study the effect of modulated fields on cell survival, dose response curves were determined for human DU-145 prostate, T98G glioma tumour cells and normal primary AGO-1552 fibroblast cells exposed to modulated and non-modulated field configurations delivered using a 6 MV Linac with multi-leaf collimator. When exposed to uniform fields delivered as a non-modulated or modulated configuration, no significant differences in survival were observed with the exception of DU-145 cells at a dose of 8 Gy (p = 0.024). Survival responses were determined for exposure to non-uniform-modulated beams in DU-145 and T98G and showed no deviation from the survival response observed following uniform non-modulated exposures. The results of these experiments indicate no major deviation in response to modulated fields compared to uniform exposures.
Collapse
Affiliation(s)
- Karl T Butterworth
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland, UK.
| | | | | | | | | |
Collapse
|
41
|
Palma DA, Verbakel WFAR, Otto K, Senan S. New developments in arc radiation therapy: a review. Cancer Treat Rev 2010; 36:393-9. [PMID: 20181430 DOI: 10.1016/j.ctrv.2010.01.004] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/14/2010] [Accepted: 01/24/2010] [Indexed: 12/01/2022]
Abstract
Arc therapies have gained widespread clinical interest in radiation oncology over the past decade. Arc therapies have several potential advantages over standard techniques such as intensity-modulated radiation therapy, with implications for patients, administrators, and oncologists. This review focuses on the rationale for arc therapy, descriptions of the modern arc techniques that are currently clinically available, and highlights some distinguishing features of arc therapies, such as dose distributions, treatment times, and imaging capabilities. Arc therapies are exciting examples of progress in radiotherapy through technological innovation, aimed at ultimately improving the therapeutic ratio for patients receiving radiation.
Collapse
Affiliation(s)
- David A Palma
- Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
| | | | | | | |
Collapse
|
42
|
Abate A, Pressello MC, Benassi M, Strigari L. Comparison of IMRT planning with two-step and one-step optimization: a strategy for improving therapeutic gain and reducing the integral dose. Phys Med Biol 2009; 54:7183-98. [PMID: 19920309 DOI: 10.1088/0031-9155/54/23/010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this study was to evaluate the effectiveness and efficiency in inverse IMRT planning of one-step optimization with the step-and-shoot (SS) technique as compared to traditional two-step optimization using the sliding windows (SW) technique. The Pinnacle IMRT TPS allows both one-step and two-step approaches. The same beam setup for five head-and-neck tumor patients and dose-volume constraints were applied for all optimization methods. Two-step plans were produced converting the ideal fluence with or without a smoothing filter into the SW sequence. One-step plans, based on direct machine parameter optimization (DMPO), had the maximum number of segments per beam set at 8, 10, 12, producing a directly deliverable sequence. Moreover, the plans were generated whether a split-beam was used or not. Total monitor units (MUs), overall treatment time, cost function and dose-volume histograms (DVHs) were estimated for each plan. PTV conformality and homogeneity indexes and normal tissue complication probability (NTCP) that are the basis for improving therapeutic gain, as well as non-tumor integral dose (NTID), were evaluated. A two-sided t-test was used to compare quantitative variables. All plans showed similar target coverage. Compared to two-step SW optimization, the DMPO-SS plans resulted in lower MUs (20%), NTID (4%) as well as NTCP values. Differences of about 15-20% in the treatment delivery time were registered. DMPO generates less complex plans with identical PTV coverage, providing lower NTCP and NTID, which is expected to reduce the risk of secondary cancer. It is an effective and efficient method and, if available, it should be favored over the two-step IMRT planning.
Collapse
Affiliation(s)
- A Abate
- Laboratory of Medical Physics and Expert Systems, Regina Elena National Cancer Institute, Rome, Italy
| | | | | | | |
Collapse
|
43
|
Altman MB, Stinauer MA, Javier D, Smith BD, Herman LC, Pytynia ML, Aydogan B, Pelizzari CA, Chmura SJ, Roeske JC. Validation of temporal optimization effects for a single fraction of radiation in vitro. Int J Radiat Oncol Biol Phys 2009; 75:1240-6. [PMID: 19857787 DOI: 10.1016/j.ijrobp.2009.06.076] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2009] [Revised: 05/06/2009] [Accepted: 06/18/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE To experimentally validate how temporal modification of the applied dose pattern within a single fraction of radiation therapy affects cell survival. METHOD AND MATERIALS Using the linear-quadratic model, we have previously demonstrated that the greatest difference in cell survival results from comparing a temporal dose pattern delivering the highest doses during the middle of a fraction and the lowest at the beginning and end ("Triangle") to one with the lowest doses at the middle and the highest at the beginning and end ("V-shaped"). Also, these differences would be greatest in situations with low alpha/beta and large dose/fraction and fraction length. Two low (WiDr, PC-3) and one high (SQ-20B) alpha/beta cell lines were irradiated in six-well plates with 900 cGy over 20 min (900 cGy/20 min), one each with a Triangle and V-shaped dose pattern. WiDr cells were subjected to the same experiments with first 180 cGy/20 min, then 900 cGy/5 min. Cell survival was assessed using the clonogenic assay. RESULTS At 900 cGy/20 min, irradiation with a V-shaped pattern resulted in an increased survival compared with use of a Triangle pattern of 21.2% for WiDr (p < 0.01), 18.6% for PC-3 (p < 0.025), and 4.7% for SQ-20B cells (p > 0.05). For WiDr cells at 180 cGy/20 min, this increase reduced to 2.7% (p > 0.05) and to -0.8% (p > 0.05) at 900 cGy/5 min. CONCLUSIONS These results verify the assertions of the modeling study in vitro, and imply that the temporal pattern of applied dose should be considered in treatment planning and delivery.
Collapse
Affiliation(s)
- Michael B Altman
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60657, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Yang W, Wang L, Larner J, Read P, Benedict S, Sheng K. Tumor cell survival dependence on helical tomotherapy, continuous arc and segmented dose delivery. Phys Med Biol 2009; 54:6635-43. [DOI: 10.1088/0031-9155/54/21/013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
45
|
Verbakel WFAR, Senan S, Lagerwaard FJ, Cuijpers JP, Slotman BJ. Comments on ‘Single-Arc IMRT?’. Phys Med Biol 2009; 54:L31-4; author reply L35-6. [DOI: 10.1088/0031-9155/54/8/l01] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
46
|
Blockhuys S, Vanhoecke B, Paelinck L, Bracke M, De Wagter C. Development ofin vitromodels for investigating spatially fractionated irradiation: physics and biological results. Phys Med Biol 2009; 54:1565-78. [DOI: 10.1088/0031-9155/54/6/011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|