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Janssen J, Staal F, Langendijk J, Both S, Brouwer C, Aluwini S. Pelvic lymph node motion during cone-beam computed tomography guided stereotactic radiotherapy. Clin Transl Radiat Oncol 2024; 47:100794. [PMID: 38798748 PMCID: PMC11127188 DOI: 10.1016/j.ctro.2024.100794] [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: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 05/29/2024] Open
Abstract
Background and purpose Stereotactic body radiotherapy (SBRT) is increasingly applied for pelvic lymph node recurrence. Thus far, knowledge on pelvic lymph node motion during CBCT-guided SBRT is lacking and the applied margins vary between institutions. This study evaluated pelvic lymph node motion during CBCT-guided SBRT and assessed the currently applied PTV margins of 3 and 5 mm. Material and methods In total, 45 pelvic lymph node metastases were included. One observer delineated 45 GTVs on planning CT, 224 GTVs on pre-fraction and 216 on post-fraction CBCT. The GTV centroid coordinates were derived from all images for inter- and intrafraction motion analysis. Additionally, we assessed the influence of treatment time and lesion location on lesion motion. The expected coverage of a 3-mm and 5-mm PTV margin was assessed using the inclusiveness index for GTVs on pre- and post-fraction CBCT. Results Lymph node interfraction motion was limited to 5 mm in 96-97 % of fractions for all translational directions and intrafraction lesion motion was limited to 3 mm in 97-100 % of fractions. Para-rectal lesions (11 %) were associated with significantly larger inter- and intrafraction motion compared to other pelvic locations and treatment duration showed no correlation with lesion motion. The mean (sd) lesion inclusiveness index was 99 % (5 %) for the 5-mm PTV margin and 96 % (9 %) for the 3-mm margin. Conclusion Pelvic lymph node motion during CBCT-guided stereotactic radiotherapy was within the widely applied PTV margin of 5 mm, providing an opportunity to reduce this margin for pelvic lymph node SBRT.
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Affiliation(s)
- J. Janssen
- Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - F.H.E. Staal
- Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - J.A. Langendijk
- Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - S. Both
- Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - C.L. Brouwer
- Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - S. Aluwini
- Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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Murr M, Bernchou U, Bubula-Rehm E, Ruschin M, Sadeghi P, Voet P, Winter JD, Yang J, Younus E, Zachiu C, Zhao Y, Zhong H, Thorwarth D. A multi-institutional comparison of retrospective deformable dose accumulation for online adaptive magnetic resonance-guided radiotherapy. Phys Imaging Radiat Oncol 2024; 30:100588. [PMID: 38883145 PMCID: PMC11176923 DOI: 10.1016/j.phro.2024.100588] [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: 01/16/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 06/18/2024] Open
Abstract
Background and Purpose Application of different deformable dose accumulation (DDA) solutions makes institutional comparisons after online-adaptive magnetic resonance-guided radiotherapy (OA-MRgRT) challenging. The aim of this multi-institutional study was to analyze accuracy and agreement of DDA-implementations in OA-MRgRT. Material and Methods One gold standard (GS) case deformed with a biomechanical-model and five clinical cases consisting of prostate (2x), cervix, liver, and lymph node cancer, treated with OA-MRgRT, were analyzed. Six centers conducted DDA using institutional implementations. Deformable image registration (DIR) and DDA results were compared using the contour metrics Dice Similarity Coefficient (DSC), surface-DSC, Hausdorff-distance (HD95%), and accumulated dose-volume histograms (DVHs) analyzed via intraclass correlation coefficient (ICC) and clinical dosimetric criteria (CDC). Results For the GS, median DDA errors ranged from 0.0 to 2.8 Gy across contours and implementations. DIR of clinical cases resulted in DSC > 0.8 for up to 81.3% of contours and a variability of surface-DSC values depending on the implementation. Maximum HD95%=73.3 mm was found for duodenum in the liver case. Although DVH ICC > 0.90 was found after DDA for all but two contours, relevant absolute CDC differences were observed in clinical cases: Prostate I/II showed maximum differences in bladder V28Gy (10.2/7.6%), while for cervix, liver, and lymph node the highest differences were found for rectum D2cm3 (2.8 Gy), duodenum Dmax (7.1 Gy), and rectum D0.5cm3 (4.6 Gy). Conclusion Overall, high agreement was found between the different DIR and DDA implementations. Case- and algorithm-dependent differences were observed, leading to potentially clinically relevant results. Larger studies are needed to define future DDA-guidelines.
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Affiliation(s)
- Martina Murr
- Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany
| | - Uffe Bernchou
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
- Laboratory of Radiation Physics, Odense University Hospital, Denmark
| | | | - Mark Ruschin
- Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
| | - Parisa Sadeghi
- Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | | | - Jeff D Winter
- Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
| | - Jinzhong Yang
- Department of Radiation Physics, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Eyesha Younus
- Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Radiation Oncology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Cornel Zachiu
- University Medical Centre Utrecht, Department of Radiotherapy, 3584 CX Utrecht, the Netherlands
| | - Yao Zhao
- Department of Radiation Physics, the University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Hualiang Zhong
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Daniela Thorwarth
- Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany
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Yen A, Shen C, Albuquerque K. The New Kid on the Block: Online Adaptive Radiotherapy in the Treatment of Gynecologic Cancers. Curr Oncol 2023; 30:865-874. [PMID: 36661715 PMCID: PMC9857810 DOI: 10.3390/curroncol30010066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/23/2022] [Accepted: 01/06/2023] [Indexed: 01/11/2023] Open
Abstract
Online adaptive radiation is a new and exciting modality of treatment for gynecologic cancers. Traditional radiation treatments deliver the same radiation plan to cancers with large margins. Improvements in imaging, technology, and artificial intelligence have made it possible to account for changes between treatments and improve the delivery of radiation. These advances can potentially lead to significant benefits in tumor coverage and normal tissue sparing. Gynecologic cancers can uniquely benefit from this technology due to the significant changes in bladder, bowel, and rectum between treatments as well as the changes in tumors commonly seen between treatments. Preliminary studies have shown that online adaptive radiation can maintain coverage of the tumor while sparing nearby organs. Given these potential benefits, numerous clinical trials are ongoing to investigate the clinical benefits of online adaptive radiotherapy. Despite the benefits, implementation of online adaptive radiotherapy requires significant clinical resources. Additionally, the timing and workflow for online adaptive radiotherapy is being optimized. In this review, we discuss the history and evolution of radiation techniques, the logistics and implementation of online adaptive radiation, and the potential benefits of online adaptive radiotherapy for gynecologic cancers.
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Affiliation(s)
| | | | - Kevin Albuquerque
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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UroLift implants as surrogate fiducial markers for cone-beam CT-based prostate image-guided radiotherapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2023. [DOI: 10.1017/s1460396923000092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Abstract
Introduction:
UroLift implants are a novel treatment for the obstructive lower urinary tract symptoms arising from benign prostatic hyperplasia. This case study aimed to assess their effectiveness as fiducial marker (FM) surrogates in prostate image-guided radiotherapy (IGRT).
Method:
Cone-beam CT images from a patient receiving prostate radiation therapy underwent manual alignment using UroLift implants and also prostate soft-tissue matching by five experienced therapeutic radiographers. The match values of both methods were compared using Bland–Altman analysis. All five observers were also asked to score the ease of matching using both approaches.
Results:
The 95% mean level of agreement for the UroLift matches were within a 2-mm threshold in all dimensions. Comparison of UroLift and prostate matches had 95% limit of agreement values of −0·98 to 1·78, −0·58 to 0·49 and −1·83 to 1·04 mm in the vertical, longitudinal and lateral planes, respectively. All of the UroLift matches were rated as ‘very easy’ or ‘possible with little difficulty’ by the five observers.
Conclusion:
A small difference between the CBCT UroLift and CBCT prostate match was found. It has been shown that IGRT to the prostate with the aid of the UroLift system implants and CBCT is feasible and can eliminate the need for FM implants. Wider evaluation in a large cohort is recommended.
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Pokhrel D, Webster A, Stephen J, St Clair W. SBRT treatment of abdominal and pelvic oligometastatic lymph nodes using ring-mounted Halcyon Linac. J Appl Clin Med Phys 2021; 22:162-171. [PMID: 34032367 PMCID: PMC8200515 DOI: 10.1002/acm2.13268] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 03/18/2021] [Accepted: 04/14/2021] [Indexed: 12/31/2022] Open
Abstract
PURPOSE/OBJECTIVES This work seeks to evaluate the plan quality, treatment delivery efficiency, and accuracy of single-isocenter volumetric modulated arc therapy (VMAT) of abdominal/pelvic oligometastatic lymph nodes (LNs) stereotactic body radiation therapy (SBRT) on Halcyon Linac. MATERIALS AND METHODS After completing the in-house multitarget end-to-end phantom testing and independent dose verification using MD Anderson's single-isocenter/multi-target (lung and spine target inserts) thorax phantom, eight patients with two to three abdominal/pelvic oligometastatic LNs underwent highly conformal single-isocenter VMAT-SBRT treatment using the Halcyon Linac 6MV flattening filter free (FFF) beam. Targets were identified using an Axumin PET/CT scan co-registered with planning CT images and a single-isocenter was placed between/among the targets. Doses between 25 and 36.25 Gy in 5 fractions were delivered. Patients were treated every other day. Plans were calculated in Eclipse with advanced AcurosXB algorithm for heterogeneity corrections. For comparison, Halcyon VMAT-SBRT plans were retrospectively generated for SBRT-dedicated TrueBeam with a 6MV-FFF beam using identical planning geometry and objectives. Target coverage, conformity index (CI), dose to 2 cm away from each target (D2cm) and dose to adjacent organs-at-risk (OAR) were evaluated. Additionally, various treatment delivery parameters including beam-on time were recorded. RESULTS Phantom measurements showed acceptable spatial accuracy of conebeam CT-guided Halcyon SBRT treatments including compliance with MD Anderson's single-isocenter/multi-targets phantom credentialing results. For patients, the mean isocenter to tumor center distance was 3.4 ± 1.2 cm (range, 1.5-4.8 cm). The mean combined PTV was 18.9 ± 10.9 cc (range, 5.6-39.5 cc). There was no clinically significant difference in dose to LNs, CI, D2cm and maximal doses to OAR between single-isocenter Halcyon and Truebeam VMAT-SBRT plans, although, Halcyon plans provided preferably lower maximal dose to adjacent OAR. Additionally, total monitor units, beam-on time and overall treatment time was lower with Halcyon plans. Halcyon's portal dosimetry demonstrated a high pass rate of 98.1 ± 1.6% for clinical gamma passing criteria of 2%/2 mm. CONCLUSION SBRT treatment of abdominal/pelvic oligometastatic LNs with single-isocenter VMAT on Halcyon was dosimetrically equivalent to TrueBeam. Faster treatment delivery to oligometastatic LNs via single-isocenter Halcyon VMAT can improve clinic workflow and patient compliance, potentially reducing intrafraction motion errors for well-suited patients. Clinical follow-up of these patients is ongoing.
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Affiliation(s)
- Damodar Pokhrel
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
| | - Aaron Webster
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
| | - Joseph Stephen
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
| | - William St Clair
- Medical Physics Graduate ProgramDepartment of Radiation MedicineUniversity of KentuckyLexingtonKYUSA
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Björeland U, Nyholm T, Jonsson J, Skorpil M, Blomqvist L, Strandberg S, Riklund K, Beckman L, Thellenberg-Karlsson C. Impact of neoadjuvant androgen deprivation therapy on magnetic resonance imaging features in prostate cancer before radiotherapy. PHYSICS & IMAGING IN RADIATION ONCOLOGY 2021; 17:117-123. [PMID: 33898790 PMCID: PMC8058024 DOI: 10.1016/j.phro.2021.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 01/19/2021] [Accepted: 01/19/2021] [Indexed: 01/01/2023]
Abstract
Background and purpose In locally advanced prostate cancer (PC), androgen deprivation therapy (ADT) in combination with whole prostate radiotherapy (RT) is the standard treatment. ADT affects the prostate as well as the tumour on multiparametric magnetic resonance imaging (MRI) with decreased PC conspicuity and impaired localisation of the prostate lesion. Image texture analysis has been suggested to be of aid in separating tumour from normal tissue. The aim of the study was to investigate the impact of ADT on baseline defined MRI features in prostate cancer with the goal to investigate if it might be of use in radiotherapy planning. Materials and methods Fifty PC patients were included. Multiparametric MRI was performed before, and three months after ADT. At baseline, a tumour volume was delineated on apparent diffusion coefficient (ADC) maps with suspected tumour content and a reference volume in normal prostatic tissue. These volumes were transferred to MRIs after ADT and were analysed with first-order -and invariant Haralick -features. Results At baseline, the median value and several of the invariant Haralick features of ADC, showed a significant difference between tumour and reference volumes. After ADT, only ADC median value could significantly differentiate the two volumes. Conclusions Invariant Haralick -features could not distinguish between baseline MRI defined PC and normal tissue after ADT. First-order median value remained significantly different in tumour and reference volumes after ADT, but the difference was less pronounced than before ADT.
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Affiliation(s)
- Ulrika Björeland
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
- Corresponding author at: Department of Medical Physics, Sundsvall Hospital, 85186 Sundsvall, Sweden.
| | - Tufve Nyholm
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Joakim Jonsson
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Mikael Skorpil
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Lennart Blomqvist
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Sara Strandberg
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Katrine Riklund
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
| | - Lars Beckman
- Department of Radiation Sciences, Umeå University, Umeå, Sweden
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Bell LJ, Eade T, Hruby G, Bromley R, Kneebone A. Intra-fraction displacement of the prostate bed during post-prostatectomy radiotherapy. Radiat Oncol 2021; 16:20. [PMID: 33482863 PMCID: PMC7821719 DOI: 10.1186/s13014-020-01743-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 12/26/2020] [Indexed: 11/30/2022] Open
Abstract
Background To measure intra-fraction displacement (IFD) in post-prostatectomy patients treated with anisotropic margins and daily soft tissue matching. Methods Pre-treatment cone beam computed tomography (CBCT) scans were acquired daily and post-treatment CBCTs for the first week then weekly on 46 patients. The displacement between the scans was calculated retrospectively to measure IFD of the prostate bed (PB). The marginal miss (MM) rate, and the effect of time between imaging was assessed. Results A total of 392 post-treatment CBCT’s were reviewed from 46 patients. The absolute mean (95% CI) IFD was 1.5 mm (1.3–1.7 mm) in the AP direction, 1.0 mm (0.9–1.2 mm) SI, 0.8 mm (0.7–0.9 mm) LR, and 2.4 mm (2.2–2.5 mm) 3D displacement. IFD ≥ ± 3 mm and ≥ ± 5 mm was 24.7% and 5.4% respectively. MM of the PB was detected in 33 of 392 post-treatment CBCT (8.4%) and lymph nodes in 6 of 211 post-treatment CBCT images (2.8%). Causes of MM due to IFD included changes in the bladder (87.9%), rectum (66.7%) and buttock muscles (6%). A time ≥ 9 min between the pre and post-treatment CBCT demonstrated that movement ≥ 3 mm and 5 mm increased from 19.2 to 40.5% and 5 to 8.1% respectively. Conclusions IFD during PB irradiation was typically small, but was a major contributor to an 8.4% MM rate when using daily soft tissue match and tight anisotropic margins.
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Affiliation(s)
- Linda J Bell
- Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.
| | - Thomas Eade
- Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.,Northern Clinical School, University of Sydney, St Leonards, NSW, 2065, Australia
| | - George Hruby
- Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.,Northern Clinical School, University of Sydney, St Leonards, NSW, 2065, Australia
| | - Regina Bromley
- Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia
| | - Andrew Kneebone
- Northern Sydney Cancer Centre, Radiation Oncology Department, Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.,Northern Clinical School, University of Sydney, St Leonards, NSW, 2065, Australia
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Target coverage and dose criteria based evaluation of the first clinical 1.5T MR-linac SBRT treatments of lymph node oligometastases compared with conventional CBCT-linac treatment. Radiother Oncol 2020; 146:118-125. [PMID: 32146257 DOI: 10.1016/j.radonc.2020.02.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 02/13/2020] [Accepted: 02/13/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND PURPOSE Patients were treated at our institute for single and multiple lymph node oligometastases on the 1.5T MR-linac since August 2018. The superior soft-tissue contrast and additional software features of the MR-linac compared to CBCT-linacs allow for online adaptive treatment planning. The purpose of this study was to perform a target coverage and dose criteria based evaluation of the clinically delivered online adaptive radiotherapy treatment compared with conventional CBCT-linac treatment. MATERIALS AND METHODS Patient data was used from 14 patients with single lymph node oligometastases and 6 patients with multiple (2-3) metastases. All patients were treated on the 1.5T MR-linac with a prescribed dose of 5 × 7 Gy to 95% of the PTV and a CBCT-linac plan was created for each patient. The difference in target coverage between these plans was compared and plans were evaluated based on dose criteria for each fraction after calculating the CBCT-plan on the daily anatomy. The GTV coverage was evaluated based on the online planning and the post-delivery MRI. RESULTS For both single and multiple lymph node oligometastases the GTV V35Gy had a median value of 100% for both the MR-linac plans and CBCT-plans pre- and post-delivery and did not significantly differ. The percentage of plans that met all dose constraints was improved from 19% to 84% and 20% to 67% for single and multiple lymph node cases, respectively. CONCLUSION Target coverage and dose criteria based evaluation of the first clinical 1.5T MR-linac SBRT treatments of lymph node oligometastases compared with conventional CBCT-linac treatment shows a smaller amount of unplanned violations of high dose criteria. The GTV coverage was comparable. Benefit is primarily gained in patients treated for multiple lymph node oligometastases: geometrical deformations are accounted for, dose can be delivered in one plan and margins can be reduced.
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Bell LJ, Eade T, Hruby G, Bromley R, Kneebone A. Implementing daily soft tissue image guidance with reduced margins for post-prostatectomy radiotherapy: research-based changes to clinical practice. J Med Radiat Sci 2019; 66:259-268. [PMID: 31680490 PMCID: PMC6920694 DOI: 10.1002/jmrs.362] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 08/15/2019] [Accepted: 09/29/2019] [Indexed: 01/04/2023] Open
Abstract
INTRODUCTION We have previously demonstrated that daily soft tissue matching with reduced anisotropic margins provides an ideal balance between prostate bed coverage and meeting organ at risk constraints. The aim of this study was to evaluate the implementation of this approach in clinical practice. METHODS Thirty-eight radiation therapists (RTs) completed offline IGRT training involving six patients. After training was completed, this approach was implemented clinically. The first 24 patients were evaluated with a central review of match displacements and geographic miss (GM). An assessment of treatment times and planning parameters was also performed. RESULTS During offline training, the anterior-posterior (AP) match discrepancy had the largest mean variation ranging from -0.46 to 0.06 cm and undetected geographic miss occurred in 17% of alignments. The mean time taken to treat the first 24 patients ranged from 12.2 to 20.6 min. The smaller anisotropic margin resulted in similar target coverage but achieved reduced doses to the bladder (V65Gy from 36% to 27%, V40Gy from 54% to 51%) and rectum (V65Gy from 20% to 19%, V60Gy from 27% to 24%, V40Gy from 42% to 38%). The matches of 806 CBCT images in 24 patients were reviewed. The mean match ranged from -0.12 to 0.17 cm AP, -0.14 to 0.14 cm superior-inferior (SI) and -0.04 to 0.04 cm left-right (LR). An undetected geographic miss was found in the prostate bed in 17 (2.1%) images and lymph nodes in 2 (0.2%) images. CONCLUSIONS Daily soft tissue IGRT with reduced anisotropic margins for post-prostatectomy radiotherapy has been successfully implemented. RTs performed better with real-time online matching than they did in offline training, perhaps influenced by having several RTs perform online matching. Daily soft tissue IGRT did not prolong treatment time.
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Affiliation(s)
- Linda J. Bell
- Northern Sydney Cancer CentreRadiation Oncology DepartmentRoyal North Shore HospitalSt LeonardsNSWAustralia
| | - Thomas Eade
- Northern Sydney Cancer CentreRadiation Oncology DepartmentRoyal North Shore HospitalSt LeonardsNSWAustralia
- Northern Clinical SchoolUniversity of SydneySt LeonardsNSWAustralia
| | - George Hruby
- Northern Sydney Cancer CentreRadiation Oncology DepartmentRoyal North Shore HospitalSt LeonardsNSWAustralia
- Northern Clinical SchoolUniversity of SydneySt LeonardsNSWAustralia
| | - Regina Bromley
- Northern Sydney Cancer CentreRadiation Oncology DepartmentRoyal North Shore HospitalSt LeonardsNSWAustralia
| | - Andrew Kneebone
- Northern Sydney Cancer CentreRadiation Oncology DepartmentRoyal North Shore HospitalSt LeonardsNSWAustralia
- Northern Clinical SchoolUniversity of SydneySt LeonardsNSWAustralia
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