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Onal C, Efe E, Bozca R, Yavas C, Yavas G, Arslan G. The impact of margin reduction on radiation dose distribution of ultra-hypofractionated prostate radiotherapy utilizing a 1.5-T MR-Linac. J Appl Clin Med Phys 2024; 25:e14179. [PMID: 38013636 PMCID: PMC10795449 DOI: 10.1002/acm2.14179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/21/2023] [Accepted: 09/28/2023] [Indexed: 11/29/2023] Open
Abstract
BACKGROUND We examined the effects of reducing the planning target volume (PTV) margin in MR-guided radiotherapy (MRgRT) on the distribution of radiation dose to target volumes and organs-at-risk (OARs). Thus, we compared MR-Linac (MRL) plans with and without reduced margin and intensity-modulated radiotherapy (IMRT) plan with conventional linac for low-risk prostate cancer patients receiving 36.25 Gy in five fractions of ultra-hypofractionated radiation therapy. MATERIALS AND METHODS Twenty low-risk prostate cancer patients treated with 1.5 T MR-Linac were evaluated. The same planning CT images were used for four plans: the MRL-R plan with reduced margin planning target volume (PTV-R) and the MRL-N plan with normal margin PTV (PTV-N), which is also used for IMRT plan. In four plans, PTV doses, organs-at-risk (OARs) doses, the homogeneity index (HI), and monitor units were compared. RESULTS All plans met the criteria for PTV coverage and OARs dose constraints. The maximum and mean PTV doses were significantly higher in the MRL-R and MRL-N plans compared to the IMRT plan. The HI was lowest in the IMRT plan (0.040 ± 0.013) and highest in the MRL-N plan (0.055 ± 0.012; p < 0.001). There was no significant difference in the PTV dosimetric parameters between the MRL-R and the MRL-N plans. The high doses in the rectum was significantly lower in the MRL-R compared to other plans. The bladder V36.25 Gy was significantly lower in the MRL-R plan (2.43 ± 1.87 Gy) compared to MRL-N (4.50 ± 2.42 Gy; p < 0.001), and IMRT plans (4.76 ± 2.77 Gy; p < 0.001). There was no significant difference in the low-dose volumes of the body, maximum femur doses, or monitor units across each plan. CONCLUSIONS Ultra-hypofractionated MR-guided RT with 1.5 T MRL is dosimetrically feasible for patients with prostate cancer. The improved soft tissue contrast and the online adaptive plan for 1.5 T MR-Linac allows for PTV margin reduction resulted in a significant dose reduction in OARs.
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Affiliation(s)
- Cem Onal
- Faculty of MedicineDepartment of Radiation OncologyBaskent UniversityAnkaraTurkey
- Adana Dr. Turgut Noyan Research and Treatment CenterDepartment of Radiation OncologyBaskent University Faculty of MedicineAdanaTurkey
| | - Esma Efe
- Faculty of MedicineDepartment of Radiation OncologyBaskent UniversityAnkaraTurkey
| | - Recep Bozca
- Adana Dr. Turgut Noyan Research and Treatment CenterDepartment of Radiation OncologyBaskent University Faculty of MedicineAdanaTurkey
| | - Cagdas Yavas
- Faculty of MedicineDepartment of Radiation OncologyBaskent UniversityAnkaraTurkey
| | - Guler Yavas
- Faculty of MedicineDepartment of Radiation OncologyBaskent UniversityAnkaraTurkey
| | - Gungor Arslan
- Faculty of MedicineDepartment of Radiation OncologyBaskent UniversityAnkaraTurkey
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Da Silva Mendes V, Nierer L, Li M, Corradini S, Reiner M, Kamp F, Niyazi M, Kurz C, Landry G, Belka C. Dosimetric comparison of MR-linac-based IMRT and conventional VMAT treatment plans for prostate cancer. Radiat Oncol 2021; 16:133. [PMID: 34289868 PMCID: PMC8296626 DOI: 10.1186/s13014-021-01858-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023] Open
Abstract
Background The aim of this study was to evaluate and compare the performance of intensity modulated radiation therapy (IMRT) plans, planned for low-field strength magnetic resonance (MR) guided linear accelerator (linac) delivery (labelled IMRT MRL plans), and clinical conventional volumetric modulated arc therapy (VMAT) plans, for the treatment of prostate cancer (PCa). Both plans used the original planning target volume (PTV) margins. Additionally, the potential dosimetric benefits of MR-guidance were estimated, by creating IMRT MRL plans using smaller PTV margins. Materials and methods 20 PCa patients previously treated with conventional VMAT were considered. For each patient, two different IMRT MRL plans using the low-field MR-linac treatment planning system were created: one with original (orig.) PTV margins and the other with reduced (red.) PTV margins. Dose indices related to target coverage, as well as dose-volume histogram (DVH) parameters for the target and organs at risk (OAR) were compared. Additionally, the estimated treatment delivery times and the number of monitor units (MU) of each plan were evaluated. Results The dose distribution in the high dose region and the target volume DVH parameters (D98%, D50%, D2% and V95%) were similar for all three types of treatment plans, with deviations below 1% in most cases. Both IMRT MRL plans (orig. and red. PTV margins) showed similar homogeneity indices (HI), however worse values for the conformity index (CI) were also found when compared to VMAT. The IMRT MRL plans showed similar OAR sparing when the orig. PTV margins were used but a significantly better sparing was feasible when red. PTV margins were applied. Higher number of MU and longer predicted treatment delivery times were seen for both IMRT MRL plans. Conclusions A comparable plan quality between VMAT and IMRT MRL plans was achieved, when applying the same PTV margin. However, online MR-guided adaptive radiotherapy allows for a reduction of PTV margins. With a red. PTV margin, better sparing of the surrounding tissues can be achieved, while maintaining adequate target coverage. Nonetheless, longer treatment delivery times, characteristic for the IMRT technique, have to be expected.
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Affiliation(s)
- Vanessa Da Silva Mendes
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany.
| | - Lukas Nierer
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Minglun Li
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Stefanie Corradini
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Michael Reiner
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Florian Kamp
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany.,Department of Radiation Oncology, Cologne University Hospital, Cologne, Germany
| | - Maximilian Niyazi
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Christopher Kurz
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Guillaume Landry
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany
| | - Claus Belka
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistraße 15, 81377, Munich, Germany.,German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany
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Frenzel T, Albers D, Grohmann M, Krüll A. Results of a multicenter intensity modulated radiation therapy treatment planning comparison study for a sample prostate cancer case. Strahlenther Onkol 2019; 195:913-922. [PMID: 31342106 DOI: 10.1007/s00066-019-01496-9] [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: 01/24/2019] [Accepted: 07/02/2019] [Indexed: 11/24/2022]
Abstract
PURPOSE To determine the influence of different medical physicists, photon energies, treatment planning systems and treatment machines on the resulting external beam radiotherapy dose distribution for a sample prostate cancer case. METHODS A pre-contoured computed tomography (CT) dataset containing planning target volume 1 (PTV1) prostate and seminal vesicles (single dose [SD] 1.8 Gy, total dose [TD] 59.4 Gy), PTV2 prostate (simultaneously integrated boost [SIB], SD 2.0 Gy, TD 66 Gy), PTV3 prostate and seminal vesicles approach (SD 1.8 Gy, TD 73.8 Gy/80.4 Gy SIB) as well as organs at risk (OAR: rectum, bladder, femoral heads, bowel, anus) was offered to the members of the task group IMRT (intensity-modulated radiation therapy) of the German Society for Medical Physics. The purpose was to calculate one combined treatment plan (TP) for PTV1 and PTV2, as well as a separate one for PTV3. Dose volume histograms (DVH), different dose values, conformity index (CI), homogeneity index (HI), gradient index (GI) and a new "better than average score" were used to analyse the dose distributions. RESULTS Altogether 44 institutions took part in this study and submitted acceptable dose distributions for the PTVs. However, there were statistically significant differences, especially for the doses administered to the OAR, such as rectum, bladder and femoral heads. Differences between the treatment plans were not easily detectable by visual inspection of the isodose distribution. Dose maxima may occur outside the PTV. Even though scoring indices are already published, the new "better than average score" was needed to identify a plan that minimises dose to all OAR simultaneously. CONCLUSION Different medical physicists or dosimetrists, photon energies, treatment planning systems, and treatment machines have an impact on the resulting dose distribution. However, the differences only become apparent when comparing DVH, analysing dose values, comparing CI, HI, GI, as well as reviewing the dose distribution in every single plane. A new score was introduced to identify treatment plans that simultaneously deliver a low dose to all OAR. Such inter- and intra-institutional comparison studies are needed to explore different treatment planning strategies; however, there is still no automatic solution for an "optimal" treatment plan.
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Affiliation(s)
- Thorsten Frenzel
- Outpatient Center of the UKE GmbH, Department for Radiation Oncology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
| | - Dirk Albers
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maximilian Grohmann
- Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas Krüll
- Outpatient Center of the UKE GmbH, Department for Radiation Oncology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.,Department of Radiotherapy and Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Choi CH, Kim JH, Kim JI, Park JM. Comparison of treatment plan quality among MRI-based IMRT with a linac, MRI-based IMRT with tri-Co-60 sources, and VMAT for spine SABR. PLoS One 2019; 14:e0220039. [PMID: 31329641 PMCID: PMC6645671 DOI: 10.1371/journal.pone.0220039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 07/08/2019] [Indexed: 11/18/2022] Open
Abstract
PURPOSE This study compares the plan quality of magnetic-resonance image (MRI)-based intensity modulated radiation therapy (IMRT) using a linac (MR-linac-IMRT), MRI-based IMRT using tri-Co-60 sources (MR-Co-60-IMRT), and volumetric modulated arc therapy (VMAT) for spine stereotactic ablative radiotherapy (SABR). METHODS Twenty patients with thoracic spine metastasis were retrospectively selected for this study. For each patient, the MR-linac-IMRT, MR-Co-60-IMRT, and VMAT plans were generated using an identical CT image set and structures, except for the spinal cord and spinal cord planning organ-at-risk volume (PRV). Those two structures were contoured based on CT image sets for VMAT planning while those were contoured based on MR image sets for MR-linac-IMRT and MR-Co-60-IMRT planning. The initial prescription doses were 18 Gy in a single fraction for every plan in this study. If the tolerance level of the spinal cord was not met, the prescription doses were reduced to meet the tolerance level of the spinal cord. Dose-volumetric parameters of each plan were analyzed. RESULTS The average spinal cord volumes contoured based on the CT and MR images were 3.8±1.6 cm3 and 1.1±1.0 cm3, respectively (p<0.001). For four patients, the prescription doses of VMAT plans were reduced to 16 Gy to satisfy the spinal cord tolerance level. For thirteen patients, the prescription doses of MR-Co-60-IMRT plans were reduced to be less than 16 Gy to meet the spinal cord tolerance level. However, for every MR-linac-IMRT plan, the initial prescription doses of 18 Gy could be delivered to the target volume while satisfying the spinal cord tolerance. The average values of D10%, V10Gy, and V14Gy of the spinal cord PRV consistently indicated that the doses to the spinal cord PRV in the MR-linac-IMRT plans were the lowest among three types of plans in this study (all with p≤0.003). CONCLUSION MR-linac-IMRT appears promising for spine SABR.
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Affiliation(s)
- Chang Heon Choi
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
- Department of Radiation Oncology, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates
| | - Jin Ho Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
| | - Jung-in Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
- * E-mail: (JMP); (JK)
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
- Robotics Research Laboratory for Extreme Environments, Advanced Institute of Convergence Technology, Suwon, Korea
- * E-mail: (JMP); (JK)
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Choi CH, Park JM, An HJ, Kim JI. Effect of low magnetic field on single-diode dosimetry for clinical use. Phys Med 2019; 60:132-138. [PMID: 31000073 DOI: 10.1016/j.ejmp.2019.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 03/18/2019] [Accepted: 04/01/2019] [Indexed: 01/22/2023] Open
Abstract
PURPOSE To evaluate the effect of a low magnetic field (B-field, 0.35 T) on QED™ for clinical use. METHODS Black and Blue QED were irradiated using tri-Co-60 magnetic resonance image-guided radiation therapy systems with and without the B-field. For both detectors, angular dependence of the beam orientation was evaluated by rotating the gantry and detector in parallel and perpendicular directions to the B-field. Angular dependence betweenthe directions of both QED and B-field was also measured. Response on the depth and output factor of both detectors was investigated for parallel and perpendicular setups, respectively. RESULTS When Black QED was placed on a surface, detector response decreased by 1.8% and 4.5% for parallel and perpendicular setups, respectively, owing to the B-field. The angular dependence of the beam orientation was not affected by B-field for both detectors. There was a significant angular dependence between Black QED and B-field direction and for the Black QED when the gantry was rotated. Owing to the B-field, the detector response at 90° decreased by 2.4%, response of Black QED on the depth was changed only on the surface, and output factor of Black QED was changed only on the surface. The response of Blue QED was not affected by the B-field for all examined situations. CONCLUSIONS Using Black QED on a surface in the same position as that in the calibration requires some correction to the B-field. Blue QED does not require correction as it is not affected by the B-field.
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Affiliation(s)
- Chang Heon Choi
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea; Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, Republic of Korea
| | - Hyun Joon An
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jung-In Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.
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Hoffmann M, Pacey J, Goodworth J, Laszcyzk A, Ford R, Chick B, Greenham S, Westhuyzen J. Analysis of a volumetric-modulated arc therapy (VMAT) single phase prostate template as a class solution. Rep Pract Oncol Radiother 2018; 24:92-96. [PMID: 30505239 DOI: 10.1016/j.rpor.2018.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/26/2018] [Accepted: 10/28/2018] [Indexed: 12/31/2022] Open
Abstract
Aim To assess a class solution template for volumetric-modulated arc therapy (VMAT) for prostate cancer using plan analysis software. Background VMAT is a development of intensity-modulated radiotherapy (IMRT) with potential advantages for the delivery of radiotherapy (RT) in prostate cancer. Class solutions are increasingly used for facilitating RT planning. Plan analysis software provides an objective tool for evaluating class solutions. Materials and methods The class solution for VMAT was based on the current static field IMRT template. The plans of 77 prostate cancer patients were evaluated using a set of in-house plan quality metrics (scores) (PlanIQ™, Sun Nuclear Corporation). The metrics compared the class solution for VMAT planning with the IMRT template and the delivered clinical plan (CP). Eight metrics were associated with target coverage and ten with organs-at-risk (OAR). Individual metrics were summed and the combined scores were subjected to non-parametric analysis. The low-dose wash for both static IMRT and VMAT plans were evaluated using 40 Gy and 25 Gy isodose volumes. Results VMAT plans were of equal or better quality than the IMRT template and CP for target coverage (combined score) and OAR combined score. The 40 Gy isodose volume was marginally higher with VMAT than IMRT (4.9%) but lower than CP (-6.6%)(P = 0.0074). The 25 Gy volume was significantly lower with VMAT than both IMRT (-32.7%) and CP (-34.4%)(P < 0.00001). Conclusions Automated VMAT planning for prostate cancer is feasible and the plans are equal to or better than the current IMRT class solution and the delivered clinical plan.
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Affiliation(s)
- Matthew Hoffmann
- Department of Radiation Oncology, Mid-North Coast Cancer Institute, Port Macquarie, New South Wales, Australia
| | - Jacqueline Pacey
- Department of Radiation Oncology, Mid-North Coast Cancer Institute, Coffs Harbour, New South Wales, Australia
| | - Josie Goodworth
- Department of Radiation Oncology, Mid-North Coast Cancer Institute, Coffs Harbour, New South Wales, Australia
| | - Andrea Laszcyzk
- Department of Radiation Oncology, Northern New South Wales Cancer Institute, Lismore, New South Wales, Australia
| | - Richard Ford
- Department of Radiation Oncology, Northern New South Wales Cancer Institute, Lismore, New South Wales, Australia
| | - Brendon Chick
- Department of Radiation Oncology, Mid-North Coast Cancer Institute, Port Macquarie, New South Wales, Australia
| | - Stuart Greenham
- Department of Radiation Oncology, Mid-North Coast Cancer Institute, Coffs Harbour, New South Wales, Australia
| | - Justin Westhuyzen
- Department of Radiation Oncology, Mid-North Coast Cancer Institute, Coffs Harbour, New South Wales, Australia
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