Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

Park, Jong Min; Kim, Jung-In; Choi, Cheol Young; Chie, Eui Kyu; Kim, Il Han; Ye, Sung-Joon

doi:10.1118/1.3682172

Cited by 21 publications

(15 citation statements)

References 39 publications

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“…In particular, our group has previously reported the feasibility of photon energy modulation techniques [5]. However, these techniques are not appropriate in saving treatment planning labors or not commercially available yet.…”

Section: Introductionmentioning

confidence: 99%

The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer

et al. 2012

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PurposeTo evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients.Materials and MethodsTwenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose.ResultsRegardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The V20 Gy of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%.ConclusionIn this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

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Section: Introductionmentioning

confidence: 99%

The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer

et al. 2012

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“…Previous studies have demonstrated that low-energy photon beams increased body integral doses owing to the low penetrating power of the photon beams when treating thicker body parts. 19,24 The body volume irradiated by doses higher than 50% of the prescription dose in the tri-Co-60 IMRT plans was larger than that of VMAT plans, showing higher values of GM. Comprehensively reviewing the dose-volumetric results, tri-Co-60 IMRT with the ViewRay system seems inappropriate for spine SABR in comparison with VMAT, since the dosevolumetric parameters of both the target volume and normal tissue indicated that the ViewRay system had a lower plan quality.…”

Section: Discussionmentioning

confidence: 99%

“…For the entire body, integral dose was calculated by multiplication of the body mean dose and the body volume. To examine doses higher than 50% of the prescription dose, the gradient measure (GM) and the gradient index (GI) by Paddick and Lippitz were calculated as follows: 19,20 Gradient measure ðGMÞ5 r V 50% 2 r V 100% (3)…”

Section: Evaluation Of the Treatment Plansmentioning

confidence: 99%

Quality of tri-Co-60 MR-IGRT treatment plans in comparison with VMAT treatment plans for spine SABR

Choi

Park

Kim

et al. 2016

The British Journal of Radiology

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FULL PAPERQuality of tri-Co-60 MR-IGRT treatment plans in comparison with VMAT treatment plans for spine SABR Objective: To investigate the plan quality of tri-Co-60 intensity-modulated radiation therapy (IMRT) plans for spine stereotactic ablative radiotherapy (SABR). Methods: A total of 20 patients with spine metastasis were retrospectively selected. For each patient, a tri-Co-60 IMRT plan and a volumetric-modulated arc therapy (VMAT) plan were generated. The spinal cords were defined based on MR images for the tri-Co-60 IMRT, while isotropic 1-mm margins were added to the spinal cords for the VMAT plans. The VMAT plans were generated with 10-MV flattening filter-free photon beams of TrueBeam STx™ (Varian Medical Systems, Palo Alto, CA), while the tri-Co-60 IMRT plans were generated with the ViewRay™ system (ViewRay inc., Cleveland, OH). The initial prescription dose was 18 Gy(1 fraction). If the tolerance dose of the spinal cord was not met, the prescription dose was reduced until the spinal cord tolerance dose was satisfied.Results: The mean dose to the target volumes, conformity index and homogeneity index of the VMAT and tri-Co-60 IMRT were 17.8 6 0.8 vs 13.7 6 3.9 Gy, 0.85 6 0.20 vs 1.58 6 1.29 and 0.09 6 0.04 vs 0.24 6 0.19, respectively. The integral doses and beam-on times were 16,570 6 1768 vs 22,087 6 2.986 Gy cm 3 and 3.95 6 1.13 vs 48.82 6 10.44 min, respectively. Conclusion: The tri-Co-60 IMRT seems inappropriate for spine SABR compared with VMAT. Advances in knowledge: For spine SABR, the tri-Co-60 IMRT is inappropriate owing to the large penumbra, large leaf width and low dose rate of the ViewRay system.

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“…To find the parameters of the electron beam incident on the vacuum window, we followed published procedures by matching our calculated depth doses and cross-beam profiles to our measurements in a water phantom [22, 29, 30]. We started with published beam parameters from a model of a linear accelerator identical to ours, and made small fine-tuning adjustments until the best match was found [22, 23, 28, 31].…”

Section: Methodsmentioning

confidence: 99%

Design and evaluation of electron beam energy degraders for breast boost irradiation

Park

Kim

et al. 2016

Radiat Oncol

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BackgroundFor breast cancer patients who require electron boost energies between 6 and 9 MeV, an energy degraders (ED) in the 9 MeV beamline was specially designed and manufactured to increase the skin dose of 6 MeV and to reduce the penetration depth of 9 MeV beams.MethodsWe used Monte Carlo (MC) techniques as a guide in the design of ED for use with linear accelerators. In order to satisfy percent depth dose (PDD) characteristics and dose profile uniformity in water, the shape and thickness of Lucite® ED in the 9 MeV beamline was iteratively optimized and then manufactured. The ED geometry consists of a truncated cone attached on top of a plane plate, with total central thickness of 1.0 cm. The ED was placed on the lower most scraper of the electron applicator. The PDDs, profiles, and output factors were measured in water to validate the MC-based design.ResultsSkin doses with the EDs increased by 8–9 %, compared to those of the 9 MeV beam. The outputs with the EDs were 0.882 and 0.972 for 10 × 10 and 15 × 15 cm2 cones, respectively, as compared to that of a conventional 9 MeV beam for a 10 × 10 cm2 cone. The X-ray contamination remained less than 1.5 %. In-vivo measurements were also performed for three breast boost patients and showed close agreement with expected values.ConclusionsThe optimally designed ED in the 9 MeV beamline provides breast conserving patients with a new energy option of 7 MeV for boost of the shallow tumor bed. It would be an alternative to bolus and thus eliminate inconvenience and concern about the daily variation of bolus setup.

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Photon energy-modulated radiotherapy: Monte Carlo simulation and treatment planning study

Cited by 21 publications

References 39 publications

The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer

The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer

Quality of tri-Co-60 MR-IGRT treatment plans in comparison with VMAT treatment plans for spine SABR

Design and evaluation of electron beam energy degraders for breast boost irradiation

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