Dosimetric effect of jaw tracking in volumetric-modulated arc therapy

Thongsawad, Sangutid; Khamfongkhruea, Chirasak; Tannanonta, Chirapha

doi:10.4103/jmp.jmp_75_17

Cited by 6 publications

(2 citation statements)

References 19 publications

(24 reference statements)

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“…Comparison of measurements on the surface dose of 6MV photon beam among three fields (jaw only vs. MLC only vs. MLC+jaw) using Varian's 120 MLC resulted in a dose reduction of approximately 2-3% at the field created using both MLC and jaw (12). Jaw tracking contributes to the dose below 10% by reducing leaf transmission (13). Our results showed a significant volume reduction of about 13.8% at doses below 10%, and this effect was also evaluated to be present in 20-40% (3.9-10.6%) of the dose distribution.…”

Section: Discussionmentioning

confidence: 99%

Effect of Jaw Tracking During Volumetric Modulated Arc Therapy for Facial Non-melanoma Skin Cancer

PARK,

KO,

CHOI

2024

In Vivo

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Background/Aim: This study aimed to analyze the dosimetric effects of jaw tracking during Volumetric Modulated Arc Therapy (VMAT) planning for facial nonmelanoma skin cancer (NMSC). Patients and Methods: This study included 50 patients with facial NMSC who underwent VMAT planning with or without jaw tracking. The target volume (TV) included the primary skin lesion with a 1-cm margin around the surface and a depth of 4 mm. A total of 55 Gy in 20 fractions was prescribed, and the plans were considered acceptable if the TV was covered by 95-105% of the isodose curve. A dosimetric comparison was performed for the volumes of the low-dose regions, which were defined as <50% of the prescription dose (V10-50%). Target coverage was evaluated using the homogeneity index (HI) and conformity index (CI). Results: The patients' mean TV was 5.137 cc (range=1. 03-15.89 cc). Jaw tracking resulted in mean volume reduction rates of 3.9%, 6.6% 10.6% and 13.8% for V40%, V30%, V20%, and V10%, respectively (all p<0.001). The volume change in V50% between the two groups was 2.7% (p=0.006). No significant differences were observed in HI (p=0.449) or CI (p=0.127). Conclusion: The application of jaw tracking during VMAT for facial NMSC is associated with a significant reduction in the volume of low dose delivered in the radiation field (V10-50%), while maintaining target coverage. Future analyses should assess whether this volume difference affects treatment-related cosmetic outcomes.

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Section: Discussionmentioning

confidence: 99%

Effect of Jaw Tracking During Volumetric Modulated Arc Therapy for Facial Non-melanoma Skin Cancer

PARK,

KO,

CHOI

2024

In Vivo

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“…Compared with those applying static jaws, plans that utilize the jaw tracking feature can achieve better organ-at-risk protection with comparable target doses maintained, especially in reducing V5 effectively. [5][6][7][8][9][10] To simplify the process, the static jaw is adopted in the test of correction models and actual applications of specific correction matrices in this paper. Extending the usage of the correction model to jaw-tracking plans is not feasible currently as it is only applicable to square fields.…”

Section: Discussionmentioning

confidence: 99%

Research on the correction method for radiotherapy verification plans based on displaced electronic portal imaging device

Guo,

Zhou,

Zeng

2024

J Applied Clin Med Phys

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BackgroundIt has been observed that under the single isocenter conditions, the potential shifts of the electronic portal imaging devices (EPID) may be introduced when executing portal dosimetry (PD) plans for bilateral breast cancer, pleural mesothelioma, and lymphoma. These shifts are relative to the calibration positions of EPID and result in significant discrepancies in the plan verification results.PurposeTo explore methods including correction model and specific correction matrices to revise the data obtained from displaced EPID.MethodsTwo methods, the correction model and the specific correction matrices, were applied to correct the data. Five experiments were designed and conducted to build correction model and to validate the effectiveness of these two methods. Gamma passing rates were calculated and data profiles along X‐axis and Y‐axis were captured.ResultsThe gamma passing rates for the EPID‐displaced IMRT validation plans after applying correction model, along with the application of specific correction matrices to VMAT and IMRT validation plans, exhibit results that are comparable to the cases with non‐displaced EPID. Except for the VMAT plans applied correction model which showed larger discrepancies (0.041 ± 0.028, 0.049 ± 0.030), the other three exhibit minimal differences in discrepancy values. In all profiles, the corrected data from displaced EPID exhibit a high level of agreement with data obtained from non‐displaced EPID. Good consistency is observed in actual application of the correction model and the specific correction matrices between gamma passing rates of data corrected and those of non‐displaced data.ConclusionsThe proposed methods involving correction model and specific correction matrices can correct the data collected from the displaced EPID, and the gamma passing rates of the corrected data show results that are comparable to some extent with those of non‐displaced data. Particularly, the results corrected by specific correction matrices closely resemble the data from non‐displaced EPID.

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The use of collimator angle optimization and jaw tracking for VMAT‐based single‐isocenter multiple‐target stereotactic radiosurgery for up to six targets in the Varian Eclipse treatment planning system

Pudsey

Cutajar

Wallace

et al. 2021

J Applied Clin Med Phys

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Island blocking occurs in single-isocenter multiple-target (SIMT) stereotactic radiotherapy (SRS) whenever targets share multi-leaf collimator (MLC) leaf pairs. This study investigated the effect on plan quality and delivery, of reducing island blocking through collimator angle optimization (CAO). In addition, the effect of jaw tracking in this context was also investigated. Methods: For CAO, an algorithm was created that selects the collimator angle resulting in the lowest level of island blocking, for each beam in any given plan.Then, four volume-modulated arc therapy (VMAT) SIMT SRS plans each were generated for 10 retrospective patients: two CAO plans, with and without jaw tracking, and two plans with manually selected collimator angles, with and without jaw tracking. Plans were then assessed and compared using typical quality assurance procedures.Results: There were no substantial differences between plans with and without CAO. Jaw tracking produced statistically significant reduction in low-dose level parameters; healthy brain V10% and mean dose were reduced by 9.66% and 15.58%, respectively. However, quantitative values (108 cc for V10% and 0.35 Gy for mean dose) were relatively small in relation to clinical relevance.Though there were no statistically significant changes in plan deliverability, there was a notable trend of plans with jaw tracking having lower gamma analysis pass rates. Conclusion:These findings suggest that CAO has limited benefit in VMAT SIMT SRS of 2-6 targets when using a low-dose penalty to the healthy brain during plan optimization in Eclipse. As clinical benefits of jaw tracking were found to be minimal and plan deliverability was potentially reduced, a cautious approach would be to exclude jaw tracking in SIMT SRS plans. How to cite this article: Pudsey LMM, Cutajar D, Wallace A, et al. The use of collimator angle optimization and jaw tracking for VMAT-based single-isocenter multiple-target stereotactic radiosurgery for up to six targets in the Varian Eclipse treatment planning system.

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Dosimetric effect of jaw tracking in volumetric-modulated arc therapy

Cited by 6 publications

References 19 publications

Effect of Jaw Tracking During Volumetric Modulated Arc Therapy for Facial Non-melanoma Skin Cancer

Effect of Jaw Tracking During Volumetric Modulated Arc Therapy for Facial Non-melanoma Skin Cancer

Research on the correction method for radiotherapy verification plans based on displaced electronic portal imaging device

The use of collimator angle optimization and jaw tracking for VMAT‐based single‐isocenter multiple‐target stereotactic radiosurgery for up to six targets in the Varian Eclipse treatment planning system

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