Key result
Cardiac-respiratory double gating reduces mean heart dose by ~28% at diastole versus single gating.
Why the study?
Few studies on radiotherapy of cardiac targets exist and none have used cardiac motion gating. This study evaluated the dose-volume advantage of cardiac-respiratory double gating versus respiratory single gating for proton radiotherapy of heart targets.
Does cardiac-respiratory double gating improve dose sparing to organs at risk compared to respiratory single gating in proton radiotherapy for cardiac soft tissue sarcoma?
Does cardiac-respiratory double gating improve dose sparing to organs at risk compared to respiratory single gating in proton radiotherapy for cardiac soft tissue sarcoma?
Cardiac-respiratory double gating in proton radiotherapy for cardiac targets may significantly spare organs at risk compared to respiratory single gating.
May reduce cardiac dose with double gating in proton therapy; hypothesis-generating and should not yet change practice.
BACKGROUND AND PURPOSE: Few studies on radiotherapy of cardiac targets exist, and none using a gating method according to cardiac movement. This study aimed to evaluate the dose-volume advantage of using cardiac-respiratory double gating (CRDG) in terms of target location with additional ECG signals in comparison to respiratory single gating (RSG) for proton radiotherapy of targets in the heart. MATERIALS AND METHODS: Cardiac motion was modeled using a cardiac-gated four-dimensional computed tomography scan obtained at the end-expiration. Plans with the prescription dose of 50 Gy (RSG and CRDG plans at diastole and systole phases) were compared in terms of clinically relevant dose-volume criteria for various target sizes and seven cardiac subsites. Potential dose sparing by utilizing CRDG over RSG was quantified in terms of surrounding organ at risk (OAR) doses while the dose coverage to the targets was fully ensured. RESULTS: The average mean dose reductions were 28 ± 10% when gated at diastole and 21 ± 12% at systole in heart and 30 ± 17% at diastole and 8 ± 9% at systole in left ventricle compared to respiratory single gating. The diastole phase was optimal for gated treatments for all target locations except right ventricle and interventricular septum. The right ventricle target was best treated at the systole phase. However, an optimal gating phase for the interventricular septum target could not be determined. CONCLUSIONS: We have studied the dose-volume benefits of CRDG for each cardiac subsite, and demonstrated that CRDG may spare organs at risk better than RSG.
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Lee et al. (2021) studied Cardiac soft tissue sarcoma. Cardiac-respiratory double gating (CRDG) vs. Respiratory single gating (RSG) was evaluated on Mean dose reduction to organs at risk (heart and left ventricle). Cardiac-respiratory double gating reduced the average mean dose to the heart by 28% at diastole and 21% at systole compared to respiratory single gating.
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