Abstract：
OBJECTIVE: Preclinical data demonstrated that the use of proton minibeam radiotherapy reduces the risk of toxicity in healthy tissue. Ventricular tachycardia radioablation is an area under clinical investigation in proton beam therapy. We sought to simulate a ventricular tachycardia radioablation with proton minibeams and to demonstrate that it was possible to obtain a homogeneous coverage of an arrhythmogenic cardiac zone with this technique.
METHODS: An arrhythmogenic target volume was defined on the simulation CT scan of a patient, localized in the lateral wall of the left ventricle. A dose of 25Gy was planned to be delivered by proton minibeam radiotherapy, simulated using a Monte Carlo code (TOPAS v.3.7) with a collimator of 19 0.4 mm-wide slits spaced 3mm apart. The main objective of the study was to obtain a plan ensuring at least 93% of the prescription dose in 93% of the planning target volume without exceeding 110% of the prescribed dose in the planning target volume.
RESULTS: The average dose in the planning treatment volume in proton minibeam radiotherapy was 25.12Gy. The percentage of the planning target volume receiving 93% (V93%), 110% (V110%), and 95% (V95%) of the prescribed dose was 94.25%, 0%, and 92.6% respectively. The lateral penumbra was 6.6mm. The mean value of the peak-to-valley-dose ratio in the planning target volume was 1.06. The mean heart dose was 2.54Gy versus 5.95Gy with stereotactic photon beam irradiation.
CONCLUSIONS: This proof-of-concept study shows that proton minibeam radiotherapy can achieve a homogeneous coverage of an arrhythmogenic cardiac zone, reducing the dose at the normal tissues. This technique, ensuring could theoretically reduce the risk of late pulmonary and breast fibrosis, as well as cardiac toxicity as seen in previous biological studies in proton minibeam radiotherapy.
METHODS: An arrhythmogenic target volume was defined on the simulation CT scan of a patient, localized in the lateral wall of the left ventricle. A dose of 25Gy was planned to be delivered by proton minibeam radiotherapy, simulated using a Monte Carlo code (TOPAS v.3.7) with a collimator of 19 0.4 mm-wide slits spaced 3mm apart. The main objective of the study was to obtain a plan ensuring at least 93% of the prescription dose in 93% of the planning target volume without exceeding 110% of the prescribed dose in the planning target volume.
RESULTS: The average dose in the planning treatment volume in proton minibeam radiotherapy was 25.12Gy. The percentage of the planning target volume receiving 93% (V93%), 110% (V110%), and 95% (V95%) of the prescribed dose was 94.25%, 0%, and 92.6% respectively. The lateral penumbra was 6.6mm. The mean value of the peak-to-valley-dose ratio in the planning target volume was 1.06. The mean heart dose was 2.54Gy versus 5.95Gy with stereotactic photon beam irradiation.
CONCLUSIONS: This proof-of-concept study shows that proton minibeam radiotherapy can achieve a homogeneous coverage of an arrhythmogenic cardiac zone, reducing the dose at the normal tissues. This technique, ensuring could theoretically reduce the risk of late pulmonary and breast fibrosis, as well as cardiac toxicity as seen in previous biological studies in proton minibeam radiotherapy.
摘要：
目的：临床前数据表明，使用质子微型束放射疗法可降低健康组织的毒性风险。室性心动过速放射消融是质子束治疗的临床研究领域。我们试图用质子微型束模拟室性心动过速放射性消融，并证明使用这种技术可以获得致心律失常心脏区的均匀覆盖。
方法：在患者的模拟CT扫描中定义了致心律失常的目标体积，位于左心室的侧壁。计划通过质子小束放射治疗输送25Gy的剂量，使用蒙特卡罗代码（TOPASv.3.7）进行模拟，准直器具有19个0.4mm宽的狭缝，间隔3mm。研究的主要目的是获得一个计划，确保在计划目标体积的93％中至少有93％的处方剂量，而不超过计划目标体积中规定剂量的110％。
结果：质子小束放射治疗计划治疗体积的平均剂量为25.12Gy。计划目标卷接收93%的百分比(V93%)，110%(V110%),处方剂量的95%(V95%)为94.25%，0%,分别为92.6%。外侧半影为6.6mm。计划目标体积中的峰谷剂量比的平均值为1.06。立体定向光子束照射的平均心脏剂量为2.54Gy，与5.95Gy相比。
结论：这项概念验证研究表明，质子微型束放射治疗可以实现致心律失常心脏区的均匀覆盖，减少正常组织的剂量。这项技术,确保理论上可以降低晚期肺纤维化和乳腺纤维化的风险，以及在质子微型束放射疗法的先前生物学研究中看到的心脏毒性。
方法：在患者的模拟CT扫描中定义了致心律失常的目标体积，位于左心室的侧壁。计划通过质子小束放射治疗输送25Gy的剂量，使用蒙特卡罗代码（TOPASv.3.7）进行模拟，准直器具有19个0.4mm宽的狭缝，间隔3mm。研究的主要目的是获得一个计划，确保在计划目标体积的93％中至少有93％的处方剂量，而不超过计划目标体积中规定剂量的110％。
结果：质子小束放射治疗计划治疗体积的平均剂量为25.12Gy。计划目标卷接收93%的百分比(V93%)，110%(V110%),处方剂量的95%(V95%)为94.25%，0%,分别为92.6%。外侧半影为6.6mm。计划目标体积中的峰谷剂量比的平均值为1.06。立体定向光子束照射的平均心脏剂量为2.54Gy，与5.95Gy相比。
结论：这项概念验证研究表明，质子微型束放射治疗可以实现致心律失常心脏区的均匀覆盖，减少正常组织的剂量。这项技术,确保理论上可以降低晚期肺纤维化和乳腺纤维化的风险，以及在质子微型束放射疗法的先前生物学研究中看到的心脏毒性。
