Joint faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi-shi, Japan.
Faculty of Medicine, Graduate School of Health Sciences, Okayama University, Okayama, Japan.
Open Vet J. 2022 May-Jun;12(3):407-413. doi: 10.5455/OVJ.2022.v12.i3.15. Epub 2022 Jun 21.
For optimal treatment, it is important to maintain optimal multi-leaf collimator (MLC) transmission in intensity-modulated radiation therapy (IMRT). However, adjustment of transmissions has not been reported in veterinary medicine.
To demonstrate that appropriate MLC parameter adjustment for IMRT using 4- and 6-MV energy can reduce the need for quality assurance revalidation in real companion animal clinical cases.
The MLC parameters (leaf transmission and leaf offset) of the treatment planning system were adjusted by evaluating seven plans (10 × 10 cm, 3ABUT, DMLC, 7segA, FOURL, HDMLC, and HIMRT) and 20 preclinical cases (10 cases each in 4- and 6-MV groups). Subsequently, 101 IMRT plans of 88 cases (77 dogs and 11 cats) were evaluated for absolute dose of plan target volume (PTV) and organs at risk (OAR) and were analyzed for the relative dose distribution by gamma analysis (3%/3 mm, >10%) using EBT3 film.
After adjustment of the MLC parameters (leaf transmission and leaf offset, 4 MV: 0.008 and 0, 6 MV: 0.005 and 0, respectively), the data from 101 plans (4 MV: 64 plans and 6 MV: 37 plans) treated with IMRT showed PTV <3%, OAR <5%, and gamma analysis pass rates ≥95% in all cases.
Clinically meaningful dose distributions can be created even with a limited validation device if the treatment parameters are adjusted appropriately, even for tumors in canines and felines, where the irradiation field is small, the target is adjacent to the OAR, and the target is often superficial.
为了达到最佳的治疗效果，在调强放射治疗（IMRT）中保持最佳多叶准直器（MLC）的传输非常重要。然而，兽医领域尚未有关于传输调整的报道。
展示使用 4 兆伏和 6 兆伏能量进行 IMRT 时，适当调整 MLC 参数可减少在实际伴侣动物临床病例中进行质量保证再验证的需求。
通过评估七个计划（10×10cm、3ABUT、DMLC、7segA、FOURL、HDMLC 和 HIMRT）和 20 个临床前病例（4- 和 6-MV 组各 10 个病例），调整治疗计划系统的 MLC 参数（叶片传输和叶片偏移）。随后，对 88 例（77 只狗和 11 只猫）的 101 个 IMRT 计划的计划靶区（PTV）和危及器官（OAR）的绝对剂量进行评估，并使用 EBT3 胶片进行伽马分析（3%/3mm、>10%），分析相对剂量分布。
调整 MLC 参数（叶片传输和叶片偏移，4MV：0.008 和 0，6MV：0.005 和 0）后，用 IMRT 治疗的 101 个计划（4MV：64 个计划，6MV：37 个计划）的数据显示，所有病例的 PTV<3%、OAR<5%、伽马分析通过率≥95%。
即使使用有限的验证设备，如果适当调整治疗参数，即使对于犬科和猫科动物的肿瘤，也可以创建有临床意义的剂量分布，这些肿瘤的照射野较小，靶区与 OAR 相邻，且靶区通常较浅。
