Malkov V N, Kemp B J, Ferrero A, Buchholtz L, Park S S, Kavanaugh J A
Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, USA.
Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
J Appl Clin Med Phys. 2025 Aug;26(8):e70147. doi: 10.1002/acm2.70147.
Using diagnostic CT for radiotherapy (RT) planning can bypass traditional CT simulation but introduces challenges in patient positioning and Hounsfield unit (HU) fidelity, affecting dose accuracy. Here a Varian Ethos adaptive-driven CT direct-to-treatment (DtT) multi-fraction stereotactic body radiation therapy (SBRT) workflow is presented.
This study employed institutional diagnostic PET-CT images to generate an initial reference Ethos treatment plan. HU and dosimetric accuracy were validated for PET-CT, Ethos CBCT images (with and without Hypersight (HS), and the gold-standard helical CT simulators). Following the SBRT reference plan creation on the low dose diagnostic PET-CT, the first fraction was delivered with a newly generated adaptive plan calculated on the HS CBCT (Ethos) images. For multi-fraction treatments, the first day CBCT images and adaptive plan become the reference for subsequent IGRT treatments. This study includes workflow validation and initial three patient experience.
The DtT adaptive SBRT workflow was successfully implemented, with initial end-to-end testing demonstrating feasibility. In-house solutions were introduced to facilitate the adaptive to IGRT plan conversion. The Ethos system, especially with HS, maintained HU fidelity and dose calculation accuracy comparable to helical CTs. On-table adaptive sessions were within 37-51 min, aligning with single-fraction palliative studies. Subsequent non-adaptive IGRT fractions were efficiently completed within 7-27 min.
This study demonstrates the feasibility of DtT adaptive-driven multifraction SBRT using diagnostic PET-CT. This approach reduces the need for on-site patient presence prior to treatment, expands planning lead times, and improves overall efficiency in radiotherapy for well selected patients.
使用诊断性CT进行放射治疗（RT）计划可以绕过传统的CT模拟，但在患者定位和亨氏单位（HU）保真度方面带来了挑战，影响剂量准确性。本文介绍了瓦里安Ethos自适应驱动的CT直接治疗（DtT）多分割立体定向体部放射治疗（SBRT）工作流程。
本研究采用机构诊断性PET-CT图像生成初始参考Ethos治疗计划。对PET-CT、Ethos CBCT图像（有无Hypersight（HS））和金标准螺旋CT模拟器的HU和剂量学准确性进行了验证。在低剂量诊断性PET-CT上创建SBRT参考计划后，第一分割采用在HS CBCT（Ethos）图像上计算的新生成的自适应计划进行治疗。对于多分割治疗，第一天的CBCT图像和自适应计划成为后续IGRT治疗的参考。本研究包括工作流程验证和最初三名患者的体验。
成功实施了DtT自适应SBRT工作流程，初步的端到端测试证明了其可行性。引入了内部解决方案以促进向IGRT计划转换的适应性。Ethos系统，特别是配备HS时，保持了与螺旋CT相当的HU保真度和剂量计算准确性。床上自适应治疗时间在37 - 51分钟内，与单分割姑息性研究一致。后续的非自适应IGRT分割在7 - 27分钟内有效完成。
本研究证明了使用诊断性PET-CT进行DtT自适应驱动的多分割SBRT的可行性。这种方法减少了治疗前患者现场就诊的需求，延长了计划准备时间，并提高了对精心挑选患者的放射治疗整体效率。
