The University of Texas MD Anderson Cancer Center / 한은영*
Abstract
Purpose: We investigated the feasibility of thoracic spine stereotactic body radiotherapy (SBRT) using the Elekta Unity magnetic resonance-guided linear accelerator (MRL) in patients who received prior radiotherapy. We hypothesized that Monaco treatment plans can improve the gross tumor volume minimum dose (GTVmin) with spinal cord preservation and maintain consistent plan quality during daily adaptation.
Methods: Pinnacle clinical plans for 10 patients who underwent thoracic spine SBRT (after prior radiotherapy) were regenerated in the Monaco treatment planning system for the Elekta Unity MRL using 9 and 13 intensity-modulated radiotherapy (IMRT) beams. Monaco adapt-to-position (ATP) and adapt-to-shape (ATS) workflow plans were generated using magnetic resonance imaging with a simulated daily positional setup deviation, and these adaptive plans were compared with Monaco reference plans. Plan quality measures included target coverage, Paddick conformity index, gradient index, homogeneity index, spinal cord D0.01cc , esophagus D0.01cc , lung V10, and skin D0.01cc .
Results: GTVmin values from the Monaco 9-beam and 13-beam plans were significantly higher than those from Pinnacle plans (p < 0.01) with similar spinal cord dose. Spinal cord D0.01cc , esophagus D0.01cc , and lung V10 did not statistically differ among the three plans. The electron-return effect did not induce remarkable dose effects around the lungs or skin. While in the ATP workflow, a large increase in GTVmin was observed at the cost of a 10%-50% increase in spinal cord D0.01cc , in the ATS workflow, the spinal cord dose increase was maintained within 3% of the reference plan.
Conclusion: These findings show that MRL plans for thoracic spine SBRT are safe and feasible, allowing tumor dose escalation with spinal cord preservation and consistent daily plan adaptation using the ATS workflow. Careful plan review of hot spots and lung dose is necessary for safe MRL-based treatment.
Affiliations
Eun Young Han 1, Debra N Yeboa 2, Tina M Briere 1, Jinzhong Yang 1, He Wang 1
1Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
2Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
편집위원
최근 관심을 끌로 있는 MRLinac을 이용한 영상유도 방사선 치료에 대한 연구결과에 대하여 다루고 있으며 특히, Re-SBRT에 대하여 다루고 있는 점에서 ㅇ미상적으로 매우 유용한 논문이라고 생각합니다
2022-12-06 15:21:24
편집위원2
MR영상유도 방사선치료기가 사용되고 나서 그 응용분야가 많이 생겼는데 그 중에서 SBRT 분야에 대한 치료계획 비교논문으로 spine SBRT에도 충분히 적용가능함을 보여준다고 하겠다.
2022-12-06 15:23:00