한림의대 / 윤제웅, 강세권*
Abstract
Background: Dry eye syndrome has been recently reported in patients who underwent whole brain radiotherapy (WBRT). WBRT based on a couch with three-degrees of freedom (3D) can occasionally be performed in which the rotational head motion is not corrected. This study assessed the dependency of the rotational errors on the mask and the dose variation of the lens and lacrimal gland in WBRT patients.
Methods: Translational and rotational setup errors were obtained at the first treatment with cone-beam CT (CBCT) for patients under WBRT and frameless stereotactic radiosurgery (SRS) (n = 20 each) immobilized using a conventional WB mask and an SRS mask with a bite block, respectively. For the CT sets of SRS cases, WBRT plans were generated for the study. To simulate the rotational error, rotated CT images were created with each rotational error, on which initial WBRT plans were copied and doses were recalculated. The lens and lacrimal gland doses with and without rotation errors were compared.
Results: Despite similar translational setup errors for the two masks, the SRS mask showed a dramatic reduction in rotational errors compared to those of the WB mask. The errors varied within -2.9° to 2.9° and -1.2° to 0.7° for the WB and SRS masks, respectively. Accordingly, the SRS mask confined the change in the maximum lens dose, mean dose of the lacrimal gland, and lacrimal volume receiving 15 Gy to one-third of those using the WB mask.
Conclusion: When the six-degrees of freedom (6D) couch is not available, the frameless SRS mask is beneficial to WBRT for the faithful treatment as it was planned.
Affiliations
1Department of Radiation Oncology, Dongtan Sacred Heart Hospital, Hwaseong, Korea.
2Department of Radiation Oncology, Chuncheon Sacred Heart Hospital, Hallym University College of Medicine, Gangwon-do, Korea.
3Department of Radiation Oncology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
4Department of Radiation Oncology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea.
5Department of Radiation Oncology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
편집위원
보통 whole brain RT는 3차원일치치료로 상대적으로 마진을 많이 두어 치료하는데 6차원으로 움직일 수 있는 정밀한 테이블을 사용하여 셋업을 수정한다면 방사선에 민감한 수정체 선량이나 눈물샘 선량을 비약적으로 줄여줄 수 있어 방사선 부작용을 줄여줄 수 있음을 보여준 논문으로 정밀한 환자테이블의 중요성을 부각시킨 논문이라 하겠다.
2023-09-06 14:18:38