Wyatt J J, Pearson R A, Frew J, Walker C, Richmond N, Wilkinson M, Wilkes K, Driver S, West S, Karen P, Brooks-Pearson R L, Ainslie D, Wilkins E, McCallum H M
Northern Centre for Cancer Care, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK; Translational and Clinical Research Institute, Newcastle University, Newcastle, UK.
Northern Centre for Cancer Care, Newcastle Upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK; Translational and Clinical Research Institute, Newcastle University, Newcastle, UK.
Radiography (Lond). 2023 Mar;29(2):347-354. doi: 10.1016/j.radi.2023.01.015. Epub 2023 Feb 1.
Magnetic Resonance (MR)-only radiotherapy for prostate cancer has previously been reported using fiducial markers for on-treatment verification. MR-Cone Beam Computed Tomography (CBCT) soft-tissue matching does not require invasive fiducial markers and enables MR-only treatments to other pelvic cancers. This study evaluated the first clinical implementation of MR-only prostate radiotherapy using MR-CBCT soft-tissue matching.
Twenty prostate patients were treated with MR-only radiotherapy using a synthetic (s)CT-optimised plan with MR-CBCT soft-tissue matching. Two MR sequences were acquired: small Field Of View (FOV) for target delineation and large FOV for organs at risk delineation, sCT generation and on-treatment verification. Patients also received a CT for validation. The prostate was independently contoured on the small FOV MR, copied to the registered CT and modified if there were MR-CT soft-tissue alignment differences (MR-CT volume). This was compared to the MR-only volume with a paired t-test. The treatment plan was recalculated on CT and the doses compared. Independent offline CT-CBCT matches for 5/20 fractions were performed by three therapeutic radiographers using the MR-only contours and compared to the online MR-CBCT matches using two one-sided paired t-tests for equivalence within ±1 mm.
The MR-only volumes were significantly smaller than MR-CT (p = 0.003), with a volume ratio 0.92 ± 0.02 (mean ± standard error). The sCT isocentre dose difference to CT was 0.2 ± 0.1%. MR-CBCT soft-tissue matching was equivalent to CT-CBCT (p < 0.001), with differences of 0.1 ± 0.2 mm (vertical), -0.1 ± 0.2 mm (longitudinal) and 0.0 ± 0.1 mm (lateral).
MR-only radiotherapy with soft-tissue matching has been successfully clinically implemented. It produced significantly smaller target volumes with high dosimetric and on-treatment matching accuracy.
MR-only prostate radiotherapy can be safely delivered without using invasive fiducial markers. This enables MR-only radiotherapy to be extended to other pelvic cancers where fiducial markers cannot be used.
先前已有关于仅使用磁共振（MR）进行前列腺癌放疗的报道，其中使用基准标记物进行治疗期间验证。MR - 锥形束计算机断层扫描（CBCT）软组织匹配不需要侵入性基准标记物，并且能够对其他盆腔癌症进行仅MR治疗。本研究评估了使用MR - CBCT软组织匹配进行仅MR前列腺放疗的首次临床应用。
20例前列腺癌患者接受了仅MR放疗，采用基于合成（s）CT优化的计划并结合MR - CBCT软组织匹配。采集了两个MR序列：用于靶区勾画的小视野（FOV）序列和用于危及器官勾画、sCT生成及治疗期间验证的大FOV序列。患者还接受了一次CT扫描用于验证。在小视野MR图像上独立勾画出前列腺轮廓，复制到配准后的CT图像上，并在存在MR - CT软组织对齐差异（MR - CT体积）时进行修改。将其与仅MR体积进行配对t检验比较。在CT上重新计算治疗计划并比较剂量。由三名放射治疗技师对20次分割中的5次进行独立的离线CT - CBCT匹配，使用仅MR轮廓，并通过两次单侧配对t检验与在线MR - CBCT匹配进行比较，以确定在±1毫米范围内的等效性。
仅MR体积显著小于MR - CT体积（p = 0.003），体积比为0.92±0.02（平均值±标准误差）。sCT等中心剂量与CT的差异为0.2±0.1%。MR - CBCT软组织匹配与CT - CBCT等效（p < 0.001），垂直方向差异为0.1±0.2毫米，纵向差异为 - 0.1±0.2毫米，横向差异为0.0±0.1毫米。
已成功在临床上实施了具有软组织匹配的仅MR放疗。它产生的靶区体积显著更小，且剂量测定和治疗期间匹配精度高。
仅MR前列腺放疗可以在不使用侵入性基准标记物的情况下安全实施。这使得仅MR放疗能够扩展到无法使用基准标记物的其他盆腔癌症。
