Departments of Radiation Oncology, Chongqing University Cancer Hospital, Chongqing, People's Republic of China.
Radiat Oncol. 2023 Jul 5;18(1):112. doi: 10.1186/s13014-023-02279-4.
Surface-guided radiotherapy (SGRT) has been demonstrated to be a promising supplement to cone-beam computed tomography (CBCT) in adjuvant breast cancer radiotherapy, but a rational combination mode is lacking in clinical practice. The aim of this study was to explore this mode and investigate its impact on the setup and dose accuracy.
Daily SGRT and weekly CBCT images were acquired for 23 patients with breast cancer who received conventional fractionated radiotherapy after lumpectomy. Sixteen modes were acquired by randomly selecting one (CBCT), two (CBCT), three (CBCT), four (CBCT), and five (CBCT) images from the CBCT images for fusion with the SGRT. The CTV-PTV margins, OAR doses, and dose coverage (V95%) of PTV and CTV was calculated based on SGRT setup errors with different regions of interest (ROIs). Dose correlations between these modalities were investigated using Pearson and Spearman's methods. Patient-specific parameters were recorded to assess their impact on dose.
The CTV-PTV margins decreased with increasing CBCT frequencies and were close to 5 mm for CBCT and CBCT. For the ipsilateral breast ROI, SGRT errors were larger in the AP direction, and target doses were higher in all modes than in the whole breast ROI (P < 0.05). In the ipsilateral ROI, the target dose correlations between all modes increased with increasing CBCT time intervals, decreased, and then increased with increasing CBCT frequencies, with the inflection point being CBCT participation at week 5. The dose deviations in CBCT, CBCT, CBCT, CBCT, and CBCT were minimal and did not differ significantly (P > 0.05). There was excellent agreement between CBCT and CBCT, and between (CBCT, CBCT) and CBCT in determining the classification for the percentage of PTV deviation (Kappa = 0.704-0.901). In addition, there were weak correlations between the patient's D (ipsilateral breast diameter with bolus) and CTV doses in modes with CBCT participation at week 4 (R = 0.270 to 0.480).
Based on weekly CBCT, these modes with ipsilateral ROI and a combination of daily SGRT and a CBCT frequency of ≥ 3 were recommended, and CBCT was required at weeks 1 and 2 for CBCT.
在辅助乳腺癌放射治疗中，表面引导放射治疗（SGRT）已被证明是锥形束 CT（CBCT）的一种很有前途的补充方法，但在临床实践中缺乏合理的组合模式。本研究旨在探讨这种模式，并研究其对设置和剂量准确性的影响。
对 23 例接受保乳手术后常规分割放疗的乳腺癌患者进行每日 SGRT 和每周 CBCT 图像采集。通过从 CBCT 图像中随机选择一个（CBCT）、两个（CBCT）、三个（CBCT）、四个（CBCT）和五个（CBCT）图像来融合与 SGRT，共获得 16 种模式。基于不同感兴趣区域（ROI）的 SGRT 设定误差，计算 CTV-PTV 边界、OAR 剂量和 PTV 和 CTV 的剂量覆盖率（V95%）。使用 Pearson 和 Spearman 方法研究这些模式之间的剂量相关性。记录患者特定参数以评估其对剂量的影响。
CTV-PTV 边界随 CBCT 频率的增加而减小，当 CBCT 和 CBCT 时接近 5mm。对于同侧乳腺 ROI，SGRT 误差在 AP 方向较大，所有模式的靶剂量均高于全乳腺 ROI（P<0.05）。在同侧 ROI 中，所有模式之间的靶剂量相关性随 CBCT 时间间隔的增加而增加，然后随 CBCT 频率的增加而减小，转折点为第 5 周 CBCT 参与。CBCT、CBCT、CBCT、CBCT 和 CBCT 的剂量偏差最小，且差异无统计学意义（P>0.05）。CBCT 与 CBCT 之间，（CBCT、CBCT）与 CBCT 之间在确定 PTV 偏差百分比的分类方面具有极好的一致性（Kappa=0.704-0.901）。此外，在第 4 周 CBCT 参与的模式中，患者的 D（同侧乳腺直径加垫）与 CTV 剂量之间存在弱相关（R=0.270 至 0.480）。
基于每周 CBCT，推荐使用同侧 ROI 模式，并结合每日 SGRT 和至少 3 次 CBCT 频率，需要在第 1 和第 2 周进行 CBCT。
