Liu Yang, Liu Peilin, Gao Xian-Shu, Wang Zishen, Lyu Feng, Shi Anhui, Wang Weihu, Gao Yan, Liao Anyan, Zhao Jing, Ding Xuanfeng
Department of Radiation Oncology, Peking University First Hospital, Beijing, 100034, China.
Department of Radiation Oncology, William Beaumont University hospital, Corewell Health, Detroit, 48073, USA.
Med Dosim. 2024;49(4):388-397. doi: 10.1016/j.meddos.2024.06.001. Epub 2024 Jul 15.
To compare the dosimetric differences in volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT) in stereotactic body radiation therapy (SBRT) of multiple lung lesions and determine a normal tissue complication probability (NTCP) model-based decision strategy that determines which treatment modality the patient will use. A total of 41 patients were retrospectively selected for this study. The number of patients with 1-6 lesions was 5, 16, 7, 6, 3, and 4, respectively. A prescription dose of 70 Gy in 10 fractions was given to each lesion. SBRT plans were generated using VMAT and IMPT. All the IMPT plans used robustness optimization with ± 3.5% range uncertainties and 5 mm setup uncertainties. Dosimetric metrics and the predicted NTCP value of radiation pneumonitis (RP), esophagitis, and pericarditis were analyzed to evaluate the potential clinical benefits between different planning groups. In addition, a threshold for the ratio of PTV to lungs (%) to determine whether a patient would benefit highly from IMPT was determined using receiver operating characteristic curves. All plans reached target coverage (V70Gy ≥ 95%). Compared with VMAT, IMPT resulted in a significantly lower dose of most thoracic normal tissues. For the 1-2, 3-4 and 5-6 lesion groups, the lung V5 was 29.90 ± 9.44%, 58.33 ± 13.35%, and 81.02 ± 5.91% for VMAT and 11.34 ± 3.11% (p < 0.001), 21.45 ± 3.80% (p < 0.001), and 32.48 ± 4.90% (p < 0.001) for IMPT, respectively. The lung V20 was 12.07 ± 4.94%, 25.57 ± 6.54%, and 43.99 ± 11.83% for VMAT and 6.76 ± 1.80% (p < 0.001), 13.14 ± 2.27% (p < 0.01), and 19.62 ± 3.48% (p < 0.01) for IMPT. The D of the total lung was 7.65 ± 2.47 Gy, 14.78 ± 2.75 Gy, and 21.64 ± 4.07 Gy for VMAT and 3.69 ± 1.04 Gy (p < 0.001), 7.13 ± 1.41 Gy (p < 0.001), and 10.69 ± 1.81 Gy (p < 0.001) for IMPT. Additionally, in the VMAT group, the maximum NTCP value of radiation pneumonitis was 73.91%, whereas it was significantly lower in the IMPT group at 10.73%. The accuracy of our NTCP model-based decision model, which combines the number of lesions and PTV/Lungs (%), was 97.6%. The study demonstrated that the IMPT SBRT for multiple lung lesions had satisfactory dosimetry results, even when the number of lesions reached 6. The NTCP model-based decision strategy presented in our study could serve as an effective tool in clinical practice, aiding in the selection of the optimal treatment modality between VMAT and IMPT.
比较容积调强弧形放疗（VMAT）和调强质子放疗（IMPT）在多肺病灶立体定向体部放疗（SBRT）中的剂量学差异，并确定基于正常组织并发症概率（NTCP）模型的决策策略，以决定患者采用哪种治疗方式。本研究回顾性选取了41例患者。病灶数为1 - 6个的患者数分别为5例、16例、7例、6例、3例和4例。每个病灶给予10次分割、总剂量70 Gy的处方剂量。使用VMAT和IMPT生成SBRT计划。所有IMPT计划均采用稳健性优化，范围不确定性为±3.5%，摆位不确定性为5 mm。分析剂量学指标以及放射性肺炎（RP）、食管炎和心包炎的预测NTCP值，以评估不同计划组之间的潜在临床获益。此外，使用受试者工作特征曲线确定PTV与肺的比值（%）阈值，以确定患者是否能从IMPT中显著获益。所有计划均达到靶区覆盖（V70Gy≥95%）。与VMAT相比，IMPT导致大多数胸部正常组织的剂量显著降低。对于1 - 2个、3 - 4个和5 - 6个病灶组，VMAT的肺V5分别为29.90±9.44%、58.33±13.35%和81.02±5.91%，IMPT的分别为11.34±3.11%（p<0.001）、21.45±3.80%（p<0.001）和32.48±4.90%（p<0.001）。VMAT的肺V20分别为12.07±4.94%、25.57±6.54%和43.99±11.83%，IMPT的分别为6.76±1.80%（p<0.001）、13.14±2.27%（p<0.01）和19.62±3.48%（p<0.01）。VMAT的全肺平均剂量（D）分别为7.65±2.47 Gy、14.78±2.75 Gy和21.64±4.07 Gy，IMPT的分别为3.69±1.04 Gy（p<0.001）、7.13±1.41 Gy（p<0.001）和10.69±1.81 Gy（p<0.001）。此外，在VMAT组中，放射性肺炎的最大NTCP值为73.91%，而IMPT组显著更低，为10.73%。我们基于NTCP模型的决策模型（结合病灶数和PTV/肺（%））的准确率为97.6%。该研究表明，即使病灶数达到6个，IMPT SBRT用于多肺病灶也有令人满意的剂量学结果。我们研究中提出的基于NTCP模型的决策策略可作为临床实践中的有效工具，有助于在VMAT和IMPT之间选择最佳治疗方式。
