Sabouri Pouya, Molitoris Jason, Ranjbar Maida, Moreau Julie, Simone Charles B, Mohindra Pranshu, Langen Katja, Mossahebi Sina
Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland.
Adv Radiat Oncol. 2023 Oct 21;9(3):101392. doi: 10.1016/j.adro.2023.101392. eCollection 2024 Mar.
Breath-hold (BH) technique can mitigate target motion, minimize target margins, reduce normal tissue doses, and lower the effect of interplay effects with intensity-modulated proton therapy (IMPT). This study presents dosimetric comparisons between BH and nonbreath-hold (non-BH) IMPT plans and investigates the reproducibility of BH plans using frequent quality assurance (QA) computed tomography scans (CT).
Data from 77 consecutive patients with liver (n = 32), mediastinal/lung (n = 21), nonliver upper abdomen (n = 20), and malignancies in the gastroesophageal junction (n = 4), that were treated with a BH spirometry system (SDX) were evaluated. All patients underwent both BH CT and 4-dimensional CT simulations. Clinically acceptable BH and non-BH plans were generated on each scan, and dose-volume histograms of the 2 plans were compared. Reproducibility of the BH plans for 30 consecutive patients was assessed using 1 to 3 QA CTs per patient and variations in dose-volume histograms for deformed target and organs at risk (OARs) volumes were compared with the initial CT plan.
Use of BH scans reduced initial and boost target volumes to 72% ± 20% and 70% ± 17% of non-BH volumes, respectively. Additionally, mean dose to liver, stomach, kidney, esophagus, heart, and lung V20 were each reduced to 71% to 79% with the BH technique. Similarly, small and large bowels, heart, and spinal cord maximum doses were each lowered to 68% to 84%. Analysis of 62 QA CT scans demonstrated that mean target and OAR doses using BH scans were reproducible to within 5% of their nominal plan values.
The BH technique reduces the irradiated volume, leading to clinically significant reductions in OAR doses. By mitigating tumor motion, the BH technique leads to reproducible target coverage and OAR doses. Its use can reduce motion-related uncertainties that are normally associated with the treatment of thoracic and abdominal tumors and, therefore, optimize IMPT delivery.
屏气（BH）技术可减轻靶区运动，最小化靶区边界，降低正常组织剂量，并减少调强质子治疗（IMPT）中相互作用效应的影响。本研究呈现了屏气和非屏气（non-BH）IMPT计划之间的剂量学比较，并使用频繁的质量保证（QA）计算机断层扫描（CT）来研究屏气计划的可重复性。
评估了77例连续患者的数据，这些患者分别患有肝脏疾病（n = 32）、纵隔/肺部疾病（n = 21）、非肝脏上腹部疾病（n = 20）以及胃食管交界部恶性肿瘤（n = 4），他们均接受了屏气肺活量测定系统（SDX）治疗。所有患者均接受了屏气CT和四维CT模拟。在每次扫描上生成临床可接受的屏气和非屏气计划，并比较这两种计划的剂量体积直方图。使用每位患者1至3次QA CT评估30例连续患者屏气计划的可重复性，并将变形靶区和危及器官（OAR）体积的剂量体积直方图变化与初始CT计划进行比较。
使用屏气扫描分别将初始靶区和追加靶区体积减少至非屏气体积的72%±20%和70%±17%。此外，采用屏气技术时，肝脏、胃、肾脏、食管、心脏和肺V20的平均剂量均分别降低至71%至79%。同样，小肠、大肠、心脏和脊髓的最大剂量均分别降低至68%至84%。对62次QA CT扫描的分析表明，使用屏气扫描时平均靶区和OAR剂量的可重复性在其标称计划值的5%以内。
屏气技术减少了照射体积，导致OAR剂量在临床上显著降低。通过减轻肿瘤运动，屏气技术实现了可重复的靶区覆盖和OAR剂量。其应用可减少通常与胸部和腹部肿瘤治疗相关的运动相关不确定性，从而优化IMPT治疗。
