Malone Ciaran, Ryan Samantha, Nicholson Jill, 'Maolalai Roisin O, O'Donovan Rebecca, McArdle Orla, Duane Frances, Armstrong John, Keenan Lorna, Glynn Aisling, Woods Ruth, McClean Brendan, Brennan Sinead
St. Luke's Radiation Oncology Network, St. Luke's Hospital, Dublin, Ireland.
St. Luke's Radiation Oncology Network, St. Luke's Hospital, Dublin, Ireland.
Radiother Oncol. 2025 Aug;209:110941. doi: 10.1016/j.radonc.2025.110941. Epub 2025 May 21.
This OPEN (Optimising Patient Experience in Head and Neck Radiotherapy) phase III trial sub-study, aimed to evaluate intrafraction motion in head and neck (H&N) cancer patients using three different facemask designs. Specifically, we compared intrafraction motion among patients immobilized with a closed facemask or one of two open-face designs, utilizing pre-/post-cone-beam computed tomography (CBCT) and surface-guided radiation therapy (SGRT).
A pre-planned interim analysis on the first 56 patients enrolled in the OPEN trial was conducted as a safety checkpoint. In the OPEN trial, patients are randomised into three arms: closed facemask, 3-point open facemask, or 5-point open facemask. Intrafraction motion was assessed using both CBCT and SGRT. CBCT provided deviations in translational and rotational dimensions based on bony alignment, while SGRT offered continuous monitoring of surface motion. Intrafraction motion metrics, (i.e. mean, standard deviation, maximum absolute deviation, and the 95th percentile of surface motion) were recorded for each open mask patient using SGRT data to fully quantify motion variation during treatment. The 95th percentile of SGRT deviations was used for direct comparison with CBCT motion data. Bayesian analysis was conducted to determine the equivalence of motion across mask types and measurement techniques. Margins to account for intrafraction motion were calculated across mask types using Van Herk's formulism.
Mean CBCT deviations were less than 0.4 mm and 0.2 degrees, while SGRT recorded 95th percentile deviations of 0.4 mm and 0.8 degrees over all patients. SGRT detected transient maximum deviations not captured by CBCT, particularly in the yaw axis. However, these differences were transient. Bayesian analysis showed no clinically significant differences in intrafraction motion between mask types or measurement methods. No correlation was found between SGRT and CBCT measured motion within the small range of motion recorded. No difference in intrafraction margin requirements were found between arms. Based on CBCT-measured intrafraction motion, margins of 1.8 mm, 1.7 mm, and 1.3 mm were calculated for the vertical (VRT), lateral (LAT), and longitudinal (LNG) directions, respectively, to account for intrafraction motion for all mask types, with SGRT confirming that patient motion during treatment remained within these margins.
Intrafraction motion, as measured by both CBCT and SGRT, remains within clinically acceptable limits and yields similar PTV margins across both open and closed mask types. Intrafraction PTV margins were found to be comparable across all mask types. The use of SGRT allowed for the detection of transient deviations and rotational differences that were not detected using CBCT alone. Overall, these findings confirm that both 3-point and 5-point open-face masks achieve intrafraction stability comparable to traditional closed facemasks in head and neck radiotherapy.
本项开放标签（优化头颈部放疗患者体验）III期试验子研究旨在使用三种不同的面罩设计评估头颈部（H&N）癌症患者的分次内运动。具体而言，我们比较了使用封闭面罩或两种开放式面罩之一固定的患者的分次内运动，利用治疗前/后锥形束计算机断层扫描（CBCT）和表面引导放射治疗（SGRT）。
对开放试验中入组的前56例患者进行了预先计划的中期分析，作为安全检查点。在开放试验中，患者被随机分为三组：封闭面罩组、三点式开放式面罩组或五点式开放式面罩组。使用CBCT和SGRT评估分次内运动。CBCT基于骨对齐提供平移和旋转维度的偏差，而SGRT提供表面运动的连续监测。使用SGRT数据记录每个开放式面罩患者的分次内运动指标（即平均值、标准差、最大绝对偏差和表面运动的第95百分位数），以充分量化治疗期间的运动变化。SGRT偏差的第95百分位数用于与CBCT运动数据进行直接比较。进行贝叶斯分析以确定不同面罩类型和测量技术之间运动的等效性。使用范·赫克公式计算不同面罩类型的分次内运动边界。
CBCT平均偏差小于0.4毫米和0.2度，而SGRT记录的所有患者第95百分位数偏差为0.4毫米和0.8度。SGRT检测到CBCT未捕获的瞬时最大偏差，特别是在偏航轴上。然而，这些差异是瞬时的。贝叶斯分析表明，不同面罩类型或测量方法之间的分次内运动在临床上无显著差异。在记录的小运动范围内，SGRT和CBCT测量的运动之间未发现相关性。各治疗组之间的分次内边界要求无差异。基于CBCT测量的分次内运动，分别计算出垂直（VRT）、横向（LAT）和纵向（LNG）方向的边界为1.8毫米、1.7毫米和1.3毫米，以考虑所有面罩类型的分次内运动，SGRT证实治疗期间患者运动仍在这些边界内。
CBCT和SGRT测量的分次内运动均保持在临床可接受的限度内，并且在开放式和封闭式面罩类型中产生相似的计划靶体积（PTV）边界。发现所有面罩类型的分次内PTV边界具有可比性。使用SGRT能够检测到单独使用CBCT未检测到的瞬时偏差和旋转差异。总体而言，这些发现证实，在头颈部放疗中，三点式和五点式开放式面罩实现的分次内稳定性与传统封闭面罩相当。
