Lian J, Song H, Liu R, Qi S, Hu A
University North Carolina, Chapel Hill, NC.
Duke University Medical Center, Durham, NC.
Med Phys. 2012 Jun;39(6Part19):3842. doi: 10.1118/1.4735681.
To compare low dose volume and integral dose of various rotational arc radiation therapy modalities, including helical tomotherapy (HT) and other volumetric modulated arc therapies (VMAT).
A digital cylindrical phantom and an anthropomorphic pelvic phantom were used in the study. HT treatment was planned on TomoTherapy Planning Station (Accuray) and VMAT plans were generated on Pinnacle (Philips) and Eclipse (Varian). Same objectives and criteria were used for all the planning tasks. Tomotherapy plans were made with both 1cm jaw and 2.5cm jaw. Pinnacle SmartArc and Eclipse RapidArc plans used 1 arc and 2 arcs. Plan quality was evaluated by dose-volume histograms, conformity index (CI), and heterogeneity index (HI). V10% and V20% of body were used in quantifying low dose volume. Integral doses were computed for each plan and compared. Dose profiles across the target center were retrieved to show the rate of dose falls off.
All arc TPS generated clinically acceptable plan with comparable target CI and HI. The V20% of body of the cylindrical phantom case were 3551cc, 4054cc, 3375cc, 3438cc, 3714cc and 3679cc for tomotherapy 1 cm and 2 cm jaw, SmartArc 1 arc and 2 arc, and RapidArc 1 arc and 2 arc plans, respectively. The integral doses were 19.67, 22.78, 18.68, 18.50, 19.78 and 19.73 Joule, respectively. For the anthropomorphic phantom, the integral doses were 81.69, 102.77, 84.5 and 82.5 Joule for tomotherapy 1cm, 2cm, SmartArc 1arc and RapidArc 1arc, respectively. Dose profiles showed tomotherapy 1cm plan had similar longitudinal penumbra as SmartArc and RapidArc, while tomotherapy 2.5cm plan produced significant broader penumbra.
Similar low dose volume and integral dose are found in SmartArc, Rapid Arc, and as well as helical tomotherapy plan of 1cm jaw. Tomotherapy plans of 2.5cm jaw, however, shows higher low dose volume and integral dose.
比较包括螺旋断层放射治疗（HT）和其他容积调强弧形治疗（VMAT）在内的各种旋转弧形放射治疗方式的低剂量体积和积分剂量。
本研究使用了数字圆柱形体模和拟人化盆腔体模。在TomoTherapy治疗计划工作站（Accuray）上制定HT治疗计划，在Pinnacle（飞利浦）和Eclipse（瓦里安）上生成VMAT计划。所有计划任务均使用相同的目标和标准。断层放射治疗计划采用1cm准直器和2.5cm准直器制作。Pinnacle SmartArc和Eclipse RapidArc计划使用1个弧形和2个弧形。通过剂量体积直方图、适形指数（CI）和不均匀性指数（HI）评估计划质量。使用身体的V10%和V20%来量化低剂量体积。计算每个计划的积分剂量并进行比较。获取靶区中心的剂量分布以显示剂量下降率。
所有弧形治疗计划系统生成的临床可接受计划具有可比的靶区CI和HI。圆柱形体模病例中，断层放射治疗1cm准直器和2cm准直器、SmartArc 1个弧形和2个弧形、RapidArc 1个弧形和2个弧形计划的身体V20%分别为3551cc、4054cc、3375cc、3438cc、3714cc和3679cc。积分剂量分别为19.67、22.78、18.68、18.50、19.78和19.73焦耳。对于拟人化体模，断层放射治疗1cm、2cm、SmartArc 1个弧形和RapidArc 1个弧形的积分剂量分别为81.69、102.77、84.5和82.5焦耳。剂量分布显示断层放射治疗1cm计划的纵向半影与SmartArc和RapidArc相似，而断层放射治疗2.5cm计划产生的半影明显更宽。
在SmartArc、Rapid Arc以及1cm准直器的螺旋断层放射治疗计划中发现了相似的低剂量体积和积分剂量。然而，2.5cm准直器的断层放射治疗计划显示出更高的低剂量体积和积分剂量。
