Meattini Icro, Marrazzo Livia, Zani Margherita, Paiar Fabiola, Pallotta Stefania, Simontacchi Gabriele, Bucciolini Marta, Livi Lorenzo
Radiotherapy Unit, Azienda Ospedaliero-Universitaria Careggi, Largo G. A. Brambilla 3, 50134, Florence, Italy.
Medical Physics Unit, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy.
Radiol Med. 2015 Nov;120(11):1078-82. doi: 10.1007/s11547-015-0541-1. Epub 2015 Apr 24.
The aim of our study was to evaluate the usefulness of the four-dimensional computed tomography (4DCT) in accelerated partial breast irradiation (aPBI) planning.
At our Institute, we have been treating the index quadrant with external intensity-modulated radiation therapy in a phase III trial. For this study, we selected a sample of 10 patients with right- or left-sided breast cancer and surgical clips at the excision site. Contouring of the target was performed both using three-dimensional computed tomography (3DCT) and 4DCT imaging. On both 3DCT and 4DCT, we recorded the clinical target volume (CTV) and the planning target volume (PTV) and the coordinates of the PTV centroid. We calculated the treatment plans, according to our protocol, using the contours drawn on the 3DCT and 4DCT and evaluated target coverage and sparing of organs at risk (OAR).
Median age of the patients was 63.5 years (range 52-75). The comparison between the 3DCT and 4DCT PTV volumes was not statistically significant (p = 0.79). Concerning centroid coordinates, the average absolute differences were 0.1 mm in the latero-lateral, 0.7 mm in the antero-posterior and 0.3 mm in the supero-inferior direction. No statistically significant differences were observed both in PTV coverage and OAR sparing; the 4D PTV contour is adequately covered when the plan based on the 3D contours is used. Target coverage was reduced on average by 1 % and no statistically significant difference was observed (p = 0.93).
In our experience, no significant differences between PTV volumes, PTV coverage, OAR sparing and centroid position are evidenced when comparing 3DCT and 4DCT plans. Conventional 3DCT-based planning is adequate for aPBI.
本研究旨在评估四维计算机断层扫描（4DCT）在加速部分乳腺照射（aPBI）计划中的实用性。
在我们研究所，我们正在一项III期试验中采用外照射调强放疗治疗靶象限。对于本研究，我们选择了10例患有右侧或左侧乳腺癌且切除部位有手术夹的患者样本。使用三维计算机断层扫描（3DCT）和4DCT成像进行靶区轮廓勾画。在3DCT和4DCT上，我们记录了临床靶区体积（CTV）、计划靶区体积（PTV）以及PTV质心的坐标。根据我们的方案，使用在3DCT和4DCT上勾画的轮廓计算治疗计划，并评估靶区覆盖情况和危及器官（OAR）的受量。
患者的中位年龄为63.5岁（范围52 - 75岁）。3DCT和4DCT的PTV体积之间的比较无统计学意义（p = 0.79）。关于质心坐标，平均绝对差值在左右方向为0.1 mm，前后方向为0.7 mm，上下方向为0.3 mm。在PTV覆盖和OAR受量方面均未观察到统计学显著差异；当使用基于3D轮廓的计划时，4D PTV轮廓得到了充分覆盖。靶区覆盖平均降低了1%，未观察到统计学显著差异（p = 0.93）。
根据我们的经验，比较3DCT和4DCT计划时，在PTV体积、PTV覆盖、OAR受量和质心位置方面未发现显著差异。基于传统3DCT的计划对于aPBI是足够的。
