Stanley Dennis N, McConnell Kristen A, Kirby Neil, Gutiérrez Alonso N, Papanikolaou Nikos, Rasmussen Karl
Radiation Oncology - Medical Physics, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
Miami Cancer Institute, Baptist Hospital, Miami, FL, USA.
J Appl Clin Med Phys. 2017 Nov;18(6):58-61. doi: 10.1002/acm2.12183. Epub 2017 Sep 13.
Historically, the process of positioning a patient prior to imaging verification used a set of permanent patient marks, or tattoos, placed subcutaneously. After aligning to these tattoos, plan specific shifts are applied and the position is verified with imaging, such as cone-beam computed tomography (CBCT). Due to a variety of factors, these marks may deviate from the desired position or it may be hard to align the patient to these marks. Surface-based imaging systems are an alternative method of verifying initial positioning with the entire skin surface instead of tattoos. The aim of this study was to retrospectively compare the CBCT-based 3D corrections of patients initially positioned with tattoos against those positioned with the C-RAD CatalystHD surface imager system.
A total of 6000 individual fractions (600-900 per site per method) were randomly selected and the post-CBCT 3D corrections were calculated and recorded. For both positioning methods, four common treatment site combinations were evaluated: pelvis/lower extremities, abdomen, chest/upper extremities, and breast. Statistical differences were evaluated using a paired sample Wilcoxon signed-rank test with significance level of <0.01.
The average magnitudes of the 3D shift vectors for tattoos were 0.9 ± 0.4 cm, 1.0 ± 0.5 cm, 0.9 ± 0.6 cm and 1.4 ± 0.7 cm for the pelvis/lower extremities, abdomen, chest/upper extremities and breast, respectively. For the CatalystHD, the average magnitude of the 3D shifts for the pelvis/lower extremities, abdomen, chest/upper extremities and breast were 0.6 ± 0.3 cm, 0.5 ± 0.3 cm, 0.5 ± 0.3 cm and 0.6 ± 0.2 cm, respectively. Statistically significant differences (P < 0.01) in the 3D shift vectors were found for all four sites.
This study shows that the overall 3D shift corrections for patients initially aligned with the C-RAD CatalystHD were significantly smaller than those aligned with subcutaneous tattoos. Surface imaging systems can be considered a viable option for initial patient setup and may be preferable to permanent marks for specific clinics and patients.
在历史上，在成像验证前对患者进行定位的过程使用一组皮下放置的永久性患者标记或纹身。在与这些纹身对齐后，应用计划特定的移位，并通过成像（如锥形束计算机断层扫描（CBCT））验证位置。由于多种因素，这些标记可能偏离期望位置，或者可能难以使患者与这些标记对齐。基于表面的成像系统是一种用整个皮肤表面而非纹身来验证初始定位的替代方法。本研究的目的是回顾性比较最初用纹身定位的患者与用C-RAD CatalystHD表面成像系统定位的患者基于CBCT的三维校正情况。
总共随机选择6000个单独的分次（每种方法每个部位600 - 900个），计算并记录CBCT后的三维校正。对于两种定位方法，评估了四种常见的治疗部位组合：骨盆/下肢、腹部、胸部/上肢和乳房。使用配对样本Wilcoxon符号秩检验评估统计学差异，显著性水平<0.01。
纹身定位的三维移位向量的平均大小，骨盆/下肢为0.9±0.4厘米，腹部为1.0±0.5厘米，胸部/上肢为0.9±0.6厘米，乳房为1.4±0.7厘米。对于CatalystHD，骨盆/下肢、腹部、胸部/上肢和乳房的三维移位平均大小分别为0.6±0.3厘米、0.5±0.3厘米、0.5±0.3厘米和0.6±0.2厘米。在所有四个部位的三维移位向量中均发现了统计学显著差异（P<0.01）。
本研究表明，最初用C-RAD CatalystHD对齐的患者的总体三维移位校正明显小于用皮下纹身对齐的患者。表面成像系统可被视为初始患者摆位的可行选择，对于特定诊所和患者可能比永久性标记更可取。
