Sakurai Takayuki, Takamatsu Shigeyuki, Shibata Satoshi, Minamikawa Risako, Yamazaki Masahiro, Kojima Hironori, Noto Kimiya, Makino Tomoyuki, Kawaguchi Shohei, Nohara Takahiro, Mizokami Atsushi, Gabata Toshifumi
Department of Radiology, Graduate School of Medicine, Kanazawa University, Kanazawa, Ishikawa, Japan.
Department of Radiology, Kanazawa University Hospital, Kanazawa, Ishikawa, Japan.
Adv Radiat Oncol. 2023 May 29;8(6):101277. doi: 10.1016/j.adro.2023.101277. eCollection 2023 Nov-Dec.
In irradiating the prostate and pelvic lymph node regions, registration based on bony structures matches the pelvic lymph node regions but not necessarily the prostate position, and it is important to identify factors that influence prostate displacement. Therefore, we investigated factors influencing prostate displacement during volumetric modulated arc therapy after single-fraction high-dose-rate brachytherapy (HDR-BT) for prostate cancer and the trends in displacement for each fraction.
Seventy patients who underwent pelvic volumetric modulated arc therapy of 46 Gy in the prone position 15 days after 13 Gy HDR-BT were included. Prostate displacement relative to bony structures was calculated using cone beam computed tomography. Systematic error (SE) and random error (RE) were evaluated in the right-left (RL), craniocaudal (CC), and anteroposterior (AP) directions. The association with clinical and anatomic factors on the planning computed tomography or magnetic resonance imaging was analyzed. Prostate volume change (PVC) was defined as the volume change at 2 days after HDR-BT. Displacement trends were individually examined from the first to 23rd fractions.
The mean SE in the RL, CC, and AP directions was -0.01 mm, -2.34 mm, and -0.47 mm, respectively. The root mean square of the RE in the RL, CC, and AP directions was 0.44 mm, 1.14 mm, and 1.10 mm, respectively. SE in the CC direction was independently associated with bladder volume ( = .021, statistic = 2.352) and PVC ( < .001, statistic = -8.526). SE in the AP direction was independently associated with bladder volume ( = .013, statistic = -2.553), PVC ( < .001, statistic = 5.477), and rectal mean area ( = .008, statistic = 2.743). RE in the CC direction was independently associated with smoking ( = .035). RE in the AP direction was associated with PVC ( = .043). Gradual displacement caudally and posteriorly occurred during the irradiation period.
Anatomic characteristics of the bladder, rectum, and prostate predict SE. Smoking and PVC predict RE. In particular, whether PVC is ≥140% affects setting internal margins.
在对前列腺和盆腔淋巴结区域进行放疗时，基于骨骼结构的配准能匹配盆腔淋巴结区域，但不一定能匹配前列腺位置，因此确定影响前列腺移位的因素很重要。所以，我们研究了前列腺癌单次大剂量率近距离放疗（HDR - BT）后容积调强弧形放疗期间影响前列腺移位的因素以及各分次的移位趋势。
纳入70例患者，这些患者在接受13 Gy HDR - BT后15天，俯卧位接受46 Gy的盆腔容积调强弧形放疗。使用锥形束计算机断层扫描计算前列腺相对于骨骼结构的移位。在左右（RL）、头脚（CC）和前后（AP）方向评估系统误差（SE）和随机误差（RE）。分析计划计算机断层扫描或磁共振成像上临床和解剖学因素的相关性。前列腺体积变化（PVC）定义为HDR - BT后2天的体积变化。从第1分次到第23分次分别检查移位趋势。
RL、CC和AP方向的平均SE分别为 - 0.01 mm、 - 2.34 mm和 - 0.47 mm。RL、CC和AP方向RE的均方根分别为0.44 mm、1.14 mm和1.10 mm。CC方向的SE与膀胱体积独立相关（P = 0.021，统计量 = 2.352）和PVC（P < 0.001，统计量 = - 8.526）。AP方向的SE与膀胱体积独立相关（P = 0.013，统计量 = - 2.553）、PVC（P < 0.001，统计量 = 5.477）和直肠平均面积（P = 0.008，统计量 = 2.743）。CC方向的RE与吸烟独立相关（P = 0.035）。AP方向的RE与PVC相关（P = 0.043）。在放疗期间，前列腺逐渐向尾侧和后侧移位。
膀胱、直肠和前列腺的解剖特征可预测SE。吸烟和PVC可预测RE。特别是，PVC是否≥140%会影响内部边界的设定。
