Creutzberg C L, Visser A G, De Porre P M, Meerwaldt J H, Althof V G, Levendag P C
Department of Radiation Oncology, Dr. Daniel den Hoed Cancer Center, Rotterdam, The Netherlands.
Radiother Oncol. 1992 Apr;23(4):257-64. doi: 10.1016/s0167-8140(92)80131-2.
A prospective study of the accuracy of patient positioning in mantle field irradiation was carried out in 13 lymphoma patients treated with curative radiotherapy. Patients were treated in the supine and prone position for anterior and posterior fields, respectively. Individually shaped divergent shielding blocks were placed in a fixed position in a template which was positioned on a tray above the patient. A total number of 94 megavoltage portal films (MV) was analysed and compared to 26 simulation films (SIM). MV-SIM differences were larger for posterior fields than for anterior fields. Regarding the position of the lung shielding blocks, mean MV-SIM differences ranged from 1.3 to 4.4 mm and errors exceeding 1 cm were found in 7.2% of cases. Most discrepancies appeared to be randomly distributed. A 4-5 mm systematic cranial shift of patients in the posterior treatment position was noted. Discrepancies in the position of the laryngeal block, spinal cord shielding block and humerus blocks were small with mean MV-SIM differences ranging from 0.3 to 2.7 mm. Differences between simulation set-up and treatment set-up were modest as compared to error rates reported in the literature. Shielding of tumour-bearing areas did not occur. It was concluded that the present standardised technique of patient positioning and the design of treatment fields results in acceptable error rates. Attention should be directed towards increasing the stability of patients in the prone treatment position in order to further reduce both systematic and random error rates.
对13例接受根治性放疗的淋巴瘤患者进行了一项关于斗篷野照射中患者体位准确性的前瞻性研究。患者分别在仰卧位和俯卧位接受前后野照射。将单独塑形的发散式屏蔽块固定放置在模板中的固定位置，模板放置在患者上方的托盘上。共分析了94张兆伏级射野片（MV），并与26张模拟片（SIM）进行比较。后野的MV-SIM差异大于前野。关于肺部屏蔽块的位置，MV-SIM平均差异在1.3至4.4毫米之间，7.2%的病例中发现误差超过1厘米。大多数差异似乎是随机分布的。注意到处于后治疗体位的患者有4至5毫米的系统性颅向移位。喉屏蔽块、脊髓屏蔽块和肱骨屏蔽块位置的差异较小，MV-SIM平均差异在0.3至2.7毫米之间。与文献报道的误差率相比，模拟设置和治疗设置之间的差异较小。未出现对含瘤区域的屏蔽不足。得出的结论是，目前标准化的患者体位技术和治疗野设计导致了可接受的误差率。应关注提高患者在俯卧治疗体位时的稳定性，以进一步降低系统性和随机误差率。
