Mazonakis Michalis, Kourinou Kalliopi, Lyraraki Efrossini, Varveris Haralambos, Damilakis John
Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion Crete 71003, Greece.
Radiat Prot Dosimetry. 2012 Dec;152(4):317-22. doi: 10.1093/rpd/ncs056. Epub 2012 Apr 13.
This study was conducted to estimate the scattered thyroid dose and relevant second cancer risk from radiotherapy for extracranial tumours during childhood. Anteroposeterior and posteronaterior field irradiations employed during the treatment of Hodgkin's disease, neuroblastoma and Wilms' tumour were simulated on two humanoid phantoms representing 5- and 10-y-old patients. Measurements were performed using thermoluminescent dosemeters. Practical thyroid lead shields with thicknesses of 2-10 mm were placed in the phantoms' neck region. The lifetime risk for cancer induction was assessed using sex- and age-specific risk factors. Thyroid dose per monitor unit varied from 28.1 to 492.4 μGy by the primary irradiation site and patient's age. The 10-mm-thick lead shield led to a dose reduction up to 28.9 %. For typical prescribed tumour doses, the total risks for thyroid cancer development after radiotherapy of 5- and 10-y-old male patients were 0.05-0.99 and 0.03-0.48 %, respectively. The corresponding risks for females increased to 0.29-5.51 and 0.17-2.94 %.
本研究旨在估算儿童期颅外肿瘤放疗时甲状腺的散射剂量及相关的继发癌症风险。在代表5岁和10岁患者的两个人形模型上模拟了霍奇金病、神经母细胞瘤和肾母细胞瘤治疗过程中使用的前后野和后前野照射。使用热释光剂量计进行测量。将厚度为2 - 10毫米的实用甲状腺铅屏蔽置于模型的颈部区域。使用性别和年龄特异性风险因素评估致癌的终生风险。根据主要照射部位和患者年龄，每个监测单位的甲状腺剂量在28.1至492.4微戈瑞之间变化。10毫米厚的铅屏蔽可使剂量降低达28.9%。对于典型的规定肿瘤剂量，5岁和10岁男性患者放疗后发生甲状腺癌的总风险分别为0.05 - 0.99%和0.03 - 0.48%。女性的相应风险分别增至0.29 - 5.51%和0.17 - 2.94%。
