Mazonakis Michalis, Zacharopoulou Fotini, Kachris Stefanos, Varveris Charalambos, Damilakis John, Gourtsoyiannis Nicholas
Department of Medical Physics, University Hospital of Iraklion, 71110 Iraklion, Crete, Greece.
Strahlenther Onkol. 2007 Jun;183(6):332-7. doi: 10.1007/s00066-007-1653-x.
To measure the scattered dose to ovaries and testes from radiotherapy for common pediatric malignancies and to assess the relevant risks for radiation-induced gonadal damage and hereditary disorders in future generations.
Radiotherapy for central nervous system tumors, acute leukemia, neuroblastoma, Hodgkin's disease, Wilms' tumor, and sarcoma was simulated on three humanoid phantoms representing patients of 5, 10, and 15 years of age. Ovarian and testicular dose measurements were performed using thermoluminescent dosimeters on a linear accelerator with multileaf collimator (MLC) producing 6-MV X-rays. The effect of lead block introduction into the primary beam on the gonadal dose was evaluated. Gonadal dose from radiotherapy for abdominal tumors was measured using an 18-MV photon beam.
For a tumor dose range of 12-55 Gy, the scattered dose to ovaries was 0.5-62.4 cGy depending upon the patient's age (corresponding phantom) and treatment site. The corresponding dose to testes was 0.4-145.0 cGy. The use of blocks for field shaping can increase the gonadal dose up to a factor of 2.0 compared to that measured using MLC. Abdominal irradiation with 18-MV instead of 6-MV X-rays reduced the gonadal dose by more than 1.3 times. For female and male patients, the risk for induction of hereditary disorders was less than 81 x 10(-4) and 188 x 10(-4), respectively.
The present dosimetric data suggest that pediatric radiotherapy is not associated with a risk for permanent damage to gonads excluded from the treatment volume. The risk for development of hereditary disorders in offspring conceived after exposure is low.
测量常见儿童恶性肿瘤放射治疗时卵巢和睾丸所受的散射剂量，并评估辐射诱发性腺损伤和后代遗传疾病的相关风险。
在代表5岁、10岁和15岁患者的三具人体模型上模拟中枢神经系统肿瘤、急性白血病、神经母细胞瘤、霍奇金病、肾母细胞瘤和肉瘤的放射治疗。使用热释光剂量计在配备多叶准直器（MLC）的直线加速器上进行卵巢和睾丸剂量测量，该加速器产生6兆伏X射线。评估在原射线束中引入铅挡块对性腺剂量的影响。使用18兆伏光子束测量腹部肿瘤放射治疗时的性腺剂量。
对于12 - 55戈瑞的肿瘤剂量范围，卵巢所受散射剂量为0.5 - 62.4厘戈瑞，具体取决于患者年龄（相应人体模型）和治疗部位。睾丸的相应剂量为0.4 - 145.0厘戈瑞。与使用MLC测量的结果相比，使用挡块进行射野塑形可使性腺剂量增加至2.0倍。用18兆伏而非6兆伏X射线进行腹部照射可使性腺剂量降低超过1.3倍。对于女性和男性患者，诱发遗传疾病的风险分别小于81×10⁻⁴和188×10⁻⁴。
目前的剂量学数据表明，儿童放射治疗与治疗体积外性腺的永久性损伤风险无关。暴露后受孕的后代发生遗传疾病的风险较低。
