A novel cerrobend block in the radiation therapy

This study was carried out to look for the substitute products of lead cerrobend block and determine whether the products can give more radiation dose to the tumor in the skin and superficial tumors in radiotherapy treatment. Five kinds of PbO/ Er203/Epoxy（E-51） samples used as the cerrobend block in the electron beam radiotherapy treatment were prepared success- fully by a solidified forming approach. The central axis depth dose and off-axis dose profiles in the water phantom were calcu- lated using BEAMnrc/DOSEXYZnrc user codes. The results revealed that there were more energy deposition events induced by low energy electron beams in the surface of the water phantom. These electron beams were attributed to Compton scattering and photoemission between photons and erbium, plumbum elements. The maximum dose （Dm） and the depth at the maximum dose （Rm） were linearly dependent on the mass fraction of erbium and plumbum element in the sample. The max dose and its depth varied depending on the combined actions of new electrons and transmission electrons.

改进鼻咽癌外照射技术的前瞻性临床研究

目的：前瞻性地观察改进鼻咽癌外照射技术对临床治疗疗效的影响。方法：从1992年3月至1995年6月，124例初治鼻咽癌病人按T、N、M分层配对分为改进方案治疗组(先面颈联合野照射40～45Gy，后用面颈分野照射至根治量或预防量，采用低熔点挡块技术)或常规方案治疗组(全程放疗均采用面颈分野)进行治疗，然后比较两组的近远期疗效及其正常组织的早发和晚发放射反应。结果：放疗后2～3月的CT检查显示改进方案治疗组原发灶完全消退率(58.06％)高于常规方案治疗组(30.64％)(P<0.05)，而改进方案治疗组口腔粘膜和胃肠早发放射反应轻于常规方案治疗组(P<0.05)。远期随访显示改进方案治疗组1、3和5年总的生存率、无瘤生存率和无局部区域复发率均高于常规方案治疗组(P<0.05)，且改进方案治疗组的后组颅神经放射损伤率(4.8％)低于常规方案治疗组(16.1％)(P<0.05)。结论：与常规方案相比，改进方案提高了鼻咽癌的局部区域控制率，提高了病人的生存率和生存质量，值得推广应用。

改进头颈部恶性肿瘤外照射放疗技术的临床观察

目的 探讨改进头颈部恶性肿瘤外照射放疗技术的疗效及副反应。方法 经病理确诊头颈部恶性肿瘤 95例 ,头颈部用头枕面罩固定 ,低熔点铅挡块技术 ,等中心照射 ,一般肿瘤根治剂量 72 ( 70～ 80 )Gy ,非霍奇金淋巴瘤 5 0～ 5 5Gy ;预防剂量 5 6( 5 0～ 60 )Gy ,非霍奇金淋巴瘤 45～ 5 0Gy。结果 放疗后 1～ 2个月CT复查可评价的肿瘤完全消退率 5 8 5 7% ,明显消退率 3 2 86% ,正常组织急性放射相关性粘膜炎发生率 0级 5 6 84% ,1级 42 10 % ,2级 1 0 5 % ,随访 1～ 2年脊髓脑干晚期放射反应为 0。结论 改进的外照射放疗技术对头颈部恶性肿瘤照射更准确 ,局部控制率高 。