Nath Ravinder, Bongiorni Paul, Chen Zhe, Gragnano Jillian, Rockwell Sara
Department of Therapeutic Radiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA.
Brachytherapy. 2004;3(3):159-72. doi: 10.1016/j.brachy.2004.08.004.
To develop an experimental technique for studying the radiobiology of continuous low-dose-rate irradiation (CLDRI) using clinical brachytherapy sources emitting low energy photons for a rat solid tumor model.
BA1112 tumors were grown between the ears of 14-week-old male WAG/Rij rats by interdermal inoculation. A radioactive source afterloading system, which consists of a lightweight helmet sutured to the rat and a nine-source polystyrene applicator, was fabricated for in vivo tumor irradiation by (125)I and (103)Pd brachytherapy sources. This system has a 12 x 12 mm opening in the center to accommodate the tumor and its growth during irradiation (the diameter of a typical BA1112 tumor was about 6 mm when radiation was applied). The spatial locations of the nine sources were optimized to produce an as uniform as possible three-dimensional dose distribution to the central portion of the applicator for both the (125)I and (103)Pd sources. Absolute dose delivered by the applicator was verified by point dose measurements using calibrated TLD in a polystyrene phantom that mimics the scattering environment of the tumor on the rat.
The feasibility of tumor cure experiments using the experimental technique presented in this work was demonstrated. The technique was used to study the influence of initial dose rate on the in vivo tumor cure probability of BA1112 tumors irradiated by (125)I and (103)Pd sources at dose rates varying from 8-20 cGy/h. The technique was also used for studying the in vitro tumor cell survival following in vivo CLDRI irradiation of the tumor.
An experimental technique using an in vivo tumor model has been developed for studying the radiobiological effects of continuous low-dose-rate irradiations using (125)I sources alone, (103)Pd sources alone, or a mixture of (125)I and (103)Pd sources.
开发一种实验技术，用于研究连续低剂量率照射（CLDRI）的放射生物学，该技术使用发射低能光子的临床近距离放射治疗源，应用于大鼠实体瘤模型。
通过皮内接种在14周龄雄性WAG/Rij大鼠两耳之间培育BA1112肿瘤。制作了一种放射性源后装系统，该系统由缝合在大鼠身上的轻质头盔和一个九源聚苯乙烯施源器组成，用于通过（125）I和（103）Pd近距离放射治疗源对体内肿瘤进行照射。该系统在中心有一个12×12毫米的开口，以在照射期间容纳肿瘤及其生长（施加辐射时典型BA1112肿瘤的直径约为6毫米）。对九个源的空间位置进行了优化，以使（125）I和（103）Pd源对施源器中心部分产生尽可能均匀的三维剂量分布。通过在模拟大鼠肿瘤散射环境的聚苯乙烯体模中使用校准的热释光剂量计进行点剂量测量，验证了施源器传递的绝对剂量。
证明了使用本研究中提出的实验技术进行肿瘤治愈实验的可行性。该技术用于研究初始剂量率对（125）I和（103）Pd源在8 - 20 cGy/h剂量率下照射BA1112肿瘤的体内肿瘤治愈概率的影响。该技术还用于研究肿瘤体内CLDRI照射后的体外肿瘤细胞存活情况。
已开发出一种使用体内肿瘤模型的实验技术，用于研究单独使用（125）I源、单独使用（103）Pd源或（125）I与（103）Pd源混合物进行连续低剂量率照射的放射生物学效应。
