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目的对１９２Ｉｒ高剂量率近距离治疗机在近距离放射治疗中的剂量率效应进行了实验室观察和探讨。方法分别在不同剂量率条件下（平均剂量率为４６．２９Ｇｙ／ｈ或５．７９Ｇｙ／ｈ）进行全腹或全胸１９２Ｉｒ近距离照射。观察指标为存活隐窝细胞数（小肠）和ＬＤ５０值（肺）。结果随平均剂量率的降低和照射时间的延长，早反应组织小肠和晚反应组织肺癌生物效应也会随之下降。不同剂量率照射后小肠的ＥＤ１０剂量之差为２．４６Ｇｙ［（１５．４１－１２．９５）Ｇｙ］，等效剂量降低了１６．０％；肺的ＬＤ５０剂量之差为４．２５Ｇｙ［（１３．２５－９．００）Ｇｙ］，等效剂量降低了３２．１％。结论在进行近距离放射治疗过程中，随剂量率的不同存在着对晚反应组织可能过量或肿瘤剂量不足的潜在生物学问题，该点应予注意。
Objective To investigate the dose-rate effects of 192Ir brachytherapy brachytherapy in brachytherapy. Methods Whole-abdominal or full-chest 192Ir brachytherapy was performed under different dose rates (mean dose rate 46.29Gy / h or 5.79Gy / h). The observed indicators were survival crypt cell number (small intestine) and LD50 value (lung). Results With the decrease of the average dose rate and the extension of irradiation time, the biological effects of lung cancer in the early reaction tissues and the late reaction tissues also decreased. The difference in ED10 dose was 2.46 Gy [(15.41-12.95) Gy] for the small intestine at different dose rates, with a 16.0% reduction in equivalent dose and 4.25 Gy in the LD50 dose in the lung [( 13.25-9.00 Gy), the equivalent dose decreased by 32.1%. Conclusions In the course of brachytherapy, there is a potential biological problem with the possibility of over-reacting with late-response tissue or insufficient tumor dose with different dose rates, which should be noted.