Harms W, Peschke P, Weber K J, Hensley F W, Wolber G, Debus J, Wannenmacher M
Department of Radiology, Clinical Radiology, University of Heidelberg, INF 400, D-69120 Heidelberg, Germany.
Int J Radiat Biol. 2002 Jul;78(7):617-23. doi: 10.1080/09553000210132324.
To study the response of the Dunning prostate carcinoma (R3327-AT1 subline) to continuous low dose-rate (CLDR) and pulsed dose-rate (PDR) brachytherapy.
After subcutaneous tumour transplantation into the thigh of the Copenhagen rat, doses of 0, 20, 30, 40 and 50 Gy were applied to the tumour surface (tumour diameter 9+/-1mm). Eight animals were irradiated per dose group and exposure condition. Interstitial PDR ((192)Ir source, 37 GBq) and CLDR ((192)Ir seed, 150 MBq) brachytherapy were carried out with 0.75 Gy/pulse h(-1) and a dose-rate of 0.75Gyh(-1), respectively. Treatment response was assessed in terms of growth delay expressed as the time (T(5)) required for each tumour to reach five times the initial tumour volume.
The median T(5) times for the CLDR groups (in the order: control, 20, 30, 40, 50 Gy) were 12 (12), 54.5 (21), 64.5 (31), 85.5 (51), and 65 (47.5) days. Values after PDR brachytherapy are given in parentheses and resulted in a significantly impaired tumour growth delay (log-rank test) in the 20Gy (p =0.006) and 30 Gy (p =0.036) groups. No significant difference was found in the 40-50 Gy dose range.
In contrast to previous results and predictions of biological models we observed dose-dependent differential effects of PDR and CLDR brachytherapy with reduced efficacy of PDR in the lower dose range.
研究邓宁前列腺癌（R3327-AT1亚系）对连续低剂量率（CLDR）和脉冲剂量率（PDR）近距离放射治疗的反应。
将肿瘤皮下移植到哥本哈根大鼠大腿后，对肿瘤表面（肿瘤直径9±1mm）施加0、20、30、40和50Gy的剂量。每个剂量组和照射条件下有8只动物接受照射。采用间质PDR（（192）Ir源，37GBq）和CLDR（（192）Ir种子源，150MBq）近距离放射治疗，剂量率分别为0.75Gy/脉冲·h-1和0.75Gy/h。根据生长延迟评估治疗反应，生长延迟定义为每个肿瘤达到初始肿瘤体积5倍所需的时间（T(5)）。
CLDR组（顺序为：对照组、20、30、40、50Gy）的中位T(5)时间分别为12（12）、54.5（21）、64.5（31）、85.5（51）和65（47.5）天。PDR近距离放射治疗后的数值列于括号内，结果显示20Gy（p =0.006）和30Gy（p =0.036）组的肿瘤生长延迟明显受损（对数秩检验）。在40 - 50Gy剂量范围内未发现显著差异。
与先前结果和生物学模型的预测相反，我们观察到PDR和CLDR近距离放射治疗存在剂量依赖性差异效应，在较低剂量范围内PDR的疗效降低。
