Fritz P, Berns C, Anton H W, Hensley F, Assman J, Flentje M, von Fournier D, Wannenmacher M
Department of Clinical Radiology, University of Heidelberg, Germany.
Radiother Oncol. 1997 Oct;45(1):23-32. doi: 10.1016/s0167-8140(97)00145-x.
For radiobiological reasons the new concept of pulsed dose rate (PDR) brachytherapy seems to be suitable to replace traditional CLDR brachytherapy with line sources. PDR brachytherapy using a stepping source seems to be particularly suitable for the interstitial boost of breast carcinoma after breast-conserving surgery and external beam irradiation since in these cases the exact adjustment of the active lengths is essential in order to prevent unwanted skin dose and consequential unfavorable cosmetic results. The purpose of this study was to assess the feasibility and morbidity of a PDR boost with flexible breast implants.
Sixty-five high risk patients were treated with an interstitial PDR boost. The criteria for an interstitial boost were positive margin or close margin, extensive intraductal component (EIC), intralymphatic extension, lobular carcinoma, T2 tumors and high nuclear grade (GIII). Dose calculation and specification were performed following the rules of the Paris system. The dose per pulse was 1 Gy. The pulse pauses were kept constant at 1 h. A geometrically optimized dose distribution was used for all patients. The treatment schedule was 50 Gy external beam to the whole breast and 20 Gy boost. PDR irradiations were carried out with a nominal 37 GBq 192-Ir source.
The median follow-up was 30 months (minimum 12 months, maximum 54 months). Sixty percent of the patients judged their cosmetic result as excellent, 27% judged it as good, 11% judged it as fair and 2% judged it as poor. Eighty-six percent of the patients had no radiogenous skin changes in the boost area. In 11% of patients minimal punctiform telangiectasia appeared at single puncture sites. In 3% (2/65) of patients planar telangiectasia appeared on the medial side of the implant. The rate of isolated local recurrence was 1.5%. In most cases geometrical volume optimization (GVO) yields improved dose distributions with respect to homogeneity and compensation of underdosage at the margins of the implant. Only in 9% of patients was the dose distribution impaired by GVO. However, GVO causes a number of substantial changes of the dose distribution which have consequences for its application.
The interstitial CLDR boost of the breast can be replaced by the PDR technique without severe acute and late complications and without deterioration of the cosmetic results.
基于放射生物学原因，脉冲剂量率（PDR）近距离放射治疗的新概念似乎适合取代传统的线源连续低剂量率（CLDR）近距离放射治疗。使用步进源的PDR近距离放射治疗似乎特别适合保乳手术和外照射后乳腺癌的组织间增量照射，因为在这些情况下，精确调整活性长度对于防止不必要的皮肤剂量及随之而来的不良美容效果至关重要。本研究的目的是评估采用可弯曲乳房植入物进行PDR增量照射的可行性和并发症发生率。
65例高危患者接受了组织间PDR增量照射。组织间增量照射的标准为切缘阳性或切缘接近、广泛导管内成分（EIC）、淋巴管内浸润、小叶癌、T2期肿瘤和高核分级（GIII）。剂量计算和规定按照巴黎系统的规则进行。每脉冲剂量为1 Gy。脉冲间歇保持恒定为1小时。所有患者均采用几何优化剂量分布。治疗方案为全乳外照射50 Gy及增量照射20 Gy。PDR照射使用标称活度为37 GBq的192铱源。
中位随访时间为30个月（最短12个月，最长54个月）。60%的患者认为美容效果极佳，27%认为良好，11%认为一般，2%认为较差。86%的患者在增量照射区域没有放射性皮肤改变。11%的患者在单个穿刺部位出现最小点状毛细血管扩张。3%（2/65）的患者在植入物内侧出现片状毛细血管扩张。孤立局部复发率为1.5%。在大多数情况下，几何体积优化（GVO）在均匀性和补偿植入物边缘剂量不足方面产生了改善的剂量分布。仅9%的患者剂量分布因GVO而受损。然而，GVO会导致剂量分布发生许多实质性变化，这对其应用有影响。
乳房的组织间CLDR增量照射可以被PDR技术取代，且不会出现严重的急性和晚期并发症，美容效果也不会恶化。
