Introduction
High dose-rate prostate brachytherapy has been implemented in Sweden in the late 1980s and early 1990s in six clinics using the same schedule: 20 Gy in two fractions combined with 50 Gy in 25 fractions with external beam radiation therapy. Thirty years have passed and during these years, various aspects of the treatment process have developed, such as ultrasound-guided imaging and treatment planning system. An audit was conducted, including a questionnaire and treatment planning, which aimed to gather knowledge about treatment planning methods in Swedish clinics.

Material and methods
A questionnaire and a treatment planning case (non-anatomical images) were sent to six Swedish clinics, in which high-dose-rate prostate brachytherapy is performed. Treatment plans were compared using dosimetric indices and equivalent 2 Gy doses (EQD2). Treatment planning system report was used to compare dwell positions and dwell times.

Results
For all the clinics, the planning aim for the target was 10.0 Gy, but the volume to receive the dose differed from 95% to 100%. Dose constraints for organs at risk varied with up to 2 Gy. The dose to 90% of target volume ranged from 10.0 Gy to 11.1 Gy, equivalent to 26.0 Gy EQD2 and 31.3 Gy EQD2, respectively. Dose non-homogeneity ratio differed from 0.18 to 0.32 for clinical target volume (CTV) in treatment plans and conformity index ranged from 0.52 to 0.59 for CTV.

Conclusions
Dose constraints for the organs at risk are showing a larger variation than that reflected in compared treatments plans. In all treatment plans in our audit, at least 10 Gy was administered giving a total treatment of 102 Gy EQD2, which is in the upper part of the prescription doses published in the GEC/ESTRO recommendations.



中文翻译：

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瑞典六家诊所对高剂量率前列腺近距离放射治疗计划的审计

简介
瑞典在1980年代末和1990年代初在六家诊所采用了相同的时间表实施了高剂量率前列腺近距离放射疗法：两部分20 Gy与25部分中的50 Gy结合外束放射疗法。30年过去了，在这些年中，治疗过程的各个方面都得到了发展，例如超声引导成像和治疗计划系统。进行了包括问卷和治疗计划在内的审核，目的是收集有关瑞典诊所治疗计划方法的知识。

材料与方法
一份问卷和一个治疗计划案例（非解剖图像）被发送到了六家瑞典诊所，在这些诊所中进行了高剂量率前列腺近距离放射治疗。使用剂量指数和等效的2 Gy剂量（EQD2）比较治疗计划。使用治疗计划系统报告比较停留位置和停留时间。

结果
对于所有诊所，目标的计划目标均为10.0 Gy，但接受剂量的范围从95％到100％不等。处于危险中的器官的剂量限制最高可达2 Gy。达到目标体积的90％的剂量为10.0 Gy至11.1 Gy，分别相当于26.0 Gy EQD2和31.3 Gy EQD2。在治疗计划中，临床目标量（CTV）的剂量非均质性比率从0.18到0.32，CTV的合格指数从0.52到0.59。

结论
对危险器官的剂量限制显示出比比较治疗方案更大的变化。在我们审核的所有治疗计划中，至少给予10 Gy的治疗，总治疗量为102 Gy EQD2，这在GEC / ESTRO建议中公布的处方剂量的上部。