Dosimetric impact of contouring and needle reconstruction uncertainties in US-, CT- and MRI-based high-dose-rate prostate brachytherapy treatment planning

作者：Rylander Susanne^*; Buus Simon; Pedersen Erik M; Bentzen Lise; Tanderup Kari

来源：Radiotherapy and Oncology, 2017, 123(1): 125-132.

DOI：10.1016/j.radonc.2017.01.007

• US-based brachytherapy
• CT-based brachytherapy
• MRI-based brachytherapy
• High-dose-rate prostate brachytherapy
• Intra observer contouring variability
• Prostate brachytherapy

Background and purpose: The purpose was to evaluate the dosimetric impact of target contouring and needle reconstruction uncertainties in an US-, CT- and MRI-based HDR prostate BT treatment planning.
Material and methods: US, CT, and MR images were acquired post-needle insertion in 22 HDR-BT procedures for 11 consecutive patients. Dose plans were simulated for an US-, CT- and MRI-based HDR-BT treatment planning procedure. Planning uncertainties in US- and CT-based plans were evaluated using MRI-based planning as reference. Target (CTVProstate) was re-contoured on MRI. Dose results were expressed in total equivalent dose given in 2 Gy fractionation dose for EBRT (46 Gy) plus 2 HDR-BT fractions.
Results: Uncertainties in US- and CT-based planning caused the planned CTVProstate-D-90% to decrease with a mean of 2.9 +/- 5.0 Gy (p = 0.03) and 2.9 +/- 2.9 Gy (p = 0.001), respectively. The intra-observer contouring variation on MRI resulted in a mean variation of 1.6 +/- 1.5 Gy in CTVProstate-D-90%. Reconstruction uncertainties on US resulted in a dose variation of +/- 3 Gy to the urethra, whereas data for CT were not available for this.
Conclusions: Uncertainties related to contouring and reconstruction in US- and CT-based HDR-BT treatment plans resulted in a systematic overestimation of the prescribed target dose. Inter-modality uncertainties (US and CT versus MR) were larger than MR intra-observer uncertainties.

• 出版日期2017-4