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A comparison of permanent prostate brachytherapy techniques: preplan vs. hybrid interactive planning with postimplant
Thomas G Shanahan1, Parashar J Nanavati, Paul W Mueller
1Department of Radiation Oncology, Memorial Medical Center, Springfield, IL 62781-0001, USA. Shanahan.thomas@mhsil.com
Purpose:
To compare preparation time, procedure time in the operating room, equipment needs, and Day 0 postimplant dosimetry between two different Mick implant techniques performed at a single institution.
Methods And Materials:
One hundred consecutive monotherapy patients treated from 1999 to 2000 with 125I transperineal permanent implantation of the prostate using an afterloading Mick applicator were evaluated. The first 40 patients were treated with a preplanned modified peripheral loading Mick technique. The next 60 were treated with a hybrid interactive image-guided Mick technique. The analysis included planning the following: ultrasound volume, time required of preplanning, Day 0 CT volume, number of seeds, number of needles, activity per seed, total activity of the implant, and procedure time. Dosimetric parameters included D(90), V(100), and V(150).
Results:
Mean planning ultrasound volume (33 vs. 37 cc), Day 0 CT volume (49 vs. 47 cc), mCi/seed (0.30 vs. 0.34 mCi/seed), number of seeds (121 vs. 96), total activity of the implant (36 vs. 32 mCi), D(90) (132 vs. 149 Gy), V(100) (86% vs. 91%), and V(150) (51% vs. 38%) were comparable. Significant differences (p < 0.01) were noted in mean preplan time (30 vs. 7 min), number of needles (32 vs. 19), and procedure time (90 vs. 40 min).
Conclusions:
Hybrid interactive Mick prostate brachytherapy consistently reduces preplanning time, procedure time, and number of needles used, reducing patient treatment time and costs while maintaining excellent dosimetric coverage. Use of hybrid interactive Mick prostate brachytherapy results in improved therapeutic ratios, i.e., maintains Day 0 D(90) >140 Gy, V(100) >90%, and V(150) <40%, without the need for sophisticated three-dimensional intraoperative planning technology.