Prostate brachytherapy in obese patients

Purpose: To identify and illustrate the potential problems with brachytherapy in obese patients. Methods and Materials: Three patients with body mass index greater than 30 were treated with prostate brachytherapy. Transrectal ultrasound (TRUS) was performed using a 6.0-MHz Siemens Sonoline Prima ultrasound machine and a Barzell-Whitmore stepper unit. The patientsʹ weight required use of an accessory table support. Results: Once set up, there was ample room to maneuver, providing that the patientʹs legs were abducted fully. TRUS imaging of the prostate was unaffected by patientsʹ obesity. The amount of periprostate adipose tissue visualized on TRUS appeared to be no different than that noted in nonobese patients. Similarly, there was no increased distance between the prostate and rectal surface, either on preimplant CT or transverse TRUS. To date, our experience is that the perineal skin to prostate distance was not so great that standard 20-cm applicator needles could not be used. For the 2 sub–350-pound patients who could be imaged on our CT scanner, postimplant target coverage (V100) was 88% and 95%. Conclusions: Standard TRUS and brachytherapy needles are sufficient to implant even the largest patients.