Thermal dosimetry analysis combined with patient-specific thermal modeling of clinical interstitial ultrasound hyperthermia integrated within HDR brachytherapy for treatment of locally advanced prostate cancer

This study presents thermal dosimetry analysis from clinical treatments where ultrasound hyperthermia (HT) was administered following high-dose rate (HDR) brachytherapy treatment for locally advanced prostate cancer as part of a clinical pilot study. HT was administered using ultrasound applicators from within multiple 13-g brachytherapy catheters implanted along the posterior periphery of the prostate. The heating applicators were linear arrays of sectored tubular transducers (∼7 MHz), with independently powered array elements enabling energy deposition with 3D spatial control. Typical heat treatments employed time-averaged peak acoustic intensities of 1 – 3 W/cm2 and lasted for 60 – 70 minutes. Throughout the treatments, temperatures at multiple points were monitored using multi-junction thermocouples, placed within available brachytherapy catheters throughout mid-gland prostate and identified as the hyperthermia target volume (HTV). Clinical constraints allowed placement of 8 – 12 thermocouple sensors ...