Implant strategies for endocervical and interstitial ultrasound hyperthermia adjunct to HDR brachytherapy for the treatment of cervical cancer.

摘要

Catheter-based ultrasound devices provide a method to deliver 3D conformable heating integrated with HDR brachytherapy delivery. Theoretical characterization of heating patterns was performed to identify implant strategies for these devices which can best be used to apply hyperthermia to cervical cancer. A constrained optimization-based hyperthermia treatment planning platform was used for the analysis. The proportion of tissue >/=41 degrees C in a hyperthermia treatment volume was maximized with constraints T(max) 200 cm(3)) is possible using multiple sectored interstitial and endocervical ultrasound devices. The endocervical device can heat >41 degrees C to 4.6 cm diameter compared to 3.6 cm for the interstitial. Sectored applicators afford tight control of heating that is robust to perfusion changes in most regularly spaced configurations. T(90) in example patient cases was 40.5-42.7 degrees C (1.9-39.6 EM(43 degrees C)) at 1 kg m(-3) s(-1) with 10/14 patients >/=41 degrees C. Guidelines are presented for positioning of implant catheters during the initial surgery, selection of ultrasound applicator configurations, and tailored power schemes for achieving T(90) >/= 41 degrees C in clinically practical implant configurations. Catheter-based ultrasound devices, when adhering to the guidelines, show potential to generate conformal therapeutic heating ranging from a single endocervical device targeting small volumes local to the cervix (<2 cm radial) to a combination of a 2 x 180 degrees endocervical and directional interstitial applicators in the lateral periphery to target much larger volumes (6 cm radial), while preferentially limiting heating of the bladder and rectum.