A new microwave applicator with integrated cooling system for intracavitary hyperthermia of vaginal carcinoma

Abstract

An improved design of a previously described intracavitary microwave hyperthermia applicator is presented. The applicator consists of a coaxial choke antenna designed to be positioned into a perspex obturator. The antenna can be fitted in the obturator in three defined positions depending on the specific clinical situation: The selected median, paramedian or lateral position can each provide differently directed heating patterns. This feature combined with the additional axial variability of the antenna position within the obturator can lead to a highly targeted heating of tumours and a reduced risk of unwanted heating of normal tissues. Various phantom studies were conducted using both liquid and solid phantoms. The saline phantom was used to check the typical action of the choke of the antenna where it was found that the antenna choke is efficiently working resulting in a heating pattern which is dependent of the insertion depth of the antenna. The solid phantom was used to measure the typical specific absorption rate (SAR) distribution of each antenna/obturator configuration.

Key Words:

• Intracavitary hyperthermia
• microwave
• intracavitary radiotherapy
• phantom studies
• vaginal carcinoma