The evolving practice of intrauterine cervix brachytherapy in Canada: a medical physics perspective

To determine the current equipment, technology, and treatment planning methods used in Canadian cancer centers for intrauterine cervix brachytherapy.

A questionnaire was developed to survey medical physicists in Canada regarding technical aspects of intrauterine cervix brachytherapy. A response was obtained from one physicist at each radiotherapy facility in Canada.

A total of 32 of the 41 Canadian radiotherapy facilities perform intrauterine brachytherapy. Most (88%) use high-dose-rate brachytherapy. Images used for treatment planning are two-dimensional (2D) X-rays (63%), CT (66%), MRI (13%), and cone beam CT (9%). Patients are moved to another room to obtain images at 66% of the centers. Dose is prescribed to a volume at 28% of centers, and dose-volume histogram information is used in evaluating dose to the organs at risk (47%) and target (31%). Manual optimization was the most common optimization method (81%). A total of 69% of the institutions made significant changes within the past 5 years, and 66% plan major changes within the next 2 years.

Intrauterine brachytherapy treatment for cervical cancer is rapidly evolving in Canada, with centers moving toward 3D image-based methods. Often these imaging modalities are not located in the brachytherapy room, so studies on immobilization and verification would be useful. Access to MRI is increasing, but remains low, correlating with a low adoption of volume-based parameters for evaluating target coverage. National treatment guidelines would be useful for centers making the transition from 2D to 3D methods and for encouraging access to MRI.