39. Pulsed dose rate brachytherapy – describing of a method and a review of clinical applications

Abstract

Introduction

Pulsed Dose Rate (PDR) treatment is a new brachytherapy modality that combines physical adventages of high-dose-rate (HDR) technology (isodose optimization, radiation safety) with the radiobiological adventages of low-dose-rate (LDR) brachytherapy.

Pulsed brachytherapy consists of using a stronger radiation source than for LDR brachytherapy and is giving a senes of short exposures of 10 to 30 minutes in every hour to approximately the same total dose in the same overall as with the LDR. Modern afterloading equipment offers some advantages over intersitial or intracavitary insertion of separate needles, tubes, seeds or wires. Isodose volumes in tissue can be created flexibly by a combination of careful placement of the catheter and adjustment of the dwell times of the computerized stepping source. Automatic removal of the radiation sources into a shielded safe eliminates radiation exposures to staff and visitors. Radiation exposure is also eliminated to the staff who formerly loaded and unloaded a multiplicity of radioactive sources into the catheters, ovoids, tubes etc.

Material and methods

This retrospective study based on summarized clinical investigations analyses the feasibility, differences between methods of brachytherapy and preliminary oncologic results of PDR brachytherapy.

Since July 2000 15 patients were treated in Greatpoland Cancer Center using PDR brachytherapy. They were 10 patients with recurrent brain malignant glioma, 2 with recurrent nasopharyngeal cancer, and patients with lip cancer, recurrent breast cancer and recurrent salivary gland cancer. Only patient with lip cancer was treated radically. Nucletron PDR unit with 1 Ci source and PLATO planning system were used.

Results

Short time of observation doesn’t allow to draw a radical conclusions. On the ground of literature and preliminary own results it seems that PDR brachytherapy is save and efficient method of treatment. The most important complication was a local infection in place of implanted catheter. In some cases (for example in patients with recurrent malignant glioma after teletherapy) PDR brachytherapy perhaps could be a treatment of choice.