Pulsed Dose Rate Brachytherapy – Description of a Method and a Review of Clinical Appli- Cations

Pulsed Dose Rate (PDR) treatment is a new brachytherapy modality that combines physical advantages of high-dose-rate (HDR) technology (isodose optimization and radiation safety) with radiobiological advantages of low-dose-rate (LDR) brachytherapy. Pulsed brachytherapy uses a stronger radiation source than that employed in LDR brachytherapy and provides a series of short 10 to 30 minutes long exposures every hour amounting to approximately the same total dose in the same overall as that administered in the LDR. Modern afterloading equipment offers some advantages over interstitial or intracavitary insertion of separate needles, tubes, seeds or wires. Isodose volumes in tissue can be created flexibly by a combination of careful positioning of the catheter and by adjusting the dwell times of the computerized stepping source. Automatic removal of radiation sources into a shielded safe eliminates radiation exposures to staff and visitors. Radiation exposure is also eliminated to the staff who previously loaded and unloaded a large variety of radioactive sources into the catheters, ovoids, tubes etc. This review, based on summarized clinical investigations, analyses the feasibility, differences between methods of brachytherapy and preliminary clinical applications of PDR brachytherapy.