[Pulsed dose rate brachytherapy: a method description and review of clinical application]

Pulsed Dose Rate (PDR) treatment is a new brachytherapy modality that combines physical advantages of high-dose-rate (HDR) brachytherapy (isodose optimization, radiation safety) with the radiobiological advantages of low-dose-rate (LDR) brachytherapy. Pulsed brachytherapy consists of using a stronger radiation source than for LDR brachytherapy and is given in a series of short exposures of 10 to 30 minute intervals in every hour to approximately the same total dose overall as with the LDR. Modern afterloading equipment offers some advantages over intestial 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 exposure 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. This retrospective study based on summarized clinical investigation analyses evaluates the feasibility, differences between methods of brachytherapy and preliminary oncologic results of PDR brachytherapy.