Determination of the accuracy of implant reconstruction and dose delivery in brachytherapy in The Netherlands and Belgium

Purpose: To gain insight into the accuracy of brachytherapy treatments. the accuracy of implant reconstruction and dose delivery was investigated in 3 3 radiotherapy institutions in The Netherlands and Belgium. Materials and methods: The accuracy of the implant reconstruction method wa s determined using a cubic phantom containing 25 spheres at well-known posi tions. Reconstruction measurements were obtained on 41 brachytherapy locali zers. 33 of which were simulators. The reconstructed distances between the spheres were compared with the true distances. The accuracy of the dose del ivery was determined for high dose rate (HDR), pulsed dose rate (PDR) and l ow dose rate (LDR) afterloading systems using a polymethyl methacrylate cyl indrical phantom containing a NE 2571 ionization chamber in its centre. The institutions were asked to deliver a prescribed dose at the centre of the phantom. The measured dose was compared with the prescribed dose. Results: The average reconstruction accuracy was -0.07 mm (+/-0.4 mm, 1 SD) for 41 localizers. The average deviation of the measured dose from the pre scribed dose was +0.9% (+/- 1.3%, 1 SD) for 21 HDR afterloading systems, +1 .0% (+/-2.3%, 1 SD) for 12 PDR afterloaders, and +1.8% (+/-2.5%, 1 SD) for 15 LDR afterloaders. Conclusions: This comparison show rd a good accuracy of brachytherapy impla nt reconstruction and dose delivery in The Netherlands and Belgium. (C) 200 1 Elsevier Science Ireland Ltd. All rights reserved.