Feasibility of permanent interstitial brachytherapy for skull base region through individual template assistance / 中华放射医学与防护杂志

ABSTRACT

Objective To evaluate the feasibility of individual template assisting permanent interstitial brachytherapy for skull base region.Methods From August 2010 to June 2012,20 patients with recurrent malignancies of skull base region received 125I seed permanent implantation.Before implanting,all patients underwent CT scan,the data were stored in Dicom format and imported into brachytherapy treatment planning system (BTPS).The preplan were finished by BTPS.Then,the digital model based on virtual needle and skin CT slices was reconstructed by Mimics and Geomagic.According to the digital model,the individual template was made from medical light-cured resin using rapid forming machine.During implanting,needles were inserted under the individual template assistance and 125I seeds were implanted according to preplan.After implanting,implantation quality was evaluated by 2D and 3D CT images and BTPS.The needles and seed distribution were observed.The actual dose distribution of target volumes D90,V100 and V150 was calculated.The complications were recorded within 72 hours.Results Interstitial implantation of 20 patients were performed successfully and efficiently under the individual template assistance without serious complications.Because of containing the virtual needle positioning and face surface feature information at the same time,the individual template significantly improved precision of needle location and orientation.The actuarial median number of 125I seeds implanted was 70 (range,20-172),and actuarial median D90,V100 and V150 was 181.6 Gy (127.4-279.6 Gy),98.2％ (94.6％-100％),43.2％ (24.3％-52.2％),respectively.The seed distribution and dosimetric quality were well controlled.Conclusions The method of individual template assisting permanent interstitial brachytherapy for skull base region is feasible,which can improve the accuracy of needle position placement.