Title :
Dosimetric study of the narrow beams of Co60 teletherapy unit for stereotactic radiosurgery
Author :
Singh, Rabi Raja ; B, Paul Ravindran ; Ayyangar, Komanduri
Author_Institution :
Dept. of Radiat. Oncology, Christian Med. Coll. & Hospital, Vellore, India
Abstract :
The aim of the study is to explore the possibility of using telecobalt unit for radiosurgery. A dosimetric study is performed for the narrow beam of Co60 unit, which is fitted with circular radiation fields with diameters of 11 mm, 17 mm, 20 mm, 27 mm, 32 mm, 35 mm, 40 mm and 44 mm. Percentage Depth Dose (PDD), Off Axis Ratio (OAR) are measured with ion chamber and radiographic film. The TAR values obtained from measurements agreed well with the calculated values for all cone sizes and depth, ranging from depth of maximum ionization to 24 cm in water. A quantitative evaluation of treatment plan with data of Co 60 and 6 MV photon beam has been carried out. The penumbra for the narrow beam of Co60 is larger than that of 6 MV beam by 1.3 mm on an average. This difference in penumbra can be attributed to large source size of Co60 unit. The above measurements and the feasibility of using narrow beam of Co60 for Stereotactic Radiosurgery/Radiotherapy are discussed
Keywords :
cobalt; dosimetry; radiation therapy; radioisotopes; surgery; 11 to 44 mm; 24 cm; 6 MV; 60Co teletherapy unit; Co; circular radiation fields; cone sizes; dosimetric study; ion chamber; maximum ionization depth; narrow beams; off axis ratio; penumbra; percentage depth dose; radiographic film; source size; stereotactic radiosurgery; therapeutic nuclear medicine; treatment plan evaluation; Cobalt; Collimators; Costs; Ionization; Linear accelerators; Neurosurgery; Oncology; Radiography; Surgery; Volume measurement;
Conference_Titel :
Engineering in Medicine and Biology Society, 2000. Proceedings of the 22nd Annual International Conference of the IEEE
Conference_Location :
Chicago, IL
Print_ISBN :
0-7803-6465-1
DOI :
10.1109/IEMBS.2000.901417
