ABSTRACT
Objective To study the dosimetry of different arrangements of 125I seeds in one plane.Methods Nine different in-plane arrangements of 9 125I seeds (2.035 × 107 Bq/seed) were simulated according to distance (cm) along x (horizontal)- and y( longitudinal )-axis using the 3-dimensional treatment planning system (TPS) (3D-TPS): x0.5, y0. 5; x0. 5, y1.0; x0. 5, y1.5; x1.0, y1.0; x1.0, y1.5;x1.5, y1.5; x0. 5, y0. 5 (2)1.0; x0.5, y1.0 (2)0.5; x1.0, y1.0 (2)0.5. The isodose curves of 40,80, 130, 145 and 200 Gy were created and the area, radius and medical cost under the 40, 80, 130, 145and 200 Gy isodose curves were calculated. Results The area, radius and medical cost under the same isodose curves were significantly different with each 125I seed arrangement. The arrangements which had the biggest area under curves of 40, 80, 130, 145 and 200 Gy isodose were x1. 5, y1. 5; x1. 0, y1. 0; x1. 0,y1. 0; x0. 5, y1. 0 and x0. 5, y1. 0, respectively. Conclusion The matched peripheral dose and therapeutic effect were affected significantly by the geometric arrangement of 125I seeds.