Dosimetric research on 125I seeds arranged in different spacing by using film dosimeter / 介入放射学杂志

ABSTRACT

Objective To investigate the dosimetric effect of same activity and same number of 125I seeds arranged in axial train but with different spacing.Methods A total of 27 film dosimeters were randomly and equally divided into group A,B and C.Each film was irradiated by three 125I seeds (activity of 1.48×107 Bq).The seeds were arranged in line,and their axial spacing was 1 mm,5 mm and 10 mm respectively.Image analysis software was used to draw iso-gray contour curves of 20,25,30 and 40 gray value on the films,and to calculate the areas contained by each curve.Results Multi-sample mean comparison variance analysis showed that the differences in area contained by 20 and 25 iso-gray contour curves were statistically significant between each other among the three groups (P＜0.001).The difference in area contained by 30 iso-gray contour curve between group A and group B was not statistically significant (P＞ 0.05),while the difference in area contained by 30 iso-gray contour curve between group A and group C as well as between group B and group C was statistically significant (P＜0.001).No statistically significant difference in area contained by 40 iso-gray contour curve existed between each other among the three groups (P=0.99).Conclusion Different spacing arrangement of same activity and same number of 125I seeds can directly influence the peripheral dose distribution.In specific dose range,seed-spacing of 1 mm arrangement may obtain better dose distribution than seed-spacing of 5 mm or 10 mm arrangement can do.