Correlation between ICRU reference point dose and dose-volume parameters of organs at risk in three-dimensional conformal brachytherapy for locally advanced cervical cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the correlation between ICRU reference point dose and dosevolume parameters of organs at risk (OARs) under different bladder and rectal filling status in threedimensional conformal brachytherapy for locally advanced cervical cancer.Methods A total of 31 patients who received magnetic resonance imaging-guided three-dimensional conformal brachytherapy for cervical cancer in 96 fractions were enrolled.The ICRU rectal and bladder reference points were determined in the treatment planning system,and the doses at these points were recorded and compared with the dose-volume parameters of the rectum and bladder.The paired t-test was used to analyze the differences between them.Results Bladder DICRU was lower than bladder D0.1cm3 and D1 cm3 (P=0.000 and 0.000),higher than bladder D5 cm3 and D10cm3 (P=0.000 and 0.000),and similar to bladder D2 cm3 (P=0.345).Under the bladder filling status,bladder DICRU was lower than D2cm3.Rectal DICRU was lower than rectal D0.1 cm3 and D1cm3 (P =0.000 and 0.002),higher than rectal D5 cm3 and D 10 cm3 (P =0.000 and 0.000),and similar to rectal D2cm3 (P=0.058).The ICRU bladder and rectal reference point doses were positively correlated with corresponding D2 cm3.In the case of bladder volume ≥ 200 cm3,the ICRU bladder reference point dose underestimated bladder D2 cm3.In the case of rectal volume ≥ 37 cm3,the ICRU rectal reference point dose overestimated rectal D2 cm3.Conclusions In three-dimensional conformal brachytherapy,it is generally safe to use D2 cm3 as an index to evaluate OARs,but when the bladder or rectum is in an empty status,the ICRU bladder or rectal reference point doses should be considered.