Clinical application of low-dose computed tomographic urography in children

Objective To evaluate the clinical feasibility of applying low-dose CT urography (CTU) in children.Methods From December 2010 to April 2012,30 children with suspected urinary malformation on screening ultrasonography (USG) undertook low-dose CTU examinations.The lowdose steps were prescribed as follows:eliminating plane scan and post-contrast parenchymal and excretory phase scanning; The preset scan procotols were modified as 100 kV/50 mAs for body weight above 25 Kg (CTU1) and 80 kV/40 mAs for body weight no more than 25 Kg (CTU2).The image quality was evaluated as good,average and poor based on the clarity of kidney outline,three-dimensional image overview and renal pelvis.The images of good or average quality were considered eligible and their rates calculated.Based on intraoperative findings and follow-ups,the diagnostic rate of lowv dose CTU was acquired.Phantom scanning dose(dose length products,DLP)with low-dose CTU and routine CTU (120 kV/85 mAs) protocols were compared.Results The image eligible rate of lowv dose CTU was 98.3％-100％ (98.3％ for renal pelvis,100％ for kidney and three-dimensional overview).The diagnostic rate of low-dose CTU was 100％.The 2 phase DLP of phantom scanning with low-dose CTU1,CTU2,64 spiral CT routine CTU,dual-source CT (DSCT) routine CTU protocols were 62,20,212 and 184 mGy cm respectively.Phantom scanning dose with low dose CTU protocols decreased 66.3％ and 90.6％ versus that of routine protocols.And it also decreased 83.2％ and 95.3％ than that of 4-phase routines.Conclusions Through expedited steps and protocol modification,low-dose CTU imaging for children is feasible and qualified for clinical diagnosis.It is recommended for clinical application. Key words: Tomography, X-ray computed;  Dose-response relationship;  Radiation;  Urethra