Study on estimation methods of absorbed dose to eye lens of infants from CT head and neck scanning based on one-year old anthropomorphic phantom

Objective To study the methods to estimate absorbed dose to eye lens of infants from CT scanning using different protocols and try to find a practical quick way for estimating absorbed dose to eye lens. Methods By scanning one-year old anthropomorphic phantom using 7 kinds of different protocols, all TLDs were measured for final estimation of absorbed dose to eye lens using two different dose conversion methods . Meanwhile, linear regression equation was established between absorbed dose to eye lens and CTDI. Results Absorbed doses to eye lens of infants from children CT scanning using 7 kinds of different protocols were (9.96±0.69) mGy in head axis, (7.01±0.42) mGy in head helical, (12.60±0.97) mGy in sinus, (12.97±0.42) mGy in inner ear, (0.63±0.03) mGy in neck soft tissue, (8.89±0.44) mGy in cervical vertebra, and (0.34±0.01) mGy in chest, respectively. There were statistically significant difference in doses among different groups (F=846.826, P<0.05). For different scanning locations, there was linear relation between absorbed dose to eye lens and CTDI(r=0.986-0.999, P<0.05). Conclusions Absorbed dose to eye lens of infants from children CT scaning with single dose may not be above threshold dose. In addition, absorbed dose to eye lens can be estimated quickly by linear regression equation between absorbed dose to eye lens and CTDI. Key words: Infants; CT; Eye lens; Absorbed dose; Estimation methods