Dose Reference Levels for Pediatric Thorax CT: Can Image Quality Be Achieved While Maintaining Dose Reduction for Different Body Mass Indices?

Organ doses were calculated for diagnostic thorax CT, using data for 573 male Bangladeshi children from 0-10 years old, accounting for age and BMI. We have computed organ doses for an average male adult (170 cm*70 kg) undergoing a thorax CT examination using the ImPACT dose calculator and constructed ratios of organ dose to CTDIvol as a function of location of organs in the thorax, using a tube voltage of 120 kV for Siemens 64 slice CT scanner. BMIs are modelled as specific diameter water cylinders to obtain the factors for organ doses relative to the organ doses received by a reference adult. Results show that age operates a reduction in absorbed dose by a factor ranging from 0.33-0.79, which are consistent with other reference studies. Conversely, an increase of 1 BMI unit implies an increase in absorbed dose of up to 13% to maintain the quality standards of diagnostic imaging.