Patient organ and effective dose estimation in CT: comparison of four software applications

Abstract

Background: Radiation dose in computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. Hence, dose tracking and organ dose calculation software are increasingly used. We evaluated the organ dose variability associated with the use of different software applications or calculation methods. Methods: We tested four commercial software applications on CT protocols actually in use in our hospital: CT-Expo, NCICT, NCICTX, and Virtual Dose. We compared dose coefficients, estimated organ doses and effective doses obtained by the four software applications by varying exposure parameters. Our results were also compared with estimates reported by the software authors. Results: All four software applications showed dependence on tube voltage and volume CT dose index, while only CT-Expo was also dependent on other exposure parameters, in particular scanner model and pitch caused a variability till 50%. We found a disagreement between our results and those reported by the software authors (up to 600%), mainly due to a different extent of examined body regions. The relative range of the comparison of the four software applications was within 35% for most organs inside the scan region, but increased over the 100% for organs partially irradiated and outside the scan region. For effective doses, this variability was less evident (ranging from 9 to 36%). Conclusions: The two main sources of organ dose variability were the software application used and the scan region set. Dose estimate must be related to the process used for its calculation.

Split-bolus computed tomography urography (CTU) achieves more than half of radiation dose reduction in females and overweight patients than conventional single-bolus computed tomography urography

“…Nonetheless, males have been considered as less radiosensitive than females because females have higher cancer risk when exposed to similar radiation dose as males [12] . This study used CT-Expo for assessing radiation doses which were based on the calculated organ doses with regard to the tissue weighting factors [ 9 , 10 ]. In assessing females, two radiosensitive organs (i.e.…”

“…In assessing females, two radiosensitive organs (i.e. : breast and ovary) were included in organ radiation calculations whereas testicles in males was the only radiosensitive organ included for organ dose evaluation [ 9 , 10 ]. Nonetheless, the default setting of CT-Expo is actually to reflect the higher radiation sensitivity and risk of females, especially for breast, potentially induced by ionizing radiation.…”

“…CT-Expo is a Microsoft Excel based application for patient CT dose calculation, and uses the dose evaluation methods mentioned in CT exposure surveys in Germany. The software allows the computation of age- and sex-specific radiation doses on the basis of the inputted scanner model, manufacturer, scanning parameters, and scanned area using one of four anthropomorphic mathematical phantoms: adult male (ADAM), adult female (EVA), children at age of seven (CHILD), and infants (BABY) [ 9 , 10 ] ( Fig. 2 ).…”

Radiation dose monitoring in computed tomography: Status, options and limitations

“…However, realistic phantoms better mimic actual patients (even pregnant ones), and in some DMS systems there is a large library of such realistic phantoms and the one that matches the specific patient in terms of his age, size and gender can be selected. The literature on anthropomorphic phantoms and their use for patient dose calculations is quite extensive and it is not limited to the referenced studies [48][49][50][51][52][53][54][55][56][57][58][59][60]. A detailed description of 50-years of evolution in the design of anthropomorphic phantoms can be found elsewhere [56].…”

“…After matching of the patient with a phantom of similar size, the DMS can determine not only of the geometrical but also of the anatomic start and end points of each the scan series. Therefore, the actual examination can be simulated in the phantom and calculate E, organ doses, and in some cases, even cancer risk estimates [57][58][59][60][61][62][63][64][65][66]. However, E values, organ doses and risk estimates reported within DMS should be used with caution, because apart from the inherent limitations of such calculations, in most cases they are not patient specific [36].…”