A comparison of pediatric and adult CT organ dose estimation methods

Gao, Yiming; Quinn, Brian; Mahmood, Usman; Long, Daniel J.; Erdi, Yusuf E.; Germain, Jean St.; Pandit‐Taskar, Neeta; Xu, X. George; Bolch, Wesley E.; Dauer, Lawrence T.

doi:10.1186/s12880-017-0199-3

Cited by 46 publications

(34 citation statements)

References 54 publications

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“…For the bone marrow, CT-Expo estimated a dose much higher than those estimated by the other three software applications. This is because the phantom implemented in CT-Expo does not have a specific representation for the bone marrow and the bone surface, but it applies a correction factor to the dose received from the entire bone structure [36].…”

Section: Discussionmentioning

confidence: 99%

“…For these organs, the scattering contribution becomes important and a statistical error has to be taken into account, due to the Monte Carlo calculation uncertainties which increase while reducing the number of photons [45]. A difference of a few millimetres in the scan extent can change the dose result by some factors [36].…”

Section: Discussionmentioning

confidence: 99%

“…For example, the bone surface, one of the tissues for which the ICRP specifies the weighting factor in the effective dose calculation, has a different meaning in each of the software applications analysed. CT-Expo refers to bone surfaces, but the phantom implemented does not actually have a different bone structure for the marrow and the surface [36]. Virtual Dose considers bone endosteum instead.…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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

et al. 2020

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“…Anatomy selection and accurate representation of patient size and composition are important considerations for pediatric CT patients, because organ dose changes are relatively greater in smaller patients depending on anatomy selection. A recent study demonstrated organ dose change resulting from inclusion or exclusion of an organ in scan range is more drastic in small patients [34]. In light of the wide range of considerations for accurate dosimetry, including patient size, age and imaging technique, a variety of dosimetry methodologies including those examined in the current study are beneficial to have on hand.…”

Section: Discussionmentioning

confidence: 99%

Patient-adapted organ absorbed dose and effective dose estimates in pediatric 18F-FDG positron emission tomography/computed tomography studies

et al. 2020

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Background: Organ absorbed doses and effective doses can be used to compare radiation exposure among medical imaging procedures, compare alternative imaging options, and guide dose optimization efforts. Individual dose estimates are important for relatively radiosensitive patient populations such as children and for radiosensitive organs such as the eye lens. Software-based dose calculation methods conveniently calculate organ dose using patient-adjusted and examination-specific inputs. Methods: Organ absorbed doses and effective doses were calculated for 429 pediatric 18F-FDG PET-CT patients. Patient-adjusted and scan-specific information was extracted from the electronic medical record and scanner dosemonitoring software. The VirtualDose and OLINDA/EXM (version 2.0) programs, respectively, were used to calculate the CT and the radiopharmaceutical organ absorbed doses and effective doses. Patients were grouped according to age at the time of the scan as follows: less than 1 year old, 1 to 5 years old, 6 to 10 years old, 11 to 15 years old, and 16 to 17 years old. Results: The mean (+/− standard deviation, range) total PET plus CT effective dose was 14.5 (1.9, 11.2-22.3) mSv. The mean (+/− standard deviation, range) PET effective dose was 8.1 (1.2, 5.7-16.5) mSv. The mean (+/− standard deviation, range) CT effective dose was 6.4 (1.8, 2.9-14.7) mSv. The five organs with highest PET dose were: Urinary bladder, heart, liver, lungs, and brain. The five organs with highest CT dose were: Thymus, thyroid, kidneys, eye lens, and gonads. Conclusions: Organ and effective dose for both the CT and PET components can be estimated with actual patient and scan data using commercial software. Doses calculated using software generally agree with those calculated using dose conversion factors, although some organ doses were found to be appreciably different. Software-based dose calculation methods allow patient-adjusted dose factors. The effort to gather the needed patient data is justified by the resulting value of the characterization of patient-adjusted dosimetry.

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“…The k-factors based on voxel phantoms should be more applicable to CT patients compared with the conversion factors calculated from stylized phantoms, especially for the organs with high tissue weighting factors such as the breast, bone marrow, colon, lungs, and stomach. Effective dose estimated from stylized phantoms is reported to be different from realistic voxel phantoms by up to 40% (for head/ neck and abdomen-pelvis scans) [9]. Lastly, k-factors from phantoms with reference size may under-or overestimate actual effective dose delivered to underweight and overweight patients, respectively [10].…”

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confidence: 99%