Calculation of Organ Doses for a Large Number of Patients Undergoing CT Examinations

Abstract

Purpose To develop and demonstrate an automated calculation method to provide organ dose assessment for a large cohort of pediatric and adult patients undergoing CT examinations. Methods We adopted two dose libraries that were previously published: the CTDIvol-normalized organ dose library and the mAs-normalized CTDIw library. We developed an algorithm to calculate organ doses using the two dose libraries and CT scan parameters available from DICOM data. To demonstrate the established method, we calculated organ doses for pediatric (n=2499) and adult (n=2043) CT scans randomly selected from four health care systems in the United States, and compared the adult organ doses with the values calculated from the ImPACT calculator. Results Median brain dose was 20 mGy (pediatric) and 24 mGy (adult), and brain dose was greater than 40 mGy for 11% (pediatric) and 18% (adult) of head scans. Both the NCI and the ImPACT methods provided similar organ doses (median discrepancy < 20%) for all organs except for the organs located close to scan boundaries. The visual comparisons of scan coverage and phantom anatomies revealed that the NCI method based realistic computational phantoms provides more realistic organ doses compared to the ImPACT method. Conclusion The automated organ dose calculation method developed in this study reduces the time needed to calculate doses on a large number of patients. We have successfully utilized this method for a variety of CT-related studies including retrospective epidemiological study and CT dose trend analysis studies.

Rapid switching kVp dual energy CT: Value of reconstructed dual energy CT images and organ dose assessment in multiphasic liver CT exams

“…Clinical applications of DECT are widely reported in abdominal imaging, particularly those related to the reduction of radiation dose and improvements in lesion detection and conspicuity [1, 9–12]. However, the dose metrics used to evaluate reductions in radiation dose from DECT typically represent dose to acrylic phantoms, not patients [13, 14]. As a result, estimates of dose reduction and any associated determination of risks may be inaccurate [14, 15].…”

“…As a result, estimates of dose reduction and any associated determination of risks may be inaccurate [14, 15]. With the growing interest in patient dose tracking and optimization of imaging protocols it is essential to have patient-specific radiation dose metrics such as organ dose [13, 14, 16]. Furthermore, the quality of each post-processed image is associated with the specific imaging task of interest, which is closely tied to the amount of radiation used to generate the image [16].…”

The Necessity of Follow-Up Brain Computed-Tomography Scans: Is It the Pathology Itself Or Our Fear that We Should Overcome?

“…There is the scarce amount of studies to evaluate the necessity of repeat CT scan in TBI. There is a risk of exposure to high iodising radiation (median dose = 20 mGy, in some cases it may pass over 40 mGy) during brain CT scans [ 8 - 11 , 20 , 21 ].…”

Thyroid Radiation Dose to Patients from Diagnostic Radiology Procedures over Eight Decades

“…We used the National Cancer Institute dosimetry system for Computed Tomography (NCICT) (Lee et al 2015, Bahadori et al 2015) for thyroid dose estimation. NCICT uses organ dose coefficients (mGy/mGy), organ absorbed dose (mGy) per volumetric Computed Tomography Dose Index (CTDI vol )(mGy), which were calculated from Monte Carlo radiation simulation of a reference CT scanner coupled with a series of computational human phantoms (Lee et al 2009).…”