TH-AB-201-03: Estimating Pediatric Entrance Skin Dose From Digital Radiography Examination Using DICOM Metadata: A Quality Assurance Tool

Authors


Abstract

Purpose:

To develop an automated pediatric dose reporting quality assurance (QA) tool for digital radiography (DR) using DICOM metadata.

Methods:

Patient examination and demographical information were gathered from metadata analysis of DICOM header data. Average patient thicknesses were measured for head, chest, abdomen, knees, and hands using volumetric images from CT. Patient entrance skin air KERMA (ESAK) was calculated by first looking up examination technique factors taken from DICOM header metadata (i.e., kVp and mAs) to derive air KERMA (kair), and then scaling kair with a backscatter factor, derived from examination kVp, and for patient thickness. Finally, patient entrance skin dose (ESD) was calculated by multiplying ESAK with a mass-energy attenuation coefficient ratio. ESD to effective dose (E) conversion factors were used to estimate patient population E. ESD and E were computed for common DR examinations at our institution: dual-view chest, anteroposterier (AP) abdomen, lateral (LAT) skull, dual-view knee, and bone age (left hand only) examination.

Results:

ESD was calculated for 3794 patients; mean age 11 ± 8 years (range 2 months to 55 years). ESD range was: 0.19–0.42 mGy for dual-view chest, 0.28–1.2 mGy for AP abdomen, 0.18–0.65 mGy for LAT skull, 0.15–0.63 mGy for dual-view knee, and 0.10–0.12 mGy for bone age examinations. Effective dose values were calculated for dual-view chest 0.04 mSv (± 0.02 mSv), AP abdomen 0.05 mSv (± 0.15 mSv), LAT skull 0.004 mSv (± 0.002 mSv), dual-view knee 0.003 mSv (± 0.002 mSv), and bone age 0.001 mSv (± 0.0002 mSv).

Conclusion:

A methodology combining DICOM header metadata and basic x-ray tube characterization was demonstrated. In a regulatory era where patient dose reporting has become increasingly in demand, this methodology was used to establish an automated dose reporting program for DR to perform patient dose related QA for digital x-ray imaging.

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