Increasing efficiency in the ACR Digital Mammography QC Manual's DBT Z-resolution evaluation

Document Type

Article

Publication Date

5-2026

Institution/Department

Radiology

Journal Title

Journal of applied clinical medical physics

MeSH Headings

Mammography (methods, standards); Humans; Retrospective Studies; Breast Neoplasms (diagnostic imaging); Phantoms, Imaging; Female; Quality Assurance, Health Care (standards); Image Processing, Computer-Assisted (methods); Radiographic Image Interpretation, Computer-Assisted (methods); Radiographic Image Enhancement (methods); Quality Control

Abstract

BACKGROUND: The Z-resolution evaluation in the ACR Digital Mammography (DM) QC manual measures a pseudo full width half max (pFWHM) from speck group signals through slices of the phantom for comparison to a baseline value. PURPOSE: The evaluation requires measurement of seven ROIs on up to nine slices, for a potential of up to 63 ROIs. This work evaluates whether measuring fewer ROIs would produce similar results. METHODS: Z-resolution data from 468 surveys from 147 mammography units were retrospectively analyzed. The pFWHM was calculated using the 6-speck mean (pFWHM) as described in the ACR manual, as well as using each single speck (pFWHM), and all combinations of a 2-speck mean (pFWHM) using the center and each peripheral speck. Deviation from the respective initial measured pFWHM was determined for all units with at least two surveys. RESULTS: The pFWHM had an average absolute error of 6.0% relative to pFWHM across all surveys, compared to 3.9% for pFWHM. For the 111 units with longitudinal data, the mean absolute deviation from pFWHM was 7.8% for pFWHM, compared to 5.6% for pFWHM, and 5.1% for pFWHM. For longitudinal testing, pFWHM produced two failures that were related to major component replacement. Both pFWHM and pFWHM methods caught those failures for a false negative rate of 0%. However, pFWHM had a false positive rate of 12.9%, while pFWHM's was only 2.8%. No positive test from any method was attributable to actual equipment failure. CONCLUSION: A single-speck pFWHM for ACR DM QC resulted in high variability and frequent unit failures for the Z-resolution evaluation. However, a 2-speck pFWHM produced results clinically equivalent to the 6-speck method. Using the 2-speck method as an alternative methodology for Z-resolution evaluation achieves similar results with 57% fewer measurements, increasing the efficiency of testing.

First Page

e70619

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