Logo PTB
symbolic picture: "magazines"

Virtual mammogram

Simulating realistic phantom images for mammography

PTB-News 3.2019
24.09.2019
Especially interesting for

medical physics experts (MPEs)

the competent surveillance authorities

equipment manufacturers

Within the scope of the mammography screening program, approved devices must ensure that radiologists are able to reliably detect even small contrasts. The imaging quality of each device is therefore checked every year by means of monitoring measurements. For this purpose, test images of phantoms are taken and assessed by means of procedures of data analysis. PTB has developed a simulation software program that is able to simulate such images realistically. The procedures of data analysis used can thus be checked and optimized as to their fitness for purpose.

Schematic setup of virtual mammography

Breast screening relies on X-rays to search for abnormalities in breast tissue in a non-invasive way. The following rule fundamentally applies: the stronger the radiation intensity, the more reliable the diagnosis. However, this also increases the risk of radiation detriment. The settings are optimal when the dose is as low as possible while the image quality remains sufficient. To ensure sufficient imaging quality for the physician to make a diagnosis, devices must be able to represent small structures with low contrast well enough. Within the scope of quality assurance, annual checks are carried out by generating images of a technical phantom that consists of small gold plates of different thicknesses and sizes. The phantom images taken are either assessed by a physician or automatically evaluated by means of procedures of data analysis that simulate human vision.
PTB has developed a simulation software program that simulates the technical phantom and generates realistic phantom images of the gold plates. This virtual mammogram provides images with properties that are exactly known. It therefore allows the analytical procedures used for quality assurance to be validated and optimized. This simulation tool is based on a mathematical model with which a primary image is computed from the transmission of simulated X-rays. Disturbing effects such as scattering or noise are then added. By comparing the generated images with real images, it has been shown that the simulation tool provides realistic mammograms.
This software program has already been used to successfully validate a new assessment procedure that was developed and improved at PTB. In the future, virtual mammograms are to be used in particular to provide a solid basis for the use of machine-learning methods in quality assurance for mammography.

Contact

Tobias Kretz
Departments 8.4, Mathematical Modelling and Data Analysis, and 6.2, Dosimetry for Radiation Therapy and Diagnostic Radiology
Phone: +49 30 3481-7978
Opens window for sending emailtobias.kretz(at)ptb.de

Scientific publication

T. Kretz, M. Anton, T. Schaeffter, C. Elster: Determination of contrastdetail curves in mammography image quality assessment by a parametric model observer, Physica Medica 62, 120–128 (2019)