The evaluation of low-contrast detectability (LCD) is an effective method to assess routine performance of radiological equipment and a proper verification of image quality (IQ). It consists in evaluating the threshold contrast visibility details for inserts of various dimensions, appropriately located in dedicated quality control (QC) phantoms. Currently, a specific phantom for a quantitative measure of IQ usually fits to a precise application. Different x-ray modalities require different detail contrasts, that means different phantoms and different units. Hence, inter-comparison between different equipment or hospitals may...

LCD defined by statistical method As stated in the review first presented by Chao et al. [1] LCD is affected not only by the amount of noise but also by the noise frequency spectrum. Thus the mere standard deviation σ of the pixel values (PV) in a homogeneous image is not an accurate indicator of LCD performance. Differently, the standard deviation of the means (σμ), calculated for identical sub-regions of interest (subROI) placed on a uniform background ROI and with a mean pixel value μ...

Static Digital detector (DR), dynamic detector (DDR) and Computed Radiography (CR) Median, minimum and maximum Cth values were calculated for DR systems. Fig 11 shows the median, minimum and maximum of c-d curves.In the same set up condition, two DDR detectors of the same model were studied; c-d curves are completely overlapped. DDR c-d curve was compared with the median DR curve in Fig 12. DDR low contrast detectability performance are significantly worse than DR in RQA5 set-up, at 2.5 µGy. The effect of beam...

A simple statistical method for LCD assessment based on single image evaluation is presented, together with its application to different imaging modalities of projective radiography. The proposed LCD test object is inexpensive, easy to assemble and handle. It can be used standalone in scatter-free condition, or in combination with different kinds of attenuator materials. The proposed evaluation software is easy to use, free and already tested by a significant number of medical physicists. The methodology’s implementation in different modalities of radiography has been quite simple;...

Nicoletta Paruccini,Medical Physicist Struttura Complessa Fisica Sanitaria ASST Monza Ospedale San Gerardo Via Pergolesi 33 20900 Phone: +390392333686 Fax: +3903923332524 e-mail :[email protected]

[1] E. H. Chao, T. L. Toth, N. B. Bromberg, E. C. Williams, S. H. Fox, and D. A. Carleton. A statistical method of defining low contrast detectability. Radiology 2000 sup.; 217:162. [2] P Monnin , N W Marshall, H Bosmans, F O Bochud and F R Verdun. Image quality assessment in digital mammography:part II. NPWE as a validated alternative for contrast detail analysis. Phys. Med. Biol. 56 (2011) 4221–4238 [3] Van Peteghem, H Bosmans and N W Marshall. NPWE model observer as a validated...