Mio Nagata, Presenter: Nothing to Disclose

Yuichi Nagai, Abstract Co-Author: Nothing to Disclose

Hitoshi Fukushima, Abstract Co-Author: Nothing to Disclose

Yoshiaki Shibata, Abstract Co-Author: Nothing to Disclose

Chieko Nagashima, Abstract Co-Author: Nothing to Disclose

Nachiko Uchiyama MD, Abstract Co-Author: Nothing to Disclose

Yukie Kobayashi, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Although it is common to use the “grid” in digital mammography,it can result in unnecessary radiation exposure for patients with small 1-2cm breasts due to increased doses. Is there an alternative to using a grid in this examination?

The measurements and image-quality evaluations, listed below, were done with and without a grid and by using different types of grids and acrylic thicknesses (none to 5cm). 1.Physical Evaluation, a)Evaluation of a grid (measurement based on Japan standard). b)Change acrylic thickness and observe outcome of each combination for Contrast to Noise Ratio (CNR). 2.Visual Evaluation-Receiver Operating Characteristic (ROC), Analysis-take mammography with and without a grid and change acrylic thickness. 3.Digital Image Processing - use image without a grid and 3-4cm acrylic thickness and change frequency processing to image using a grid.

1.Physical Evaluation a)Higher grid lines resulted in higher contrast, but also higher Bucky`s Factor. b)Increasing acrylic thickness produced higher CNR. 2.Visual Evaluation a)Thinner acrylic appeared to eliminate need for using a grid. 3.Digital Image Processing - using intense frequency causes higher contrast, but it was harder to find the simulation mass because of noise surrounding noise.

A clear image cannot be obtained by setting up a grid without exposing a patient to more than a fixed dose, but a clear image can be seen without using a grid if a patient has small breasts. Such a procedure can decrease the possibility of exposing a patient to unnecessary radiation although a grid should be used for patients eith larger breasts otherwise anti-scattering cannot be removed from the image. Use of a grid is necessary in digital mammography, therefore, but it is not needed for patients who have small 1-2cm breasts. In order to reduce patients being exposed to radiation, some kind of equipment is needed with a function that can remove or replace the need for a grid.

These test results can be used for reducing patient exposure to radiation. Without information from the above experiment, equipment cannot be developed to increase image quality in the near future.

Nagata, M, Nagai, Y, Fukushima, H, Shibata, Y, Nagashima, C, Uchiyama, N, Kobayashi, Y, et al, , et al, , The Necessity of Using the Grid in Digital Mammography.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5008792.html