The Radiology Research Laboratory of the Department of Radiology 1609 N. Warren Building 211 - The Radiology Research Laboratory is located in close proximity to the University Medical Center. It opened in Feb. 1988 and contains 10,000 net assignable square feet of office and laboratory space.

a. The Psychophysics Laboratory - The facilities for psychophysical research consist of two large research laboratories with 413 square feet of floor space. These laboratories are connected to the research laboratory network and to the Internet. The rooms are designed to maintain maximum control of all extraneous variables (e.g., ambient room light) during experimental sessions. A standard radiologic viewbox is available in the psychophysics lab for viewing film images.

Key to the psychophysics lab is a Series 6000SU Eye-Tracker (Applied Science Laboratories, Bedford, MA) with a magnetic head-tracking device. This system is an advanced eye-tracker that accurately and unobtrusively measures point of gaze and gaze duration information. The 4000SU is ideal for use in a clinical radiology setting because it provides for an unlimited field of view with free head and body motion.
The 4000SU is capable of measuring point of gaze with a precision of less than one-
half a degree and accuracy of less than one degree. The system comes with an extensive software library to collect and analyze data.

A number of software packages are available for use in the psychophysics applications. The main statistical software that Dr. Krupinski uses for analyzing general data is StatView (SAS Institute). It is used for general descriptive statistics as well as comparative tests (ANOVA, Chi-Squared etc.). IN addition Dr. Krupinski has the software to run a variety of Receiver Operating Characteristic (ROC) analyses including: CLABROC, CORROC2, INDROC, LABMRMC, LABROC1, LROC, MRMC, PLOTROC, ROCFIT, ROCKIT, RSCORE and ROCPWRPC. Dr. Krupinski maintains the website for the Medical Image Perception Society (http://www.radiology.arizona.edu/krupinski/mips/rocprog.html) that provides links to all of the programs from the various sites that developed them. As new programs become available they are added to the site.

We also have customized software for image display and analysis developed by Dr. Dallas (IMPROCRad). This software takes any type of image (e.g., DICOM, .tif, .img) and displays it on any monitor. There are various navigation functions available (e.g., next image, zoom, pan) as well as image analysis functions (e.g., image statistics such as noise calculations for a given region of interest). When image processing techniques are developed for a given study, these too are implemented in the software for ready use during observer studies.

b. The display device evaluation facility
CRT evaluation is performed on a mobile evaluation facility consisting of a very stable heavy cart carrying the equipment for precision scanning of a photomultiplier/slit/lens assembly, or precision imaging with CCD cameras, and a lighter cart carrying the support electronics. The instrumentation located on both carts includes:

Fairchild-Loral CCD with the following features:

- 2048 x 2048 pixels of 0.015 mm x 0.015 mm size
- cooled to -25 0C.
- digitization to 12 bits
- read-out noise at 500 K-pixels/sec read-out is about 40 electrons
- A variety of 35 mm type photographic Nikkon lenses as well as microscope lenses to permit operating with a variety of optical magnifications to achieve resolution on the CRT to well below 0.020 mm

A high performance, "portable" CCD Camera, controlled by a laptop computer and
based on a Kodak CCD with the following features:

- 1317 H x 1035 V pixels of 0.0068 mm x 0.0068 mm size
- cooled to -25 0C.
- digitization to 14 bits
- read-out noise at 500 K-pixels/sec read-out is about 40 electrons

A variety of 35 mm type photographic Nikkon lenses as well as microscope lenses to permit operating with a variety of optical magnifications to achieve resolution on the CRT to well below 0.020 mm

A mobile cart with leveling feet, carrying a medium grade X-Y-Z positioner to position
the "portable" CCD camera in front of most CRT displays used in the clinical environment.

Image analysis software based on the IDL development package is available on the PCs for:

- data correction
- data analysis
- Fourier Transforms (for noise power spectra and MTF measurements; evaluation
of modulation)
- data display