<title>Performance Characteristics Of A Translate-Rotate Head Scanner With Xenon Detectors</title>

Abstract

The performance and dosimetric characteristics of the first U.S-installed hybrid head scanner developed commercially by CGR have been evaluated. Using a translate-rotate motion with a xenon gas detector array, the scanner produces excellent low contrast resolution at low dose levels (single slice surface dose of 1 rad). Console selection of scanning parameters, viz.: scan time, kV, mA, beam filtration, slice width, and pixel size permits optimization of image quality for various exams. For optimizing either spatial or low contrast resolution, a push-button choice of reconstruction algorithms is available. Using the AAPM CT phantom, spatial resolution and line spread functions for both algo-rithms were determined from the graphical display of CT numbers. Low contrast resolution was measured at various contrast levels as a function of kV, dose, beam width, pixel size, and algorithm. Values for noise (σ)were also recorded for these scanning parameters. Patient dose distributions for various operator-selectable beam widths (3,6,9 mm) were obtained using film and TLD's. CT number linearity and contrast scale were determined using different plastic rods.