Biomedical subjects

G F Knoll

Publications and source records attributed to G F Knoll.

3 recordsLinked to original sources

PubMed1984

Performance evaluation of SPRINT, a single photon ring tomography for brain imaging.

SPRINT, a prototype single photon tomograph, has been designed primarily for high-resolution brain imaging in humans with I-123-labeled compounds such as iodoamphetamine, hydroxyiodopropyldiamine (HIPDM), and iodobenzene (IBZ). SPRINT uses a ring of stationary, discrete Nal detectors, and fan-beam sampling is accomplished with a rotating eight-slit aperture ring that acquires a complete projection set in 1/8 revolution. In-plane and cross-plane resolutions are 8mm and 10mm FWHM, respectively, measured on axis. Sensitivity with an 18% energy window is 1000 cprs per microCi/cc for Tc-99m in a 20 cm diameter phantom. A detailed evaluation of system performance has been completed, and preliminary human brain blood flow images have been obtained using HIPDM.

Brain↗

PubMed1981

A measure of Anger-camera linearity: results with and without a corrector.

A method for measuring the X and Y linearity of an Anger camera coupled to a computer is presented. It has similarities to, and differences from, the method recommended by the National Electrical Manufactures Association (NEMA). Test images are taken through a lead plate with parallel and equally spaced slots, and the locations of the lines in the images are fitted by least-squares with an equation that allows for slight misalignment. Discrepancies from the fit are calculated and displayed as a distribution over the camera field. The maximum and average discrepancies are tabulated. The field of view that is of interest is selectable within the analysis program. Among four large-field-of-view uncorrected cameras, three 37-tube types (two measured using Tc-99m and one with Au-195) show a similar degree of nonlinearity. However, the maximum and average discrepancies from linearity for a 61-tube prototype camera, measured using Tc-99m over a 15-in. field of view, are 40% of those for the other three. For the four cameras, an event-shifting on-line corrector with best-case sampling improves linearity by an average factor of 5.5, including both 15-and 11.25-in. fields of view.

Computers↗

PubMed1975

Digital tomographic imaging with time-modulated pseudorandom coded aperture and Anger camera.

The properties of a time-modulated pseudorandom coded aperture with digital reconstruction are compared with those of conventional collimators used in gamma-ray imaging. The theory of this coded aperture is given and the signal-to-noise ratio in an element of the reconstructed image is shown to depend on the entire source distribution. Experimental results with a preliminary 4 X 4-cm pseudorandom coded aperture and an Anger camera are presented. These results include phantom and human thyroid images and tomographic images of a rat bone scan. The experimental realization of the theoretical advantages of the time-modulated coded aperture gives reason for continuing the clinical implementation and further development of the method.

Radionuclide Imaging↗