Gamma camera Q.C :Gamma camera Q.C By: Madelaine Vasquez June 19, 2006


What is gamma camera Q.C? :What is gamma camera Q.C? Gamma camera quality control is performed to identify equipment problems It is also performed to ensure the desired level of performance for patient safety Quality control is divided into 5 parts


What is gamma camera? :What is gamma camera? A gamma camera is a complex device consisting of one or more detectors mounted on a gantry The gamma camera consists of a collimator, crystal (Na I Tl), p.m.t’.s, and p.h.a.’s


Field Uniformity :Field Uniformity It is the ability of a scintillation camera to give a uniform image when the source provides a uniform distribution of photons over the detector Measurements of field uniformity can be intrinsic or extrinsic


Field uniformity cont… :Field uniformity cont… Intrinsic testing operates with a sodium iodide crystal and electronics associated with the scintillation camera detector and is done with the collimator off Extrinsic is performed with the collimator in place and it gives a truer reading


Spatial resolution :Spatial resolution It is the ability of a scintillation camera to separate small objects in space or how much an image is blurred Spatial resolution can also be measured intrinsic or extrinsic with the appropriate bar or multi-hole phantom


Spatial resolution cont… :Spatial resolution cont… There are four types of bar phantoms Hine-Duley phantom consists of lead bars and spaces of three different widths Four quadrant bar phantom contains lead bars and of four different widths Parallel-Line equal space phantom all lead bars and spaces are of equal width Orthogonal-Hole phantom consists of a lead sheet containing holes of equal diameter


Spatial linearity :Spatial linearity It is the ability of a camera to produce a uniform image with straight lines that correspond to the straight lines in a phantom It is the accurate portrayal of a true organ shape when looked at it in the clinical way


Sensitivity :Sensitivity It is the ability to detect ionizing events in a sodium iodide crystal expressed in counts per second per microcurie It can be measured simultaneously when uniformity is performed if the activity of the source and room background are known


Sensitivity :Sensitivity Sensitivity can be affected by incorrect energy settings, incorrect collimation, or improper detector to source distance A change in sensitivity can be affected by an indicator of minor or slow degradation of the system


Pixel calibration :Pixel calibration Pixel calibration is done to obtain an accurate measurement of organ or lesion size It is performed by placing two point sources about 30 cm apart on the camera surface The exact distance is measured and an image of the sources is obtained


References :References Review of nuclear medicine technology by Ann M Steves 3rd edition Society of nuclear medicine 1850 Samuel Morse Drive Reston, VA 20190 Internet http:// www.auntminnie.com