Gamma camera systems may also be of conventional or pixelated design. New methods are proposed and described to examine the quality of gamma camera collimators in two special performance categories, namely, uniformity in regional efficiency and regional. Intrinsic flood image to test detector only, especially at the periphery. Used to magnify the area of interest and is the exact opposite effect of diverging. In one form, the collimator includes a gamma ray attenuating plate, several core plates, and a ramp. The evaluation and calibration of fanbeam collimators. Conebeam collimators use the same principle for cardiac imaging so that a large field of view camera will magnify a smaller area of interest. Thus the required septal thickness also depends strongly on the vray energy for which the collimator is designed to be used. The line spread function lsf of an imaging system incorporating a pinhole of 0. Spect image quality also can be optimized by proper camera setup and patient.
The scanner is used to record the regional transmission rate of a radioactive source through a piece of collimator core on a pointbypoint basis as a two. Pdf gamma camera collimator characteristics and design. Sensitivity measurements were carried out and the fwhm and fwtm were determined in. Basic principles of gamma camera imaging and quality control sharon l. Most commonly used scintillation crystal in nuclear instrumentation is sodium iodide with thallium doping, written naitl scintillation crystals in a gamma camera are typically 10 to 25 inches in diameter or rectangular and are 14 to 1 inch thick like the screens that are used in projection. Most gamma cameras can be used in three essentially different modes. Moire interference in gamma camera quality assurance images.
Quality control of scintillation cameras planar and spect michael k. Gamma rays emitted from the patient pass through the collimator to form an image in the scintillation. Extrinsic flood image is preferred and tests heavily used collimators. The aims of this study were a to determine the true focal length of a fanbeam collimator and b to calibrate image size mmpixel for each collimator to permit inter. The first scintillation camera or gamma camera proposed by hal anger 1957 consisted of a singlepinhole collimator, a 4indiameter by 14inthick naitl crystal, seven 1. The detection element at the heart of a gamma camera is a large rectangular crystal of sodium iodide doped with thallium. Slides to iaea nuclear medicine physics handbook human health. Before we look at a patient being imaged and some of the images which can be obtained using this technique, we will look in a bit more detail at how a gamma camera works. Quizlet flashcards, activities and games help you improve your grades. Some collimators can be flipped resulting allowing the technologist to go between converging to.
Recently dual headed gamma cameras with pet capability have been produced, and one of these is in use here. High resolution and sensitivity gamma camera with active. Application of gamma camera gamma camera used to locate cancerous tumours,minor bone fractures,abnormal functioning of organs and other medical. Instrumentation chapter 7 collimators flashcards quizlet. Gammaray detectors for small animal imaging have generally used parallel hole collimators since they provide a good tradeoff between sensitivity to photons and image resolution. New methods are proposed and described to examine the quality of gamma camera collimators in two special performance categories, namely, uniformity in regional efficiency and regional variations in channel tilt. It is used for clinical studies producing better image and making diagnosis. Collimators that are used to converge light beams are referred to as optical collimators, while those that are used to collimate energy particles are called neutron, gamma. Resolution of pinhole collimators used with gamma cameras resolution of pinhole collimators used with gamma cameras goulet, pierre. Resolution of pinhole collimators used with gamma cameras. Quality assurance testing of gamma camera and spect. Collimators study guide by nicolezader includes 40 questions covering vocabulary, terms and more. In order to be able to detect the 511kev gamma rays produced in pet, the camera heads on this scanner contain thicker sodium iodide crystals than are normally used for gamma imaging.
Quality control of scintillation cameras planar and spect. Planar scintigraphy used in nuclear medicine imaging emission imaging radioactive. Some collimators can be flipped resulting allowing the technologist to go between converging to diverging collimation. Beam collimators are beam direction devices used in the xray tube housing, along with an arrangement of mirrors and lights, in such a way that the light and xray fields match each. Quality assurance testing of gamma camera and spect systems.
Combination of converging collimators for highsensitivity brain spect ruben terantonyan1, ronald j. A tripleheaded gamma camera equipped with ultrahighenergy collimators was used to image 18f. In xray optics, gamma ray optics, and neutron optics, a collimator is a device that filters a stream of rays so that only those traveling parallel to a specified direction are allowed through. For each gamma camera head, the following characteristics should be evaluated at lead annually. Combination of converging collimators for highsensitivity. Collimator geometry used to derive the expression for the full width at half maximum. Parallel hole collimators are classified as low, medium or high energy. Other collimators can be designed using different techniques. Quality assurance testing of gamma camera and spect systems sharon l. Planar scintigraphy used in nuclear medicine imaging emission imaging radioactive source inside patients body in both spect and planar scintigraphy radiation source used mainly 99 a 140 kev rays hence the name gamma camera. Pdf a collimator study for a small field, high resolution. The main purpose of gamma camera with 2 spect system is to scan brain heart, respiratory, liver and kidney. The gamma camera is the equipment used to detect the distribution of radiopharmaceutical within the patient. These facts translate to an increase in resolution of the gamma camera.
Oconnor, mayo clinic, rochester, mn the purpose of quality control qc is to detect changes in the performance of. If radionuclides other than 99mtc are used such as 67ga, 111in, 123i and 201tl certain tests must be repeated using these radionuclides. Disclaimers gamma camera images and photographs of equipment are not intended to advertise or. The other sources are placed in line, both radially and axially at a distance of. Experimental results and predictive calculations for. Imaging and detectors for medical physics lecture 5. A collimator is the first processing layer of a gamma camera to encounter photons from. Physics in nuclear medicine university of michigan. A perspective and a description of the singlehole collimator on probes and then a multihole focused collimator used for imaging is presented. Most commonly used scintillation crystal in nuclear instrumentation is sodium iodide with thallium doping, written naitl scintillation crystals in a gamma camera are typically 10 to.
Collimators collimators are used as mechanical lenses, to provide. Collimators for a camera to work, we need to be able to reconstruct where the gamma ray. Characterisation of the attenuation properties of 3d. Gamma camera collimators journal of nuclear medicine. White, phd university of alabama at birmingham july 16, 2015. Basic principles of gamma camera imaging and quality control. Pdf new methods of examining gamma camera collimators. In order to determine the spatial resolution of both the bottom detector and the active septa, monte carlo optical simulations have been performed. Gamma camera operation g g array of photomultiplier tubes pmts.
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