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. May 03, 2020 a gamma camera is a piece of medical equipment that is capable of detecting gamma radiation. Knowledge of the functions and capabilities of the computer is a vital component in delivering quality in scintigraphic images for diagnostic imaging. Dead time effects on gamma detectors gamma explorer. This gamma camera does not record events with energy below. Quality assurance testing of gamma camera and spect systems. Pulse pileup, dead time, derandomization, and count rate. Basic physics of nuclear medicinenuclear medicine imaging. Performance evaluation of a new czt detector for nuclear medicine. Imaging and detectors for medical physics lecture 5. The effects of the following parameters on intrinsic uniformity were studied. The applications of scintigraphy include early drug development and nuclear medical imaging to view and analyse images of the human body or the distribution of.
The model includes an initial paralyzable dead time, pileup rejection, a second paralyzable dead time, energy windowing, an nbin derandomizer and a nonparalyzable dead time. List basic gamma camera calibrations and how they affect performance. Spect systems are often identified as paralyzable or non paralyzable. Dead time effects on gamma detectors1 rick mccain for practically all detectors, there is a point at which events are too close together to be counted correctly.
Manufacturing and remanufacturing an economical and ecological approach to gamma camera. At the cameras heart were cadmium zinc telluride crystals, which converted gamma rays into electrical signals. Quality control of scintillation cameras planar and spect michael k. The dedicated gamma camera that was used consists of a 5 in diameter position sensitive photomultiplier tube hamamatsu r3292, coupled to two. The gamma cameras permit the dynamic acquisition of the images with better spatial resolution, and can be oriented in any direction around the patient. This report was prepared by the nuclear medicine committee of the. It is well known that resolution on a gamma camera varies as a function of distance, scatter and the cameras characteristics collimator type, crystal thickness, intrinsic resolution etc. A semiparalyzable detector exhibits an intermediate behaviour, in which the event arriving during dead time does extend it, but not by the full amount, resulting in a detection rate that decreases when the event rate approaches saturation. The scintillations are detected by an array of pm tubes whose outputs are fed to a. Oconnor, a professor of radiologic physics at mayo clinic in rochester, minnesota. Gamma camera definition of gamma camera by medical. With such additional shielding, the weight of the gamma camera is about 40 kg.
The scintillation crystal usually nai ti, is maybe the most important component of gamma camera. Its function is to convert the incident gamma rays, originating from the patient, into scintillation photons. Solo is a versatile, costefficient and compact gamma camera system designed for use in hospital environments, outpatient clinics or private office. Performance evaluation of a new czt detector for nuclear. Nov 05, 2019 gamma rays are emitted in all directions from the organ and those heading in the direction of the gamma camera enter the crystal and produce scintillations note that there is a device in front of the crystal called a collimator which we will discuss later. A monte carlo calculation has been performed to simulate the count rate capability of a complete scintillation gamma camera system. These gammaray mammography cameras use cadmiumzinctelluride detectors and are highly accurate, says michael k. Radionuclide imaging laboratories are found in almost every hospital, performing hundreds and even thousands of imaging procedures per month in larger institutions. We report the performance characteristic of gamma camera by intrinsic calibration and. Not all gamma cameras do all types of imaging some do only planar, or only spect. A gamma camera is a perfect device for detecting nuclear fission products from either nuclear detonations or nuclear power plant reactors accidents. The radiation can be recorded on film or displayed on a monitor. System components figure 1 illustrates the basic principles of image formation with the gamma camera.
The amount of radiation you receive depends on the examination being performed. Evaluation of count rate performance crp is an integral component of gamma camera quality assurance and system deadtime. With our recommended parameters, the intrinsic uniformity and relative sensitivity quality control testing can be performed in 56 min. The aim of this work was to develop and evaluate an approach to gamma camera calibration for absolute quantification in tomographic imaging with 177 lu. A method is described for estimating deadtimes and applying corrections to the observed counting rates using a two component model where the gamma camera is considered to have a purely. The cameras offer improved resolution of tissue with their 1. Pdf quality control of gamma camera with spect systems. Solo is a versatile, costefficient and compact gamma camera system designed for use in hospital environments, outpatient clinics or. Your nuclear medicine gamma camera scan continued are there any risks. A planar static image of a line source, filled with about 200 mbq of 99m tc activity and inserted in the center of a nema spect triple line source phantom as in fig.
Quality assurance testing of gamma camera and spect. Gamma camera calibration and validation for quantitative spect imaging with 177 lu. For r 0max 74 kcps, the dead time is estimated to be approximately 4. Characterization of the count rate performance of modern. Quality control of scintillation cameras planar and spect. Gamma camera radioactive decay gamma rays are produced by unstable nuclei when protons and neutrons rerange to a more stable configuration. When a gamma interacts with a detector, there will be a period of time in microseconds after the interaction during which the detector is incapable of detecting another gamma. Intrinsic uniformity and relative sensitivity quality. Making the portable gamma camera symmetry magazine.
In the present study both gamma cameras were considered to have a purely non paralyzable deadtime, as suggested by the manufacturer. The performance of a gamma camera system is defined by the sharpness and detail of the images it produces, the efficiency with which it detects incident radiation, its ability to measure the energy of the incident. The quality control qc tests for iu, performed with the collimator removed, and rs are usually performed by exposing the gamma camera s crystal to a uniform flux of gamma radiation from a 99m tc point source. The dead time of our gammacamera system was found to be 4. The main components of a gamma camera are described below. The crp of three modern gamma cameras was characterized using. The collimator localizes the origin of the gamma ray as somewhere along a specific line through the patient, since only gamma rays traveling parallel to the holes will go through. We are all exposed to radiation naturally background radiation. Pdf portable gamma camera for clinical use in nuclear. The gantry of the gamma camera provides mechanical support to the detector head. Paralyzable and non paralyzable behaviour a detector, or detection system, can be characterized by a paralyzable or non paralyzable behaviour. Intrinsic uniformity and relative sensitivity quality control. Pdf portable gamma camera for clinical use in nuclear medicine.
The dedicated gamma camera that was used consists of a 5 in diameter position sensitive photomultiplier tube hamamatsu r3292, coupled to two different pixelated scintillators, both made of csi. The gamma camera has an option for additional internal shields. Such procedures are minimally invasive and can be performed in a hospital or. Jun 23, 2017 intro for first years on the different generations of gamma cameras. Basic principles of gamma camera imaging and quality control. Sep 18, 2009 gamma camera developed by hal anger at berkeley in 1957 therefore also called anger camera an electronic device that detects gamma rays emitted by radio pharmaceautical e. List qc tests for gamma cameras required by accrediting organizations. The applications of scintigraphy include early drug development and nuclear medical imaging to view and analyse images of the human body or the distribution of medically injected, inhaled, or. Nuclear medicine scanning involves the use of radioisotopes and so has the usual risks associated with ionising radiation. Gamma cameras see through dense tissue symmetry magazine. The gamma camera has thus become the most widely used nuclearimaging instrument for clinical applications. Describe how to perform basic qc tests and assess acceptable performance.
A new gamma camera at a fraction of the cost drawing on many years of manufacturing experience since 1981, mie have developed a system of remanufacturing to deliver cost effective process is also ce certifed and fda registered. It is designed to provide users of the scintillation cameras with test procedures for performance evaluation. Oconnor, mayo clinic, rochester, mn the purpose of quality control qc is to detect changes in the performance of a gamma camera system that may adversely affect the interpretation of clinical studies. Lars johansson, in principles of translational science in medicine. A gamma camera is a piece of medical equipment that is capable of detecting gamma radiation. Review of how a gamma scintillation camera works cameras artifacts collimators 24. These devices are used in medical imaging studies that are designed to show doctors what is happening inside a patients body.
Nuclear nuclear gamma camera equipment guide model. Evaluation of count rate performance crp is an integral component of gamma camera quality assurance and measurement of system dead time. This report,scintillation camera acceptance testing and performance evaluation, is the sixth in a series of aapm reports. Such assessment of radionuclide distribution is performed by gamma cameras that primarily comprise naitl detectors and the associated electronics described in the previous chapter.
Gamma camera developed by hal anger at berkeley in 1957 therefore also called anger camera an electronic device that detects gamma rays emitted by radio pharmaceautical e. We assessed the gamma camera calibration factors for a philips irix and philips axis gamma camera system using various reference geometries, both in air and in water. The gamma camera is the equipment used to detect the distribution of radiopharmaceutical within the patient. Correction for deadtime losses in a gamma cameradata. The purpose of the general scatter windows c and d, table 1 and fig. Characterization of the count rate performance and evaluation of the effects of high count rates on modern gamma cameras michael stephen silosky, b. Quality control of gamma camera with spect system is highly valuable for assurance performance characteristic. A method is described for estimating deadtimes and applying corrections to the observed counting rates using a two component model where the gamma camera is considered to have a purely paralyzable deadtime and the data analysis system a purely nonparalyzable deadtime. When radiation is released from the patient it can exit at any angle and hit the detector in a location that doesnt correlate with the location of its origin. Manufacturers frequently provide only a few precalculated resolution values using a line source in air, 1015 cm from the collimator surface and without scattering.
Jun 15, 2011 our aim was to develop and validate a qspect protocol using a commercially available spectct camera system and its bundled software. Below cps, its hard to see much effect from dead time. Evaluation of count rate performance crp is an integral component of gamma. Breastspecific gamma imaging bsgi using the dilon 6800 gamma camera dilon technologies inc. This work characterizes the crp of three modern gamma cameras and estimates. Collimators for a camera to work, we need to be able to reconstruct where the gamma ray came from. The observed crp curves for each gamma camera agreed with the pdm at low count rates but deviated substantially from it at high count rates. Physics in nuclear medicine university of michigan. Analytical and experimental fwhm of a gamma camera.
Digirads portable gamma camera was to have been a key tool for verifying nuclear weapons reductions. List performance characteristics of gamma cameras and features affecting performance. We sought to determine the best parameters for rapid performance of daily quality control testing of intrinsic uniformity and relative sensitivity for the singlehead gamma camera system in our nuclear medicine department. Because the anger camera is by far the most frequently used type of gamma or scintillation camera today, the terms are often used interchangeably. Nuclear nuclear gamma camera equipment guide model information. According to sorensen and phelps 1, the system dead time. The gamma camera can also provide signals to a computer for further analysis of the images. Gamma decay usually follows an alpha or beta decay and does not change element. Gamma camera calibration and validation for quantitative. A method is described for estimating deadtimes and applying corrections to the observed counting rates using a two component model where the gamma. Such procedures are minimally invasive and can be performed.