Quality control can be defined as the procedure intended to make sure that any product manufactured or any service performed usually adheres to quality criteria set that always meets the clients’ requirements. Quality control might have in inclusion any actions that are necessary to give the verification of some services and products. Quality control has been present in the life of man since the manufacturing industry was started. However, the first application of it was done in 1924, in the laboratories of the bell telephone. Quality control has also been used in the gamma camera system and CAT scan. This paper discusses how quality control has been used in the gamma camera system, as well as in CAT scan.
Quality control has been used in the modern scanners; most modernized scanners have extremely good programs used for the maintenance. The procedure was first invented by a German, Karl Friedrich Benz, who made the governments value for the higher quality products. Quality control started when the manufacture of commodities began and the consumers would often compare the product which was the most attractive (Harkness, 2000).
The quality control system was applied in the gamma camera after the use of Positron Emission Tomography for scanning. The gamma camera PET had inferior images, but it had additional flexibility in comparison to the PET scanner. The quality control was invested to have better images to be used for treatments. Some scanners have links to the engineering support, which makes them able to fix themselves before the user of the scanners knows. These nuclear medical imaging techniques need the quality control to have maintenance of the objective standard to make sure that image produced is of high quality, dose, and safety for the operator. The quality control is necessary to visualize the next decision to take concerning the patient. This is because the results, which get seen, can simply get used to know the next action level (Konrad & Schulthess, 2007). The actions include calling the engineer, making further tests or stop the scanning process. The quality control presence has been used in today’s life. The reason is many services’ places and business centers use the indicated system to give customers the satisfaction required. Total quality control system has provided business with the ability to have its effectiveness, efficiency, competitiveness and flexibility improved so as to suit the needs of the clients best. It has progressed since it was invented: it is used in gamma cameras and other computerized machines to offer the best quality to the clients.
The quality control can be applied in the gamma camera system by using some isotopes to have uniformity of the images. In the gamma cameras, before the images begin, there is certain extrinsic flood image, which tends to be preferred, and some tests which are used heavily for collimators. The quality control system tests the image of the intrinsic flood image, which is usually used for the FOV periphery. The analyzed system is then used for resolution, where the intrinsic, which is mostly preferred, and the extrinsic images count majorly for a better image quality. It is also applied for linearity of the intrinsic images and the uniformity correction matrix. When the quality control is installed in the gamma cameras, there are some indications of improved performances in many cameras (Beekman, 2003).
CT Based Attenuation Correction
There are many artifacts that can be found in the CT image. These ones are mainly the physics based, patient based and scanner based artifacts. One of the main advantages that CT scanner has is its image used in the attenuation source of rod. The CT amount of scan reduced may help in acquisition the time and the improvements done aid in improving the factor that have precise the attenuation correction. After a CT scan gets completed, the corresponding coefficients of the CT attenuation have different types of tissue which get mapped to the PET energies that they belonged (Dharmendra & Perkins, 2009).
In the physics based artifacts, some of the most common ones are the noise, beam hardening and the partial volume artifact. Since noise is unwanted, it is either randomly or non-randomly distributed as a disturbance signal that happens to block the information that gets sent form the observer as content. Noise usually affects the images which get produced by the beam of the units of the CT making a reduction of the low contrast resolutions. This makes it rather difficult to differentiate the low density tissues, and hence minimizing its ability to have effective segments (Mahesh, 2012). In the beam hardening artifact, there is the x-ray beam in the medical radiography machine. This radiography consists of a number of x-rays that have a wide spectrum of energies. A heterogeneous beam transverse through an absorbing medium due to the low energy x-rays tend to be strongly attenuated than the high energy ones. They become richer proportionally in the high energy protons and thus penetrate more and become harder.
When the quality control gets done in an improper manner, there is the emergence of the scanner based artifacts. The most common scanner artifact is the ring artifact. If there is a detector that is out of the calibration on a scanner, which is a third generation, the detector tends to give some error readings consistently in each and every angular position that result to a circular artifact. A scanner that has got some solid-state detectors and all those happen to being separate entities then it is in a principle of being more susceptible to the ring artifacts than any scanner that has gas detectors (Hander, 1985). The ring with gas detectors usually consist of xenon-filled chamber that is singer, which gets subdivided by the electrodes. The rings that are visible in the air or in a phantom that get uniformed may not be any visible on the image which is clinical if the window used is wide. Even if they happen to be visible, they are less likely to be confused with the disease. However, they have the power to damage the diagnostic quality of the image gotten. This can happen particularly if the central detectors get affected and then creating a smudge that is dark at the image center. Nevertheless, this is avoidable, and the software used can be corrected. If an image has circular artifacts, it is a clear indication there is a need for the detector gain to be recalibrated or repaired (Capehart & Capehart, 2005).
Since the introduction of computed tomography in 1972, several improvement generations has been made. Some of these include the multidetector of the row helical CT, which has helped in improving the spatial and also temporal resolution, the iterative reconstruction and the dual energy CT. There is a number of artifacts from the exact first days of the CT, which has reduced substantially. Nonetheless, there are some remaining artifacts, as well as new technologies which have been introduced and characterized incompletely the artifacts. The latter usually originate from a variety of sources and have the ability to degrade the CT image quality to varying degrees. The design features that get incorporated into the modern scanners help in minimizing some artifacts’ categories while some of them can be corrected well by the software which scans. However, there are particular instances where a careful patient may have a better positioning and an optimum selection of the scan perimeters, which tend to be the most influential in trying to avoid the image artifacts.