Diagnostic X-Ray Imaging Quality Assurance Term Paper

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It is observed that majority of the beams have in them positive beam limiting collimators -- PBL. The distinguishing features of these devices are that these are automatic collimators which gauge the proportion of the image receptor and make adjustment of the collimating shutters to that size. (Bushong, n. d.)

Focal-spot size: The spatial resolution of radiographic system is basically found out by calculating the focal-spot size of the x-ray tube. At the time when new equipment or a replacement x-ray tube is deployed, the focal-spot size should compulsorily be measured. The three most important tools which are used for calibration of focal-spot size are the pinhole camera, the star pattern and the slit camera. While the pinhole camera poses difficulty in use and needs a great exposure time, the star pattern is simple to use but has a great deal of limitations for focal-spot sizes less than 0.3 mm. The preciseness of the exposure timer must be evaluated every year or in fewer intervals in case a component of the operating console or the high-voltage generator has been put under major repairs. A preciseness of 20% both on the positive or negative side is acceptable for exposure time of 10 ms or lower. Subsequently Automatic Exposure Control -- AEC needs also to be evaluated. These instruments have been designed to give a fixed optical density irrespective of the thickness of the tissue, make-up, or the lack of success of the reciprocity law. (Bushong, n. d.)

Fluoroscopy Quality Control: Fluoroscopic tests can outcome in high patient dose. The entrance skin exposure -- ESE in case of an adult shows an average of 3 to 5 R/min or 30 to 50 mGy/min at the time when the fluoroscopy is being conducted and it can outcome in a skin dose of 10 rad or 100 mGy in case of a lot of fluoroscopic examinations. Fairly accurate doses are to be administered to patients which can be guaranteed through the performance of suitable QC measurements. Some of the measurements might be needed more on a regular basis following changes in the operating console, high voltage generator or the x-ray tubing. (Bushong, n. d.)

Automatic Exposure Systems: Every fluoroscope is built-in with some type of automatic brightness control -- ABC or Automatic Exposure Control -- AEC. Every system works similar to the photo-timer of a radiographic imager generating regular image brightness on the video monitor irrespective of the thickness or constitution of the anatomy. Since these systems are prone to damage or failure with use; fluoroscopic ABC must be examined every year. (Bushong, n. d.)

Tomography Quality Control: Apart from the evaluations conducted in the tenure of a QC of a radiographic system, a lot of additional measurements are needed in case of those systems which are also able to perform normal tomography. However, accurate performance standards are not present in case of conventional tomography. QC measurements are devised to guarantee that the features examined stay constant. It is important that the patient exposure must be measured for the most usual type of tomographic examinations. Exhibit -I shows a sample of the results derived from a three phase system and six representative tomographic examinations. (Bushong, n. d.)

Standard Quality Control -- QC tests that are undertaken with care during prescribed period of time are devised to spot gradually evolving functional X-ray and problems in the ancillary apparatus and to allow remedial action prior to major decline of image quality happens. The important cause for a QA program is undertaken in order to optimize the process of diagnosis and thus the benefits are obtained. A QA program merits the expenses that include (i) personnel costs - QA duties consists of not just the performance of QC tests but also initial education as also training (ii) Test equipment: QC test equipment cost is comparatively small as compared to total capital outlay of a radiology department (iii) reduction in patient flow from testing: It is imperative that QC tests are conducted outside the normal working hours, to the extent possible. (Parelli, n. d.)

The main cost savings in case of QA program happens to be the result of a lowering in repeat studies i.e. avoidance of unwarranted radiation dose to the patient. The savings in cost also comprise (i) Reduction in film wastage (ii) reduction in the wastage of chemicals (iii) reduced wear and tear of the equipment (iv) Reduced downtime of equipment (v) less time consumption of the personnel (vi) patient flow improvement (vii) lowered cost of equipment service. It is important that each X-Ray units has a QA Manual containing the list of names and qualifications of personnel responsible for supervision of QA, performance of QC tests and troubleshooting or servicing X-Ray and its allied apparatus. Besides, QA and QC records are also needed to be maintained for X-ray equipments and allied apparatus which must include (i) performance evaluation of the X-ray machine, covering acceptance testing and surveys of radiation safety. (ii) Confirmation that the X-ray apparatus is functioning in a secured operating manner and conducting of later QC tests outcomes are done. The most important QC lies with ensuring Photographic QC. Under this are included quality of the image, contrast, density, base plus fog and also the exposure of patients. The Optical density range must be within the ideal range of 0.5 to 2.5 OD values. (Parelli, n. d.)

Ensuring QC in conventional radiographic systems:- Under the conventional radiographic systems there are a lot of constituents whereby each one is subjected to variability with the passage of time. Within this system, the elements which are important are (i) kilovoltage (kVp) (ii) Milliamperage (mA) (iii) Exposure time (iv) X-ray beam filtration (v) Collimation i.e. X-ray beam restriction (vi) focal spot size (vii) Grid under which the parameters to be checked are type, uniformity and alignment. (viii) Intensifying screens (ix) Cassettes (x) Radiographic or X-ray films (xi) Darkroom conditions and (xii) photographic processors and chemicals. Any of the above components within the system holds the potential to sway or damage in such a manner so that the image quality might be degraded. Hence, to undertake all the activities in a feasible way, it is imperative to calibrate and control all of the suitable variables in the radiographic imaging chain. The correct QC tests shall be done, following the repair and replacement of any constituent of the X-ray system, before making use of the equipment in humans and whether such repair and/or replacement might impact (i) quality of image (ii) phototimer reproducibility (iii) accuracy of the exposure timer (iv) Linearity of Milliampere-seconds (v) kilovolt peak (kVp) accuracy (vii) skin entrance radiation dose (viii) Focal spot size. (Parelli, n. d.)

Radiation Safety/QA Program: It is important that every facility establishes a committee of individuals to be responsible for the radiation safety/QA program including those departments that employ X-rays for diagnostic purposes. The Committee must be constituted of at least a Radiologist, the Chief technologist, the QC Technologist and also a Medical Physicist and a member of the internal X-ray service or engineering group in case of availability. The Committee shall allocate QC responsibilities in writing. Particular assignments must be recorded in the manual. The persons charged with the responsibilities shall have to be properly directed. Proof of continuing education shall be available in case of the individuals actively involved in the QC testing and evaluation process. As regards Equipment Monitoring, every facility shall prepare various tests at the duration stated, and keep records of the data. The type of experiments as also the frequency of the experiments might also be changed at the orders of the Department in case the facility is able to display recorded proof that other tests or programs will guarantee efficient diagnostic image quality. (Department of Health: New York State, 2007)

Test Frequency: Every day at the time of the X-Ray generator start up and prior to conducting the x-ray, it is important the operator verifies for defects of indicator dial as also the mechanical and electric safety of the X-ray system. Defects and other risky conditions have to be remedied at the earliest. Besides, the solution temperatures and rates of exhaustion must also be verified at the time when correcting speed and contrast defects. The Half Value Layer -- HVL has also to be checked. In case of certified equipment the minimum HHVL must not fall below the figures as stated in Exhibit -II. Fluoroscopic Timers: The certified equipment shall show with a signal which is audible to the operator, the ending of a pre-determined time gap, not higher than 5 minutes. At the time of the engagement, the signal must go on until the reset button is pressed. In case of equipments that are not certified, the passage of a preset time, not higher than 5-minute should be recorded by a signal that is audible to the operator or an interruption of the fluoroscopic beam. The…

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