Qc in xray

Describes QC and QA of radiography machine.

1. QUALITY CONTROL(QC) AND QUALITY ASSURANCE(QA) OF X-RAY MACHINE

2. TOPIC TO BE DISCUSSED: QUALITY CONTRO AND QUALITY ASSURANCE TEST TO BE DONE TO CONTROL QUALITY LEVELS OF QUALITY CONTROL(FREQENCY) TOOLS REQUIRED PROBLEM BASED AREAS.

3. QUALITY CONTROL Series of tests to assure radiographic system is functioning properly and radiographs are of acceptable quality. Quality control tests should be conducted for x ray machines. logs of tests performed dates results and corrective action should be kept.

4. QUALITY ASSURANCE An organized effort by staff operating a facility to ensure that the diagnostic image produced are of a sufficiently high quality so that they consistently provide adequate diagnostic information at the lowest possible cost and with the least possible exposure of the patient to radiation

5. QUALITY ASSURANCE PROGRAM THIS PROGRAM HAS MANY FACETS INCULDING 1) QUALITY COTROL TESTS 2 )ADMINSTRED PROCEDURE 3 )PREVENTIVE MAINTANCE PROCEDURE 4 )TRANING

6. QUALITY CONTROL TESTS 1 )CENTRAL BEAM ALIGNMENT 2)FOCAL SPOT SIZE 3)TUBE VOLTAGE 4)TIMER CHECK 5)TUBE HOUSING LEAKAGE

7. CENTRAL BEAM ALIGNMENT I f the x ray beam is not perpendicular to the image receptor ,the image may be distorted I f grid is used the distortion will be magnified resulting in total loss of minute details.

8. FOCAL SPOT SIZE T he ability for resolving the smallest size of the image (i.e. Details) in a radiograph depends on the focal spot size. Since, the focal spot size may be altered as a result of bombardment of electrons on the target, it has to be checked periodically to ensure that focal spot size is within acceptable limits.

9. TUBE VOLTAGE(KVP) T he applied kvp affects the quality and quantity of x-rays reaching the image receptors. I f there is variation in kvp setting, it will affect the image quality, hence it is necessary to check the kvp settings periodically.

10. TIMER CHECKING I f the exposure time set on the diagnostic x-ray unit is not optimal, the radiograph can be under exposed or over exposed. This may lead to repeat examinations. Hence, there is a need to test the timer of the x-ray unit periodically.

11. TUBE HOUSING LEAKAGE T he leakage of radiation from r-ray tube housing adds the radiation dose to the patient and to the operator too. T ube housing leakage test must be periodically done to insure the radiation safety.

12. TOOLS REQUIRED BEAM ALIGNMENT TEST TOOL B eam alignment test tool is kept on the collimator test tool, such way that the stainless steel ball of lower side of tool is just above the centre of the collimator test-tool. the film is exposed and processed. I f the beam alignment is perfect, the image of the top ball will merge with the image of the ball at the bottom. The deviation of beam from the perpendicular is determined from the location of the image of top ball in the circles in the radiographs.

13. BEAM ALIGNMENT TEST TOOL

14. FOCAL SPOT TEST TOOL T est tool consist of hollow cylinder with an acrylic circular disc fastened at one end which contains 12 groups of bar patterns ingraved on a tungsten plate. E ach group consist of 6 lines-sub group of 3 parallel lines,perpendicular to another sub group whose size and spacing decreases by steps of 16%. T he focal spot size value are computed for magnification of 4/3 being ffd 60cm and OFD 45.as shown in table:

15. T est tool placed on a non screen cassette loaded with film,(ffd 60 cm )constant such that vertical pattern are within the anode to cathode direction. Film is exposed and processed and bar pattern on radiograph is observed-smallest group on which all 6 bars are clearly resolved is identified and corresponding focal spot size can be obtained from the table.

16. FOCAL SPOT TEST TOOL

17. TIMER CHECKING SPINNING TOP TEST TOOL Spinning top test tool is used to check the exposure time. It consist of a rotating circular brass plate with small rectangular portion cut(hole) at its periphery. The tool is placed on the cassette, loaded with film. For a set time, the unit is energized, while the top is rotating. The pulses passing through the hole of the circular plate, produces equally spaced rectangular density patterns, on the film.

18. SPINNING TOP TEST TOOL

19. TUBE VOLTAGE Kvp METER Kvp meter,employes two solid state detector with different beam hardening filters.when exposed to radiation,the ratio of the signals produced by these detectors will be proportional to the peak tube voltage. Corrections for beam filtration should be applied if necessary .

20. Kvp METER

21. TUBE HOUSING LEAKAGE RADIATION SURVEY METER The radiation leakage measurement is carried with an ionization radiation survey meter. For checking the leakage radiation,the collimator of the tube housing is fully closed and the tube is energized at maximum rated tube potential and current at that kvp. The exposure rate at one meter from the target is measured at different location from the tube housing and collimator . The tolerance limit of leakage radiation at 1 m from the focus is >115 mR in one hour

22. RADIATION SURVEY METER

23. FREQUENCY OF QUALITY CONTROL. Test Frequency kVp Once in three year Timer Once in 3 months Output,mR/ mAs Monthly Inherent filtration Once in 3 months Focal spot size Once in a year Central beam alignment Once in 2 months Congruence of radiation and optical field Once in 2 months Grid alignment Annually and whenever film density appears non uniform

24. QA COMMITTEE & THEIR ROLE Includes: Medical physicist Radiologist Biomedical engineer Imaging technologist (radiographer) IT technician

25. MEDICAL PHYSICIST Conducting test to ensure the safety and proper performance of imaging equipment used. Assignment of biomedical engineering service staff for corrective maintenance or preventive actions Training of personal utilized for quality control. Develop and implement a radiation protection program.

26. RADIOLOGIST Determine the overall quality of the output image Select the technologist to be the primary QC technologist, performing the prescribed QC test. Ensure that appropriate test equipment and materials are available to perform the QC tests. Ensuring that medical physicist and radiographers have adequate training and continuous education.

27. BIOMEDICAL ENGNEER Corrective and preventive maintenance. Fault reporting

28. IMAGING TECHNOLOGIST AND RADIOGRAPHER Ensuring that the appropriate protocol and technique factors are used for the requested examination Ensuring that the QC tests are performed, interpreted and recorded appropriately. Perform all the checks for the daily ,monthly and quarterly QC testing of equipment. Report faults immediately, any deviation in trend of equipment performance to QA manager Undertaking additional continuous education courses.

29. IT TECHNICIAN Maintenance of the integrity of system database to ensure continuous and accurate operation of the information systems