Basic quality control tests in medical radiography

1. Basic quality control tests in medical radiography Finals Topics

2. -DARKROOM QUALITY CONTROL -QUALITY CONTROL FOR X-RAY EQUIPMENT AND ACCESSORIES

3. Films • Determination of the Optimum Developing Time • Check for the consistency of the generator output • Check for mAs linearity • Check for Timer Accuracy DARKROOM QUALITY CONTROL

4. Collimator Check • Check for Alignment of the X-ray Tube Column and the X-ray Table • Test for Grids • Test for Bucky Movement • Test for Lead Rubber Aprons and Gloves QUALITY CONTROL FOR X-RAY EQUIPMENT AND ACCESSORIES

5. FILMS • Checking for: - Expiry date * “FIFO” method should be observed - Storage conditions * temperature at about 20-25 C * away from sources of heat and where chemical vapors may leak and fog the film * boxes of films should not be stored on the floor; should be stacked vertically to avoid pressure marks DARKROOM QC

6. DETERMINATION OF THE OPTIMUM DEVELOPING TIME • Objective - To determine the developing time that will give the film’s maximum density without an increase in base + fog. • Procedure - Expose the loaded cassette in strips (6 strips) using the lowest kVp and mAs setting at 100cm SID. The exposure factors may be adjusted until we are able to produce a density of 1.0 on the middle strip. The last strip is not exposed to radiation. DARKROOM QC

7. PRODUCTION OF SENSITOMETRIC STRIPS X-ray film Lead sheet Cut into a number of strips

8. DETERMINATION OF THE OPTIMUM DEVELOPING TIME • Procedure - Inside the darkroom, cut the film into strips and process them using different developing times, e.g. 30s, 60s, 90s, 120s, 150s & 180s. DARKROOM QC

9. DARKROOM QC DETERMINATION OF THE OPTIMUM DEVELOPING TIME Evaluation - Examine the film strips, look at the middle step and determine which strip exhibit the maximum density at an acceptable basic fog. The time used to develop this strip is considered the optimum developing time.

10. CHECK FOR THE CONSISTENCY OF THE GENERATOR OUTPUT • Objective - To determine whether the generator produces the same density every time the same exposure factors are selected. • Procedure - Position the water phantom on the loaded cassette and expose the film with set factors. Process the film the usual way. QC FOR X-RAY EQUIPMENT AND ACCESSORIES

11. CHECK FOR THE CONSISTENCY OF THE GENERATOR OUTPUT 10cm H2O 10cm H2O 10cm H2O 10cm H2O QC FOR X-RAY EQUIPMENT AND ACCESSORIES Exposure 1 Exposure 2 Exposure 1 Exposure 2 A. Consistent generator output B. Inconsistent generator output

12. CHECK FOR mAs LINEARITY • Objective - To determine any differences in photographic density when different mA settings are used for equal mAs value. • Procedure - Position the water phantom on the loaded cassette and expose the film with set factors. Process the film the usual way. QC FOR X-RAY EQUIPMENT AND ACCESSORIES

13. CHECK FOR mAs LINEARITY Good Linearity 10cm H2O 10cm H2O 10cm H2O QC FOR X-RAY EQUIPMENT AND ACCESSORIES Exposure 1 50mA & 0.2s Exposure 2 100mA & 0.1s Exposure 3 200mA & 0.05s

14. CHECK FOR mAs LINEARITY Poor Linearity 10cm H2O 10cm H2O 10cm H2O QC FOR X-RAY EQUIPMENT AND ACCESSORIES Exposure 1 50mA & 0.2s Exposure 2 100mA & 0.1s Exposure 3 200mA & 0.05s

15. CHECK FOR TIMER ACCURACY • Objective - To determine the accuracy of the x-ray timer. • Procedure - Position the spinning top on the loaded cassette and expose the film using the clinically used exposure times. Process the film the usual way. QC FOR X-RAY EQUIPMENT AND ACCESSORIES

16. CHECK FOR TIMER ACCURACY QC FOR X-RAY EQUIPMENT AND ACCESSORIES

17. CHECK FOR TIMER ACCURACY For mains supply with 60Hz frequency: One-pulse (self rectified) unit Set time (sec) No. of dots 0.05 3 0.10 6 0.50 30 1.00 60 Two-pulse (full wave rectified) unit Set time (sec) No. of dots 0.05 6 0.10 12 0.50 60 1.00 120 QC FOR X-RAY EQUIPMENT AND ACCESSORIES

18. COLLIMATOR CHECK • Objective - To check if the radiation field is the same as the area illuminated by the light from the collimator. • Procedure - Center the loaded cassette in the useful beam at a commonly used SID. Collimate the field to approximately half the film’s size and place a metal marker at the center of the illuminated area and mark the inside edges with lead wires. Make an exposure using appropriate technique factors. Make a second exposure with the collimator fully opened. Process the film the usual way. QC FOR X-RAY EQUIPMENT AND ACCESSORIES

19. COLLIMATOR CHECK 1st exposure 2nd exposure QC FOR X-RAY EQUIPMENT AND ACCESSORIES

20. COLLIMATOR CHECK Radiation field Light field QC FOR X-RAY EQUIPMENT AND ACCESSORIES The misalignment should not exceed 2% of the SID

21. CHECK FOR THE ALIGNMENT OF THE X-RAY TUBE COLUMN AND THE X-RAY TABLE • Check for table alignment with the x-ray beam QC FOR X-RAY EQUIPMENT AND ACCESSORIES

22. CHECK FOR THE ALIGNMENT OF THE X-RAY TUBE COLUMN AND THE X-RAY TABLE • Check whether the column is vertical • - Using a plumb bob, hold the string’s end against the tube • column making sure that the string hangs unobstructed. If • the column is parallel to the string, the column is vertical. • Check whether the table top is horizontal • - Place a bowl of water on top of the table at different • locations and measure the depth of water around the edge of • the bowl. If the table is horizontal, the depth of the water • will not vary across the bowl. • Check whether the horizontal arm is still horizontal • - Measure the distance between the cross-arm and the table • top in front of the cross-arm and from the back. The arm is • horizontal if the distance is the same from both ends. QC FOR X-RAY EQUIPMENT AND ACCESSORIES

23. TEST FOR GRIDS • Objective - To check whether the grid gives a uniform density over its area. • Procedure - Place the loaded cassette on the cassette tray or under the loose stationary grid. Place metal markers on the cassette to indicate the position of the grid on the film. Expose the film using the recommended SID and process the film the usual way. QC FOR X-RAY EQUIPMENT AND ACCESSORIES

24. TEST FOR BUCKY MOVEMENT • Objective - To check whether the grid bucky is moving throughout the whole exposure. • Procedure - Place the loaded cassette on the cassette tray. Place metal markers on the cassette to indicate the position of the grid on the film. Expose the film in the bucky mode and process the film the usual way. Check for presence of grid lines on the radiograph. QC FOR X-RAY EQUIPMENT AND ACCESSORIES

25. LEAD RUBBER APRONS AND GLOVES • Care -clean with soap and water, weekly or as necessary -should not be stored near a heat source -aprons should be hung up using hangers; should not be fold -gloves should be stored flat or upright on a custom holder • Checking for damage -to surface covering, seams and fasteners of aprons (if any) -check for flexibility, feeling for cracks QC FOR X-RAY EQUIPMENT AND ACCESSORIES

26. LEAD RUBBER APRONS AND GLOVES • Test to detect cracks on aprons and gloves Method -place the apron or gloves to be tested on the table top -use fluoroscopy system to examine the whole article *if radiography is to be used, placed cassettes under test articles and make separate exposures, ensuring that the whole article is examined • Evaluation -Look for cracks or other abnormal variations of density in the image QC FOR X-RAY EQUIPMENT AND ACCESSORIES