MEDICAL RADIATION SCIENCE/MEDICAL IMAGING PRACTICE 1
Quality Control Test 1
PART A
Visual Inspection of Radiographic Unit & Accessories
PART B
Beam Collimation
Developed May 2011
By Dr Curtise K.C. Ng
Updated July 2015 By
Mr YasasBotenne
Medical Imaging Laboratory Rules
Students will only be allowed to enter the laboratory environment if they observe the following requirements
1. Radiation monitoring badges must be worn correctly and observable on the students’ person.
2. Name badges must be worn to allow the laboratory supervisor to identify students.
3. Closed in foot wearmust be worn.
4. Clothing should be appropriate to allow a free range of movement (NOTE – clinical uniforms will be requested to be worn once these have become available).
These requirements will be enforced regardless of the use or non-use of x-radiation.
Students will be refused entry if these requirements are not regardless of the purpose of a student to enter the laboratory area.
General Rules of Conduct while inside the laboratory environment
• Strictly Noeating, drinking or smoking.
• Alwaysact responsibly.
• Obeyallinstructions from supervisors.
• Ask if unsure.
• All individuals MUST be behind the protective screen before an exposure is made.
• Students must see supervisor before leaving the sessions.
• Leave the rooms tidyat the end of the sessions. All equipment placed back into cupboards.
REPORT any accidental exposure to x-radiation to a supervisor immediately.
N.B.: Although students are arranged into laboratory groups, all students should participate in all aspects of the laboratory activities. Each group will be allocated to an x-ray unit in the Medical Imaging laboratory facilities. The following activities and questions must be performed and answered. Each student is to complete the following exercises and questions INDIVIDUALLY. The expressions of answers for the questions should be unique and different from other students. If IDENTICAL / VERY SIMILAR EXPRESSIONS are found in two or more submissions, this issue will be followed SERIOUSLY. PENALTY will be given if PLAGIARISM IS IDENTIFIED. The completed MS WORD document is to be submitted by two weeks after each laboratory session via Blackboard. There is a submission channel called “Assessments” inside the “Medical Imaging Practice 1” Blackboard homepage. Exact due dates provided in the program calendar.
QUALITY CONTROL TEST 1
PART A
Visual Inspection of Radiographic Units & Accessories
Objectives
1. To implement a quality control test for radiographic units & accessories (Unit Learning Outcome 3)
2. To critically assess their safe working conditions in regard to radiation protection, electromechanical safety and appropriate regulations or standards (Unit Learning Outcome 2)
Materials
• X-ray unit (No.: ___1___)
• Ancillary devices
• Measuring tape
• Protractor
Methods
1. Visually verify the following items for the allocated X-ray unit.
Control Panel
a. All panel lights, meters & switches function as designed. These include switches to select exposure techniques and their corresponding indicators & meters.
b. Proper (unobstructed) view of the exposure room through window of control panel, i.e. any position within the room designated for imaging including radiographic table, erect bucky& area for X-raying patients on stretchers can be seen from the control panel.
c. Appropriate exposure switch placement. Exposure switch must be positioned at least 1m from the edge of the control booth and in the appropriate rack if presence.
d. Presence of updated technique chart.
Overhead Tube Crane
e. Condition of high-voltage cables & other wires. Check presence of any discoloring & fraying.
f. Condition of cable bracket, clamp & tie-downs. Check whether they are intact & functioning properly.
g. Stability & proper movement of system. Move all movable parts of the X-ray tube and feel whether movement is smooth & stable.
h. Detent operation. Release hands when moving movable parts of the X-ray tube. Check whether it can stop properly.
i. Lock function. Observe whether the tube can hold its position after releasing hands in the previous item (i).
j. Bucky center light. Check whether the center of the light field of the collimator aiming at the center of the bucky when tube alignment function is used.
k. Collimator light brightness. Check whether the light field of the collimator can be seen when 100cm FFD is set.
l. Accuracy of FFD displayed on the tube head / label. Compare the FFD measured by a measuring tape with the displayed value. Acceptable deviation is +/- 2% of the FFD. The FFD should be measured from the focal spot.
Accuracy of displayed angle of tube tilting. Tilt the tube to any angle between 0° & 90°. Compare the titling angle measured by a protractor with the displayed angle. The acceptable deviation is +/- 5°.
Radiographic Table & Erect Bucky
a. Radiographic table & erect bucky surface condition. Check whether there is any damage & their cleanliness.
b. Switches for radiographic table & erect bucky movements. Check whether the table & erect bucky can be moved in the directions suggested by the corresponding switches.
c. Locks of bucky& cassette. Check whether the relevant locks can hold the bucky& cassette.
d. Radiographic table & erect bucky stability. Feel whether the table & erect bucky are stable when moving (& lying on the table).
Protective Lead Apparel & Gonad Shield
e. Presence of protective lead apron (having at least 0.5mm Pb equivalent thickness) & gonad shield.
f. Properly maintain. Check whether lead apron is hanging properly & gonad shield must not be folded.
g. Presence of any crack or hole. Check whether there is any crack or hole.
Miscellaneous Equipment
h. Presence & cleanliness of positioning sponges.
i. Integrity of any step stool & intravenous fluid stands. Check their presences & conditions.
2. Fill in the performances of various items checked in step 1 into the following table.
Results
Results of Visual Inspection for Radiographic Units & Accessories
Item Comments Pass / Fail
Control Panel
a. All panel lights, meters & switches function as designed pass
b. Proper view of the exposure room through window of control panel pass
c. Appropriate exposure switch placement fail
Overhead Tube Crane
e. Condition of high-voltage cables & other wires. Check presence of any discoloring & fraying pass
f. Condition of cable bracket, clamp & tie-downs pass
g. Stability & proper movement of system pass
h. Detent operation pass
i. Lock function pass
j. Bucky center light pass
k. Collimator light brightness pass
l. Accuracy of FFD displayed on the tube head / label pass
m. Accuracy of displayed angle of tube tilting pass
Radiographic Table & Erect Bucky
n. Radiographic table & erect bucky surface condition pass
o. Switches for radiographic table & erect bucky movements pass
p. Locks of bucky& cassette pass
q. Radiographic table & erect bucky stability pass
Protective Lead Apparel & Gonad Shield
r. Presence of protective lead apron & gonad shield pass
s. Presence of any cracks or holes Cables
Miscellaneous Equipment
t. Presence & cleanliness of positioning sponges pass
u. Integrity of any step stool & intravenous fluid stands pass
Discussion
1. What were the failed item(s) and explain why this may have happened? (3 marks)
The failed item was the appropriate exposure switch placement. This happen because the appropriate exposure switch placement was not safe for the operator (the cables was not covered).
2. What is the importance of the quality control test conducted in this laboratory session in relation to radiation protection, electromechanical safety and clinical utilization? Provide examples to support your answer. (3 marks)
The importance of the quality control testin relation to radiation protection is ALARA, monitoring of radiation output of equipment, safety of operators and safety of patients.
The importance of the quality control test in relation to electromechanical safety is electric shock, physical injury, running costs and prolongs equipment life.
The importance of the quality control test in relation to clinicalutilisation is image quality maintenance, better patient outcome, radiation protection and ALARA.
For example, if wedo notconducted the quality control test, we will have the risk to repeat the x-ray for the patients. This will lead to unnecessary radiation exposure for both the operators and the patients.
3. Are there any alternatives to the quality control test conducted in this laboratory session? (2 marks)
No, there are no alternatives to the quality control test conducted in this laboratory session.
QUALITY CONTROL TEST 1
PART B
Beam Collimation
Objectives
3. To implement a quality control test for the light localisation function of the collimator, i.e. nine-penny test (Unit Learning Outcome 3)
4. To critically assess its safe working conditions in regard to radiation protection, electromechanical safety and appropriate regulations or standards (Unit Learning Outcome 2)
Materials
• X-ray unit (No.: ___1___)
• 9 five-cent coins
• 18X24cm & 35X43cm CR cassettes
Methods
1. Erase the CR cassette (N.B.: 1. Press the blue button next to the indicator light (LED) of the CR digitizer;
2. Insert the CR cassette (with its red marker facing up and on the right-hand side) into the cassette slot of the digitizer along its left border
3. Slide the CR cassette laterally to the right border of the cassette slot of the digitizer.
4. Remove the CR cassette out from the digitizer when the indicator light changes to solid yellow colour).
5. Set a FFD of 1m.
6. Center the light field to the center of the 35X43cm CR cassette.
7. Collimate to an 18X24cm field size at 100cm FFD (N.B. Use the 18X24cm cassette as an indicator of the required 18X24cm field size).
8. 4 five-cent coins placed on the inside edge of the light field.
9. 4 five-cent coins placed outside the light field (opposite to & in contact with the previous 4 five-cent coins).
10. Put the last (9th) five-cent coin in the bottom right hand corner of the light field (the illustration of the experiment setup is shown below).
11. Expose the 35X43cm cassette with 60kVp & 5mAs.
12. Process the 35X43cm CR cassette.
13. Login to the CR console (You need to press Ctrl-Alt-Delete to enter the login windows – User name: RAD1 & password: RAD1).
14. Click the ‘New Exam’ button of the ‘Worklist’ interface of the AGFA NX V.2.0 program.
15. Input ‘IMIS_Lab2_GpX’ for the ‘Last Name:’ and ‘ID:’ fields of the menu (where X is your group number).
16. Click the ‘OK’ button.
3. Click the ‘HAND’ button.
4. Click the ‘PA’ button twice.
5. Click the ‘OK’ button.
6. Insert the CR cassette (with its red marker facing up and on the right-hand side) into the cassette slot of the digitizer along its left border
7. Slide the CR cassette laterally to the right border of the cassette slot of the digitizer
8. Once image has been processed click on editing tab to display image.
9. Adjust the image brightness & contrast to visualize exposed area if necessary.
10. Click on close and send all when image review is completed.
Discussion
1. Describe the appearance of the CR image. (2 marks)
The x-ray field aligns perfectly with the vertical 5 cent pieces on either sides of the border on the right hand side of the image however all the others are slightly misaligned to a small degree.
2. Is the performance of the light localisation function of the collimator acceptable? Justify your response. (3 marks)
Yes. The x-ray field should cover/align the whole area of the collimator light field almost perfectly on all four borders. The results depend on where the x-ray field falls; if it falls within half of the coins distance from the border the results are ideal, however if it exceeds the proper location by more than the diameter of one five-cent coin the results are unacceptable. As for our image, the x-ray collimation border falls in between the pairs of pennies, no more than half the coins diameter from the border, therefore causing less than a 2cm error margin on either side of the x-ray field, producing an ideal test result.
3. Can you explain the function of the 9th five-cent coin in the nine-penny test? Can the test be done without it? Why? (2 marks)
The ninth five-cent coin is used as the orientation marker in the nine-penny test to distinguish which is the anode/cathode end.
4. What is the importance of the nine-penny test in relation to radiation protection and clinical utilisation? (3 marks)
Verification of the proper alignment of the collimator light field with the x-ray field is essential in radiographic quality control as it has a significant impact on radiation protection and clinical utilisation.
In regards to radiation protection, as mentioned earlier, if anatomy was cut off from the first image a second will need to be taken as it is unacceptable to have only part of the anatomy on an image because it would make it undiagnosable. Depending on the degree of misalignment of the x-ray filed, the second image would need to be corrected by increasing the collimation field, this would mean exposing unintended anatomy and increasing the collimation field size increases the total amount of scatter radiation. Repeating an x-ray causes the patient to receive additional radiation.
In terms of clinical utilization, increasing the collimation field would have an impact on the quality of the image as optimal collimation reduces image noise caused by scatter radiation originating from outside the area of interest. In addition to this, if the radiographer had to repeat examinations because the collimation beam was off it would mean that the examination would take longer than it should for many patients. This would cause a longer wait for the patients in the waiting room.
1. Can you suggest an alternative for the quality control test conducted in this laboratory session? (2 marks)
Collimator and Beam Alignment Test Tools: It evaluates collimator light field and x-ray field congruence plus ensures accurate x-ray beam alignment.
Verification of the proper alignment of the collimator light field with the x-ray field is essential in radiographic quality control. The collimator test tool is designed to evaluate the collimator light field and x-ray field congruence. The beam alignment test tool provides a simple test of the x-ray beams alignment. When used with the collimator test tool, x-ray beam misalignments of 2% can be visualised without the need for measuring or calculating.
Collimator and Beam Alignment Test Tools
http://www.pnwx.com/Accessories/NuclearAssociates/Rad-Fluoro/ProductDetail.php?PartNum=07-661