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
• If the x ray beam is not perpendicular to the
image receptor ,the image may be distorted
• If grid is used the distortion will be magnified
resulting in total loss of minute details.

8. FOCAL SPOT SIZE
• The 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)
• The applied kvp affects the quality and
quantity of x-rays reaching the image
receptors.
• If 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
• If 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
• The leakage of radiation from r-ray tube
housing adds the radiation dose to the patient
and to the operator too.
• Tube housing leakage test must be periodically
done to insure the radiation safety.

12. TOOLS REQUIRED
BEAM ALIGNMENT TEST TOOL
• Beam 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.
• If 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
• Test 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.
• Each 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%.
• The focal spot size value are computed for
magnification of 4/3 being ffd 60cm and OFD 45.as
shown in table:

16. • Test 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.

17. FOCAL SPOT TEST TOOL

18. 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.

19. SPINNING TOP TEST TOOL

20. 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 .

21. Kvp METER

22. 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

23. RADIATION SURVEY METER

24. 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

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

26. 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.

27. 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.

28. BIOMEDICAL ENGNEER
• Corrective and preventive maintenance.
• Fault reporting

29. 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.

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