The document discusses quality control procedures for a computed radiography (CR) system at different levels and frequencies. It describes daily, weekly/biweekly, and annual quality control tests performed by technologists and medical physicists to evaluate the CR system's performance and ensure optimal operation. Key tests include dark noise evaluation, exposure calibration and linearity, uniformity, and laser beam function which assess parameters like exposure response, spatial resolution, and image quality. Limit values are provided for test indicators to verify performance is within specifications.

1. QC ON CR

2. PENGANTAR CR
X-ray
unit
Imaging
Plate
Reader
Unit
Output
device

4. PENGANTAR QC
• Acceptance testing : validates performance
What ? How ?
• Quality control : verifies optimal operation
What ? How ? How often ?

5. QUALITY CONTROL
Quality Control Three levels of system performance
quality control Three levels of system performance
quality control
1. Routine: Technologist level - no radiation
measurements
2. Full inspection: Physicist level - radiation
measurements and non-invasive adjustments
3. System adjustment: Vendor service level -
hardware and software maintenance

6. PERIODIC QUALITY CONTROL
DAILY
Daily (technologist)
– Inspect CR system and status.
– Interfaces: PACS broker, ID terminal, QC
workstation
– Erase image receptors (if status unknown). Erase
image receptors (if status unknown).

7. OBJECTIVE INDICATORS OF
CR PERFORMANCE CHARACTERISTICS
1 Definitions according to AAPM TG10 (Samei et al 2001).
2 Definitions according to Kodak Guidelines (Kodak 2001).
3 Definitions introduced in this study

8. PERIODIC QUALITY CONTROL PERIODIC
QUALITY CONTROL
WEEKLY / BIWEEKLY
(technologist)
– Calibrate review workstation monitors (SMPTE).
– Acquire QC phantom test images. Verify
performance.
– Check filters / vents and clean as necessary
– Clean screens with recommended agents.

9. PERIODIC QUALITY CONTROL
QUARTERLY (TECHNOLOGIST)
– Inspect cassettes. Clean with recommended agents.
– Review image retake rate and exposure trends
– Update QC log. Review out of tolerance issues.

10. PERIODIC QUALITY CONTROL
ANNUALLY (PHYSICIST)
– Perform linearity / sensitivity / uniformity tests
– Inspect / evaluate image quality
– Re-establish baseline values (Acceptance Tests)
– Review retakes, exposures, service records.

11. Dark noise Average signal and its standard deviation within 80% of the image area (1)
Exposure index value (1)
Uniformity Signal standard deviation within 80% of the image area(1)
Maximum difference between quadrants average pixel values(2)
Differential and integral uniformity evaluated on a 1 cm × 1 cm ROI matrix(3)
Exposure
calibration
Exposure indicator response normalized to a 1 mR entrance exposure(1)
Linearity and
autoranging
Slope of the system response (expressed in terms of logarithm of exposure) versus
logarithm of actual exposurea
Noise and low-
contrast resolution
Correlation coefficient of the linear fit to logarithm of pixel value standard deviation
versus logarithm of actual exposure(1)
Number of phantom details with a contrast noise ratio above a specified
threshold(2)

12. Limiting resolution Modulation transfer function values (1)
Spatial accuracy Difference between measured and actual distances in the orthogonal
directions(1)
Laser beam function Jitter dimension in pixels(1)
Resolution Uniformity Differences between subarrays Fourier spectrum peak amplitude(3)
Spatial accuracy
uniformity
Differences between subarrays Fourier spectrum peak position(3)
Erasure thoroughness Average signal and standard deviation within 80% of the reread
unexposed image(1)
Contrast-noise-ratio of the supposed ghost image(3)

13. THE DARK NOISE EVALUATION IS ONLY AFFECTED BY THE CR
READER AND PLATE CHARACTERISTICS, BECAUSE NO
EXPOSURE IS INVOLVED IN THE TEST. THE EXPOSURE
INDICATOR VALUE OBTAINED FROM THE READING OF THE
UNEXPOSED PLATE SHOULD NOT EXCEED A SPECIFIED
THRESHOLD: PV80% > 744 FOR FUJI, EIGP < 80 AND
EIHR < 380 FOR KODAK (SAMEI ET AL 2001).
DARK NOISE

15. EXPOSURE CALIBRATION AND
LINEARITY
The exposure calibration and linearity are strongly dependent on
the exposure conditions (additional filtration, distance, etc),
and therefore it is very important to check the constancy of these
parameters, in order to perform the test correctly. The linearity of
the exposure indicator value is tested by exposing the same IP to
approximately 0.1, 1 and 10 mR (1 mR = 2.58 × 10−7 C kg−1)
entrance exposures in a sequence of three exposure-reading
cycles.

16. UNIFORMITY
Uniformity of response is a fundamental parameter for
detectors in all medical imaging fields. A uniform exposure
should result in a uniform response of the CR system.
Many definitions (Kodak 2001, Samei et al 2001, Masden
1997, AAPM 2005) have been proposed to establish
uniformity indicators. In this study we used three different
approaches

17. After the image separation into four discrete quadrants, a
uniformity index (Uquad) was evaluated as the difference
between the average values (P V i, i = 1,... 4) of the two quadrants
with the highest (MAX(PVi)) and lowest (MIN(PVi) average pixel
values (Kodak 2001)
Standard deviation of pixel value within 80% of the image area
(Samei et al 2001).The percentage difference between the images
(evaluated using the same ROI of the uniformity analysis)
resulted to be less than 2%.

19. LASER BEAM FUNCTION

21. PROCEDURE
Laser beam scan line integrity, beam jitter, signal dropout, and focus are
evaluated in this test. Use a radiographic technique of ~60 kVp, 180 cm SID,
and mAs to deliver an incident exposure of ~5 mR. Place the steel ruler on a
35 43 cm (14 17 in.) centered on the cassette and nearly perpendicular to,
approximately 5° from the laser beam scan lines.
Laser beam jitter (inconsistent gray-level output caused by timing errors with
the location of the beam or synchronization with the ADC) is evaluated by
examining the edge of the ruler on the image. Ruler edges should be straight
and continuous over the full length of the hard-copy or soft-copy image.
Scan lines in light to dark transitions along the ruler edge that do

22. Qualitative criteria : Ruler edges should be straight and
continuous without under- or overshoot of scan lines in
light to dark transitions.
Quantitative criteria: There should not be more than
occasional 1 pixel jitters over the ruler edges.

23. OUTPUT DEVICE
WITH SPMTE TEST

24. Lisensi
VECTOR STOCK

25. Lisensi FROSTENSTEIN

26. Lisensi CREATIVE COMMON