( Principles Lec 9) Quality Assurance/Quality Control in Radiology

is the total assessment of the x-ray exam process as it relates to the patient (includes pt. scheduling, reception, exam preparation, image interpretation & diagnosis, and correlation of diagnosis with actual pathology ,etc)
Quality Assurance (QA)
is a part of QA which relates specifically to testing of the imaging chain (equipment, processor, etc)
Quality Control (QC)
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1. Equipment testing (kVp, mAs, timers, etc)
2. Processor sensitometry (CR , DR don’t have any standardized guidelines yet )
3. Darkroom and Screen cleanliness
4. Safelight testing, Film-screen contact
5. Viewboxes & viewing conditions
6. Repeat analysis (Reject analysis for CR,DR )
7. Other tests by needs or specific areas
( mammo, etc )
What are the Components of QC
QC Parameters from Bushong
QC Parameters from Bushong
Whenever a Radiology Dept. buys new x-ray equip-ment or changes a major component (x-ray tube, generator, etc) of existing equipment, QC testing of the unit must be performed-
Quality Control – Acceptance Testing
is the term used to specify QC testing of new x-ray units (or used equipment if it is new to your facility) prior to its being placed in service for pt. use.

While the manufacturer will also normally do this testing on new equipment, the facility must do all QC tests independent of the manufacturer to be sure that they are being honest and the equipment meets all State/National legal requirements!

What is Acceptance testing?
Daily Processor control/sensitometer strips
Sensitometer (greater consistency) vs Step-wedge/Penetrometer (requires use of same cassette, generator/tube, technique factors)
One box of film set aside for processor QC and used only for that purpose until finished
Daily Plotting of results (1) Fog/Background index (clear area of film) (2) Speed index (3) Contrast index
QC for Film Processors:


1) Fog/Background index (clear are of film)
2) Speed Index
3) Contrast Index
Daily Plotting Results in?
Sensitometric strip and H & D(Hurter-Driffield)Curve derived from its measurement

Plots of film density (log of opacity) versus the log of exposure
Sensitometric strip and H & D (Hurter-Driffield) Curve derived from its measurement

Plots of film density (log of opacity) versus the log of exposure

A. Speed Index

B. Contrast Index

C. Base + Fog
A. Speed Index

B. Contrast Index

C. Base + Fog

Exampleof FUJI interpretive chart for Process or QC
Example of FUJI interpretive chart for Process or QC
– Care of unexposed film, check expiration dates{rotate, inspect box integrity
(QC for Film Processors)

Film Storage

Mixed properly, replenishment rates (checked & recorded), lids seated on replenishment tanks ( decrease oxidation)
(QC for Film Processors)

Processing Chemicals –

Cleaned regularly by manufacturer schedule, preventive maintenance
(QC for Film Processors)

Processor Cleaning –

{ ± 1-2°F, thermometer used to check developer temp. daily, H2O and fixer checked/recorded regularly{weekly, etc.
(QC for Film Processors)

Temperature Control

The analysis of film/image repeats/rejects, whether for film-screen or CR/ddR systems is an important aspect of QC.

If one doesn’t know why films are being repeated(faulty equipment, misunderstanding of dept exam protocols, sloppy positioning practices, etc…), there is less chance that improvements will be made or implemented.

While technique errors with digital systems will be relatively minimal, knowing what errors are leading to the majority of repeat radiographs will improve RT quality and decrease pt. exposure levels as well.

Film / Image Repeat Analysis
Example of arepeat analysis chart with %of errors fora film-screendepartment
Example of a repeat analysis chart with % of errors for a film-screen department
1. missed information / possible repeats
2. check x-ray field, light beam congruence
3. 2%
4. SID Indicators
5. Centuring Accuracy
QC Tests Collimator Accuracy

Misalignment of the collimated light field with the actual x-ray field may result in missed 1. ________ or ________. Semi-annual 8 coin test may 2. __________________ which must not exceed 3. ________ of the SID utilized.

4. _________ must test accurate to plus or minus 2% of the SID being used and

5. ________ must be to within 1 % of the SID. Some States require PBL (positive beam limita-tion)(the x-ray beam can be no larger than the image receptor except in the override mode).

An Eight Penny Collimator Test
An Eight Penny Collimator Test
Annual test results may vary depending on stated FSS.

<0.8mm = ± 50%; 0.8-1.5 mm = ± 40%; > 1.5 mm = ± 30%

(50% commonly used as maximum value).

What are the results of tests stated on FSS?
Most accurate but expensive & hard to set-up. Not used routinely. Shows actual FSS & condition.
(QC Tests Focal Spot Size)

*What is Pinhole Camera?*

Relatively inexpensive & easy to use but requires non-screen film/receptor. Measure geometric blurring to fairly accurately show FSS & condition.
(QC Tests Focal Spot Size)

*What is Star Test Patter?*

simple “pass/fail” test for FS condition.
(QC Test Focal Spot Size)

*What is Multiple Bar Pattern?*

Recommended by NEMA for measuring FSS, focal spot blooming and MTF.
(QC Test Focal Spot Size)

*What is Slit Camera?*

Plus or minus 5% of the set time for exposures greater than 10 ms.
(QC Tests Exposure Timer Accuracy)

Annual testing of exposure timer accuracy must be within…?

Newer testing is done by digital dosimeter which is very accurate and can be used with single- or three-phase equipment.

Expensive, but provides digital readout and can be shown as time or pulses.

(QC Tests Exposure Timer Accuracy)

How is Newer testing done?

Spinning top (manual) is effective for single-phase equipment & synchronous (motor driven) spinning tops can be used with three-phase or high frequency generators (single phase as well).
(QC Tests Exposure Time Accuracy)

What is Spinning Top (Manual)

1. Penetration & Image density/contrast
2. Pt. dose
3. Oscilloscopes
QC Tests kVp Calibration

Proper kVp calibration is important since this factor is set by the RT for every x-ray exam. Variations in kVp not only affect beam 1. ________ & ________ but also produce changes in 2. _______. Most physicists use filtered ion chambers or filtered photodiodes for kVp testing. 3. ________ can be used and are very accurate but require long set-up times.

*Older kVp test cassettes (Ardran-Crookes or Wisconsin test cassettes) are rarely used today. Accuracy: Mammo ± 1 kVp; Diagnostic ± 4-5 kVp or 10% of set kVp value*

1. Digital Dosmeter
2. 10%
3. 4 step-wedge
4. Consistency
QC Tests Exposure Linearity

Also known as mA or mAs linearity. Annual test commonly uses a 1. _______ _______ to measure different mA stations at a constant time setting to check radiographic output. Must be accurate to ± 2. _______% among adjacent mA stations. Checked after time settings are found to be accurate.

Older method used 3. ___ _____-______ exposures on cassette at different mA stations & compensated time settings to produce the same mAs. Density of the same step on all 4 exposures checked for 4.__________.

*This test is really measuring mAs reciprocity – any mA & time that produce the same mAs, should produce the same density*

1. Radiographic output
2. 5%
3. using an ionization chamber type meter or digital dosimeter
4. Erratic output
QC Tests- Exposure Reproducibility

This test measures the x-ray machines ability to produce the same 1. _________ _______ using the same exposure factors after being reset from a prior exposure at the same setting.

This should be done annually and may vary by ± 2. __________. 3-10 exposure are made at a given technique setting 3. _____________________ to measure actual tube output in (R) or (mR/mAs or R/100mAs). Technique setting may be used that RT’s have reported as having 4.__________ if appropriate.

*This test requires great accuracy because it is measuring actual pt. exposure levels!*

Filtration is usually the most important patient protection characteristic of a x-ray unit. General filtration requirements are to have a minimum total filtration of 2.5 mm of Al equivalency. Since it is hard to measure the amount of filtration in the x-ray beam directly, a measurement of HVL (half-value layer) is normally used. Measured HVL’s must meet or exceed published values. This testing must be done annually or whenever new equipment or tubes/housing is installed.
QC Tests

Filtration/Beam Quality/ HVL


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