QA Policies
About QA policies
A QA policy is a collection of individual QA test definitions. When operational, the local QAWeb agents will communicate with the QAWeb server and will resolve which QA policy is applicable for the workstation’s displays (see Summary: How the QA tests and calibration settings are determined for individual displays). The applicable QA policy will determine which QA tests should be executed, what the test parameters are, and at which frequency each test should be scheduled. The QA Status of a workstation is determined by aggregating the results of the individual QA tests. (see QA Status and Schedule Status)
Most QA tests are executed at display level. One exception is the multi-display uniformity test - which is applied to multiple displays and can be viewed as a workstation-level test.
QA test schedule
Each QA test in the policy should have a schedule (execution frequency) defined.
The following frequencies can be configured:
Daily
Weekly
Biweekly
Monthly
Quarterly
Half yearly
Yearly
Custom
This is described in detail in the chapter How the task schedule determines the execution time of tasks.
Sensor used for executing QA tests
Several QA tests have a Sensor parameter, which controls how the measurement will be done. It can have the following values:
Internal (if available): If the display has an internal luminance sensor (as most Barco displays do), then this sensor will be used and the test execution will be automatic / intervention-free. However, if this QA test becomes applicable for a display that does not have a supported internal sensor, then the QA test for that display will create a manual task for the workstation and will require a manual intervention using a supported external luminance sensor.
External: If this option is selected, the test must be executed with an external luminance sensor. Such QA tests will never execute automatically and requires manual interaction at the workstation.
For a list of supported external sensors, see the system requirements in the QAWeb Enterprise Agent user guide.
Individual tests and bundled tests
A QA policy can be composed of any number QA tests, which can be further classified as:
Individual tests: QA tests that evaluate one individual criterium and return one result. Example: DICOM GSDF Luminance Response Test.
Bundled tests: QA tests that are a combination of several individual tests. These tests will be executed together, and must all meet the criterium for the bundled test to produce a positive result. Example: Mammography Compliance Test.
Acceptance tests and constancy tests
A bundled test may define an acceptance test and constancy tests.
Acceptance test: A test that should be performed once and is used to certify the correct configuration and functionally of the image display system. Upon first installation of the agent, an acceptance test will become due automatically. The acceptance test does not have a repeating schedule. Workstation administrators should manually re-execute an acceptance test when making significant changes to a workstation (such as adding a display or replacing a display or graphics board)
Constancy test: QA tests with a repeating schedule, similar to the schedule of individual QA tests.
Regional regulations
QAWeb Enterprise supports different regional regulations. To avoid cluttering the interface with regulations which in most cases are not applicable to your situation, regional regulations are by default hidden. Based on the country where your hospital organization is located, QAWeb Enterprise will suggest showing the regional regulation which applies to you and suggest to apply it as default for your organization. This suggestion is shown to every user with sufficient permissions during login. QAWeb Enterprise will continue to show the suggestion until it has been answered. To change the option later, navigate to the My organization page, under the Administration section.
These regional regulations are available:
DIN 6868-157, applicable for Germany
JESRA X-0093, applicable for Japan
BAG Wegleitung R-08-06, applicable for Switzerland
To disable a regional regulation, make sure that:
The related default QA policy is not longer used.
Related tasks are not longer part of a custom policy.
Related ambient light policies are not longer in use.
In case one of the above is not met, disabling the regional regulation will fail.
QA policy test types
The different QA tests that a QA policy can be composed of, are described below:
DICOM GSDF Luminance response test (LRT)
The DICOM GSDF luminance response test (LRT) verifies that the measured grayscale luminance response function conforms to the DICOM GSDF luminance response function. This is done by measuring the luminance (in cd/m²) at 18 digital driving levels (DDL) and calculating the deviation from the standard curve. The reflected ambient light is taken into account.
Parameters:
Error Tolerance: Defines the maximum deviation, expressed as a percentage (%) of the measured luminance versus the standard DICOM curve. If at least one of the measurements exceeds the error tolerance, then the test will fail.
sRGB Luminance response test
The sRGB luminance response test verifies that the measured grayscale luminance response function conforms to the sRGB response function.
This test has two parameters:
Error Tolerance: Defines the maximum deviation, expressed as a percentage (%) of the measured luminance versus the standard sRGB curve.
Sensor: Choose between Internal (if available) and External.
Note that this test will only succeed if the display is calibrated for an sRGB luminance response.
Gamma Luminance response test
The gamma luminance response test verifies the conformity of the display grayscale luminance response function with the defined gamma response function.
Parameters:
Gamma: Defines the gamma slope (possibilities: 1.8, 2.0, 2.2, 2.4. Default: 2.2)
Error Tolerance: Defines the maximum deviation, expressed as a percentage (%) of the measured luminance versus the defined gamma curve. (default: 15%)
Sensor: Choose between Internal (if available) and External. (default: Internal)
Custom Luminance response test
The custom luminance response test verifies the conformity of the display grayscale luminance response function with the custom luminance response function.
Parameters:
Name: Arbitrary name of the custom luminance response function.
Curve: Defines the custom slope.
Error Tolerance: Defines the maximum deviation, expressed as a percentage (%) of the measured luminance versus the defined custom curve. (default: 15%)
Sensor: Choose between Internal (if available) and External. (default: Internal)
Note
The file format (*.gam files) of the custom luminance response function needs to adhere to the syntax specified in custom file specification.
Maximum luminance test
The maximum luminance test verifies that the white luminance (L’max) meets a minimum required value, expressed in cd/m².
Parameters:
Minimum white luminance: The test will return a negative result if the measured white luminance does not meet the configured threshold value (unit: cd/m²).
Luminance ratio test
The luminance ratio test can be used to verify that sufficient contrast is present between white and black values. It calculates the ratio between the white luminance (L’max) and the black luminance (L’min)
Parameters:
Minimum luminance ratio: The test will return a negative result if the measured ratio is lower than the configured ratio.
Luminance uniformity test
The luminance uniformity test is a used to verify the uniformity at different regions of the display. Due to the definition of this evaluation method, this test can only be executed with an external sensor, and requires manual execution.
A luminance uniformity test consists of measuring the luminance at five locations on the display (center and four corners) using the TG18-UNL80 (or optionally TG18-UNL10) test pattern. The maximum luminance deviation is calculated as a percent difference between the highest and lowest luminance values relative to their average value:
200 × (Lhighest - Llowest)/(Lhighest + Llowest).
Parameters:
Error Tolerance: The test will return a negative result if the calculated deviation exceeds the configured threshold value.
Video Level: Choose between 80% or 10% to define the digital driving level at which to measure the uniformity.
Multi-display luminance uniformity test
The multi-display luminance uniformity test is used to evaluate the white luminance uniformity on image display systems with multiple displays (as typically encountered in mammography reading applications). This QA test is only applicable on workstations that have at least two displays with the same configured use.
The maximum luminance deviation is calculated as a percent difference between the highest and lowest luminance values relative to their average value:
100 * (Lhighest - Llowest)/Llowest.
Parameters:
Error Tolerance: The test will return a negative result if the calculated deviation exceeds this configured threshold value
Visual test
This test will launch a series of visual tests with questions based on predefined test patterns. The current version of QAWeb Enterprise supports the following visual test standards:
Barco default (TG18-OIQ)
New York State
New York City
Temporal Response
Custom
A visual test is alway executed by a user at the workstation; it can never be executed automatically using internal sensors.
The custom visual test allows the user to define a series of questions on one or more patterns.
SteadyColor response test
The SteadyColor test measures the color response of your display and checks that the perceptual difference between colors is proportional to their Digital Driving Level (DDL) difference.
The color response test can only be executed on Barco color displays with an I-Guard™ sensor and SteadyColor™ technology.
Parameters:
Error Tolerance: The test will return a negative result if the measurements exceed the configured threshold percentage.
Grayscale chromaticity test
The grayscale chromaticity test verifies that the different values of gray have a similar chromaticity. The test calculates distance in the u’v’ plane of the measured chromaticity for the TG18-LN test patterns with respect to the measurement chromaticity of white at maximum luminance.
Parameters:
Maximum u’v’: The test will return a negative result if the maximum calculated distance in the u’,v’ plane exceeds this value.
White point chromaticity test
The white point chromaticity test verifies that the measured chromaticity of white at maximum luminance is within range of a reference chromaticity value.
Parameters:
Maximum delta u’v’: The test will return a negative result if the distance between the measured and reference white point chromaticity in the u’v’ color plane exceeds this value.
White point chromaticity: The reference value to which the measurement should be compared to. The value can be defined as either
preset : Select Bluebase / Clearbase / D65 / D75
Kelvin : Enter a value in Kelvin unit
xy : Enter a value defined in x,y color coordinates
Mammography compliance test
A set of QA tests part of the recommended quality assurance for Barco mammography display systems (see documents K5905208, K5905277):
Mammography compliance acceptance test: A bundled test consisting of:
DICOM GSDF luminance response test: see DICOM GSDF Luminance response test (LRT)
Calibrated whitepoint deviation test: The test will return a negative result when the actual white deviates more than the configured percentage from the calibrated whitepoint.
Multi-display uniformity test: see Multi-display luminance uniformity test. Only applicable when at least two displays with an identical use are connected to the workstation.
A visual test using the TG18-OIQ pattern
Mammography compliance constancy test: A bundled test with a default weekly schedule. It is equal to the acceptance test, except for the absence of the visual test.
DICOM GSDF luminance response test
Calibrated whitepoint deviation test
Multi-display uniformity test
ONR 195240-20:2017 (Austria)
This test implements the ONR 195240-20 guideline, published by the Austrian Standards Institute. If this test is applicable to a workstation, the following tests will be available:
ONR Acceptance test: This should be executed when installing a new display system
ONR Half-yearly Constancy test: To be executed with half-yearly frequency
sRGB color space test
The sRGB color space test verifies that the display conforms to the sRGB color space. It measures the color of 216 different RGB values, and calculates the difference with the sRGB color space specification.
Note that this test will only succeed if the display is calibrated for an sRGB gamut and an sRGB luminance response.
ICC Compliance test
The ICC compliance test verifies the actual measured color space versus the currently installed ICC profile (installed in the operation system). It measures the color of 216 different RGB values, and calculates the difference with the installed ICC profile.
DIN 6868-157 (Germany)
The test is currently limited to the migration of test results made by the QAWeb for DIN application. Results of the tests are submitted to the QAWeb Enterprise Server, where they are used in various reports.
To comply with the DIN regulation, please use the dedicated ambient light policies relating to room class 1-6. By default, the DIN policy applies to all clinical displays governed by the policy.
The results of the individual tasks are available:
Acceptance test
Half-yearly constancy test
Daily constancy test
An integrated workstation report is available which is targeted to be used as official audit report.
Note that the DIN tests are only visible when the DIN regional regulation is enabled. (see Regional regulations)
JESRA X-0093 (Japan)
The JESRA X-0093 tests implements the JESRA X-0093 B-2017 regulation. During the test, the diagnostic displays which are connected to the workstation are subject to the test. The tests are conducted using an external sensor.
The results of the individual tasks are available:
Acceptance test
Yearly constancy test
Daily constancy test
An integrated workstation report is available which is targeted to be used as official audit report.
Note that the JESRA tests are only visible when the JESRA regional regulation is enabled. (see Regional regulations)
BAG Wegleitung R-08-06 (Switzerland)
This task option is a bundle of tasks implementing the BAG Wegleitung R-08-06 regulation. This will add these tasks to be be run on the workstation:
Acceptance - Constancy test
Weekly visual test
An integrated workstation report is available which is targeted to be used as official audit report.
Note that the BAG tests are only visible when the BAG regional regulation is enabled. (see Regional regulations)