VMS Detector Quality Assurance Software
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Features
- Permits monitoring of any system parameter, determining if a detector is calibrated properly, and assuring that measurements can be repeated
- Allows centroids and FWHMs of several key energy lines to be monitored in a standard spectrum
- Allows several key nuclides to be monitored for many different samples
- Supports manually entered parameters
- Includes reporting, trend plotting, parameter calculation and alarm thresholds
Description
The Detector QA Software measures spectroscopy system performance over time. The software allows the user to monitor any detection system parameter and any other manually entered parameters. Parameter values are stored in the quality assurance database. The database file is an Indexed Sequential Access Method (ISAM) file.
One of the most common applications for this package is radiation detector QA which allows monitoring the centroids and FWHMs of several key energy lines in a standard spectrum. If performed on a periodic basis, the system indicates when detector performance is outside of tolerable limits so that appropriate action can be taken.
Nuclide activity monitoring is another application of the QA software. The activities of several key nuclides are monitored for many different samples. Activity values outside of limits are flagged for further investigation.
Any MCA configuration parameter can be monitored. The software transfers the parameter values from the configuration to the QA database automatically. Parameters which are not stored in the configuration can also be monitored since the QA editor allows entry of new parameter values as well. Thus, readings from air monitors, dosimeters, etc., can be stored and analyzed.
BASIC SOFTWARE
The heart of the quality assurance package is the quality assurance file. For detector quality assurance, a separate file should be set up for each detector/geometry to be used. Although it is not necessary, it is recommended that a separate QA file be created for any manually entered parameters.
The QA file contains two different types of records: the parameter definition record and the results record. The parameter definition record contains information which describes a single parameter to be monitored. The results record contains the values of the parameters being monitored for a single run. For example, a single results record is created every time a detector calibration is performed.
Since the operating system dynamically extends the size of the QA file every time it fills up, only the size of the disk limits the number of records (parameter definition plus results) that can be stored in a single QA file. Since the results record is of limited size, a maximum of 34 single precision and 12 double precision values can be stored in a single results record.
Quality Assurance Editor, GUI Mode
STATISTICAL TESTS
The data stored in QA files can be used for documenting instrument performance, recognizing trends or providing go/no-go feedback. Sets of data are analyzed using multiple methods:
N-Sigma Test: All the data stored for a particular parameter is used to compute a mean and standard deviation of the data set. Discrete points within the data set are compared against the computed mean value. Two thresholds, Investigate and Action, are defined in the QA file in terms of a ± N standard deviations (e.g. Investigate = ±2s, Action = ±3s). Discrete points which exceed the thresholds are flagged in reports accordingly. Plots display mean, investigate and action limits in addition to discrete points.
Sample Driven Test: This test functions identically to the N-Sigma test except the mean and standard deviation are computed over a user entered date/time window.
User Defined Mean Test: This test functions identically to the N-Sigma test except the user enters the predetermined mean and standard deviation.
Bias Test: This test allows definition of a true value, and the mean is expressed as a function of the true value. Investigate and Action limits are provided.
Bounds Test: The threshold limits are limited to an upper and lower value, which are user entered. No statistical computations are performed.
These methods provide the requisite flexibility to report and analyze a wide range of data types. Every parameter in a QA file can be defined to utilize one or more of the tests defined above.
Parameter Editing Screen
QUALITY ASSURANCE EDITOR (QAE)
The Quality Assurance Editor exists in three different versions:
- A command line editor (QAE) which allows defining parameters and editing results.
- A screen oriented, character cell environment (QAE/SCREEN) which allows defining parameters, editing results, display of control charts and viewing numerical results.
- An editor (QAE/GUI) that runs under DEC windows/Motif and Genie-ESP that allows complete management of QA files including defining parameters, editing results, display of control charts, viewing numerical results, printing hardcopy reports and providing the functions of the QAXFER program.
The variants of the QA editors provide all the functions for definition and maintenance of QA files. They can be operated from a variety of interface devices (VT or X-windows terminal) or can be built into command procedures. This flexibility allows the most efficient choice for utilizing the QA software.
DETECTOR QA EDITOR (QAE/CALIBRATE)
This program is a special version of the full quality assurance editor (QAE) which simplifies the process of entering parameter definition records for detector QA files. For a periodic detector calibration (daily, weekly, etc.), the program asks if the centroid, FWHM and efficiency are to be monitored for each certificate energy.
For non-periodic or source check calibrations, the program asks if the energy FWHM and activity are to be monitored for each certificate energy line. To monitor the activity, an absolutely calibrated source must be used.
Parameter Results Report
QA FILE TRANSFER PROGRAM (QAXFER)
This program transfers all configuration parameters defined in the QA file from a configuration to the QA file. Unlike other CANBERRA software, QAXFER does not know which programs must be run before it does its job. Therefore the configuration must be processed before invoking QAXFER. For example, to monitor the activity of a particular nuclide based on a single energy line, PEAK, EFF and NID must be run before invoking QAXFER.
CALIBRATION CHECK PROGRAM (CHKCAL)
This program performs a detector calibration check by comparing measured parameter values, which have been transferred from a calibration configuration to a QA file, with expected or true parameter values. The program indicates whether the current detector performance corresponds to the calibration equations in the configuration. In addition, CHKCAL quickly determines whether the detection system can correctly identify the activities in an absolutely calibrated source.
QA ANALYZE PROGRAM (QAANALYZE)
This program performs out-of-range tests for each parameter defined in a QA file. The Lower/Upper Bound Test uses the lower and upper bounds specified to define out-of-range parameter values. A Below or Above message is printed on the report for any out-of-range value.
For the N-Sigma, Sample Driven, User Defined Mean and Bias Tests, points falling outside the investigation level but within the action level are tagged with an Investigate message on the report. Points falling outside the action level are tagged with an Action message on the report.
Two reports can be generated by QAANALYZE. The Last Report determines whether each parameter in the last results record is in range. The report itself has a single line for each monitorable parameter which shows its value and an out-of-range message if applicable. The Full Report analyzes all QA results records for a specified parameter.
QUALITY ASSURANCE PLOT (QAPLOT)
This program generates a plot, otherwise known as a control chart, which shows the value of a parameter versus run number (i.e., time). Horizontal lines indicating out-of-range data points are also plotted. Out-of-range points are determined either by the Lower/Upper Bound Test or the N-Sigma Investigation/Action Level Test described above. Hard copy plots can be output to compatible printer, and plotters supporting Sixel, HP-PCL, Epson and HPGL graphics languages if plotter software is installed.
Control Chart
DEC, VT, Motif, X Windows and X and HP are registered trademarks of their respective owners.
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Note to our International Customers: If you would like a quote on this product, please contact your Local Sales Office for assistance. |
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| Models | Description | |
| 480206LL | VMS Detector QA Software - Unlimited Use License - AXP | |
| 480206AS | VMS Detector QA Software Support - 1 Yr | |