Weekly Quality Control Tests

In the weekly protocol, system calibration and plane efficiency are performed by using a uniform standard phantom filled with radioactivity, and normalization is carried out by using a long-lived radionuclide rotating around the field of view or a standard phantom with radioactivity placed at the center of the scanner. 

System Calibration A system calibration scan is obtained by placing the standard phantom containing a positron emitter in a phantom holder at the center of the FOV for uniform attenuation and exposure. The reconstructed images are checked for any nonuniformity. A bad detector indicates a decreased activity in the image, and warrants the adjustment of PM tube voltage and the discriminator settings of PHA. 

CF is applied to the measured activity in the ROI of interest of the patient scan to calculate the absolute activity in the ROI that is used in the calculation of SUV. Note that if the radionuclide in the patient study is different from the calibration source radionuclide, the branching ratio Nof the radionuclide must be taken into calculation. This calibration of PET scanners should be performed at installation, after major service or at least annually. 

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Describe the methods of daily and weekly quality control tests for PET and CT scanners. 

The samples need to be brought to controlled test conditions before the test is carried out. If they were used as a quality control test, the product in many cases would be at the customer before the test was completed. A typical example is that tests such as the tensile tests require a week to settle down before the test is carried out after the 18-hour cure cycle. In many cases an approximate value is obtained by testing as soon as the sample has reached room temperature after it has had its full cure. 

In the image formation of an object using PET scanners, several parameters related to the scanners play a very important role. To ensure high quality of images, several quality control tests must be performed routinely on the scanner. The frequency of these tests is either daily or weekly, or even at a longer interval depending on the type of parameter to be evaluated. 

For accreditation, the ICANL requires physicians to be board-certified in Nuclear Medicine or in Radiology with special competency in nuclear medicine, whereas special competency in nuclear medicine is not required by ACR. While both standards mandates the quality control tests to be performed daily, weekly, monthly, or annually, ACR requires the presence of a medical physicist in the facility for monitoring the tests but the ICANL only recommends for such an individual. Technologists are required to be certified by ARRT (N) or NMTCB. Continuing education of specified hours is required for each professional category for continuation of accreditation. For detailed information, refer to http //www.acr.org and http //www.icanl.org. 

ATP is an ideal indicator of cell viability. Blood or blood cell concentrates prepared for transfusion are stored for periods of a few days to several weeks in the blood bank. Viability checking of the blood cells is necessary to avoid posttransfusional reactions [94], This quality control of the conserved red blood cells and platelets can easily be performed by measuring the ATP concentration as an expression of their integrity. By the same measurement it was possible to confirm the diagnosis and monitor the treatment effects in various cases of platelet disease [97], The possibility of determining cells viability can be exploited to examine more free cells or tissue, as in the spermatozoa viability test, based on the correlation between ATP content and mobility. 

There is no experimentally established optimum frequency for the distribution of samples. The minimum frequency is about four rounds per year. Tests that are less frequent than this are probably ineffective in reinforcing the need for maintaining quality standards or for following up marginally poor performance. A frequency of one round per month for any particular type of analysis is the maximum that is likely to be effective. Postal circulation of samples and results would usually impose a minimum of two weeks for a round to be completed and it is possible that over-frequent rounds have the effect of discouraging some laboratories from conducting their own routine quality control. The cost of proficiency testing schemes in terms of analysts time, cost of materials and interruptions to other work has also to be considered. 

It is also desirable to have predictive tests that are rapid and are grounded by benchmarking with older exposure-based tests. Rapid validated tests are necessary for quality control and lot release inspection. Often the results of such tests are needed within hours. Cabinet exposure testing that requires days or weeks is obviously impractical. 

Laboratory quality control schemes should be applied to guarantee consistent results of the adopted analytical procedure by testing the overall calibration procedure. The routine analyses of sea water CRMs are carried out in general, at least once per week (93, 94). Tables 5.1 and 5.3 show recent results obtained on the NASS 4 CRM by ICP-MS and DPASV measurements, respectively (93). 

The quality control (QC) tests discussed in Sections 10.5 and 11.2.9 are integral parts of QA designed to check results. Some QC measures are prompt indicators that warn of problem occurrence at the time of analysis others are delayed indicators that require backtracking to And when a problem first arose. Control charts for radiation detector operation are an example of a prompt indicator of reliability. Records of deviations from the norm in an analysis or a measurement may also be prompt indicators if immediately considered. Periodic blank, blind, and replicate analyses, especially interlaboratory comparisons, are delayed indicators for which results may not be available for days or weeks after a problem has arisen. Review and assessment of compiled data are delayed indicators of information quality. 

Jane has worked for three weeks straight on the same batch of samples all of the tested samples have met quality control standards. With a holiday weekend approaching, she decides to end her week early by entering similar results for untested samples. 

On the other hand, is it worth fighting for a change of the following well-known and accepted situation A deadline is fixed and therefore a vahdation must be finished in two weeks. Later, the burden of subsequent, substantial costs for a repeat of the measurements, complaints, out-of-spec situations, etc., which inevitably result because an analytical method can hardly be validated within two weeks under real conditions, is not placed on us but on quality control, and as testing costs they have been accepted since decades in the absence of overall considerations. The reader may imagine the consequences, or viewed more positively, the possibilities for improvement. 

As a commercial company that provides analytical services for the determination of radionuclides for a wide variety of clients, AMEC required a more accurate and reliable method to be developed. It needed to use relatively low hazard chemicals, have improved accuracy and precision and utilise common radiochemical analytical laboratory equipment such as liquid scintillation counters and gravity fed chromatography columns. In addition, the process must have realistic and commercially viable batch sizes, operator time and turnaround times, so that samples can be analysed in a cost-effective manner. Ideally the whole process for a batch of samples should not exceed more than one working week. As part of the validation process both internal and external quality control (QC) samples were used along with statistical tests, such as zeta (Q scores and student t-tests , to determine the accuracy of the improved method. In addition, elution profiles for iodine and chlorine and decontamination tests for potentially interfering radionuclides were also carried out in order to further validate the process. 

Quality control was maintained by both internal and external means. Frequent preparation and testing of aqueous and matrix-matched standards on a daily or weekly basis was used to assess changes in day-to-day precision and accuracy. External monitoring of laboratory performance was done via participation in the Center for Disease Control s (CDC) proficiency testing for PbB determinations. The laboratory s performance has been quite good over the range of PbB levels encountered in the CDC proficiency survey. Further evaluation was done using certified blood samples of known metal content, either from a commercial source (Kaulson Laboratories) or the NY State Health Department. 

When starting a new water treatment program, both baseline and operational information regarding levels of steam and condensate contamination generally are required. It may take several weeks of sampling work to fine-tune the program and determine any limitations with regard to steam purity and quality. Thereafter, individual control parameters such as sodium limits or antifoam concentration may need to be selectively raised or lowered in the BW and the effects tested for in the steam. 

Narcolepsy is a lifelong disorder without a known cure. At present, ideally, the goal is to control the symptoms to enable the affected individual to have a good quality of life. Patients with narcolepsy should be referred to a sleep specialist for evaluation and treatment. Regular retesting is recommended however, the patient needs to be medication free for a minimum of 2 weeks to facilitate repeat testing. 

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