PurposeThe purpose of this guideline is to provide a list of critical performance tests in order to assist the Qualified Medical Physicist (QMP) in establishing and maintaining a safe and effective quality assurance (QA) program. The performance tests on a linear accelerator (linac) should be selected to fit the clinical patterns of use of the accelerator and care should be given to perform tests which are relevant to detecting errors related to the specific use of the accelerator.MethodsA risk assessment was performed on tests from current task group reports on linac QA to highlight those tests that are most effective at maintaining safety and quality for the patient. Recommendations are made on the acquisition of reference or baseline data, the establishment of machine isocenter on a routine basis, basing performance tests on clinical use of the linac, working with vendors to establish QA tests and performing tests after maintenance.ResultsThe recommended tests proposed in this guideline were chosen based on the results from the risk analysis and the consensus of the guideline's committee. The tests are grouped together by class of test (e.g., dosimetry, mechanical, etc.) and clinical parameter tested. Implementation notes are included for each test so that the QMP can understand the overall goal of each test.ConclusionThis guideline will assist the QMP in developing a comprehensive QA program for linacs in the external beam radiation therapy setting. The committee sought to prioritize tests by their implication on quality and patient safety. The QMP is ultimately responsible for implementing appropriate tests. In the spirit of the report from American Association of Physicists in Medicine Task Group 100, individual institutions are encouraged to analyze the risks involved in their own clinical practice and determine which performance tests are relevant in their own radiotherapy clinics.

Aust. 1. BioI. Sci. 1987, 40, 365-77 Fetal and placental growth, and fetal and maternal urea synthesis in late gestation, were studied in 2-yearold Corriedale ewes on a maintenance ration (M) except when subjected to moderate dietary restriction from day 50 to day 100 (RM), day 100 to day 135 (MR) or day 50 to day 135 (RR). In comparison with fetuses of ewes maintained throughout the experiment (MM), RR fetuses were smaller and RM fetuses were larger whereas MR fetuses were unaffected; all restrictions were associated with increased placental size. Fetal urea synthesis at day 133 in the well-nourished ewes (MM) was 21.5 mg N h-i kg-i increasing to, respectively, 25.7, 27.3 and 38.8 mg N h-i kg-i in groups MR, RM and RR; these values were 1.6, 3.9,2.2 and 3.8 times the maternal rates of synthesis. On the basis of the observed urea synthesis rates, amino acid oxidation could have accounted for up to, respectively, 32, 38, 40 and 571110 of fetal oxygen consumption in groups MM, MR, RM and RR. Amino acids, in addition to their role in tissue accretion, may be key energy substrates for the fetus.

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The rates of passage of solutes, microbes and particulate matter were measured at different stages of gestation in multiparous Corriedale ewes. The mean retention times (MRT) of each of these constituents in the rumen decreased as gestation progressed. There was an increase in the MRT of digesta distal to the stomach which was sufficient to compensate for the decrease in solute MRT in the rumen. Thus, for the whole tract, only the MRT of particulate matter decreased during gestation. There were good relationships between the rate of passage from the rumen of microbes and of particulate matter and that of water, reflecting the importance of water as the vehicle for passage from the rumen. The fractional outflow rate of the particle-associated marker 103Ru-phen was greater than the net value for microbes, but was similar to the calculated value for non-microbial, non-ammonia nitrogen. The proportion of the rumen microbial population that was free-floating declined to a minimum of 0.18 as the fractional outflow rate of water increased. A peristaltic activity index showed a tendency to decline, particularly in the duodenum, as gestation progressed.

The value of the urinary dipstick in the assessment of proteinuria was investigated in a study correlating laboratory measurements of protein and albumin against the dipstick protein in the same samples of urine; 94 patients (100 admissions) were studied at the Royal Air Force Renal Unit, each patient collecting two 24-h urine samples. Along with each 24-h sample, 10-ml aliquots of urine were obtained at 3 designated times during the day for both ward dipstick testing and laboratory assay; + or more on the dipstick correlated with abnormal proteinuria (greater than or equal to 150 mg/24 h) in 88% of cases, whilst trace values straddled the level of significant proteinuria. Further differentiation of trace was possible by repeat testing during the day. The subsequent presence of a dipstick negative during that day correlated with normality in all but 5% of cases. In order to ensure detection of renal disease presenting as isolated orthostatic proteinuria, assay of the mid-morning sample is recommended.