Optimizing geometric accuracy of four-dimensional CT scans acquired using the wall- and couch-mounted Varian® Real-time Position Management™ camera systems.

OBJECTIVE: The aim of this study was to identify sources of anatomical misrepresentation owing to the location of camera mounting, tumour motion velocity and image processing artefacts in order to optimize the four-dimensional CT (4DCT) scan protocol and improve geometrical-temporal accuracy. METHODS: A phantom with an imaging insert was driven with a sinusoidal superior-inferior motion of varying amplitude and period for 4DCT scanning. The length of a high-density cube within the insert was measured using treatment planning software to determine the accuracy of its spatial representation. Scan parameters were varied, including the tube rotation period and the cine time between reconstructed images. A CT image quality phantom was used to measure various image quality signatures under the scan parameters tested. RESULTS: No significant difference in spatial accuracy was found for 4DCT scans carried out using the wall- or couch-mounted camera for sinusoidal target motion. Greater spatial accuracy was found for 4DCT scans carried out using a tube rotation speed of 0.5 s rather than 1.0 s. The reduction in image quality when using a faster rotation speed was not enough to require an increase in patient dose. CONCLUSION: The 4DCT accuracy may be increased by optimizing scan parameters, including choosing faster tube rotation speeds. Peak misidentification in the recorded breathing trace may lead to spatial artefacts, and this risk can be reduced by using a couch-mounted infrared camera. ADVANCES IN KNOWLEDGE: This study explicitly shows that 4DCT scan accuracy is improved by scanning with a faster CT tube rotation speed.

Improvement in clinical step and shoot intensity modulated radiation therapy delivery accuracy on an integrated linear accelerator control system.

PURPOSE: The dose delivery accuracy of 30 clinical step and shoot intensity modulated radiation therapy plans was investigated using the single integrated multileaf collimator controller of the Varian Truebeam linear accelerator (linac) (Varian Medical Systems, Palo Alto, CA) and compared with the dose delivery accuracy on a previous generation Varian 2100CD C-Series linac. METHODS AND MATERIALS: Ten prostate, 10 prostate and pelvic node, and 10 head-and-neck cases were investigated in this study. Dose delivery accuracy on each linac was assessed using Farmer ionization chamber point dose measurements, 2-dimensional planar ionization chamber array measurements, and the corresponding Varian dynamic log files. Absolute point dose measurements, fluence delivery accuracy, leaf position accuracy, and the overshoot effect were assessed for each plan. RESULTS: Absolute point dose delivery accuracy increased by 1.5% on the Truebeam compared with the 2100CD linac. No improvement in fluence delivery accuracy between the linacs, at a gamma criterion of 3%/3 mm was measured using the 2-dimensional ionization chamber array, with median (interquartile range) gamma passing rates of 98.99% (97.70%-99.72%) and 99.28% (98.26%-99.75%) for the Truebeam and 2100CD linacs, respectively. Varian log files also showed no improvement in fluence delivery between the linacs at 3%/3 mm, with median gamma passing rates of 99.97% (99.93%-99.99%) and 99.98% (99.94%-100%) for the Truebeam and 2100CD linacs, respectively. However, log files revealed improved leaf position accuracy and fluence delivery at 1%/1 mm criterion on the Truebeam (99.87%; 99.78%-99.94%) compared with the 2100CD linac (97.87%; 91.93%-99.49%). The overshoot effect, characterized on the 2100CD linac, was not observed on the Truebeam. CONCLUSIONS: The integrated multileaf collimator controller on the Varian Truebeam improves clinical treatment delivery accuracy of step and shoot intensity modulated radiation therapy fields compared with delivery on a Varian C-series linac.

The behavioural outcomes of quality improvement teams: the role of team success and team identification.

This study investigates the relationship between hospital quality improvement (QI) team success and changes in empowerment, 'organizational commitment, organizational citizenship behaviour' (OCB) and job behaviour related to QI. Data were collected from administrative staff, healthcare professionals and support staff from four community hospitals. The study involved a field investigation with two data collection points. Structured questionnaires and interviews with hospital management were used to collect data on the study variables. High scores were observed for organizational commitment, OCB and job behaviour related to QI when individuals identified with teams that were successful. Low scores were observed when individuals identified with teams that were unsuccessful. Empowerment was positively related to job behaviour associated with QI. It is concluded that participation on QI teams can lead to organizational learning, resulting in the inculcation of positive 'extra-role' and 'in-role' job behaviour.

Fatigue in women with breast cancer receiving radiation therapy.

Fatigue is a common complaint of individuals receiving treatment for cancer. There is a dearth of rigorous research investigating the clinical course and prognosis of fatigue over the course of radiation therapy. Seventy six patients with breast cancer receiving external radiation therapy were followed longitudinally from the onset of treatment to 6 months post-treatment. Fatigue significantly increased over the course of treatment, was highest at the last week of treatment, and returned to pretreatment levels by 3 months after treatment. Fatigue was not influenced by the patient's age, stage of disease, time since surgery, weight, and length of time since diagnosis. Fatigue was significantly related to symptom distress, psychologic distress, and self-reported fatigue relief strategies. The most frequently reported self-relief strategies were "sit" and "sleep." Fatigue had a negative impact on the patient's quality of life. Impairment in quality of life was evident by the end of treatment, with improvement by 3 and 6 months after treatment. The second week through to the last week of radiation therapy are critical times to target interventions for the management of fatigue. The amelioration of concomitant symptoms is a supportive approach that might be helpful. Self-help strategies focusing on the cessation of activity and increasing rest were reported as successful by patients.

Job satisfaction and turnover among nurses: integrating research findings across studies.

A meta-analytic study investigated the causal relationships among job satisfaction, behavioral intentions, and nurse turnover behavior. A theoretical model was proposed in which behavioral intentions were viewed as a direct antecedent to turnover behavior. Job satisfaction was expected to be indirectly related to turnover by virtue of the mediating role of behavioral intentions. Consistent with these expectations, a strong positive relationship was indicated between behavioral intentions and turnover; a strong negative relationship between job satisfaction and behavioral intentions; and a small negative relationship between job satisfaction and turnover. The results of the modifier analysis suggested that effect sizes are fairly robust to differences in study designs, response rates, and methods of measuring job satisfaction, but the manner in which behavioral intentions were operationalized appeared to moderate the relationship between behavioral intentions and turnover and job satisfaction. Of variables related to nursing job satisfaction, work content and work environment had a stronger relationship with job satisfaction than economic or individual difference variables.

A critical appraisal of the research literature investigating fatigue in the individual with cancer.

Fatigue is a commonly experienced symptom, which may be a component of virtually any disease and can have a psychological, physical, or mixed origin. Nurses need to understand the onset, duration, and progression of fatigue to intervene successfully with the cancer patient adapting to diagnosis and treatment. While the literature is an important source of information, results of research studies must be critically interpreted before proceeding with practice guidelines based on research findings. A critical appraisal of the research literature investigating the problem of fatigue in individuals with cancer was conducted. There is strong evidence to suggest that fatigue is a prevalent problem among cancer patients receiving chemotherapy and radiation therapy. However past research has been limited by methodological problems. Typically, studies fail to include a control group, do not control for possible confounding variables, and have restricted measurement to unidimensional scales with limited reliability and validity. While several correlates of fatigue have been postulated, research to date has found no consistent relationships among such correlates as weight loss, anemia, or psychological distress. This article reviews what is currently known about fatigue in the cancer patient and how future research could be designed to improve on past measurement and sampling problems.

Rapid separation of milk whey proteins by anion exchange chromatography.

A fast protein liquid chromatography system was used to fractionate the major proteins of sweet and acid wheys. Fifty to 500 microliter of whey were fractionated with a stepwise ionic strength gradient using water (buffer A) and increasing concentrations of .7 M sodium acetate (buffer B). Six well-resolved peaks were obtained: 1) amino acids (tentative identification), 2) low molecular weight peptides (tentative identification), 3) highly enriched alpha-lactalbumin, 4) highly enriched serum albumin 5) electrophoretically pure beta-lactoglobulin B, and electrophoretically pure beta-lactoglobulin A. A poor baseline or unresolved peaks resulted when .02 M bis-tris or .02 M histidine was used for buffer A and .7 M sodium acetate in .02 M bis-tris or histidine was used for buffer B. When sodium chloride was used in place of sodium acetate, beta-lactoglobulins A and B were poorly resolved. The column was cleaned after each run by injecting 2 ml of the following reagents: glacial acetic acid, 2 N sodium chloride, 2 N sodium hydroxide, 2 N sodium chloride, 2% detergent, and 100% acetonitrile. Time required to run each sample including column cleanup was 40 min.

Source and Persistence of Salmonella muenster in Naturally Contaminated Cheddar Cheese.

Public health authorities in Oxford, Middlesex and Elgin Counties, Ontario, seized raw milk Cheddar cheese due to presence of Salmonella muenster . Investigations by these units and the University of Guelph traced the source of Salmonella to one particular milk supplier shipping to a cheese factory. Analysis of milk samples from a herd of 35 cattle revealed only one cow shedding S. muenster directly into the milk (ca. 200 CFU/ml). Eleven of 181 vats of cheese, produced at the factory between May and October 1982, were positive for Salmonella at the curd stage. Only 2 vats of the finished raw milk Cheddar, however, were positive. One lot of Salmonella -positive cheese was still positive after the legally required 60-d holding period and remained so for 125 d.

Nitrates and N-Nitrosamines in Cheese.

Use of nitrate in the manufacture of certain cheeses is sometimes questioned because of its potential involvement in formation of N-nitrosamines. Unlike cured meats, there was not much information available, until recently, regarding the presence of N-nitrosamines in cheese and other dairy products. This paper briefly reviews the mechanism of formation of such compounds in foods and discusses the necessity of selective and sensitive methods of analysis. Factors which may possibly influence formation of N-nitrosamines in cheese as well as further areas of research are also discussed.