Assessment of CBCT-based synthetic CT generation accuracy for adaptive radiotherapy planning.

PURPOSE: Cone-beam CT (CBCT)-based synthetic CT (sCT) dose calculation has the potential to make the adaptive radiotherapy (ART) pathway more efficient while removing subjectivity. This study assessed four sCT generation methods using 15 head-and-neck rescanned ART patients. Each patient's planning CT (pCT), rescan CT (rCT), and CBCT post-rCT was acquired with the CBCT deformably registered to the rCT (dCBCT). METHODS: The four methods investigated were as follows: method 1-deformably registering the pCT to the dCBCT. Method 2-assigning six mass density values to the dCBCT. Method 3-iteratively removing artifacts and correcting the dCBCT Hounsfield units (HU). Method 4-using a cycle general adversarial network machine learning model (trained with 45 paired pCT and CBCT). Treatment plans were created on the rCT and recalculated on each sCT. Planning target volume (PTV) and organ-at-risk (OAR) structures were contoured by clinicians on the rCT (high-dose PTV, low-dose PTV, spinal canal, larynx, brainstem, and parotids) to allow the assessment of dose-volume histogram statistics at clinically relevant points. RESULTS: The HU mean absolute error (MAE) and minimum dose gamma index pass rate (2%/2 mm) were calculated, and the generation time was measured for 15 patients using the rCT as the comparator. For methods 1-4 the MAE, gamma index analysis, and generation time were as follows: 59.7 HU, 100.0%, and 143 s; 164.2 HU, 95.2%, and 232 s; 75.7 HU, 99.9%, and 153 s; and 79.4 HU, 99.8%, and 112 s, respectively. Dose differences for PTVs and OARs were all <0.3 Gy except for method 2 (<0.5 Gy). CONCLUSION: All methods were considered clinically viable. The machine learning method was found to be most suitable for clinical implementation due to its high dosimetric accuracy and short generation time. Further investigation is required for larger anatomical changes between the CBCT and pCT and for other anatomical sites.

Quality of recovery assessment of day case and multiday stay patients undergoing elective laparoscopic cholecystectomy.

Objectives: Many laparoscopic cholecystectomy operations are performed with at least overnight admission. Current research shows that laparoscopic cholecystectomy is safe and feasible to do as a day case. Patient centred outcomes are less well understood. Material and Methods: Elective laparoscopic cholecystectomy patients at a single metropolitan hospital in Melbourne, Australia were surveyed 24 hours after surgery using the 15-question Quality of Recovery (QoR-15) survey. A comparison was made between day case surgeries and multi-day surgeries. Results: One hundred and eight patients were recruited consisting of 34 day case and 74 multi-day patients. Patient groups did not differ in terms of age, sex or postoperative morbidity. The multi-day group had a higher proportion of comorbid patients (p-value = 0.03). There was no significant dif- ference in overall QoR-15 score between the two groups, although there was an observed trend towards a higher score in the day case group (132.0 vs 127.9, p= 0.147). QoR-15 individual question results showed that day cases rated significantly better for sleep quality and for less feelings of anxiety or worry. The differences narrowed when comparing patient groups as they were booked (intention-to-treat). There were no identified sub-groups that had a significantly higher score if admitted multi-day. Conclusion: Quality of recovery following day case laparoscopic cholecystectomy is just as good, if not better, than multi-day cases. Laparoscopic cholecystectomy as a day case is both safe and economically superior to multi-day management. This gives further weight to current recommendations suggesting that the majority of laparoscopic cholecystectomy operations could be performed as day cases.

Identification of Cytauxzoon felis antigens via protein microarray and assessment of expression library immunization against cytauxzoonosis.

BACKGROUND: Cytauxzoonosis is a disease of felids in North America caused by the tick-transmitted apicomplexan parasite Cytauxzoon felis. Cytauxzoonosis is particularly virulent for domestic cats, but no vaccine currently exists. The parasite cannot be cultivated in vitro, presenting a significant limitation for vaccine development. METHODS: Recent sequencing of the C. felis genome has identified over 4300 putative protein-encoding genes. From this pool we constructed a protein microarray containing 673 putative C. felis proteins. This microarray was probed with sera from C. felis-infected and naïve cats to identify differentially reactive antigens which were incorporated into two expression library vaccines, one polyvalent and one monovalent. We assessed the efficacy of these vaccines to prevent of infection and/or disease in a tick-challenge model. RESULTS: Probing of the protein microarray resulted in identification of 30 differentially reactive C. felis antigens that were incorporated into the two expression library vaccines. However, expression library immunization failed to prevent infection or disease in cats challenged with C. felis. CONCLUSIONS: Protein microarray facilitated high-throughput identification of novel antigens, substantially increasing the pool of characterized C. felis antigens. These antigens should be considered for development of C. felis vaccines, diagnostics, and therapeutics.

'Weather Value at Risk': A uniform approach to describe and compare sectoral income risks from climate change.

We extend the concept of 'Weather Value at Risk' - initially introduced to measure the economic risks resulting from current weather fluctuations - to describe and compare sectoral income risks from climate change. This is illustrated using the examples of wheat cultivation and summer tourism in (parts of) Sardinia. Based on climate scenario data from four different regional climate models we study the change in the risk of weather-related income losses between some reference (1971-2000) and some future (2041-2070) period. Results from both examples suggest an increase in weather-related risks of income losses due to climate change, which is somewhat more pronounced for summer tourism. Nevertheless, income from wheat cultivation is at much higher risk of weather-related losses than income from summer tourism, both under reference and future climatic conditions. A weather-induced loss of at least 5% - compared to the income associated with average reference weather conditions - shows a 40% (80%) probability of occurrence in the case of wheat cultivation, but only a 0.4% (16%) probability of occurrence in the case of summer tourism, given reference (future) climatic conditions. Whereas in the agricultural example increases in the weather-related income risks mainly result from an overall decrease in average wheat yields, the heightened risk in the tourism example stems mostly from a change in the weather-induced variability of tourism incomes. With the extended 'Weather Value at Risk' concept being able to capture both, impacts from changes in the mean and the variability of the climate, it is a powerful tool for presenting and disseminating the results of climate change impact assessments. Due to its flexibility, the concept can be applied to any economic sector and therefore provides a valuable tool for cross-sectoral comparisons of climate change impacts, but also for the assessment of the costs and benefits of adaptation measures.

Role of graduate mental health workers within primary care.

The concept of primary healthcare graduate mental health workers came into being following the implementation of The NHS Plan (Department of Health, 2000) and the National Service Framework for Mental Health (DH, 1999). It is now generally agreed that service users must be consulted in order to fully understand and judge the effectiveness of this new role. It is this knowledge that can then position precisely where this new role will fit within the NHS's mental health organisational structure.

Adverse health-care events: Part 4. Challenge of a blame-free culture.

This, the final paper in this series analysing the significance of adverse health-care events and near-miss reporting, explores the requirement of a shift towards a 'blame-free' culture and the potential contribution such a change could bring to health care in terms of reducing risk for patients. Barriers to achieving a blame-free, or 'blame-fair', culture are also examined.

Adverse health-care events: Part 2. Incident reporting systems.

This paper, the second in a series of four on adverse health events, outlines the process for reporting, investigating and learning from clinical incidents. It outlines the nursing contribution and nurses' responsibility with regards to effective clinical risk management in order to achieve a major cornerstone of clinical governance--making the NHS safer for patients.

Adverse health-care events: Part 1. The nature of the problem.

Adverse events are a significant cause of unnecessary harm in health care and can lead to both physical and psychological injury and, in some cases, death. This paper, the first in a series of four, outlines the nature and extent of the problem. The overall aim of the series is to enhance knowledge levels among nurses in an attempt to reduce the number of adverse events.