Optimizing dual energy cone beam CT protocols for preclinical imaging and radiation research

Objective: The aim of this work was to investigate whether quantitative dual-energy CT (DECT) imaging is feasible for small animal irradiators with an integrated cone-beam CT (CBCT) system. Methods: The optimal imaging protocols were determined by analyzing different energy combinations and dose levels. The influence of beam hardening effects and the performance of a beam hardening correction (BHC) were investigated. In addition, two systems from different manufacturers were compared in terms of errors in the extracted effective atomic numbers (Z(eff)) and relative electron densities (rho(e)) for phantom inserts with known elemental compositions and relative electron densities. Results: The optimal energy combination was determined to be 50 and 90kVp. For this combination, Z(eff) and r rho(e) can be extracted with a mean error of 0.11 and 0.010, respectively, at a dose level of 60cGy. Conclusion: Quantitative DECT imaging is feasible for small animal irradiators with an integrated CBCT system. To obtain the best results, optimizing the imaging protocols is required. Well-separated X-ray spectra and a sufficient dose level should be used to minimize the error and noise for Z(eff) and rho(e). When no BHC is applied in the image reconstruction, the size of the calibration phantom should match the size of the imaged object to limit the influence of beam hardening effects. No significant differences in Z(eff) and rho(e) errors are observed between the two systems from different manufacturers. Advances in knowledge: This is the first study that investigates quantitative DECT imaging for small animal irradiators with an integrated CBCT system

The mapping of emotions in a respiratory illness: transferability of illness experience from Pulmonary Arterial Hypertension to COVID-19

Objectives: Covid-19 poses an existential threat that has increased death anxiety at the individual and societal levels. In prior work, we have examined existential conversations in patients with Pulmonary Arterial Hypertension (PAH), an incurable respiratory disease with symptom overlap. In this mixed method study, we analyse the emotional qualities of these conversations in PAH. By understanding the emotions in PAH, we may learn something about the feelings that can also be evoked in people coping with Covid-19. Methods: We interviewed 30 PAH patients from 2016-2018 about the meaning and impact of illness on their lives. We analysed transcripts and audio recordings for heightened emotional moments and categorised the emotional responses and topics that were discussed. A multiple correspondence analysis was conducted to identify the associations between emotions and topics. Clini cal illustrations are provided for interpretation. Results: Mean age and illness duration was 52 and 6 years, and 77% were female. Participants had a mean of 5 emotional moments, each lasting on average 20 seconds. Half occurred in the first 20 minutes. Coping with diagnosis and the healthcare system was accompanied by feelings of shock and unfairness; relational issues involving close others evoked complicated feelings of isolation, worthlessness, and self-blame; and the experience of physical limitations and mortality salience elicited much anger and fear. Conclusion: People confronted by the threat of mortality from disease may have powerful feelings that they would benefit from sharing. These emotions are readily expressed because opportunities to discuss them are rare. Psychoeducation about illness experiences may help healthy people to relate to the medically ill and destigmatise the discussion of illness-related concerns. Research on coping with existential distress may be applied to the illness experience of Covid-19

Clinically important deep vein thrombosis in the intensive care unit: a survey of intensivists

INTRODUCTION: Outside the intensive care unit (ICU), clinically important deep vein thrombosis (DVT) is usually defined as a symptomatic event that leads to objective radiologic confirmation and subsequent treatment. The objective of the present survey is to identify the patient factors and radiologic features of lower limb DVT that intensivists consider more or less likely to make a DVT clinically important in ICU patients. METHODS: Our definition of clinically important DVT was a DVT likely to result in short-term or long-term morbidity or mortality if left untreated, as opposed to a DVT that is unlikely to have important consequences. We asked respondents to indicate the likelihood that patient factors and ultrasonographic features make a DVT clinically important using a five-point scale (from 1 = much less likely to 5 = much more likely). RESULTS: Of the 71 Canadian intensivists who responded, 70 (99%) rated three patient factors as most likely to make a DVT clinically important: clinical suspicion of pulmonary embolism (mean score 4.6), acute or chronic cardiopulmonary morbidity that might limit a patient's ability to tolerate pulmonary embolism (score 4.5), and leg symptoms (score 4.2). Of the ultrasound features, proximal (score 4.7), large (score 4.2), and totally occlusive (score 3.9) thrombi were considered the three most important. CONCLUSION: When labeling a DVT as clinically important, intensivists rely on different patient specific factors and thrombus characteristics than are used to assess the clinical importance of DVT outside the ICU. The clinical importance of DVT is influenced by unique factors such as cardiopulmonary reserve among mechanically ventilated patients

Critical care procedure logging using handheld computers

INTRODUCTION: We conducted this study to evaluate the feasibility of implementing an internet-linked handheld computer procedure logging system in a critical care training program. METHODS: Subspecialty trainees in the Interdepartmental Division of Critical Care at the University of Toronto received and were trained in the use of Palm handheld computers loaded with a customized program for logging critical care procedures. The procedures were entered into the handheld device using checkboxes and drop-down lists, and data were uploaded to a central database via the internet. To evaluate the feasibility of this system, we tracked the utilization of this data collection system. Benefits and disadvantages were assessed through surveys. RESULTS: All 11 trainees successfully uploaded data to the central database, but only six (55%) continued to upload data on a regular basis. The most common reason cited for not using the system pertained to initial technical problems with data uploading. From 1 July 2002 to 30 June 2003, a total of 914 procedures were logged. Significant variability was noted in the number of procedures logged by individual trainees (range 13–242). The database generated by regular users provided potentially useful information to the training program director regarding the scope and location of procedural training among the different rotations and hospitals. CONCLUSION: A handheld computer procedure logging system can be effectively used in a critical care training program. However, user acceptance was not uniform, and continued training and support are required to increase user acceptance. Such a procedure database may provide valuable information that may be used to optimize trainees' educational experience and to document clinical training experience for licensing and accreditation