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Aim: VARSKIN provides a convenient way of calculating skin dose from predefined geometries but the models are limited to concentric shapes such as discs, cylinders and point sources. The aim of this article is to use the Geant4 Monte Carlo code to independently compare the cylindrical geometries available in VARSKIN to more realistic droplet models obtained from photography. It may then be possible to recommend an appropriate cylinder model that can be used to represent a droplet within acceptable accuracy., Method: Geant4 Monte Carlo code was used to model various droplets of radioactive liquid on the skin based on photographs. The dose rates were then calculated to the sensitive basal layer 70 µm beneath the surface for three droplet volumes (10, 30 and 50 µl) and 26 radionuclides. The dose rates from the cylinder models were then compared against the dose rates from the 'true' droplet models., Results: The table gives the optimum cylinder dimensions that best approximate a true droplet shape for each volume. The mean bias and 95% confidence interval (CI) from the true droplet model are also quoted., Conclusion: The evidence from the Monte Carlo data suggests that different droplet volumes require different cylinder aspect ratios to approximate the true droplet shape. Using the cylinder dimensions in the table in software packages such as VARSKIN, dose rates from radioactive skin contamination are expected to be within ± 7.4% of a 'true' droplet model at 95% CI., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Aim: There is increasing interest in using collimated gamma cameras for [75Se]tauroselcholic acid (SeHCAT) studies to image the distribution and to make use of the collimator pressure sensitive devices (PSD) for patient safety. However, the use of a collimator will substantially decrease the sensitivity of the gamma camera. The aim of this article is to enable departments to calculate the uncertainty of SeHCAT retention measurements so that the acquisition time can be optimised to perform a reliable SeHCAT study., Method: We derive a mathematical equation from the first principles that can be used to calculate the uncertainty in SeHCAT retention measurements on the basis of Poisson counting statistics. The equation takes account of background subtraction, use of the geometric mean for anterior/posterior attenuation compensation and the day 7 to day 0 quotient calculation., Results: Uncertainties in SeHCAT retention measurement using an intrinsic (uncollimated) gamma camera counting for 100 s are very low, typically of the order 15 ± 0.1%. Uncertainties from collimated gamma camera counting significantly increase for the same 100 s counting duration: 15 ± 0.8% for slim patients and 15 ± 4% for obese patients., Conclusion: The acquisition time must be increased for collimated gamma camera SeHCAT counting to achieve acceptable counting statistics for an acceptable total uncertainty in the SeHCAT retention measurement. For slim patients, a minimum counting time of 2 min is required. For larger patients, the acquisition time needs to be increased to 30 min and further increased to 50 min for obese patients., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Aim: A recent audit has highlighted that there is a large variation in the way gastric emptying scintigraphy is performed, analysed and reported in the UK. In this study, we have established a comprehensive protocol on how to perform gastric emptying including normal ranges for two of the most widely used meals. A standardized scrambled egg sandwich was used as the main meal. Normal ranges were also established for oat porridge as an alternative gluten-free meal. We have calculated normal ranges for several functional parameters which may be used to assess gastric emptying. We hope that establishing a reliable normal range for these two simple and commonly used meals will encourage adoption of a universally accepted protocol for measurement of solid gastric emptying in the UK., Method: A total of 42 volunteers (20 male, 22 female, age range 22-68) with no history of gastrointestinal symptoms or diabetes were studied. Each volunteer fasted overnight and consumed two meals with similar nutritional composition on two separate days: scrambled eggs with two slices of bread were consumed on one day and gluten-free porridge (40 g in 200 mL whole milk) was consumed on a different day. Each meal was radiolabelled with 10 MBq of Tc-DTPA. Simultaneous anterior-posterior 2-min static images were acquired with the patient standing between the gamma camera detectors. Images were acquired every 5 min over a 2 hour period, followed by a single image at 3 hour. The data were modelled using a power-exponential function that allowed measurements of gastric emptying functional parameters including lag time, half-emptying time (HET), peak emptying rate, time-to-peak emptying (TPE) and exponential half-life (EHL). Three-hour retention was also calculated. Paired t-tests were used to compare the two meals and two-sample t-tests were used to assess gender-related differences. Regression analysis was used to assess correlation of the functional parameters with age and body habitus (body surface area, BSA)., Results: All gastric emptying functional parameters were significantly different between the two meals (P < 0.001). The normal range for lag time was 0-13 min for porridge and 1-34 min for scrambled egg. The normal range for HET was 18-73 min for porridge and 44-116 min for scrambled egg. The normal range for EHL was 21-57 min for porridge and 20-82 min for scrambled egg. The normal range for 3 hour retention was <7% for porridge and <17% for scrambled egg. Only weak significance was found for gender-related differences in gastric function for the two meals (0.05 < P < 0.10). Weak correlation was also observed for some functional parameters when plotted against age and BSA (0.05 < P < 0.10)., Conclusion: We have established gastric emptying normal ranges for the two most commonly used meals in the UK. The normal ranges are meal specific and not interchangeable, with porridge showing significantly faster transit than scrambled egg for all measured parameters. Scrambled egg sandwich is the recommended meal for solid gastric emptying studies as it is more reproducible and more comparable to a normally consumed solid meal for our population. Porridge would be a suitable alternative for patients who are unable to eat egg sandwiches, for example, patients with egg allergy or gluten intolerance.

This guidance document is a brief consensus document covering the range and breadth of nuclear medicine practice in the UK, and identifies a few steps individual nuclear medicine practitioners and departments can take in the best interests of their patients. This guidance document should be used to inform local practice and does not replace local Trust policies or any relevant legislation. At all times, the best interests of the patients should be paramount. Please read this guidance in conjunction with previous editorial (COVID-19- Nuclear Medicine Departments, be prepared! by Huang HL, Allie R, Gnanasegaran G, Bomanji. J Nucl Med Commun 2020; 41:297-299). Although some aspects of this guidance are time-sensitive due to the nature of the global emergency, we believe that there is still sufficient information to provide some key guiding principles.

Study Design: Retrospective cohort study of the American College of Surgeons National Surgical Quality Improvement Program database from 2011 to 2012., Objective: Minimizing the morbidity of posterior cervical fusion can be improved with identification of patient risk factors., Summary of Background Data: Posterior cervical fusion is an effective technique for treating a variety of pathology. Stability and neurological improvement have been well documented. The increasing frequency of these procedures necessitates further investigation into the factors that may negatively impact perioperative care., Methods: The American College of Surgeons National Surgical Quality Improvement Program was queried for all patients undergoing posterior cervical fusion in 2011 and 2012. Preoperative and intraoperative variables were investigated for correlation to complications, readmissions, prolonged intubation, reintubation, and reoperation. A frailty-based score was used to assess preoperative risk. Regression models for prediction were performed., Results: The study identified 5627 patients of posterior cervical fusion in 2011 and 2012. Of these, 2029 patients (36.1%) had any of our identified complications. Transfusion was the most common in 1482 (26.3%) patients. Excluding transfusion, the complication rate was 9.8%. Prolonged intubation greater than 48 hours occurred in 83 (1.5%) patients. Reintubation occurred in 72 (1.3%) patients. Readmission occurred in 398 (7.8%) patients. Reoperation was necessary in 273 (4.9%) patients with postoperative infection being the most common reason. The frailty-based score was shown to be predictive of any of the above events (P < 0.0001). The majority of patients (54.9%) in the group that had complications was found to have a frailty score of 1 or higher., Conclusion: The predictors for any event included female sex, increased surgical time, combined anterior-posterior procedures, preoperative inpatient status, diabetes, smoking, American Society of Anesthesiologists class 3 or higher, and increasing age. The frailty-based score is a viable option to predict morbidity in posterior cervical fusion.Level of Evidence: 3., (Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.)

TauroH-23-((75)Se)selena-25-homocholic acid (SeHCAT) retention has been used for the diagnosis of bile acid malabsorption since the early 1980s. Bile acid malabsorption has been increasingly recognized as an important cause of severe chronic diarroea with subsequent increase in the number of referrals for the SeHCAT test. In this study, we review and discuss the standard techniques for the measurement of SeHCAT retention and describe a simple and modified technique using a noncollimated whole-body scanner, suitable for most modern dual-headed cameras.

Background: In this study, we have investigated the feasibility of a 180 degrees DaTSCAN brain SPECT acquisition. This technique has the advantage of being 'open view' for the patient and therefore more acceptable for claustrophobic patients. It also enables easier access for a technologist to hold the patient's head during acquisition to reduce movement in confused patients or in those with severe tremor., Methods: In the first part of this study, we validated the practicality and image quality of a 180 degrees acquisition using a DaTSCAN Alderson head phantom with different camera configurations on GE Infinia and Philips AXIS gamma cameras. The effect on image quality of using half the acquisition time was also assessed. In the second part of the study, 50 sets of patient data were reprocessed by reconstructing half of the 360 degrees data to mimic a single-head 180 degrees acquisition. The 180 degrees images were then compared with 360 degrees images for the same patient using a visual score system. The effect of half-time 180 degrees data acquisition on quantification was also assessed using GE QuantiSPECT software., Results: All phantom images from 180 degrees acquisitions contained some degree of distortion at the periphery, but clearly retain the presence of centrally positioned caudate and putamen; hence 180 degrees acquisitions were deemed to produce clinically useful diagnostic images. The shorter (half) acquisition time leads to noisier but acceptable images for all configurations. In the patient study, there was complete agreement between the two reporters with no clinical difference in the diagnostic accuracy between the 180 degrees and 360 degrees images. However, 6 of 50 180 degrees images were marked as poor quality but reportable, compared with 0 of 50 in 360 degrees images. Quantification gave consistently lower nuclei to background ratio values for 180 degrees compared with 360 degrees for normal and abnormal patients., Conclusion: It is possible to obtain diagnostic DaTSCAN images using 180 degrees acquisition in difficult patients. The total length of the study may also be shortened by half using L-mode or V-mode camera head configuration.

Study Design: An imaging study assessing agreement between computed tomographic (CT) scans and plain radiographs when measuring acute thoracolumbar spinal deformity., Objective: To compare the ability of the screening CT scans to measure spinal deformity in the thoracolumbar spine with that of portable plain radiographs., Summary of Background Data: At the time of arrival at many trauma centers, patients undergo screening whole body CT as the initial imaging evaluation for trauma. The thoracolumbar spine is well visualized on both coronal and sagittal reconstructions., Methods: Images of patients who underwent screening CT and portable supine plain radiography of thoracolumbar fractures were reviewed. Four observers, at 2 separate times, measured pathologic kyphosis and scoliosis on each image by using the Cobb method. Data were analyzed for statistical differences., Results: In the sagittal plane, screening CT scans and plain radiographs showed an average mean difference of -1.13 degrees+/-SD of 3.76 degrees. In the coronal plane, CT scans and radiographs showed an average mean difference of 0.10 degrees+/-SD of 2.52 degrees. The interobserver correlation coefficients among the 4 observers were 0.913 in the sagittal plane and 0.953 in the lateral plane, indicating excellent interobserver correlation., Conclusions: Screening CT demonstrates excellent correlation with plain radiography for measuring thoracolumbar spinal deformity in the coronal and sagittal planes for patients with trauma.