A comparison of effective dose and risk for different collimation options used in AP shoulder radiography

INTRODUCTION

Radiography forms the cornerstone of the evaluation of shoulder disorders. While the benefits of radiography exceed the risks, there continues to be a compelling case for reduction of radiation exposure from diagnostic radiography. The aim of this project was to evaluate the radiation dose and risk for a variety of collimation settings used during anteroposterior (AP) shoulder radiography.

METHODS

This was a phantom based study where an ATOM adult dosimetry phantom was loaded with 272 thermoluminescent dosimeters (TLDs). Following loading, the phantom was setup for an AP shoulder X-ray projection with standard 25 × 30 cm rectangular collimation. The phantom was exposed three times and then the TLDs were removed and read. The experiment was repeated using a diamond shaped collimation and rectangular collimation with a minimum field of view to portray only relevant anatomy. Using the TLD dose measurements the effective doses and radiation risks were determined and compared.

RESULTS

As expected, organs neighbouring the shoulder experienced the highest absorbed doses (greater than 0.01 mGy); these organs included breast, lung and thyroid gland. The effective doses for standard rectangular, small rectangular and diamond collimation were 0.011, 0.008 and 0.016 mSv, respectively. When compared to standard collimation, a small field of view reduced effective dose by 27.3% and when moving to a diamond shape there was a 45.5% increase. The differences are likely driven by differences in the coverage of the radiosensitive lung and breast tissue.

CONCLUSION

By utilising a variety of different collimation settings, effective dose can be reduced. Reducing the radiation dose is both financially beneficial and results in a lower stochastic risk for patients. Image quality must also be considered when choosing different collimation settings. It stands to reason that by reducing the field size, dose will be reduced, and our study has served to quantify the effects in a practical situation.

IMPLICATIONS FOR PRACTICE

The utilisation of smaller/tight collimation is recommended as it offers the lowest dose when compared with other types of collimations. Although well-known this study serves to remind practitioners of the practical importance of collimation and is associated effect on effective dose and risk.

Habitual cold-water swimming and upper respiratory tract infection

It has long been claimed that non-wetsuit cold water swimming (CWS) benefits health (1), and anecdotally cold-water swimmers claimed to suffer fewer and milder infections, though this was not directly measured. A boost to immunity is biologically plausible: stress hormones are released during cold-water immersion (2), and short-term stress may ready the immune system for injury or infection (3). However, very few studies have investigated immune system markers and/or actual illness in habitual cold-water swimmers.

Contribution of the shear wave ultrasonic reflectometry to the stickiness measurements

Today, non-invasive quantification of the adhesion of a deposit to a surface is always a challenge and, unfortunately, few tools are available in this area. This is an obstacle, in several industrial processes, to the identification of conditions limiting the fouling and to the establishment of eco-efficient cleaning strategies. In this paper, a non-invasive ultrasonic technique was developed in the aim of characterizing the adhesion of viscoelastic fluids or solid deposited on a substrate. We adopted the idea that the more a deposit is difficult to clean the more adherent it is. From this point of view the value of the reflection coefficient of an ultrasonic shear wave informs us about the adhesion of the deposit on a surface. A large bibliography on the adhesion measurement is given. Then the principle of ultrasonic test is presented and cares required for the measurement of the reflection coefficient are widely discussed. The ultrasonic reflection coefficients obtained with different controlled samples covering a wide range of interfaces (liquid/substrate, solid/substrate) are presented and compared with other indicators of adhesion. All the data on various samples showed that the ultrasonic test is a tool to discriminate non-destructively a large range of interface quality, allowing ranking according to the adhesive strength.

Anatomical and neuromuscular variables strongly predict maximum knee extension torque in healthy men

PURPOSE

This study examined the relative influence of anatomical and neuromuscular variables on maximal isometric and concentric knee extensor torque and provided a comparative dataset for healthy young males.

METHODS

Quadriceps cross-sectional area (CSA) and fascicle length (l f) and angle (θ f) from the four quadriceps components; agonist (EMG:M) and antagonist muscle activity, and percent voluntary activation (%VA); patellar tendon moment arm distance (MA) and maximal voluntary isometric and concentric (60° s(-1)) torques, were measured in 56 men. Linear regression models predicting maximum torque were ranked using Akaike's Information Criterion (AICc), and Pearson's correlation coefficients assessed relationships between variables.

RESULTS

The best-fit models explained up to 72 % of the variance in maximal voluntary knee extension torque. The combination of 'CSA + θ f + EMG:M + %VA' best predicted maximum isometric torque (R (2) = 72 %, AICc weight = 0.38) and 'CSA + θ f + MA' (R (2) = 65 %, AICc weight = 0.21) best predicted maximum concentric torque.

CONCLUSION

Proximal quadriceps CSA was included in all models rather than the traditionally used mid-muscle CSA. Fascicle angle appeared consistently in all models despite its weak correlation with maximum torque in isolation, emphasising the importance of examining interactions among variables. While muscle activity was important for torque prediction in both contraction modes, MA only strongly influenced maximal concentric torque. These models identify the main sources of inter-individual differences strongly influencing maximal knee extension torque production in healthy men. The comparative dataset allows the identification of potential variables to target (i.e. weaknesses) in individuals.

An overview of internet biosurveillance

Internet biosurveillance utilizes unstructured data from diverse web-based sources to provide early warning and situational awareness of public health threats. The scope of source coverage ranges from local media in the vernacular to international media in widely read languages. Internet biosurveillance is a timely modality that is available to government and public health officials, healthcare workers, and the public and private sector, serving as a real-time complementary approach to traditional indicator-based public health disease surveillance methods. Internet biosurveillance also supports the broader activity of epidemic intelligence. This overview covers the current state of the field of Internet biosurveillance, and provides a perspective on the future of the field.

Beyond cattle: potential futures of the pastoral industry in the Northern Territory

The pastoral industry of the Northern Territory faces a suite of environmental and economic challenges associated with, inter alia, export markets, costs of production, climate change, change in government policies, and potential cattle diseases. A participatory planning process was adopted by the industry’s principal representative body, the Northern Territory Cattlemen’s Association to explore the complexity and extent of possible impacts on the industry, and to initiate conversations about anticipating potential futures. The process was facilitated by a system dynamics model, named the Pastoral Properties Future Simulator (PPFS). The PPFS combined a systems modelling approach of the pastoral industry with scenario explorations to gauge the likely impacts on, and possible industry adaptations to, beef price variation, productivity improvements, diversification of land use, climate change, climate policy and employment. The PPFS was used as an interactive tool during stakeholder workshops and results underpinned discussions about impacts and adaptation strategies. Land use and enterprise diversification emerged as key strategies for building enterprise and industry resilience, but with regionally diverging emphasis. The research illustrates the benefits of applied systems dynamic modelling for participatory strategic planning in the face of an uncertain future. The PPFS helped industry members and stakeholders understand the complexity of drivers affecting the industry’s future, risk profiles, possible adaptation strategies and trade-offs.

Landscape of international event-based biosurveillance

Event-based biosurveillance is a scientific discipline in which diverse sources of data, many of which are available from the Internet, are characterized prospectively to provide information on infectious disease events. Biosurveillance complements traditional public health surveillance to provide both early warning of infectious disease events and situational awareness. The Global Health Security Action Group of the Global Health Security Initiative is developing a biosurveillance capability that integrates and leverages component systems from member nations. This work discusses these biosurveillance systems and identifies needed future studies.

Spiral computed tomography-intravenous cholangiography with three-dimensional reconstructions for imaging the biliary tree

This study aimed to assess the ability of CT-i.v. cholangiography to show the perihilar biliary and cystic duct anatomy and to assess the relative performance of axial, maximum intensity projection and surface rendered displays. We also assessed the correlation between serum bilirubin levels and adequacy of biliary opacification. Spiral CT was carried out following infusion of 100 mL of Biliscopin in 181 patients with suspected biliary disease. The display of biliary anatomy was of high quality, with 91% of patients having good opacification of at least first-order bile ducts and 84% having good opacification of at least third-order right and left hepatic ducts. The quality of biliary opacification correlated inversely to serum bilirubin levels, with levels above two to three times the normal value being associated with lower rates of good opacification. Maximum intensity projection and surface rendered reformats aided anatomical interpretation to a similar degree. The relative frequency of types of perihilar branching patterns and cystic duct junctional anatomy correlated closely to those reported from previous anatomical studies.

A randomized clinical trial of agents to reduce sensitivity after crown cementation

Three desensitizing agents were evaluated for the control of sensitivity after cementation of 77 crowns. Information was collected on pain in response to hot, cold, or bite preoperatively; and postoperatively with temporary crowns at one week and at one month after cementation of crowns. No medicament was clearly better than the placebo.

Phaeochromocytoma in pregnancy

The Royal Women's Hospital, Melbourne, is a tertiary referral hospital with over 7,000 deliveries per year. We report 3 cases of phaeochromocytoma in pregnancy at the hospital in the 20-year period since 1976. The first case was unsuspected and resulted in a maternal death. The subsequent 2 cases were diagnosed antenatally with successful outcomes for both mother and baby. The 3 cases demonstrate the importance of an early antenatal diagnosis and the special management problems of phaeochromocytoma in pregnancy. The diagnosis of phaeochromocytoma should be considered in any pregnant women with severe hypertension, particularly if presenting before 20 weeks' gestation, labile, or associated with sweating, palpitations or headaches.

Relapsing pancreatitis due to juxta-pancreatic duodenal duplication cyst with pancreatic ductal communication

A 21 year old patient first presented with acute pancreatitis in infancy, followed by subsequent episodes of relapsing pancreatitis in childhood. The cause of the pancreatitis defied diagnosis, despite two laparotomies in infancy and childhood, until twenty years later when a juxta-pancreatic duodenal duplication--a rare congenital lesion--was finally discovered. The duplication communicated with the main pancreatic duct via a long, aberrant duct, resulting in the relapsing pancreatitis. Abdominal ultrasonography and computerized tomography scan, and endoscopic retrograde cholangiopancreaticogram were useful in demonstrating the lesion. Surgical excision of part of the cyst, with marsupialization of the remaining structure to the stomach, abolished further symptoms and recurrence of pancreatitis.

Obstructive jaundice due to foramen of Winslow hernia: a case report

An unusual case of obstructive jaundice due to foramen of Winslow hernia is presented. The hernia re-entered into the general peritoneal cavity through the lesser omentum and this appeared to be important in the pathogenesis of jaundice in this patient. Accurate pre-operative diagnosis of this uncommon condition remains difficult despite the advent of modern imaging techniques such as computerized tomography. Optimal outcome demands a high index of suspicion and early surgical intervention, together with operative measures to prevent future recurrence. The pathoanatomy of caecal herniation through the foramen of Winslow is also discussed.

Interindividual differences in the activation of two hepatic carcinogens to mutagens by human liver

The possibility that the presence of malignant disease can influence the metabolic activation of two carcinogens, 2-acetylaminofluorene and aflatoxin B1, has been investigated in a group of patients with secondary carcinoma of the liver. Mutagenic activation by subcellular fractions from biopsy samples from the patients was determined in the Ames/Salmonella test and the results compared with those obtained from a group of control patients. No significant differences were observed between the groups of patients in their ability to activate the two compounds to mutagenic metabolites. A tenfold range in ability to activate aflatoxin B1 was observed whereas only a threefold range was obtained with 2-acetylaminofluorene. Human liver activates aflatoxin B1 approximately 100 times more efficiently than 2-acetylaminofluorene, a proven carcinogen in many species. This raises the question of the true risk to man from hepatocarcinogenicity from aflatoxin B1.

Basal, sham feed and pentagastrin stimulated gastric acid, pepsin and electrolytes after omeprazole 20 mg and 40 mg daily

Gastric secretion was measured in nine patients with duodenal ulcer before, and after treatment for four weeks with omeprazole 20 mg or 40 mg daily. Basal acidity and acid output were affected variably by 20 mg, but inhibited totally by 40 mg daily. Sham feed stimulated acid output was reduced by 20 mg daily and completely inhibited by 40 mg daily. Maximal pentagastrin stimulated acid output was halved by 20 mg omeprazole daily and 84% inhibited by 40 mg daily. The reduction in acidity was always greater than the reduction of volume. Pepsin output after pentagastrin was little altered but with the reduced secretory volume pepsin concentrations were increased by both doses. The major cause of reduced aspirate acid output after omeprazole is decreased secretion of the primary acid component of the parietal cell by the proton pump H+K+ ATPase. Duodenogastric alkaline reflux is, however, markedly increased after omeprazole and is an additional factor in the resultant hypoacidity or even anacidity after this drug.

Major complications of central venous catheterisation: a report of five cases and a brief review of the literature

Complications of central venous catheterisation are not uncommon, although, fortunately, the majority are not serious. Five patients suffering major complications are reported and a brief review of the literature presented.

Carcinoma of the stomach: the need for a new approach

An analysis was performed of 229 cases of carcinoma of the stomach presenting between 1970 and 1975 and followed up until 1980. The average age of the patients was 67 years with a range of 24 to 96 years. The predominant symptoms were weight loss, epigastric pain, anorexia, vomiting and an abdominal mass of two of 18 months duration. All cancers were adenocarcinomata, most commonly in the distal third of the stomach; most were bulky (T3) on diagnosis and of poor histological differentiation. Some tumours had not spread to nodes but most had nodal involvement of the first and second order. Over half showed evidence of wide-spread dissemination at presentation. The operative mortality of all procedures including curative resection, palliative resection and by-pass was high, reflecting the high exploration rate (81.6%), high resection rate (56%) and the extent and hazards of major operation. Total gastrectomy was associated with twice the operative mortality of subtotal gastrectomy. Five year survival was in each case 17.3% and 16.3% respectively but it should be noted that the larger, more bulky and infiltrative tumours could not have been dealt with by anything less than total gastric resection. Average survival time in the "curative" surgery group was 27.9 months and of all 229 patients presenting, only 11 (4.8%) were alive after five years. Factors which may lead to improvement in this dismal outlook are discussed. Earlier diagnosis and multimodal chemotherapy as an adjunct to traditional surgery appear to offer the greatest prospects of improvement.