A retrospective descriptive analysis of race-day injuries of greyhounds in New Zealand.

OBJECTIVES: To describe the distribution, and determine the incidence, of veterinary reported injuries experienced by greyhounds during racing in New Zealand. MATERIALS AND METHODS: This retrospective cohort study utilised data obtained on all greyhound race starts and all racing injuries sustained in New Zealand between 10 September 2014 and 19 June 2019. Greyhound injuries were described by the number and percentage of the type, location, and presumed cause of injuries. The overall incidence of injuries per 1000 racing starts was calculated and stratified incidence rates were calculated for race year, racetrack, race number, sex of the greyhound, country of origin of the greyhound, starting box number, race type, race class and race distance. Poisson regression was used to calculate incidence rate ratios for the outcome of injury and race exposure variables. RESULTS: There were 213,630 race starts and 4100 injuries. The incidence of injury was 19.2 per 1000 starts, while the number of fatalities at the track was 1.3 per 1000 race starts. Most injuries experienced by greyhounds on race-day were minor (soft-tissue). Most injuries affected the limbs of the greyhounds (82.8%, n = 3393/4100). The rate of injuries was higher in Australian dogs compared with New Zealand dogs, the incidence rate of injury increased with advancing age group and the incidence rate varied among racetracks. CONCLUSION: The injury rates were similar to those previously reported for racing greyhounds in New Zealand. This study highlighted the need for greater uniformity and conciseness around the classification of injuries to permit comparisons across jurisdictions.

A multicentre audit of HDR/PDR brachytherapy absolute dosimetry in association with the INTERLACE trial (NCT015662405).

A UK multicentre audit to evaluate HDR and PDR brachytherapy has been performed using alanine absolute dosimetry. This is the first national UK audit performing an absolute dose measurement at a clinically relevant distance (20 mm) from the source. It was performed in both INTERLACE (a phase III multicentre trial in cervical cancer) and non-INTERLACE brachytherapy centres treating gynaecological tumours. Forty-seven UK centres (including the National Physical Laboratory) were visited. A simulated line source was generated within each centre's treatment planning system and dwell times calculated to deliver 10 Gy at 20 mm from the midpoint of the central dwell (representative of Point A of the Manchester system). The line source was delivered in a water-equivalent plastic phantom (Barts Solid Water) encased in blocks of PMMA (polymethyl methacrylate) and charge measured with an ion chamber at 3 positions (120° apart, 20 mm from the source). Absorbed dose was then measured with alanine at the same positions and averaged to reduce source positional uncertainties. Charge was also measured at 50 mm from the source (representative of Point B of the Manchester system). Source types included 46 HDR and PDR 192Ir sources, (7 Flexisource, 24 mHDR-v2, 12 GammaMed HDR Plus, 2 GammaMed PDR Plus, 1 VS2000) and 1 HDR 60Co source, (Co0.A86). Alanine measurements when compared to the centres' calculated dose showed a mean difference (±SD) of +1.1% (±1.4%) at 20 mm. Differences were also observed between source types and dose calculation algorithm. Ion chamber measurements demonstrated significant discrepancies between the three holes mainly due to positional variation of the source within the catheter (0.4%-4.9% maximum difference between two holes). This comprehensive audit of absolute dose to water from a simulated line source showed all centres could deliver the prescribed dose to within 5% maximum difference between measurement and calculation.

Dosimetric audit in brachytherapy.

Dosimetric audit is required for the improvement of patient safety in radiotherapy and to aid optimization of treatment. The reassurance that treatment is being delivered in line with accepted standards, that delivered doses are as prescribed and that quality improvement is enabled is as essential for brachytherapy as it is for the more commonly audited external beam radiotherapy. Dose measurement in brachytherapy is challenging owing to steep dose gradients and small scales, especially in the context of an audit. Several different approaches have been taken for audit measurement to date: thimble and well-type ionization chambers, thermoluminescent detectors, optically stimulated luminescence detectors, radiochromic film and alanine. In this work, we review all of the dosimetric brachytherapy audits that have been conducted in recent years, look at current audits in progress and propose required directions for brachytherapy dosimetric audit in the future. The concern over accurate source strength measurement may be essentially resolved with modern equipment and calibration methods, but brachytherapy is a rapidly developing field and dosimetric audit must keep pace.

Comparison of methods for the measurement of radiation dose distributions in high dose rate (HDR) brachytherapy: Ge-doped optical fiber, EBT3 Gafchromic film, and PRESAGE® radiochromic plastic.

PURPOSE: Dose distribution measurement in clinical high dose rate (HDR) brachytherapy is challenging, because of the high dose gradients, large dose variations, and small scale, but it is essential to verify accurate treatment planning and treatment equipment performance. The authors compare and evaluate three dosimetry systems for potential use in brachytherapy dose distribution measurement: Ge-doped optical fibers, EBT3 Gafchromic film with multichannel analysis, and the radiochromic material PRESAGE(®) with optical-CT readout. METHODS: Ge-doped SiO2 fibers with 6 µm active core and 5.0 mm length were sensitivity-batched and their thermoluminescent properties used via conventional heating and annealing cycles. EBT3 Gafchromic film of 30 µm active thickness was calibrated in three color channels using a nominal 6 MV linear accelerator. A 48-bit transmission scanner and advanced multichannel analysis method were utilized to derive dose measurements. Samples of the solid radiochromic polymer PRESAGE(®), 60 mm diameter and 100 mm height, were analyzed with a parallel beam optical CT scanner. Each dosimetry system was used to measure the dose as a function of radial distance from a Co-60 HDR source, with results compared to Monte Carlo TG-43 model data. Each system was then used to measure the dose distribution along one or more lines through typical clinical dose distributions for cervix brachytherapy, with results compared to treatment planning system (TPS) calculations. Purpose-designed test objects constructed of Solid Water and held within a full-scatter water tank were utilized. RESULTS: All three dosimetry systems reproduced the general shape of the isolated source radial dose function and the TPS dose distribution. However, the dynamic range of EBT3 exceeded those of doped optical fibers and PRESAGE(®), and the latter two suffered from unacceptable noise and artifact. For the experimental conditions used in this study, the useful range from an isolated HDR source was 5-40 mm for fibers, 3-50 mm for EBT3, and 4-21 mm for PRESAGE(®). Fibers demonstrated some over-response at very low dose levels, suffered from volume averaging effects in the dose distribution measurement, and exhibited up to 9% repeatability variation over three repeated measurements. EBT3 demonstrated excellent agreement with Monte Carlo and TPS dose distributions, with up to 3% repeatability over three measurements. PRESAGE(®) gave promising results, being the only true 3D dosimeter, but artifacts and noise were apparent. CONCLUSIONS: The comparative response of three emerging dosimetry systems for clinical brachytherapy dose distribution measurement has been investigated. Ge-doped optical fibers have excellent spatial resolution for single-direction measurement but are currently too large for complex dose distribution assessment. The use of PRESAGE(®) with optical-CT readout gave promising results in the measurement of true 3D dose distributions but further development work is required to reduce noise and improve dynamic range for brachytherapy dose distribution measurements. EBT3 Gafchromic film with multichannel analysis demonstrated accurate and reproducible measurement of dose distributions in HDR brachytherapy. Calibrated dose measurements were possible with agreement within 1.5% of TPS dose calculations. The suitability of EBT3 as a dosimeter for 2D quality control or commissioning work has been demonstrated.

Open access to MRI for general practitioners: 12 years' experience at one institution -- a retrospective analysis.

The aim of this study was to evaluate 12 years of general practitioner (GP) use of open access MRI services at a single London teaching hospital. A retrospective analysis of reports from all GP requests for MRI scans between 1994 and 2005 was performed. The date, scanned body part, and requester details from 1798 scans requested by 209 individual GPs over a continuous 12-year period were recorded. All scans were then graded into four categories based on the severity of reported findings from normal to gross abnormality. Over the study period, GP requests as a percentage of the total (MRI) department workload remained low at approximately 2.6%. Spine, knee and brain requests constituted 86% (n = 1546) of requested scans. 48% (n = 868) of scans were reported as normal or minor degenerative changes only. 26% (n = 466) of scans demonstrated serious pathology that was likely to warrant hospital consultant referral. There was a wide range of scans requested per requester, from 1 to 240 over the period, with an average of 8.5 scans per GP. In conclusion, any department wishing to set up open access to MRI services for GPs could cover the majority of requests by offering spine, knee and brain imaging. The percentage of normal report rates for GP requests is comparable with previous studies of outpatient referrals. A large variation in requesting patterns between GPs suggests the need for increased communication between GPs and imaging departments to optimise use of the service.

The impact of zidovudine use in HIV-infected pregnant women on vertical transmission of HIV in Mississippi.

In February 1994, results of a large placebo-controlled trial of zidovudine (ZDV) use during pregnancy (ACTG 076) showed a dramatic reduction in vertical transmission of HIV. In August 1994, the Public Health Service (PHS) recommended routine ZDV use in HIV infected pregnant women and their neonates for the prevention of vertical transmission. We retrospectively reviewed vertical transmission rates of HIV in Mississippi from 1/1/90 to 8/30/94 before the PHS guidelines were released and from 9/1/94 to 12/31/97 after the PHS guidelines were released. We also reviewed data on ZDV use in HIV infected pregnant women and their neonates from 9/1/94 to 12/31/97. Antenatal, intrapartum and neonatal ZDV use increased from 61%, 59% and 73% respectively to 79%, 77% and 92% respectively. After 9/1/94, vertical transmission rates fell by 44%. Zidovudine use during pregnancy has increased in Mississippi since release of the PHS guidelines resulting in a dramatic decline in vertical transmission rates.

Rothia endocarditis in a child.

Rothia dentocariosa, an organism inhabiting the oral flora, has been reported to cause endocarditis in adults but not in children. Most patients reported with Rothia endocarditis have a history of poor dentition. We report a case of Rothia endocarditis in a child with congenital heart disease without other known risk factors.

Adverse effects of maternal enterovirus infection on the fetus and placenta.

Gestational outcome in a murine model of congenital enterovirus infection was evaluated. Pregnant mice were inoculated intravenously with Theiler's murine encephalomyelitis virus (TMEV), a murine enterovirus, or with BHK 21 cell lysate (control) at 6-7 days of gestation (early) and sacrificed 6 or 12 days later, and their placentas and fetuses were studied. High rates of gross and histologic abnormalities (50%-87%) were seen in placentas and fetuses from dams infected with TMEV and sacrificed 6 days later. TMEV-infected dams sacrificed 12 days after inoculation had lower rates of placental-fetal abnormalities (25%-57%) but an additional 42% rate of complete pregnancy loss. Pregnancy loss (9%) and placental-fetal abnormalities (4%-7%) were uncommon in control animals. Rates of fetal abnormalities and placental infection in infected dams exceeded fetal viral infection, suggesting that TMEV infection adversely affects pregnancy either directly by fetal damage or indirectly by placental compromise.

Evaluation of suprapubic bladder aspiration for detection of group B streptococcal antigen by latex agglutination in neonatal urine.

Our objective was to determine whether urine collection by suprapubic bladder aspiration (SBA) improves the specificity of the group B streptococcal (GBS) latex agglutination (LA) test by avoiding contamination of urine with GBS from perineal and rectal colonization that can result in a positive LA test in an uninfected infant when the urine is collected by bag. Part 1 consists of a retrospective review of the medical records of 113 infants who had urine collected by SBA for GBS LA testing as part of evaluation for possible sepsis. The sensitivity and specificity of the urine LA test was assessed by comparing it with blood culture results. In part 2, a prospective analysis was performed of 19 newborns who had rectal and vaginal/penile cultures as well as urine by SBA and bag for GBS cultures and LA. Results of LA testing on urine collected by both of these methods were compared with results of urine, perineal, and rectal cultures. In the retrospective review of GBS LA testing performed on 113 consecutive urine specimens collected by SBA from neonates being evaluated for suspected sepsis, the sensitivity and specificity were 67% and 89%, respectively, when compared with blood culture results. Twelve infants who had a positive LA test result but a sterile blood culture (BC-,LA+) were compared with 95 infants with both blood cultures and urine LA tests negative for GBS (BC-, LA-). BC-, LA+ infants were more likely than those with BC-, LA- to have an immature to total neutrophil (I/T) ratio > or = 0.16 at 12 and 24 hours (p = 0.04 and 0.02, respectively). In the prospective study, we found that a positive GBS LA test can be due to perineal contamination and possibly to gastrointestinal absorption of GBS antigen. No false positive LA test results occurred on urine obtained by SBA; however, use of this method failed to detect the one infant with GBS bacteremia. Because of suboptimal sensitivity and specificity, use of the GBS LA test on urine obtained either by SBA or bag cannot be recommended for diagnosis of early onset GBS disease.

Aspheric profile gauging using a bootstrap data interpretation technique.

Accurate electromechanical gauging of steep aspheric profiles is often complicated by the complexity of the elationship between the locus of the probe tip center of curvature and the probe tip/asphere contact point. Solving for the contact point is usually done in an iterative manner, which is a fairly laborious computing chore. But since a considerable amount of sag information is conventionally produced by the lens design program generating the aspheric surface, it is possible to shortcut the process by using these data to solve directly for the probe tip coordinates as a function of the aspheric prescription.