USDA regulatory guidelines and practices for veterinary Leptospira vaccine potency testing

Batch-release potency testing of leptospiral vaccines licensed by the United States Department of Agriculture (USDA) historically was conducted through animal vaccination-challenge models. The hamster vaccination-challenge assay was Codified in 1974 for bacterins containing Leptospira pomona, Leptospira icterohaemorrhagiae, and Leptospira canicola, and in 1975 for bacterins containing Leptospira grippotyphosa. In brief, 10 hamsters are vaccinated with a specified dilution of bacterin. After a holding period, the vaccinated hamsters, as well as nonvaccinated controls, are challenged with virulent Leptospira and observed for mortality. Eighty percent of vaccinated hamsters must survive in the face of a valid challenge. The high cost of the Codified tests, in terms of monetary expense and animal welfare, prompted the Center for Veterinary Biologics (CVB) to develop ELISA alternatives for them. Potency tests for other serogroups, such as Leptospira hardjo-bovis, that do not have Codified requirements for potency testing continue to be examined on a case-by-case basis.

The potential for an enhanced role for MRI in radiation-therapy treatment planning

The exquisite soft-tissue contrast of magnetic resonance imaging (MRI) has meant that the technique is having an increasing role in contouring the gross tumor volume (GTV) and organs at risk (OAR) in radiation therapy treatment planning systems (TPS). MRI-planning scans from diagnostic MRI scanners are currently incorporated into the planning process by being registered to CT data. The soft-tissue data from the MRI provides target outline guidance and the CT provides a solid geometric and electron density map for accurate dose calculation on the TPS computer. There is increasing interest in MRI machine placement in radiotherapy clinics as an adjunct to CT simulators. Most vendors now offer 70 cm bores with flat couch inserts and specialised RF coil designs. We would refer to these devices as MR-simulators. There is also research into the future application of MR-simulators independent of CT and as in-room image-guidance devices. It is within the background of this increased interest in the utility of MRI in radiotherapy treatment planning that this paper is couched. The paper outlines publications that deal with standard MRI sequences used in current clinical practice. It then discusses the potential for using processed functional diffusion maps (fDM) derived from diffusion weighted image sequences in tracking tumor activity and tumor recurrence. Next, this paper reviews publications that describe the use of MRI in patient-management applications that may, in turn, be relevant to radiotherapy treatment planning. The review briefly discusses the concepts behind functional techniques such as dynamic contrast enhanced (DCE), diffusion-weighted (DW) MRI sequences and magnetic resonance spectroscopic imaging (MRSI). Significant applications of MR are discussed in terms of the following treatment sites: brain, head and neck, breast, lung, prostate and cervix. While not yet routine, the use of apparent diffusion coefficient (ADC) map analysis indicates an exciting future application for functional MRI. Although DW-MRI has not yet been routinely used in boost adaptive techniques, it is being assessed in cohort studies for sub-volume boosting in prostate tumors.

TNFα from classically activated macrophages accentuates epithelial to mesenchymal transition in obliterative bronchiolitis

Bronchiolitis obliterans syndrome is characterized by fibrotic obliteration of small airways which severely impairs graft function and survival after lung transplantation. Bronchial epithelial cells from the transplanted lung can undergo epithelial to mesenchymal transition and this can be accentuated by activated macrophages. Macrophages demonstrate significant plasticity and change phenotype in response to their microenvironment. In this study we aimed to identify secretory products from macrophages that might be therapeutic targets for limiting the inflammatory accentuation of epithelial to mesenchymal transition in bronchiolitis obliterans syndrome. TNFα, IL-1β and IL-8 are elevated in bronchoalveolar lavage from lung transplant patients prior to diagnosis of bronchiolitis obliterans syndrome. Classically activated macrophages secrete more TNFα and IL-1β than alternatively activated macrophages and dramatically accentuate TGF-β1-driven epithelial to mesenchymal transition in bronchial epithelial cells isolated from lung transplant patients. Blocking TNFα, but not IL-1β, inhibits the accentuation of epithelial to mesenchymal transition. In a pilot unblinded therapeutic intervention in five patients with progressive bronchiolitis obliterans syndrome, anti-TNFα treatment improved forced expiratory volume in 1 second and 6-min walk distances in four patients. Our data identify TNFα as a potential new therapeutic target in bronchiolitis obliterans syndrome deserving of a randomized placebo controlled clinical trial.

Variability of dental cone beam CT grey values for density estimations

OBJECTIVE

The aim of this study was to investigate the use of dental cone beam CT (CBCT) grey values for density estimations by calculating the correlation with multislice CT (MSCT) values and the grey value error after recalibration.

METHODS

A polymethyl methacrylate (PMMA) phantom was developed containing inserts of different density: air, PMMA, hydroxyapatite (HA) 50 mg cm(-3), HA 100, HA 200 and aluminium. The phantom was scanned on 13 CBCT devices and 1 MSCT device. Correlation between CBCT grey values and CT numbers was calculated, and the average error of the CBCT values was estimated in the medium-density range after recalibration.

RESULTS

Pearson correlation coefficients ranged between 0.7014 and 0.9996 in the full-density range and between 0.5620 and 0.9991 in the medium-density range. The average error of CBCT voxel values in the medium-density range was between 35 and 1562.

CONCLUSION

Even though most CBCT devices showed a good overall correlation with CT numbers, large errors can be seen when using the grey values in a quantitative way. Although it could be possible to obtain pseudo-Hounsfield units from certain CBCTs, alternative methods of assessing bone tissue should be further investigated.

ADVANCES IN KNOWLEDGE

The suitability of dental CBCT for density estimations was assessed, involving a large number of devices and protocols. The possibility for grey value calibration was thoroughly investigated.

Using electronic referral with digital imaging between primary and secondary ophthalmic services: a long term prospective analysis of regional service redesign

PURPOSE

Demands on publicly funded ophthalmic services worldwide continue to increase with new treatments, waiting time targets, working time limits, and restricted budgets. These highlight the necessity to develop innovative ways of utilising existing capacity more effectively.

METHOD

A new regional, fully electronic ophthalmic-referral service with digital imaging was trialled using existing information-technology (IT) infrastructure. Following successful pilot study, the service was rolled out regionally. Service delivery data was prospectively collated for all the attendances in the year prior to (2006) and the year following (2008) introduction.

RESULTS

Comparing 2006 against 2008, median waiting times reduced (14 vs 4 weeks), and fewer new patients were observed (8714 vs 7462 P<0.0001), with 1359 referrals receiving electronic diagnosis (e-diagnosis). New patient did not arrive (635 vs 503 P<0.0001) and emergencies also reduced (2671 v 1984 P<0.0001).

DISCUSSION

Novel use of existing IT infrastructure improves communication between primary and secondary care. This promotes more effective use of limited outpatient capacity by retaining patients with non-progressive, asymptomatic pathology in the community, whilst fast-tracking patients with sight-threatening disease. Resultant significant, sustained improvements in regional service delivery point to a simple model that could easily be adopted by other providers of universal healthcare globally.

Dose distribution for dental cone beam CT and its implication for defining a dose index

OBJECTIVES

To characterize the dose distribution for a range of cone beam CT (CBCT) units, investigating different field of view sizes, central and off-axis geometries, full or partial rotations of the X-ray tube and different clinically applied beam qualities. The implications of the dose distributions on the definition and practicality of a CBCT dose index were assessed.

METHODS

Dose measurements on CBCT devices were performed by scanning cylindrical head-size water and polymethyl methacrylate phantoms, using thermoluminescent dosemeters, a small-volume ion chamber and radiochromic films.

RESULTS

It was found that the dose distribution can be asymmetrical for dental CBCT exposures throughout a homogeneous phantom, owing to an asymmetrical positioning of the isocentre and/or partial rotation of the X-ray source. Furthermore, the scatter tail along the z-axis was found to have a distinct shape, generally resulting in a strong drop (90%) in absorbed dose outside the primary beam.

CONCLUSIONS

There is no optimal dose index available owing to the complicated exposure geometry of CBCT and the practical aspects of quality control measurements. Practical validation of different possible dose indices is needed, as well as the definition of conversion factors to patient dose.

Estimation of paediatric organ and effective doses from dental cone beam CT using anthropomorphic phantoms

OBJECTIVES

Cone beam CT (CBCT) is an emerging X-ray technology applied in dentomaxillofacial imaging. Previous published studies have estimated the effective dose and radiation risks using adult anthropomorphic phantoms for a wide range of CBCT units and imaging protocols.

METHODS

Measurements were made five dental CBCT units for a range of imaging protocols, using 10-year-old and adolescent phantoms and thermoluminescent dosimeters. The purpose of the study was to estimate paediatric organ and effective doses from dental CBCT.

RESULTS

The average effective doses to the 10-year-old and adolescent phantoms were 116 μSv and 79 μSv, respectively, which are similar to adult doses. The salivary glands received the highest organ dose and there was a fourfold increase in the thyroid dose of the 10-year-old relative to that of the adolescent because of its smaller size. The remainder tissues and salivary and thyroid glands contributed most significantly to the effective dose for a 10-year-old, whereas for an adolescent the remainder tissues and the salivary glands contributed the most significantly. It was found that the percentage attributable lifetime mortality risks were 0.002% and 0.001% for a 10-year-old and an adolescent patient, respectively, which are considerably higher than the risk to an adult having received the same doses.

CONCLUSION

It is therefore imperative that dental CBCT examinations on children should be fully justified over conventional X-ray imaging and that dose optimisation by field of view collimation is particularly important in young children.

Initiation of antiretroviral therapy in patients with a CD4 count of less than 350 cells: a retrospective audit against key indicators from the CQUIN payment framework

A proportion of funding for the South Yorkshire HIV Network is dependant on meeting the targets of the Commissioning for Quality and Innovation (CQUIN) payment framework. This states that 85% of patients with a CD4 count below 350 should be on antiretroviral therapy (ART). We also audited how many patients we started on treatment within six weeks. We found 88% of the 243 patients were on ART at the end of the audit, but significantly less had been started on treatment within six weeks of their CD4 count falling below 350. Although the target was achieved, there were patients who should be excluded as shown by other clinical guidelines, for example patients on treatment for tuberculosis. If these patients were excluded and the threshold level increased, it would help emphasize the at-risk patient group and lead to a fairer allocation of funding.

P3-13-05: Analysis of Heart Dose-Volume Parameters and Cardiac Events among Node Positive Breast Cancer (NPBC) Patients Treated with Three-Dimensional Conformal Radiation Therapy (3D-CRT)

Background

For NPBC patients the use of regional nodal irradiation (RNI) to the supraclavicular, axillary, internal mammary lymph nodes (IMN) in addition to the chest wall and/or breast can maximize locoregional control and improve overall survival. However, comprehensive RNI for breast cancers located on the left side has been linked to late cardiac morbidity, potentially lessening the therapeutic benefit of treatment. The optimal radiation dose-volume constraints for the heart in this setting are not fully understood. We examined NPBC patients treated with RNI using 3D-CT based radiation therapy (RT) to evaluate cardiac dose and incidence of cardiac events.

Methods: Between 2000 and 2007, 150 NPBC patients were treated with RNI following lumpectomy or mastectomy using 3D-CRT. In all cases, treatment target and normal tissue volumes were delineated on treatment CT scans. The heart contour included the ventricles and the left atrium. The dose-volume histogram of the cardiac doses delivered and the incidence of cardiac events is reported.

Results: Median follow-up of surviving patients is 7 (1-10.6) years. Median patient age is 50 (27-91). 52.35% are premenopausal, 75.7% estrogen receptor positive, 66.3% progesterone receptor positive and 15.92% HER-2 positive. Mean positive lymph nodes is 5 (1-29). Extracapsular extension is present in 47.31%. Mean microscopic tumor size is 3.73 (0.1-21) cm. The IMN receive &gt; 40 Gy in 65.5%. 94% had chemotherapy, and in 82.3% it was anthracycline-based. At the time of RT, 12.2% smoked, 9.5% had diabetes, 32.4% with hypertension, and 4.7% with a history of coronary artery disease.

There was 1 (0.7%) right sided patient with cardiac events and 4 (2.7%) left sided experiencing cardiac events (p = 0.121, Fisher's Exact test). A total of 10 cardiac diagnoses were experienced among the 5 patients: coronary artery disease with myocardial infarction (3), congestive heart failure (2), cardiomyopathy (2), and arrhythmia (3). The median time interval to onset of the events is 2.5 years (0-4.3 years).

The cardiac doses among 150 patients are as follows: mean V25 is 5.7, (0.0 - 20.0%), V25 is &lt; 9 % in 74.4% of patients, mean V45 is 1.8% (0-13.3%), V45 is &lt; 5.5% in 91.8%. The mean maximum point dose is 42.8 Gy, and the mean heart dose is 5.6 Gy (0.2−25.3 Gy). The mean V25 and V45 in those 5 patients with a cardiac event is 6.7% (0.9−11.9%) and 3.7% (0-6.6%), respectively; in the 145 remaining patients, 5.7% (0-20.0%) and 1.7% (0-13.3%), respectively. The mean heart dose in those with an event is 5.2 Gy (2.4−7.3 Gy) versus 5.6 Gy (0.2−25.3 Gy) in the remaining patients.

Conclusions: The cardiac event rate among these NPBC patients treated with RNI and anthracycline-based chemotherapy is low. However, those patients with cardiac events have a higher mean V45. No other dose-volume relationships are discernible. Additional analysis using 3DCRT volumes are important to validate these findings and better define the dose-volume parameters for cardiac toxicity.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-13-05.

A randomised controlled trial of two analgesic techniques for paediatric tonsillectomy*

Investigators from Bristol described a fentanyl- and diclofenac-based analgesic technique for tonsillectomy with low postoperative nausea and vomiting rates and low pain scores. This study compared the effectiveness of a modified Bristol technique with a codeine-based regimen with respect to PONV and analgesia. Sixty-five children, ASA 1-2, were randomly assigned to either the Bristol group (fentanyl 1-2 μg.kg(-1) and diclofenac 1-2 mg.kg(-1)) or codeine group (codeine 1.5 mg.kg(-1)). All children received paracetamol 15 mg.kg(-1) and dexamethasone 0.1 mg.kg(-1) . Postoperative nausea and vomiting and pain scores were recorded hourly, and fitness for discharge was assessed at 4 h. The overall incidence of postoperative nausea and vomiting was 21% with no difference between groups (Bristol group 8/30, codeine group 5/32, p = 0.29). Children in the Bristol group required analgesia earlier than those in the codeine group (p < 0.005), but maximum pain scores were not different (Bristol group median (IQR [range) 4.5 (3-5 [0-5]), codeine group 4.0 (2-5 [1-5]), p = 0.15). Twenty-three per cent of children were assessed as not fit for discharge at 4 h. The codeine-based regimen may have a small advantage over the Bristol regimen, but neither technique seems ideally suited for a day-case service without a longer period of observation. You can respond to this article at http://www.anaesthesiacorrespondence.com.