Advances in treatment planning dosimetry for a high energy neutron beam

Before starting the clinical programme, a series of physical measurements were made using the Clatterbridge high energy neutron facility. These consisted of measurements made under standard conditions, e.g. with square fields, full scatter conditions and perpendicular beam incidence. Further measurements have now been performed to include various clinically relevant non-standard conditions. These included the effects of field shape, backscatter, oblique incidence, bolus and beam blocking on dose distributions.     

Lymphography--current role in oncology

A review of the use of lymphography at this hospital, a major oncology centre, is presented. The advent of computed tomography has brought a dramatic reduction in the number of lymphograms currently performed for diseases such as lymphoma, testicular tumours and gynaecological malignancies. This study analyses the reasons for this decline, and concludes that valuable information can still be obtained from lymphography in certain selected groups of patients.     

Successful intra-arterial thrombolytic therapy for a right middle cerebral artery stroke in a 2-year-old supported by a ventricular assist device

Embolic stroke is a common complication in patients on ventricular assist devices in both adults and children. The reported incidence of strokes in children supported by VAD's varies from 7 to 38%. The rapid increase in recent years in the availability of both adult and pediatric VADs will likely add to the overall prevalence of strokes in patients being bridged to heart transplant. Strokes in this population can be lethal as they frequently necessitate withdrawal of the extracorporeal device support and withdrawal from the organ transplant waiting list. We present a case of a fully anti-coagulated 29-month-old supported on a Berlin EXCOR LVAD (Berlin, Germany) with embolic stroke which was treated successfully with direct thrombolysis with recombinant tissue plasminogen activator. This is the first report which uses intra-arterial thrombolytics while on a ventricular assist device in a pediatric patient.     

Regional bone metabolism at the lumbar spine and hip following discontinuation of alendronate and risedronate treatment in postmenopausal women

Summary

The aim of this study was to examine the effects of bisphosphonate discontinuation on bone metabolism at the spine and hip measured using ¹⁸?F-fluoride PET. Bone metabolism at the spine remained stable following discontinuation of alendronate and risedronate at 1?year but increased in the hip in the alendronate group only.

Introduction

Bisphosphonates such as alendronate (ALN) or risedronate (RIS) have persistent effects on spine BMD following discontinuation.

Methods

Positron emission tomography (PET) was used to examine regional bone metabolism in 20 postmenopausal women treated with ALN (n?=?11) or RIS (n?=?9) for a minimum of 3?years at screening (range 3–9?years, mean 5?years for both groups). Subjects underwent a dynamic scan of the lumbar spine and a static scan of both hips at baseline and 6 and 12?months following treatment discontinuation. ¹⁸?F-fluoride plasma clearance (K_i) at the spine was calculated using a three-compartment model. Standardised uptake values (SUV) were calculated for the spine, total hip, femoral neck and femoral shaft. Measurements of BMD and biochemical markers of bone turnover were also performed.

Results

With the exception of a significant decrease in spine BMD in the ALN group, BMD remained stable. Bone turnover markers increased significantly from baseline by 12?months for both study groups. Measurements of K_i and SUV at the spine and femoral neck did not change significantly in either group. SUV at the femoral shaft and total hip increased significantly but in the ALN group only, increasing by 33.8% (p?=?0.028) and 24.0% (p?=?0.013), respectively.

Conclusions

Bone metabolism at the spine remained suppressed following treatment discontinuation. A significant increase in SUV at the femoral shaft and total hip after 12?months was observed but for the ALN group only. This study was small, and further clinical studies are required to fully evaluate the persistence of BP treatment.     

A list of device-specific thresholds for the clinical interpretation of peripheral x-ray absorptiometry examinations

The UK National Osteoporosis Society (NOS) has recently issued new guidelines on the use of peripheral x-ray absorptiometry (pDXA) devices in managing osteoporosis. The NOS guidelines recommend a triage approach in which patients bone mineral density (BMD) measurements are interpreted using upper and lower thresholds specific to each type of pDXA device. The thresholds are defined so that patients with osteoporosis at the hip or spine are identified with 90% sensitivity and 90% specificity. Patients with a pDXA result below the lower threshold are likely to have osteoporosis at the hip or spine, patients with a result above the upper threshold are unlikely to have osteoporosis, while those between the two thresholds require a hip and spine BMD examination for a definitive diagnosis. This report presents data from a multicenter study to establish the triage thresholds for a range of pDXA devices in use in the UK. The subjects were white female patients aged 55–70 years who met the normal referral criteria for a BMD examination. For each device, at least 70 women with osteoporosis at the hip or spine and 70 women without osteoporosis were enrolled. All women had hip and spine BMD measurements using axial DXA systems that were interpreted using the National Health and Nutrition Examination Survey (NHANES) reference range for the hip and the manufacturers reference ranges for the spine. Data are presented for five different devices: the Osteometer DTX-200 (forearm BMD), the Schick AccuDEXA (hand BMD), the GE Lunar PIXI (heel BMD), the Alara MetriScan (hand BMD), and the Demetech Calscan (heel BMD). The clinical measurements were supplemented by theoretical modeling to estimate the age dependence of the triage thresholds and the effect of the correlation coefficient between pDXA and axial BMD on the percentage of women referred for an axial BMD examination. In summary, this study provides thresholds for implementing the new NOS guidelines for managing osteoporosis using pDXA devices. The figures reported apply to postmenopausal white women aged 55–70 years who meet the conventional criteria for a BMD examination. The results confirm that the thresholds are specific to each type of pDXA device and that the NOS triage algorithm requires 40% of women to have an axial DXA examination.On behalf of the National Osteoporosis Society Bone Densitometry Forum.     

Ureteroscopic management of upper urinary tract transitional cell carcinoma

PURPOSE OF REVIEW: Traditionally, nephroureterectomy has been the treatment of choice for transitional cell carcinoma of the upper urinary tract. In an effort to preserve renal function, conservative therapy has evolved from complex open surgery to minimally invasive ureteroscopic therapy. Considering the relatively recent emergence of ureteroscopic therapy, a review of technical considerations and treatment outcome is timely. RECENT FINDINGS: There is emerging evidence that ureteroscopic treatment of low grade upper tract lesions provides an acceptable oncologic result while preserving functioning renal parenchyma. In patients with low grade upper tract urothelial lesions, progression is rarely reported. Ureteroscopy has for over a decade been the premier diagnostic tool, with the actively deflectable flexible instrument being employed to map the entire intrarenal collecting system. Improvements in instrumentation and refinement in technique have broadened the application of the ureteroscope in treating upper urinary tract urothelial tumors. SUMMARY: For low grade lesions, which make up more than 50% of all presentations, ureteroscopic management has proven efficacious. As with similar grade lesions in the bladder, these patients require careful, consistent, and often lifelong follow up as many will develop recurrent lesions throughout the urothelium. Here too, ureteroscopy has a central role in surveillance.     

Genetic and environmental determinants on bone loss in postmenopausal Caucasian women: a 14-year longitudinal twin study

Summary  This longitudinal twin study documented that genetic factors explain 44–56% of the between-individual variance in bone loss at femoral neck, lumbar spine, and forearm in postmenopausal Caucasian women, providing a rationale for identifying the specific genes involved. Introduction  Although there is a significant genetic effect on peak BMD, until recently, no substantive studies on heritability of bone loss in human were available. The aim of the study was to estimate the heritability of the bone loss at multiple sites in postmenopausal Caucasian women. Methods  Postmenopausal female monozygotic (MZ) and dizygotic (DZ) twins aged 40 or above at baseline were selected from the TwinsUK registry and followed up for an average of 8 years (range 5–14 years). All twins were noncurrent hormone replacement therapy users and not on any osteoporosis treatment. They had dual-energy X-ray absorptiometry (DXA) scans of their hip, lumbar spine, and forearm several times (range 2–9) during the follow-up period. Individual bone losses at femoral neck, lumbar spine, and forearm were estimated by linear regression modeling. Structural equation modeling was utilized to estimate the heritability of the bone loss. Results  A total of 712 postmenopausal Caucasian female twins (152 MZ and 204 DZ pairs) were included. MZ twins were older and had slightly lower BMD at all sites than DZ twins. DZ twins had slightly higher bone loss at lumbar spine, but similar at femoral neck and forearm compared to MZ twins. Intraclass correlation coefficients (ICC) for the bone loss at all sites were significantly higher in MZ than DZ twin pairs (p = 0.0045, 0.0003, and 0.0007 for femoral neck, lumbar spine, and forearm, respectively), indicating a significant genetic influence on bone loss at these sites. After adjustment for age at baseline and weight change during the follow-up, the heritability estimate was 47% (95% CI 27–63%) for bone loss at femoral neck, 44% (95% CI 27–58%) for lumbar spine, and 56% (95% CI 44–65%) for forearm. Conclusions  Our data suggest that up to 56% of the between-individual variance in bone loss is due to genes, providing a rationale to identify specific genetic factors for bone loss.