Publications by authors named "Poynter A"

The superior dose conformity provided by proton therapy relative to conventional x-ray radiotherapy necessitates more rigorous quality assurance (QA) procedures to ensure optimal patient safety. Practically however, time-constraints prevent comprehensive measurements to be made of the proton range in water: a key parameter in ensuring accurate treatment delivery.A novel scintillator-based device for fast, accurate water-equivalent proton range QA measurements for ocular proton therapy is presented.

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Anxiety disorders are the most common mental health concerns affecting Canadian children and adolescents. The Canadian Paediatric Society has developed two position statements that summarize current evidence regarding the diagnosis and management of anxiety disorders. Both statements offer evidence-informed guidance to support paediatric health care providers (HCPs) making decisions around the care of children and adolescents with these conditions.

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Purpose: Relative stopping powers (RSPs) for proton therapy are estimated using single-energy computed tomography (SECT), calibrated with standardized tissues of the adult male. It is assumed that those tissues are representative of tissues of all age and sex. Female, male, and pediatric tissues differ from one another in density and composition.

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Aims: Twenty per cent of patients with non-small cell lung cancer present with stage III locally advanced disease. Precision radiotherapy with pencil beam scanning (PBS) protons may improve outcomes. However, stage III is a heterogeneous group and accounting for complex tumour motion is challenging.

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The increasing production of Ag nanoparticle (AgNP) containing products has inevitably led to a growing concern about their release into the aquatic environment, along with their potential behaviour, toxicity, and bioaccumulation in marine organisms exposed to NPs released from these products. Hence, this study is focused on the effects of AgNPs in Saccostrea glomerata (rock oyster) in artificial seawater (ASW); evaluating the NP's stability, dissolution, and bioaccumulation rate. AgNPs NM300K (20 ± 5 nm) in concentrations of 12.

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Clinical observations have suggested that limited hamstring flexibility may be associated with sagittal spinal curvatures in spine flexed postures. Thus, limited hamstring flexibility may be related to large amounts of spine flexion in "slumped" sitting postures which could contribute to low back pain and injury. The aim of this study was to determine if hamstring and pelvic flexibility are associated with flexed sitting postures using a backless office chair.

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Article Synopsis
  • The study looked at how different patients get treated with radiotherapy for breast tumors and if they need different space around the tumor area when using lasers or checking bone structure.
  • They used images from 218 patients to figure out how accurate the positioning was with lasers versus using bone anatomy.
  • The findings suggest that certain patients, like those with larger breasts or visible seromas, might need more space when using lasers or bone checks, and that margins should be 8 to 10 mm depending on the method used.
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Background: Although prior studies have shown patient-controlled analgesia (PCA) to be appropriate for use by children and adults, no studies have specifically evaluated the ability of elderly patients to use the technology correctly.

Purpose: To determine whether elderly, postoperative patients can properly use PCA devices.

Methods: Using a descriptive study design, a convenience sample of elderly, postoperative orthopedic patients was observed while using a PCA device and surveyed about the proper use of the device.

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Objective: To investigate whether planning target volume (PTV) margins may be safely reduced in radiotherapy of localized prostate cancer incorporating daily online tube potential-cone beam CT (CBCT) image guidance and the anticipated benefit in predicted rectal toxicity.

Methods: The prostate-only clinical target volume (CTV2) and rectum were delineated on 1 pre-treatment CBCT each week in 18 randomly selected patients. By transposing these contours onto the original plan, dose-volume histograms (DVHs) for CTV2 and the rectum were each calculated and combined, for each patient, to produce a single mean DVH representative of the dose delivered over the treatment course.

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We have synthesized an oxaliplatin derivative using N,N'-dimethyl-1,2-diaminocyclohexane (Medach) as the diamine ligand. The complex (S,R,R,S)-Pt(Medach)(oxalate), where S,R,R,S represents the chiralities at N,C,C,N, respectively, was prepared and characterized by H NMR spectroscopy, COSY, NOESY, and HMQC. Oxaliplatin reacts with N-acetylmethionine (N-AcMet) to form [Pt(dach)(N-AcMet-)] and [Pt(dach)(N-AcMet-)], with the former favored at higher molar ratios of N-AcMet.

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Purpose: This study investigates (i) the effect of verification protocols on treatment accuracy and PTV margins for partial breast and boost breast radiotherapy with short fractionation schema (15 fractions), (ii) the effect of deformation of the excision cavity (EC) on PTV margin size, (iii) the imaging dose required to achieve specific PTV margins.

Methods And Materials: Verification images using implanted EC markers were studied in 36 patients. Target motion was estimated for a 15 fraction partial breast regimen using imaging protocols based on on-line and off-line motion correction strategies (No Action Level (NAL) and the extended NAL (eNAL) protocols).

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This paper outlines the guidelines for the development of intensity-modulated radiotherapy (IMRT) in the UK. The guidelines are designed to cover the complete implementation of IMRT, with guidelines in the following categories: commissioning, quality, clinical, audit, and training and education. These guidelines have been compiled by the Radiotherapy Development Board of the Royal College of Radiologists and will support the safe application of IMRT in the UK.

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Aims: The aim of the study was to measure how long the intensity-modulated radiotherapy (IMRT) process takes, both for planning and delivery, using several IMRT techniques and departments.

Materials And Methods: Timings were measured at three radiotherapy centres for each step of the process of outlining, planning and delivering IMRT for head and neck cancers. Times were measured for a total of 63 patients; 27 with helical tomotherapy, 37 with dynamic sliding window (26 in one centre, 11 in another) and nine with step-and-shoot.

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At the Ipswich Hospital implementation of intensity-modulated radiotherapy (IMRT) commenced in February 2001 based on an established 3D conformal radiotherapy (3D CRT) service. This paper describes our experiences as we commissioned a fully-integrated IMRT planning and delivery system, and established IMRT within the department. Commissioning measurements incorporated a series of tests to ensure the integrity of the system and form the basis of routine quality assurance (QA) procedures.

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A new drug, trans sodium crocetinate (TSC), has been suggested for use in resuscitation after trauma. TSC has been shown to increase survival in a rat model of hemorrhagic shock. It also results in an increase in blood pressure and a decrease in plasma lactate levels when given immediately after hemorrhage.

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A simple method for directly measuring the reference air kerma rate from J-type 137Cs sources using a Farmer 2571 chamber has been evaluated. The method is useful as an independent means of verifying manufacturers' test data.

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Measurements of the high contrast spatial resolution and contrast-to-noise ratio of the production standard Eliav "PORTpro" portal imaging system have been made using a commercially available quality assurance phantom. The spatial resolution of the images is comparable with published data for other commercial systems, but somewhat lower than that published previously for the prototype of this system. These data may be of use to those involved in the selection, commissioning or quality assurance testing of electronic portal imaging systems.

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The main manifestation of cystic fibrosis (CF) of the lungs is an obstructive ventilation disturbance. The fact that the administration of atropine improves pulmonary function in patients with CF suggests a vagal mechanism for the development of bronchal obstruction. In a single-blind, placebo-controlled study, we investigated the effect of 250 micrograms of an inhalation solution of the anticholinergic substance ipatropium bromide (IB) on the pulmonary function of 11 patients with CF (age range: 8 to 29 years).

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Antenatal steroid therapy reduces the incidence of respiratory distress syndrome (RDS) in premature infants. However, animal studies showed a decrease in lung cell number and lower lung weights in fetal rabbits exposed to hydrocortisone. This prompted us to measure flows and lung volumes (by spirometry and helium-dilution method) in children greater than 6 years who were part of a study by the Collaborative Group on Antenatal Steroid Therapy.

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To assess the role of histamine as a mediator in the response to exercise and isocapnic hyperventilation of cold air (IHCA) in asthma, we studied nine asthmatic subjects, age 13 to 25 years. All had exercise induced asthma (EIA) and positive responses to IHCA. Baseline lung function was measured before standardized challenges with histamine, exercise and IHCA.

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Statistical information relating to the offence of drunken driving in New Zealand is reviewed. The relationship between alcoholism and this offence is discussed. Two groups of offenders who should be dealt with separately can be identified.

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