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A novel method for producing customized x-ray test objects and clinically realistic phantoms has been developed. Test objects can be created with a drawing software package and the digital images can be printed on a standard inkjet printer but using potassium iodide solution in place of the cartridge's ink. The reproducibility and the consistency, the limiting spatial resolution, the uniformity as well as the potassium iodide thickness per print have been evaluated. The relationship between the number of prints, grey levels and the radiation contrast was investigated and quantified. A copy of the Leeds TO10 contrast detail test object was printed and the x-ray images of the Leeds TO10 and of the printed Leeds TO10 were compared. In addition, the potential use of this method was demonstrated by reproducing a percutaneous transluminal coronary angioplasty clinical digital image. The reproducibility and consistency of this method was found to be better than 0.1%. The limiting spatial resolution of the printer using ink was found to be 3.55 lp mm⁻¹ but it deteriorated when the ink was replaced with potassium iodide and as the print density increases. The uniformity across the printed area was found to be satisfactory although an artefact due to the printer was present in the x-ray images. The comparison between the Leeds TO10 and the printed Leeds TO10 gave differences less than 10%. A good agreement between the clinical image and the printed clinical image was found. In conclusion, the method is a reliable, cost-effective, flexible and alternative way for producing x-ray test objects and clinically related phantoms.

To determine the optimal collimation, pitch and reconstruction interval for CT colonography, 10 spherical polyps between 1 mm and 10 mm diameter and made of tissue equivalent material with a CT number of 40 Hounsfield units (HU) were placed in the colon of an anthropomorphic phantom. The phantom was scanned at slice thicknesses of 3 mm, 5 mm and 7 mm and pitches of 1.0, 1.3, 1.5, 1.7 and 2.0 on an IGE Hispeed advantage system. Images were reconstructed for each scanning parameter at the minimum intervals allowed along the z-axis. The optimum scanning protocol was assessed by measuring maximum contrast between the polyp and air, sensitivity for detection of each polyp along the z-axis, and relative radiation dose. In addition, images were reviewed separately by two radiologists who graded polyp conspicuity as: 0, not seen; 1, faintly seen; 2, well seen. It was found that varying the scanning parameters caused a marked alteration in the maximum contrast between each polyp and air. For example, for the 5 mm polyp, the range of contrasts from best to worst case was 910–490 HU. It was noted that with contrasts of less than 500 HU, polyps were only faintly seen. A slice thickness of 3 mm with a pitch of 2 offers optimal polyp conspicuity with a relatively low radiation dose, we conclude that scanning parameters can be optimized for threshold contrast, radiation dose and subjective conspicuity. We propose an optimal parameter of 3 mm slice thickness and pitch 2.

The aim of this study was to determine the effect of reducing mAs on the diagnostic quality of images and the radiation dose to the orbits in patients undergoing sinus CT. We studied 40 consecutive patients undergoing paranasal sinus CT for inflammatory disease prior to functional endoscopic sinus surgery (FESS). Four groups of 10 patients were scanned at 200 mAs, 150 mAs, 100 mAs and 50 mAs, respectively. Orbital radiation dose was measured using thermoluminescent dosemeters. Images were reviewed independently by two observers who were unaware of the mAs setting used. Image quality was evaluated using a semi-quantitative scoring system for six anatomical structures. The osteomeatal complex, uncinate process, infundibulum, frontal recess, middle turbinate and optic nerve were assessed as: clearly demonstrated (2 points); demonstrated but not clearly visualized (1 point); or not seen (0 points). No significant difference was shown between any of the four groups in terms of image quality according to the scoring system used in this study. Mean radiation dose to the orbit was reduced by 77%, from 13.5 mGy at 200 mAs to 3.1 mGy at 50 mAs (p<0.05). CT of the sinuses can be performed in patients prior to FESS at greatly reduced mAs without loss of diagnostic quality of the images. This is important in reducing the radiation dose to the lens.

Attentional ability in 19 survivors of acute lymphoblastic leukaemia and 19 sibling controls was assessed using a neuropsychological model of attention. Analysis revealed that children who had received treatment for leukaemia exhibited significantly poorer performance on measures of the "focus encode" and "focus execute" elements of attention and on measures of the ability to respond to external cues and feedback. No significant differences in performance were found for measures of sustained attention and the ability to shift attention. These results indicate that children who have received treatment for leukaemia may experience highly specific attentional deficits that could have an impact on academic performance, particularly mathematical and reading skills. It is suggested that this underlying attentional deficit might be the source of the neuropsychological sequelae associated with the disease. Future attempts at remediation should incorporate activities specifically designed to ameliorate focusing difficulties.

A controlled clinical trial was conducted of three methods of closing elective paramedian laparotomy wounds-catgut layer suture alone, catgut layer suture with tension sutures and wire sutures alone. Three hundred and twenty-four patients were entered in the trial. The combined incidence of wound dehiscence and subsequent incisional herniation in patients who did not manifest overt dehiscence in the immediate postoperative period was significantly higher after catgut layer suture alone (14 per cent) than after catgut layer suture with tension stitches (4.8 per cent) or wire sutures alone (0.9 per cent). There seemed to be more wound sespis and sinus formation associated with catgut layer suture and tension sutures than with either of the other methods of closure. In 4 patients a wire suture had to be extracted, because of sinus formation in 2 and on account of pain in 2.

This is the first reported use of low-angle X-ray scattering for the investigation of urinary calculi. Low-angle X-ray scattering (LAXS) measures the diffraction of a broad spectrum of X-rays at a single angle and uses a conventional diagnostic X-ray beam, and could thus be developed for use in vivo. A total of 45 calculi were investigated using this technique. Calcium oxalate stones showed a bimodal signature with peaks of almost even photon energies. Signatures for the other stone types were less well-defined. The results are discussed in more detail below. Our preliminary results show that the technique is capable of distinguishing between calcium oxalate stones and other stone types in vitro. Further work is in progress to correlate the results of this technique with objective parameters of stone hardness.

Energy dispersive x-ray diffraction (EDXRD) has been developed as a tool for the detection of explosives in passenger baggage. The measured spectra result from the combined diffraction from each of the materials within a scattering volume. Multivariate regression was used to identify known components within very noisy data, permitting the rapid detection of explosive materials in the presence of overlying media for security screening applications. Explosives can be positively identified in spectra containing as few as several hundred counts and the error associated with the prediction is consistent from statistically reliable data (10⁶ integrated counts) down to spectra containing in the region of 10³ counts. This analysis can be employed in any situation where qualitative information is required from poor quality spectral data. © 1998 John Wiley & Sons, Ltd.

The helical scanning mode in computed tomography (CT) entails continuous table movement during image acquisition. The projections acquired in this mode will not be consistent with those in the axial scanning mode. A comparison of the helical and axial modes of scanning on the IGE HiSpeed Advantage CT system (software version ZA) has been made using a contrast-detail phantom. Differences seen between the two modes include shadow and streaking artefacts and an increase in the partial volume effect in the helical scan mode.

Abstract: Life history data are presented for a population of vervets, Cercopithecusaethiops sabaeus, in Barbados, West Indies. The data were obtained from two habituated troops and from vervets captured during a large-scale trapping program. Individuals of known age from one troop were weighed periodically, and separate growth curves generated for males and females. The mean weight of captured adult females was 3.3 kg; that of adult males, 5.3 kg. The average age at sexual maturity is estimated at 34 months for females and 60 months for males. Vervets give birth throughout the year, but most infants are born between April and July. The average interbirth interval following a surviving infant is 11.8 months. The mortality of juveniles is heaviest between birth and 2 years of age and decreases thereafter. Males emigrate from their natal troops at sexual maturity and one incident of a juvenile female emigrating is reported.

Three experiments examine features of a simple memory task on which right-handed, right eye dominant subjects have been reported to recall digits projected to the right eye more accurately than those projected simultaneously to the left eye. Superior recall by these subjects of information projected to the right eye was observed only when stimuli projected simultaneously to both eyes were seen as overlapped in the binocular percept. Under monocular presentations, accuracy of recall was not related to the eye with which stimuli were viewed. The binocular oveslap condition has a significance other than that of simply increasing the difficulty of identifying the elements in a visual display for there were no differences in accuracy of recall from each eye when overlapped stimuli were viewed monocularly. More accurate recall of right eye information appears to reflect the resolution of a conflict between inputs from each eye. The possible relation of this finding to cerebral dominance is also discussed. Order of recall in these experiments depended mainly on spatial cues provided by the experimental situation.

Three experiments examine features of a simple memory task on which right-handed, right eye dominant subjects have been reported to recall digits projected to the right eye more accurately than those projected simultaneously to the left eye. Superior recall by these subjects of information projected to the right eye was observed only when stimuli projected simultaneously to both eyes were seen as overlapped in the binocular percept. Under monocular presentations, accurracy of recall was not related to the eye with which stimuli were viewed. The binocular oveslap condition has a significance other than that of simply increasing the difficulty of identifying the elements in a visual display for there were no differences in accuracy of recall from each eye when overlapped stimuli were viewed monocularly. More accurate recall of right eye information appears to reflect the resolution of a conflict between inputs from each eye. The possible relation of this finding to cerebral dominance is also discussed. Order of recall in these experiments depended mainly on spatial cues provided by the experimental situation.

A clean colon is a prerequisite to a successful double contrast barium enema. Two different techniques of colonic lavage have been in use in this hospital for some years, one employing the Henderson colonic lavage machine (MacCarthy's Surgical Division) and the other, a simpler method, which we deem “the shortened preparation”. As the latter technique is more acceptable to the patient, simpler to perform and requires no specialized equipment, we thought a comparison of the results of both techniques would be of interest.The films of the double contrast enemas of 40 outpatients were examined retrospectively. All had been examined using the St. Mark's modification of the Malmo double contrast barium enema (Young, 1964), but taking only double contrast films on six of which the rectum is included. The examinations were selected by one of us (S.F.). Twenty patients from each group, matched for sex and age, were chosen.Preparation before attending the department was similar in both groups, namely three Senokot (SDX) tablets at 21.00 hours two nights before and 1 oz. (28.35 g) of castor oil at 14.00 hours on the day prior to the examination. Apart from an early morning drink, no food was allowed on the day of attendance. 1 mg of Atropine was given orally, unless medically contra-indicated, when the patient arrived in the department.

Ten people met for the first time as trainees after lunch on Thursday, 4 February, 1988 at an hotel near Ipswich. They were to live and work together until teatime on Saturday. Twelve trainers joined them from late afternoon on Friday, staying on after the trainees left, until lunchtime on the Sunday. The occasion was the start of the 1988 vocational training schemes for East Anglia and North East Thames Regions. In this article, J. K. Horrocks and W. R. Allen given an account of what happened during this time, and how people felt about it

Over the last two decades, CSIRO surveys of the seagrass communities in the south-western Gulf of Carpentaria and at Groote Eylandt, the Northern Territory, have provided opportunities for the collection of marine macroalgae from this poorly explored, remote region. Although the cruises did not concentrate on macroalgal communities which typically grow on rocky substrates, 64 specific and subspecific taxa of marine Chlorophyta, Phaeophyceae and Rhodophyta were collected, including 30 species newly recorded for the Gulf. The majority of Gulf species also occur on the tropical eastern Australian coast. One hundred and thirteen macroalgal taxa are now known to occur in the Gulf of Carpentaria, the number from the present study supplemented by collections from the 1948 Arnhem Land Expedition and from an ethnobiological study on Groote Eylandt during the 1970s. Twelve species are recorded by all three Gulf studies and 23 species are reported by two studies. The relatively low number of species common to more than one study is thought to result from each study's narrow sampling window which fails to adequately document the considerable spatial and temporal variability of macroalgal species. Accordingly, the number of species presently recorded for the Gulf is considered to be an underestimate of macroalgal biodiversity for the region. It is clear that further detailed taxonomic and ecological investigations are urgently required before the full extent of macroalgal biodiversity in tropical Australia can be appreciated.