Teletransmission of radiographic images. Preliminary report

A digital system for transmission of images over telephone lines using a 256 X 256 X 6 bits matrix provided for communication between a county hospital and a university hospital is presented. During a three-month period radiologic diagnostic problems encountered in 62 patients (computed tomography in 46 and conventional radiography in 16) were referred by transmitting selected images from each examination. Transmission of computed tomograms was performed without significant degradation of image quality and there was no loss of diagnostic information. Deterioration of image quality was noticed when conventional films especially those of the chest, were digitized and transmitted, though in no instance were they non-diagnostic. The consultations gave valuable information to the transmitting radiologist in approximately 50 per cent of the cases. Review by the consulted radiologists of all original films in each of the examinations 6 months later did not improve the diagnostic results. Thus, a few carefully selected images, digitized and transmitted over telephone lines, may be sufficient for adequate consultation.     

Macroradiography using conventional radiographic X-ray equipment

Macroradiography is a radiographic imaging technique used to increase the size of the image relative to that of the object. Macroradiographic images suffer degradation due mainly to geometric unsharpness (U(g)). U(g) results from the finite size of the focal spot of the X-ray tube. Specialized equipment with a small effective focal spot size (Eff FSS) is generally used to perform macroradiography. The specialized nature of the equipment means macroradiographic examinations are not commonly undertaken. Macroradiographic examinations can also be performed on conventional radiographic equipment because the Eff FSS varies in the X-ray beam along the cathode-anode axis. Calculations and measurements of FSSs at different positions along the cathode-anode direction of the X-ray beam have been made. A simple technique of angling the X-ray tube 10 degrees towards the cathode reduces the Eff FSS in one dimension while still maintaining a vertical central ray. Reduced beam coverage results from this technique and an increase in radiographic exposure is required to compensate for the anode heel effect. Macroradiographic images of line pair phantoms and a hand-wrist phantom, at various tube angles, have been obtained to compare image detail.     

Tomography using a diode-array digital radiographic system

Computer-aided-tomography (CAT) is being widely used in medical diagnostics. CAT has also found a wide acceptance in engineering applications for detecting defects in materials. In the research reported in this paper reconstruction tomography is applied to a linear scanning diode-array digital radiographic (DADR) system. In partic lar the reconstruction uses the filtered back projection technique. The basic difference between the method described here and the procedure used in standard CAT is that the object is rotated, and the x-ray source and the detector array are stationary. The number of views needed and the number of projections required for an acceptable reconstruction are discussed in terms of spatial resolution and time to reconstruct. The C programming language proved to be quicker than FORTRAN. The image resolution was excellent and defects half the pixel size could be visualized.     

Optimising default radiographic exposure factors using Deviation Index

IntroductionRadiographers have a duty to ensure that radiation doses to patients are as low as reasonably achievable. With digital technologies, exposure factors which achieve the optimum balance between image noise and patient dose must be sought. In digital radiography, Deviation Index (DI) values provide the radiographer with feedback on the appropriateness of individual exposures but can also be tracked as part of a departmental quality assurance programme.MethodsIn November 2017, exposure logs were extracted from six digital radiography (DR) x-ray systems, collated and analysed. Five examinations were identified which frequently produced DI values outside the manufacturer's recommended Optimal Range (-3 to +2). Incremental improvements were made to the default exposure settings for these examinations via a cyclical process of modification and re-evaluation. A full data collection exercise was then repeated in April 2019.ResultsAt baseline, 10,658 out of 29,637 (36.0%) exposures had DI values outside the manufacturer's recommended Optimal Range, but for some individual examinations the proportion was as high as 547 out of 725 (74.5%). Following multiple optimisation cycles, the overall proportion of examinations outside the Optimal Range had fallen to 7611 out of 26,759 (28.4%). Default milliampere-seconds (mAs) values for these examinations were reduced by between 22% and 50%.ConclusionA marked reduction in patient doses can be achieved through a departmental programme of DI value monitoring and targeted optimisation of default exposure settings.Implications for practiceDI values should be routinely monitored as part of routine quality assurance programmes. Radiographers have a responsibility to ensure that they possess a clear understanding of DI values and that appropriate exposure settings are selected for each individual patient.     

Coralline hydroxyapatite bone graft substitutes: preliminary report of radiographic evaluation

A new bone graft substitute made by conversion of the calcium carbonate exoskeleton of reef-building sea coral into hydroxyapatite has recently become clinically available. The normal radiographic appearance of two forms of this material is described. In the immediate postoperative period, the exoskeletal architecture of these implants is readily appreciated. With graft incorporation over the ensuing months, their intrinsic structure is gradually lost in association with poor marginal definition. Evolving radiographic findings reflect the biocompatible nature of these implants, which provides the potential for ingrowth of native bone with preservation of the coralline scaffold, resulting in enhanced biomechanical properties.     

Measurement of structural abnormalities in arthritis using radiographic images

This article reviewed the current methods for scoring radiographic abnormalities in RA with emphasis on reliability. There is disagreement on the expected course of RA with usual treatment and there is no clear resolution of this disagreement although several factors that contribute to this disagreement have been identified. Scoring joint damage has been effective in establishing benefit from drug treatment for nine agents, five within the last 3 years. Scoring will continue to be used to examine the benefit of new agents in the immediate years to come. A panel of experienced readers agreed that some repair of erosion damage was seen with available treatment. The extent of damage that is reversible has not been established and the frequency of any degree of repair remains unknown. Several methods of true measurement of erosions and joint space width have been reported. They have not found a place in daily practice or in research studies, probably because experience is too limited to know whether they are more powerful in detecting real progression of disease than scoring methods. Several problems that are related to standardizing methods of measuring joint space width were identified.     

The POEMS syndrome: report of three cases with radiographic abnormalities

Three cases of a unique multisystemic syndrome with polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes (the POEMS syndrome) are presented, along with a review of the literature. Clinical and radiographic features of this syndrome and etiological considerations are discussed. A variety of osteosclerotic lesions, nonspecific pleural effusion and ascites are characteristic radiographic manifestations.     

Nasolabial cyst with radiographic contrast medium: report of two cases

Two cases are presented of a nasolabial cyst (NC) on which a radiographic contrast medium was used in order to define the real extension of the lesion. Use of contrast is important for visualizing the definite extensions of NC primarily in cases when plain radiographs may not show any detectable changes and CT can not be used.     

Accuracy of radiographic caries diagnosis using different X-ray generators

Dental X-ray machines utilizing five different combinations of X-ray generators and tube voltages (Philips Oralix 65 kV, Siemens Heliodent EC 60 kV, Siemens Heliodent 70 kV, Soredex Minray DC 60 kV and Soredex Minray DC 70 kV) were compared with respect to the accuracy of radiographic diagnosis of proximal caries. Nine observers diagnosed proximal caries in radiographs of extracted premolars. The findings of the observers were compared to the actual presence or absence of caries. The ROC-curve technique was used to evaluate differences in diagnostic accuracy between the X-ray machines. The results showed small differences in diagnostic accuracy between the different X-ray generators but they proved to be statistically non-significant.     

Automated perfusion-weighted MRI using localized arterial input functions

PURPOSE: To investigate the utility of an automated perfusion-weighted MRI (PWI) method for estimating cerebral blood flow (CBF) based on localized arterial input functions (AIFs) as compared to the standard method of manual global AIF selection, which is prone to deconvolution errors due to the effects of delay and dispersion of the contrast bolus. MATERIALS AND METHODS: Analysis was performed on spin- and gradient-echo EPI images from 36 stroke patients. A local AIF algorithm created an AIF for every voxel in the brain by searching out voxels with the lowest delay and dispersion, and then interpolating and spatially smoothing them for continuity. A generalized linear model (GLM) for predicting tissue outcome, and MTT lesion volumes were used to quantify the performance of the localized AIF method in comparison with global methods using ipsilateral and contralateral AIFs. RESULTS: The algorithm found local AIFs in each case without error and generated a higher area under the receiver operating characteristic (ROC) curve compared to both global-AIF methods. Similarly, the local MTT lesion volumes had the least mean squared error (MSE). CONCLUSION: Automated CBF calculation using local AIFs is feasible and appears to produce more useful CBF maps.     

Automated generation of curved planar reformations from volume data: method and evaluation

The authors developed and evaluated a method to automatically create interactive vascular curved planar reformations with computed tomographic (CT) angiographic data. The method decreased user interaction time by 86%, from 15 to 2 minutes. Expert reviewers were asked to indicate their confidence in differentiating automatically created images from clinical-quality manually produced images. The area under the receiver operating characteristic curve was 0.45 (95% CI: 0.39, 0.51), and a test of equivalency indicated that reviewers could not distinguish between images. They also graded image quality as equivalent to that with manual methods and found fewer artifacts on automatically created images. Automatic methods rapidly produce curved planar reformations of equivalent quality with reduced time and effort.     

无放射影像异常的颈脊髓损伤7例报告

分析无放射影像异常的颈脊髓损伤７例，探讨其发病机制、损伤的病理基础及临床特点，强调及早了解脊髓损伤原因和程度，可判定预后及选择治疗方式。