Automated quality control in computed radiography.

PURPOSE: The purpose of this paper is to describe the automation of quality control procedures on photo-stimulable imaging plates by means of an image-processing tool providing automatic reading of the images and automatic calculation of the quality parameters monitored. MATERIALS AND METHODS: Quality-control procedures were performed according to the main available guidelines. The quality assurance programme was applied to several Kodak and Philips devices in four radiological departments. The automatic image-processing tool was developed using public domain software (Java-based ImageJ software) and contains both reading and computation procedures. RESULTS: The quality checks and algorithms described were successfully applied, proving useful for identification of defective plates and for implementation of the quality assurance programme. The use of automation allowed significant savings in the time required for quality checks. CONCLUSIONS: Completely automated image reading allows substantial economic and human resources savings, as it eliminates much of the transfer, reproduction, processing and filing procedures.

Quantitative assessment of computed radiography quality control parameters.

Quality controls for testing the performance of computed radiography (CR) systems have been recommended by manufacturers and medical physicists' organizations. The purpose of this work was to develop a set of image processing tools for quantitative assessment of computed radiography quality control parameters. Automatic image analysis consisted in detecting phantom details, defining regions of interest and acquiring measurements. The tested performance characteristics included dark noise, uniformity, exposure calibration, linearity, low-contrast and spatial resolution, spatial accuracy, laser beam function and erasure thoroughness. CR devices from two major manufacturers were evaluated. We investigated several approaches to quantify the detector response uniformity. We developed methods to characterize the spatial accuracy and resolution properties across the entire image area, based on the Fourier analysis of the image of a fine wire mesh. The implemented methods were sensitive to local blurring and allowed us to detect a local distortion of 4% or greater in any part of an imaging plate. The obtained results showed that the developed image processing tools allow us to implement a quality control program for CR with short processing time and with absence of subjectivity in the evaluation of the parameters.

Oral food challenges in children in Italy.

BACKGROUND: Epidemiological surveys identify a 900,000-strong potential paediatric population who may self-report with food allergy in Italy. As the reference test is the double-blind, placebo-controlled food challenge for diagnosis, we carried out a nation-wide questionnaire survey of hospital-based paediatric allergy centres between 1 January and 30 June 2003. METHODS: All registered centres received a 27-point questionnaire polling logistics and protocols of oral food challenge. Items polled included medical facilities and personnel, selection of patients, foods tested, blinding, placebo use, evaluation criteria, number of tests and positive outcome rates in 2002. RESULTS: Two hundred and two of 456 responders (44.3%) carried out food challenges (a ratio of one centre to 37,400 children in the general population). 11,728 challenges were performed in 2002 (an average of 58 procedures per centre; range: 1-500) and 3350 procedures were claimed positive (28.6%). Cow's milk was tested by all centres, egg by 77.2%, beef by 19.8% and cereals, peanuts, fish or fruit collectively by 37.6%. Twenty-nine of 202 centres performed blinded tests, 18 of which under double-blinded conditions. In cow's milk challenges, placebos included lyophilized cow's milk capsules, soy formula, extensive whey hydrolysate or extensive casein hydrolysate. CONCLUSION: Our survey reveals great differences in challenge test criteria, facilities and procedures and that many centres perform relatively few procedures. This argues in favour of greater rationalization in the allocation of tertiary-level resources before procedure standardization can be contemplated in the diagnostic workup of food allergy.

Characterization of bovine serum albumin epitopes and their role in allergic reactions.

OBJECTIVE: This review provides updated information on conformational and sequential epitopes identified in bovine serum albumin (BSA) and summarizes available data about the role of structural modifications on BSA antigenicity/allergenicity. DATA SOURCES: Data on beef allergy and BSA antigenicity are reported, with reference both to the basic literature and to clinical results obtained by our group. RESULTS AND DISCUSSION: BSA is an important allergen involved in milk and beef allergy. The presence of conformational epitopes has been suggested by indirect evidence, while at least one sequential epitope has been experimentally identified. The role of structural modifications on BSA antigenicity is discussed as well as the increased tolerance observed in allergic subjects consuming beef as strained (homogenized) and freeze-dried derivatives. CONCLUSION: Study of the molecular characteristics of a known major allergen allows the identification of technological processes that may be capable of improving the tolerance of allergic subjects to a specific food. Even though any hoped for reduced allergenicity must be verified under medical supervision, the use of new products could obviate the need to avoid important foods such as meat in childhood.

Evaluation of residual immunoreactivity in red and white wines clarified with gluten or gluten derivatives.

Gluten or hydrolyzed gluten could be a suitable alternative to animal proteins in the wine clarification process, but their residues could represent a risk for individuals suffering from coeliac disease or allergic to cereal proteins. The aim of this study was to investigate the presence of gluten in wines treated with gluten or its hydrolysate in the clarification process and to assess its antigenicity in commercial products. The presence of residual immunoreactive gluten was evaluated by electrophoresis (SDS-PAGE) and immunoblotting. Data obtained in several red and white wine samples showed that no residue was detectable in any of the red wines. In white wines, gluten reduced the protein content less completely, but most samples showed no immunoreactivity after the wine had been treated with gluten or its derivatives, either alone or combined with bentonite, silica gel or tannins. The use of gluten derivatives coupled with bentonite was the most effective method of removing immunoreactive protein in white wines. In conclusion, the use of gluten derivatives in wine clarification seems to exclude a risk for subjects susceptible to coeliac disease or gluten allergy. However, it is recommended that wine producers continuously monitor the clarification process in order to protect the most sensitive individuals.

Measurement of dose-width product in panoramic dental radiology.

The National Radiological Protection Board has recommended the introduction of dose-width product (DWP) for the measurement of patient dose in panoramic dental radiology. The present work describes a method for measuring DWP using a pencil ionization chamber. The technique was tested on five panoramic dental units; the reproducibility of the method was 5.7%. In order to test the method, DWP was also assessed using thermoluminescent dosemeters and film. The results obtained agreed within 8.6% with those obtained using the pencil ionization chamber method. The proposed method appears to be simple and precise.

[Check of compliance with quality criteria for diagnostic radiographic images in quality control]. / Verifica del rispetto dei livelli diagnostici di riferimento nella radiodiagnostica nell'ambito dei controlli programmati della qualità.

PURPOSE: To devise and implement a programme of measurements to assess the entrance surface dose for a standard-sized patient and to check the compliance with diagnostic reference levels. MATERIAL AND METHODS: Dose evaluation was performed on 40 radiographic instruments. The exposure parameters were collected for the main radiographic procedures (chest, skull, spine, pelvis, abdomen) each performed with instrument on a standard-sized patient. The output of each X-ray tube at 70, 80, 90, 100, 110 and 120 kV was measured with a solid state detector during quality controls. Beam quality and geometric characteristics of the equipment were also determined. The entrance surface dose for a standard patient was assessed for each procedure carried out with the 40 instruments, thus obtaining a total of 155 radiographic techniques. Finally, the method was validated by comparing the values obtained with the solid state and an ionization chamber for X-ray beam detector. RESULTS: The comparison between the solid state detector and the ionisation chamber demonstrated a good agreement. Results show that reference diagnostic levels are respected in most examinations (147/155) even if exposure values do not always comply with those indicated by European guidelines. The measurement programme seems to be applicable in hospital practice where the large number of radiographics instruments and procedures requires the acquisition and processing of a large number of data. CONCLUSIONS: The evaluation of patient dose during quality control is feasible and allows a first check of compliance with reference levels in order to identify which procedures can be optimised by means of more specific measurements and assessments.

[Evaluation of patient doses in interventional radiology]. / Valutazioni di dose al paziente in radiologia interventistica.

PURPOSE: To verify the suitability of indicative quantities to evaluate the risk related to patient exposure, in abdominal and vascular interventional radiology, by the study of correlations between dosimetric quantities and other indicators. MATERIAL AND METHODS: We performed in vivo measurements of entrance skin dose (ESD) and dose area product (DAP) during 48 procedures to evaluate the correlation among dosimetric quantities, and an estimation of spatial distribution of exposure and effective dose (E). To measure DAP we used a transmission ionization chamber and to evaluate ESD and its spatial distribution we used radiographic film packed in a single envelope and placed near the patient's skin. E was estimated by a calculation software using data from film digitalisation. RESULTS: From the data derived for measurements in 27 interventional procedures on 48 patients we obtained a DAP to E conversion factor of 0.15 mSv / Gy cm2, with an excellent correlation (r=.99). We also found a good correlation between DAP and exposure parameters such as fluoroscopy time and number of images. The greatest effective dose was evaluated for a multiple procedure in the hepatic region, with a DAP value of 425 Gy cm2. The greatest ESD was about 550 mGy. For groups of patients undergoing similar interventional procedures the correlation between ESD and DAP had conversion factors from 6 to 12 mGy Gy-1 cm-2. CONCLUSION: The evaluation of ESD and E by slow films represents a valid method for patient dosimetry in interventional radiology. The good correlation between DAP and fluoroscopy time and number of images confirm the suitability of these indicators as basic dosimetric information. All the ESD values found are lower than threshold doses for deterministic effects.