LOCAL DRLS FOR PAEDIATRIC CT EXAMINATIONS BASED ON SIZE-SPECIFIC DOSE ESTIMATES IN KERMANSHAH, IRAN

Due to the radiosensitivity of paediatric patients to X-ray, it is necessary to survey the paediatric DRLs using size-specific dose estimates (SSDE). In the present study, we determined the local diagnostic reference levels (DRLs) for paediatric chest, head and abdomen-pelvis CT examinations and their Surview scans in Kermanshah city, Iran. For ≤1 year, 1-5 years, 5-10 years and 10-15 years the DRLs (mGy) based on SSDE were determined N/A, 6.00, 6.25, 8.27 for abdomen-pelvis, and 8.74, 7.45, 11.15, 10.45 for chest and 19.05, 18.33, 18.22, 20.14 for head examinations, respectively. The differences between body size and default phantom defined in CT scanners are significant and should be considered when determining the DRLs. Based on our findings, use of CTDIv and SSDE parameters for determining DRLs leads to significant different results in children; thus SSDE is suggested as a more accurate index than CTDIV for establishing DRLs in paediatric CT examinations.

Reducing risk in the emergency department: a 12-month prospective longitudinal study of radiographer preliminary image evaluations

INTRODUCTION

Innovations are necessary to accommodate the increasing demands on emergency departments whilst maintaining a high level of patient care and safety. Radiographer Preliminary Image Evaluation (PIE) is one such innovation. The purpose of this study was to determine the accuracy of radiographer PIE in clinical practice within an emergency department over 12 months.

METHODS

A total of 6290 radiographic examinations were reviewed from 15 January 2016 to 15 January 2017. The range of adult and paediatric examinations incorporated in the review included the appendicular and axial skeleton including the chest and abdomen. Each examination was compared to the radiologist's report this allowed calculated mean sensitivity and specificity values to indicate if the radiographer's PIE was of a true negative/positive or false negative/positive value. Cases of no PIE participation or series' marked as unsure for pathology by the radiographer were also recorded. This allowed mean sensitivity, specificity and diagnostic accuracy to be calculated.

RESULTS

The study reported a mean ± 95% confidence level (standard deviation) for sensitivity, specificity, accuracy, no participation and unsure of 71.1% ± 2.4% (6.1), 98.4% ± 0.04% (0.9), 92.0% ± 0.68% (1.9), 5.1% (1.6) and 3.6% (0.14) respectively.

CONCLUSIONS

This study has demonstrated that the participating radiographers provided a consistent PIE service while maintaining a reasonably high diagnostic accuracy. This form of image interpretation can complement an emergency referrer's diagnosis when a radiologist's report is unavailable at the time of patient treatment. PIE promotes a reliable enhancement of the radiographer's role with the multi-disciplinary team.

ABDOMEN-PELVIS COMPUTED TOMOGRAPHY PROTOCOL OPTIMIZATION: AN IMAGE QUALITY AND DOSE ASSESSMENT

Computed tomography (CT) has a high level of sensitivity and specificity for the diagnosis and follow-up of pathologies of the abdomen-pelvis region. Some features, such as automatic tube current modulation (ATCM), permits the acquisition of quality images with low radiation doses. This study evaluated the image quality and radiation dose of abdomen-pelvis CT protocols with ATCM technique. Were performed five CT protocols using 16-slice and 64-slice scanners, an anthropomorphic phantom for dosimetric measurements, an analytical phantom and retrospective examinations for image quality analysis. Were found significant reduction in effective dose. The highest absorbed doses were found in the stomach and spleen (56.1 and 47.2 mGy, respectively). Objective parameters as noise, low contrast and spatial resolution did not significantly differ between the protocols (p > 0.05). All protocols received the range of 'Optimum/Acceptable' in patient's image quality analysis. This methodology can be reproduced in any clinical routine to optimize CT protocols.

RADIATION DOSE DETERMINATION IN ABDOMINAL CT EXAMINATIONS OF CHILDREN AT SUDANESE HOSPITALS USING SIZE-SPECIFIC DOSE ESTIMATES

In this study, we thought to estimate the radiation exposure of children undergoing multi-detector CT examinations using size-specific dose estimates (SSDE). Console-displayed volume computed tomography dose index (CTDIvol) were recorded for a total of 78 paediatric abdominal CT examinations performed in six hospitals. Measurements of the patient diameters were taken from the mid-slice location on the transverse and scout CT images. Size-specific conversion coefficients were used to translate CTDIvol to the SSDE, according AAPM Report 204. For children aged 0-1 y, CTDIvol, SSDEtrans (from transverse images) and SSDEsco (from scout images) were: 12.80 ± 16.10, 14.43 ± 13.22; and 14.37 ± 13.03 mGy; respectively. For children aged 1-5 y, CTDIvol, SSDEtrans and SSDEsco were: 12.11 ± 14.47, 18.8 ± 18.61 and 16.51 ± 13.55 mGy; respectively. The obtained doses are higher than the corresponding diagnostic reference levels. SSDE increase with patient size as results of tube current modulation and is therefore a valuable tool for dose optimisation.

Reliability of Radiomic Features Across Multiple Abdominal CT Image Acquisition Settings: A Pilot Study Using ACR CT Phantom

We studied the reliability of radiomic features on abdominal computed tomography (CT) images reconstructed with multiple CT image acquisition settings using the ACR (American College of Radiology) CT Phantom. Twenty-four sets of CT images of the ACR CT phantom were attained from a GE Discovery 750HD scanner using 24 different image acquisition settings, combinations of 4 tube currents (25, 50, 100, 200 Effective mAs), 3 slice thicknesses (1.25, 2.5, 5 mm), and 2 convolution kernels (STANDARD and SOFT). Polyethylene (-95 HU) and acrylic (120 HU) of the phantom model were selected for calculating real feature value; a noise-free, computer-generated phantom image series that reproduced the 2 objects and the background was used for calculating reference feature value. Feature reliability was defined as the degree of predicting reference feature value from real feature value. Radiomic features mean, std, skewness, kurtosis, gray-level co-occurrence matrix (GLCM)-energy, GLCM-contrast, GLCM-correlation, GLCM-homogeneity were investigated. The value of R2 ≥ 0.85 was considered to be of high reliability. The reliability of mean and std were high across all image acquisition settings. At 200 Effective mAs, all features except GLCM-homogeneity showed high reliability, whereas at 25 Effective mAs, most features (except mean and std) showed low reliability. From high to low, reliability was ranked in the following order: mean, std, skewness, kurtosis, GLCM-energy, correlation, contrast and homogeneity. CT image acquisition settings affected the reliability of radiomic features. High reliable features were attained from images reconstructed at high tube current and thick slice thickness.

Society of Abdominal Radiology disease-focused panel on renal cell carcinoma: update on past, current, and future goals

The disease-focused panel (DFP) program was created by the Society of Abdominal Radiology (SAR) as a mechanism to "improve patient care, education, and research" in a "particular disease or a particular aspect of a disease". The DFP on renal cell carcinoma (RCC) was proposed in 2014 and has been functional for 4 years. Although nominally focused on RCC, the scope of the DFP has included indeterminate renal masses because many cannot be assigned a specific diagnosis when detected. Since its founding, the DFP has been active in a variety of clinical, research, and educational projects to optimize the care of patients with known or suspected RCC. The DFP is utilizing multi-institutional and cross-disciplinary collaboration to differentiate benign from malignant disease, optimize the management of early stage RCC, and ultimately to differentiate indolent from aggressive cancers. Several additional projects have worked to develop a quantitative biomarker that predicts metastatic RCC response to anti-angiogenic therapy. While disease focus is the premise by which all DFPs are created, it is likely that in the future the RCC DFP will need to expand or create new panels that will focus on other specific aspects of RCC-a result that the program's founders envisioned. New knowledge creates a need for more focus.

Assessment of image quality in abdominal CT: potential dose reduction with model-based iterative reconstruction

PURPOSE

To estimate potential dose reduction in abdominal CT by visually comparing images reconstructed with filtered back projection (FBP) and strengths of 3 and 5 of a specific MBIR.

MATERIAL AND METHODS

A dual-source scanner was used to obtain three data sets each for 50 recruited patients with 30, 70 and 100% tube loads (mean CTDIvol 1.9, 3.4 and 6.2 mGy). Six image criteria were assessed independently by five radiologists. Potential dose reduction was estimated with Visual Grading Regression (VGR).

RESULTS

Comparing 30 and 70% tube load, improved image quality was observed as a significant strong effect of log tube load and reconstruction method with potential dose reduction relative to FBP of 22-47% for MBIR strength 3 (p < 0.001). For MBIR strength 5 no dose reduction was possible for image criteria 1 (liver parenchyma), but dose reduction between 34 and 74% was achieved for other criteria. Interobserver reliability showed agreement of 71-76% (κw 0.201-0.286) and intra-observer reliability of 82-96% (κw 0.525-0.783).

CONCLUSION

MBIR showed improved image quality compared to FBP with positive correlation between MBIR strength and increasing potential dose reduction for all but one image criterion.

KEY POINTS

• MBIR's main advantage is its de-noising properties, which facilitates dose reduction. • MBIR allows for potential dose reduction in relation to FBP. • Visual Grading Regression (VGR) produces direct numerical estimates of potential dose reduction. • MBIR strengths 3 and 5 dose reductions were 22-34 and 34-74%. • MBIR strength 5 demonstrates inferior performance for liver parenchyma.

DETERMINATION OF NATIONAL DIAGNOSTIC REFERENCE LEVELS IN COMPUTED TOMOGRAPHY EXAMINATIONS OF IRAN BY A NEW QUALITY CONTROL-BASED DOSE SURVEY METHOD

National diagnostic reference levels (NDRLs) of Iran were determined for the four most common CT examinations including head, sinus, chest and abdomen/pelvis. A new 'quality control (QC)-based dose survey method', as developed by us, was applied to 157 CT scanners in Iran (2014-15) with different slice classes, models and geographic spread across the country. The NDRLs for head, sinus, chest and abdomen/pelvis examinations are 58, 29, 12 and 14 mGy for CTDIVol and 750, 300, 300 and 650 mGy.cm for DLP, respectively. The 'QC-based dose survey method' was further proven that it is a simple, accurate and practical method for a time and cost-effective NDRLs determination. One effective approach for optimization of the CT examination protocols at the national level is the provision of an adequate standardized training of the radiologists, technicians and medical physicists on the patient radiation protection principles and implementation of the DRL concept in clinical practices.

Determination of Examination-Specific Diagnostic Reference Level in Computed Tomography by A New Quality Control-Based Dose Survey Method

A new "quality-control-based (QC-based) dose survey method" has been developed for determination of diagnostic reference levels (DRL) in Computed Tomography (CT) examinations. The "QC-based dose survey method" is based on the use of retrospective data in the QC documents and reports, which are typically available from the National Regulatory Authority database. The method was applied to 70 CT scanners in Tehran, Iran, by using the available QC reports from the database. The commonly used "data collection method" was also applied by filling each questionnaire on-site to validate the new method. Using the new QC-based and data collection methods, the DRLs of four common CT examinations: head, sinus, chest, and abdomen/pelvis were determined and compared. The DRLs determined by the "QC-based method" for head, sinus, chest, and abdomen/pelvis are 59, 29, 10, and 13 mGy, respectively, for the volume computed tomography dose index (CTDIVol) and 834, 235, 233, and 522 mGy-cm for the dose length product (DLP), respectively. The difference between the DRLs obtained by the two methods is on the average 6.7 ± 5.7%, which is within the acceptance tolerance level of the IAEA for QC dosimetry tests. The "QC-based dose survey method" is believed to be an effective alternative method to the other commonly used "data collection" and "direct dose measurement method" for determination of CT examination DRLs. This new method has unique characteristics such as simplicity, time and cost effectiveness, highly reduced clinical interruptions and collaborations, and potential for large-scale surveys with capability for more frequent review of national DRL values.

Emergency Room Plain Radiograph Imaging Study Indications: An Analysis of Quality and Trends at a Large Academic Medical Center

RATIONALE AND OBJECTIVES

This study aimed to assess the quality of and analyze trends among clinical indications received for emergency room radiograph studies.

MATERIALS AND METHODS

Clinical indications provided by the emergency room and rapid care for consecutive chest, abdominal, and musculoskeletal radiographs were reviewed. Chart review was performed to analyze the provided indications compared to clinical information known to the ordering providers. Chest and abdominal radiograph indications were graded according to symptoms and physical examination signs and relevant past medical history. Musculoskeletal indications were graded according to symptoms, mechanism of injury, and positive physical examination findings. Each study indication was graded on a scale from 0 to 2 according to scales modified from those of prior published studies. Grades were further stratified according to ordering location, time of shift, ordering provider level, and specific anatomy involved.

RESULTS

For chest and abdomen studies, mean scores for symptom and physical examination and provided past medical history grades were 1.16 and 0.36, respectively. There was a trend toward a significant difference in mean medical history grades among ordering provider levels. For musculoskeletal studies, mean scores for symptom, mechanism, and physical examination grades were 1.04, 0.89, and 0.51, respectively. Mean symptom and examination grades for physician extenders were significantly less than those of attendings and residents. Mean symptom and mechanism grades for extremity studies were significantly less than those for spinal studies.

CONCLUSIONS

For plain radiographs ordered through the emergency department, certain critical pieces of study indications tended to be underreported relative to other components. Furthermore, significant differences in select categories were seen among ordering provider levels and anatomic location.

Evaluation of dose-area product of common radiographic examinations towards establishing a preliminary diagnostic reference levels (PDRLs) in Southwestern Nigeria

In Nigeria, a large number of radiographic examinations are conducted yearly for various diagnostic purposes. However, most examinations carried out do not have records of doses received by the patients, and the employed exposure parameters used are not documented; therefore, adequate radiation dose management is hin-dered. The aim of the present study was to estimate the dose-area product (DAP) of patients examined in Nigeria, and to propose regional reference dose levels for nine common examinations (chest PA, abdomen AP, pelvis AP, lumbar AP, skull AP, leg AP, knee AP, hand AP, and thigh AP) undertaken in Nigeria. Measurement of entrance surface dose (ESD) was carried out using thermoluminescent dosimeter (TLD). Measured ESDS were converted into DAP using the beam area of patients in 12 purposely selected hospitals. Results of the study show that the maximum/ minimum ratio ranged from 3 for thigh AP to 57 in abdomen AP. The range of determined mean and 75th percentile DAPs were 0.18-17.16, and 0.25-28.59 Gy cm2, respectively. Data available for comparison show that 75th percentile DAPs in this study (in chest PA, abdomen AP, pelvis AP, lumbar AP) are higher than NRPB-HPE reference values. The DAP in this study is higher by factor of 31.4 (chest PA), 9.9 (abdomen AP), 2.2 (pelvis AP), and 2.1 (lumbar AP) than NRPB-HPE values. The relative higher dose found in this study shows nonoptimization of practice in Nigeria. It is expected that regular dose auditing and dose optimization implementation in Nigeria would lead to lower DAP value, especially in abdomen AP. The 75th percentile DAP distribution reported in this study could be taken as regional diagnostic reference level in the Southwestern Nigeria; however, a more extensive nationwide dose survey is required to establish national reference dose.

Evaluation of digital radiography practice using exposure index tracking

Some digital radiography (DR) detectors and software allow for remote download of exam statistics, including image reject status, body part, projection, and exposure index (EI). The ability to have automated data collection from multiple DR units is conducive to a quality control (QC) program monitoring institutional radiographic exposures. We have implemented such a QC program with the goal to identify outliers in machine radiation output and opportunities for improvement in radiation dose levels. We studied the QC records of four digital detectors in greater detail on a monthly basis for one year. Although individual patient entrance skin exposure varied, the radiation dose levels to the detectors were made to be consistent via phototimer recalibration. The exposure data stored on each digital detector were periodically downloaded in a spreadsheet format for analysis. EI median and stan-dard deviation were calculated for each protocol (by body part) and EI histograms were created for torso protocols. When histograms of EI values for different units were compared, we observed differences up to 400 in average EI (representing 60% difference in radiation levels to the detector) between units nominally cali-brated to the same EI. We identified distinct components of the EI distributions, which in some cases, had mean EI values 300 apart. Peaks were observed at the current calibrated EI, a previously calibrated EI, and an EI representing computed radiography (CR) techniques. Our findings in this ongoing project have allowed us to make useful interventions, from emphasizing the use of phototimers instead of institutional memory of manual techniques to improvements in our phototimer calibration. We believe that this QC program can be implemented at other sites and can reveal problems with radiation levels in the aggregate that are difficult to identify on a case-by-case basis.

Prefecture-wide multi-centre radiation dose survey as a useful tool for CT dose optimisation: report of Gunma radiation dose study

The aim of this study was to verify the usefulness for the dose optimisation of setting a diagnostic reference level (DRL) based on the results of a prefecture-wide multi-centre radiation dose survey and providing data feedback. All hospitals/clinics in the authors' prefecture with computed tomography (CT) scanners were requested to report data. The first survey was done in July 2011, and the results of dose-length products (DLPs) for each CT scanner were fed back to all hospitals/clinics, with DRL set from all the data. One year later, a second survey was done in the same manner. The medians of DLP in the upper abdomen, whole body and coronary CT in 2012 were significantly smaller than those of the 2011 survey. The interquartile ranges of DLP in the head, chest, pelvis and coronary CT were also smaller in 2012. Radiation dose survey with data feedback may be helpful for CT dose optimisation.

Establishment of diagnostic reference levels for CT trunk examinations in the western region of Saudi Arabia

Diagnostic reference levels (DRLs) are an important optimisation tool, which aid in identifying abnormally high dose levels. These are currently not available in Saudi Arabia, and this research aims to remedy this. CT dose data (DLP and CTDIvol) were collected for a minimum number of 10 adult patients of average size (60-80 kg) presenting for a range of CT examinations from public hospitals in the western region of Saudi Arabia. These include routine chest, high-resolution chest (HRCT), pulmonary angiography (CTPA), abdomen and pelvis (AP) and the combined chest, abdomen and pelvis (CAP) CT examinations. Mean values for each site were calculated, and the 75th percentile of DLP and CTDIvol was used as a basis for DRLs. Data for 550 patients were collected from 14 hospitals over a 7-month period. The rounded third-quartile CTDIvol and DLP were 18 mGy and 630 mGy cm(-1) for chest CT, 20 mGy and 600mGy cm(-1) for HRCT, 18 mGy and 480 mGy cm(-1) for CTPA, 15 mGy and 800 mGy cm(-1) for AP, and 16 mGy and 1040 mGy cm(-1) for CAP, respectively. Regional DRLs have been proposed from this study. Dose variations across CT departments have identified an urgent need for optimisation to improve distribution of observed doses for CT examinations.

A Comprehensive CT Dose Reduction Program Using the ACR Dose Index Registry

PURPOSE

The purpose of this article is to demonstrate the role of the ACR Dose Index Registry(®) (DIR) in a dose reduction program at a large academic health care system.

METHODS

Using the ACR DIR, radiation doses were collected for four common CT examination types (head without contrast, chest with contrast, chest without contrast, and abdomen and pelvis with contrast). Baseline analysis of 7,255 CT examinations from seven scanners across the institution was performed for the period from December 1, 2011, to March 15, 2012. A comprehensive dose reduction initiative was guided by the identification of targets for dose improvement from the baseline analysis. Data for 14,938 examinations from the same seven scanners were analyzed for the postimplementation period of January 1, 2013, to July 1, 2013.

RESULTS

The program included protocol changes, iterative reconstruction, optimization of scan acquisition, technologist education, and continuous monitoring with feedback tools. Average decrease in median dose-length product (DLP) across scanners was 30% for chest CT without contrast, 29% for noncontrast head CT, 26% for abdominal and pelvic CT with contrast, and 10% for chest CT with contrast. Compared with average median DLP in the ACR DIR, the median institution-wide CT DLPs after implementation were lower by 33% for chest CT without contrast, 32% for chest CT with contrast, 26% for abdominal and pelvic CT with contrast, and 6% for head CT without contrast.

CONCLUSIONS

A comprehensive CT dose reduction program using the ACR DIR can lead to substantial dose reduction within a large health care system.

Radiation dose levels for conventional chest and abdominal X-ray procedures in elected hospitals in Sudan

This study aimed to assess patient entrance surface air kerma (ESAK) during chest and abdominal X-ray procedures in screen film radiography (SFR) and computed radiography (CR) to establish dose reference levels. Patients' doses were measured in five hospitals for a total of 196 patients. ESAK was calculated from exposure parameters using DosCal software. The X-ray tube output (mGy mAs(-1)), accuracy of exposure factors, linearity and reproducibility were measured using an Unfors Xi dosimeter. The overall mean and range of ESAK during chest X-ray were 0.6 ± 0.3 (0.1-1.3) mGy, while for abdominal X-rays they were 4.0 ± 3.2 (1.3-9.2) mGy. Hospital with a CR system was found to use relatively higher doses. Dose values for abdominal X-ray procedures were comparable with previous studies. The dose for chest X-ray procedure was higher by a factor of 2-3 compared with the current international reference levels.

Evaluation of organ doses in adult and paediatric CT examinations based on Monte Carlo simulations and in-phantom dosimetry

The aim of this study was to validate the computed tomography dose index (CTDI) and organ doses evaluated by Monte Carlo simulations through comparisons with doses evaluated by in-phantom dosimetry. Organ doses were measured with radio-photoluminescence glass dosemeter (RGD) set at various organ positions within adult and 1-y-old anthropomorphic phantoms. For the dose simulations, the X-ray spectrum and bow-tie filter shape of a CT scanner were estimated and 3D voxelised data of the CTDI and anthropomorphic phantoms from the acquired CT images were derived. Organ dose simulations and measurements were performed with chest and abdomen-pelvis CT examination scan parameters. Relative differences between the simulated and measured doses were within 5 % for the volume CTDI and 13 % for organ doses for organs within the scan range in adult and paediatric CT examinations. The simulation results were considered to be in good agreement with the measured doses.

Local diagnostic reference level based on size-specific dose estimates: assessment of pediatric abdominal/pelvic computed tomography at a Japanese national children's hospital

BACKGROUND

A child's body size is not accurately reflected by volume CT dose index (CTDIvol) and dose-length product (DLP). Size-specific dose estimation (SSDE) was introduced recently as a new index of radiation dose. However, it has not yet been established as a diagnostic reference level (DRL).

OBJECTIVE

To calculate the SSDE of abdominal/pelvic CT and compare the SSDE with CTDIvol. To calculate the DRLs of CTDIvol and SSDE. Our hypotheses are: SSDE values will be greater than CTDIvol, and our DRL will be smaller than the known DRLs of other countries.

MATERIALS AND METHODS

The CTDIvol and DLP of 117 children who underwent abdominal/pelvic CT were collected retrospectively. The SSDE was calculated from the sum of the lateral and anteroposterior diameters. The relationships between body weight and effective diameter and between effective diameter and CTDIvol/SSDE were compared. Further, the local DRL was compared with the DRLs of other countries.

RESULTS

Body weight and effective diameter and effective diameter and SSDE were positively correlated. In children ages 1, 5 and 10 years, the SSDE is closer to the exposure dose of CTDIvol for the 16-cm phantom, while in children ages 15 years, the SSDE falls between CTDIvol for the 16-cm phantom and that for the 32-cm phantom. The local DRL was lower than those of other countries.

CONCLUSION

With SSDE, the radiation dose increased with increasing body weight. Since SSDE takes body size into account, it proved to be a useful indicator for estimating the exposure dose.

Towards dose reduction in CT: patient radiation dose assessment for CT examinations at university health center in Canada and comparison with national diagnostic reference levels

Dose indicators such as the computed tomography dose index (CTDI) and dose-length product (DLP) were gathered for all routine abdomen-pelvis, chest and head examinations performed on all computed tomography (CT) scanners at a University Health Center (UHC) in Canada. These indicators were analysed and compared with the range of diagnostic reference levels (DRLs) suggested by Health Canada and with DRLs in other countries. Mean DLP values varied from one scanner to another, but mean values at the UHC (750 mGy cm(-1) for abdomen-pelvis CT, 349 mGy cm(-1) for chest CT and 1181 mGy cm(-1) for head CT) were all below the upper limit of the range of DRLs suggested by Health Canada. Local DRLs at the UHC were set to 810 mGy cm(-1) for abdomen-pelvis CT, 345 mGy cm(-1) for chest CT and 1205 mGy cm(-1) for head CT. Results, however, show the need for protocols revisions, since some scanners exhibit mean DLP values slightly below or above the upper limit of the range of DRLs suggested by Health Canada.

Ionizing radiation in abdominal CT: unindicated multiphase scans are an important source of medically unnecessary exposure

PURPOSE

CT radiation exposure has come under increasing scrutiny because of dramatically increased utilization. Multiphase CT studies (repeated scanning before and after contrast injection) are a potentially important, overlooked source of medically unnecessary radiation because of the dose-multiplier effect of extra phases. The purpose of this study was to determine the frequency of unindicated multiphase scanning and resultant excess radiation exposure in a sample referral population.

METHODS

Abdominal and pelvic CT examinations (n = 500) performed at outside institutions submitted for tertiary interpretation were retrospectively reviewed for (1) the appropriateness of each phase on the basis of clinical indication and ACR Appropriateness Criteria(®) and (2) per phase and total radiation effective dose.

RESULTS

A total of 978 phases were performed in 500 patients; 52.8% (264 of 500) received phases that were not supported by ACR criteria. Overall, 35.8% of phases (350 of 978) were unindicated, most commonly being delayed imaging (272 of 350). The mean overall total radiation effective dose per patient was 25.8 mSv (95% confidence interval, 24.2-27.5 mSv). The mean effective dose for unindicated phases was 13.1 mSv (95% confidence interval, 12.3-14.0 mSv), resulting in a mean excess effective dose of 16.8 mSv (95% confidence interval, 15.5-18.3 mSv) per patient. Unindicated radiation constituted 33.3% of the total radiation effective dose in this population. Radiation effective doses exceeding 50 mSv were found in 21.2% of patients (106 of 500).

CONCLUSIONS

The results of this study suggest that a large proportion of patients undergoing abdominal and pelvic CT scanning receive unindicated additional phases that add substantial excess radiation dose with no associated clinical benefit.

Entrance surface dose of the common radiological investigations in Abuth, Zaria

The entrance surface Dose (ESD) was determined among patients who presented for routine radiological examinations using thermoluminescent dosimeter (TLD) chips placed on averagely built adult [(30 cm) chest width, 60-90kg weight and 20-40years)] by multiplying the incident dose/entrances dose by the back scattered factor [BSF] gotten from an experiment. The values obtained from ESD measurements are as follows 8.03 mGy for Abdomen, 0.13 mGy for chest AP, 0.69 mGy for chest lateral, 0.5 mGy for cervical spine; AP: 0.38 mGy for cervical spine lateral; 4.75 mGy for hip AP: 12.83 mGy for hip lateral: 5.74mGy for lumbar spine, AP lumbar spine lateral is 15.15 mGy. 1.38m Gy is for pelvis AP. 2.93mGy for skull AP/PA 1.2mGy for skull lateral, 5.46mGy for thorax AP, while the lateral is 14.90m Gy. The average dose value is 9.28mGy Range 0.13-14.90mGy (Percentage standard error; +/- 1.45). From this studies Radiation doses delivered for routine investigations are generally lower than IAEA reference doses. Using these values for optimization of radiation protection practices for patient should be ensured since it does not rule out options for stochastic radiation.

Survey of patient doses from conventional diagnostic radiographic examinations in Syria

The aim of this study is to evaluate radiation doses received by adult patients undergoing eight routine common types of X-ray examination in Syria. These types cover chest PA, lumbar spine PA, lumbar spine LAT, urography, abdomen, pelvis and hip, head and shoulder. This work consisted of measurements for 926 X-ray examinations for patients in 26 governmental hospitals. The mean and third quartile of the dose area product (DAP) to each patient per examination have been measured. The corresponding average effective doses have been computed from the DAP measurement for each examination using NRPP X-Dose software. Comparison of the results was done with those from similar surveys published by the United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2000, 2007). The present measurements will provide a useful baseline to establish, for the first time, national diagnostic reference levels. These results can be used in the future to evaluate the collective dose to the population from medical exposure and the radiation risks from the various radiological procedures.

Nationwide surveys of chest, abdomen, lumbosacral spine radiography, and upper gastrointestinal fluoroscopy: a summary of findings

This paper reports findings from Nationwide Evaluation of X-ray Trends surveys conducted in 2001, 2002, and 2003 of clinical facilities that perform routine radiographic examinations of the adult chest, abdomen, lumbosacral spine, and upper gastrointestinal fluoroscopic examinations. Randomly identified clinical facilities were surveyed in approximately 40 participating states. For the surveyed radiographic exams, additional facilities that use computed radiography or digital radiography were surveyed to ensure adequate sample sizes for determining comparative statistics. State radiation control personnel performed site visits and collected data on patient exposure, radiographic/fluoroscopic technique factors, image quality, and quality-control and quality-assurance practices. Results of the NEXT surveys are compared with those of previous surveys conducted in 1964 and 1970 by the U.S. Public Health Service and the Food and Drug Administration. An estimated 155 million routine adult chest exams were performed in 2001. Average patient entrance skin air kerma from chest radiography at facilities using digital-based imaging modalities was found to be significantly higher (p < 0.001), but not so for routine abdomen or lumbosacral spine radiography. Digital-based imaging showed a substantial reduction in patient exposure for the radiographic portion of the routine upper gastrointestinal fluoroscopy exam. Long-term trends in surveyed diagnostic examinations show that average patient exposures are at their lowest levels. Of concern is the observation that a substantial fraction of surveyed non-hospital sites indicated they do not regularly have a medical physics survey conducted on their radiographic equipment. These facilities are likely unaware of the radiation doses they administer to their patients.

[Comparative evaluation of six different body regions of the dog using analog and digital radiography]

In this study the quality of digital and analog radiography in dogs was compared. For this purpose, three conventional radiographs (varying in exposure) and three digital radiographs (varying in MUSI-contrast [MUSI = MUlti Scale Image Contrast], the main post-processing parameter) of six different body regions of the dog were evaluated (thorax, abdomen, skull, femur, hip joints, elbow). The quality of the radiographs was evaluated by eight veterinary specialists familiar with radiographic images using a questionnaire based on details of each body region significant in obtaining a radiographic diagnosis. In the first part of the study the overall quality of the radiographs was evaluated. Within one region, 89.5% (43/48) chose a digital radiograph as the best image. Divided into analog and digital groups, the digital image with the highest MUSI-contrast was most often considered the best, while the analog image considered the best varied between the one with the medium and the one with the longest exposure time. In the second part of the study, each image was rated for the visibility of specific, diagnostically important details. After summarisation of the scores for each criterion, divided into analog and digital imaging, the digital images were rated considerably superior to conventional images. The results of image comparison revealed that digital radiographs showed better image detail than radiographs taken with the analog technique in all six areas of the body.

Plain abdominal radiography with transabdominal native tissue harmonic imaging ultrasonography vs unenhanced computed tomography in renal colic

OBJECTIVE

To compare plain film kidney, ureter and bladder radiography (KUB) with transabdominal native tissue harmonic imaging ultrasonography (NTHI-US) vs unenhanced computed tomography (CT) for the diagnosis of urinary calculi in patients with acute flank pain.

PATIENTS AND METHODS

In all, 112 patients who presented to the urological department with clinical suspicion of ureteric calculi were included. These patients had KUB with NTHI-US and unenhanced CT. Of the 112 patients, 14 were lost to follow-up and therefore excluded. For the remaining 98 patients (53 men, 45 women; mean age 43.3 years, range: 19-74) the KUB with NTHI-US findings were compared with the CT findings, which served as the 'gold standard'.

RESULTS

In all, 75 patients were confirmed to have ureteric calculi. KUB with transabdominal NTHI-US detected 72 of the 75 patients with calculi (sensitivity 96%, specificity 91%, and accuracy 95%). Unenhanced CT detected urolithiasis in all 75 patients (sensitivity, specificity and accuracy of 100%). Both techniques showed further extra-urinary pathologies.

CONCLUSION

This prospective study shows that CT is the most accurate technique for detecting urolithiasis. However, KUB with transabdominal NTHI-US is an alternative to unenhanced CT with comparable results.

[Acute abdomen film: is there hope of changing referring patterns?]

An abdomen radiograph (KUB) is frequently requested by ER physicians as part of the inital work-up of patients. However, other imaging studies are now routinely available in the acute setting that may make the KUB an obsolete and unnecessary examination. The first part of this study was to assess the current referral patterns for urgent KUB in our center; the improper referral pattern for KUB in terms of requests for unnecessary exams 48,5% as well as number of technical errors in terms of inadequate radiographic projection for the suspected pathology 47% were recorded. In a second part, the impact of corrective actions at one month, 2 months and 6 months was assessed and we observed a decrease of about 20% of the number of KUB scheduled by the ER physician. Our results confirm that it is possible to teach ER physicians to more appropriately order imaging studies, which should improve patient care and generate savings. Long term correction of referral patterns is possible if all actors remain involved in this process.

[Quality control--patient doses--guidance dose levels from diagnostic radiology in Tunisia]

BACKGROUND

Radiation doses from diagnostic radiology are the most important exposure collective doses of the man. Entrance Surface Dose is one of the basic dosimetric quantities for measuring the patient dose and hence, an excellent tool for optimization purposes and for comparison with the international reference values.

AIM

The aim of the study was to assess the delivred quantitis of rayon x to patients who undervent radiography;

METHODS

For the first time in Tunisia the doses delivered to the patient undergoing the most common type of X ray examinations (chest, abdomen, lumbar spin) were performed in two university hospitals of Tunis. Entrance Surface Dose measurements were conducted using thermoluminescent dosimeters calibrated at the National Centre of Radiation Protection. Before measurements, quality control tests were carried out on each radiological equipment used for examinations.

RESULTS

From this study of 112 patients, it was deduced that the obtained values were comparable to the internationally recommended guidance levels. The diagnostic guidance dose levels established for Tunis area are preliminary results. The study should therefore be implemented on a national scale as an approach to establish the national guidance levels.

Abdominal multislice CT for obese patients: effect on image quality and radiation dose in a phantom study

RATIONALE AND OBJECTIVES

To evaluate the effect of a modified abdominal multislice computed tomography (CT) protocol for obese patients on image quality and radiation dose.

MATERIALS AND METHODS

An adult female anthropomorphic phantom was used to simulate obese patients by adding one or two 4-cm circumferential layers of fat-equivalent material to the abdominal portion. The phantom was scanned with a subcutaneous fat thickness of 0, 4, and 8 cm using the following parameters (detector configuration/beam pitch/table feed per rotation/gantry rotation time/kV/mA): standard protocol A: 16 x 0.625 mm/1.75/17.5 mm/0.5 seconds/140/380, and modified protocol B: 16 x 1.25 mm/1.375/27.5 mm/1.0 seconds/140/380. Radiation doses to six abdominal organs and the skin, image noise values, and contrast-to-noise ratios (CNRs) were analyzed. Statistical analysis included analysis of variance, Wilcoxon rank sum, and Student's t-test (P < .05).

RESULTS

Applying the modified protocol B with one or two fat rings, the image noise decreased significantly (P < .05), and simultaneously, the CNR increased significantly compared with protocol A (P < .05). Organ doses significantly increased, up to 54.7%, comparing modified protocol B with one fat ring to the routine protocol A with no fat rings (P < .05). However, no significant change in organ dose was seen for protocol B with two fat rings compared with protocol A without fat rings (range -2.1% to 8.1%) (P > .05).

CONCLUSIONS

Using a modified abdominal multislice CT protocol for obese patients with 8 cm or more of subcutaneous fat, image quality can be substantially improved without a significant increase in radiation dose to the abdominal organs.

Irreversible JPEG 2000 compression of abdominal CT for primary interpretation: assessment of visually lossless threshold

To estimate the visually lossless threshold for Joint Photographic Experts Group (JPEG) 2000 compression of contrast-enhanced abdominal computed tomography (CT) images, 100 images were compressed to four different levels: a reversible (as negative control) and irreversible 5:1, 10:1, and 15:1. By alternately displaying the original and the compressed image on the same monitor, six radiologists independently determined if the compressed image was distinguishable from the original image. For each reader, we compared the proportion of the compressed images being rated distinguishable from the original images between the reversible compression and each of the three irreversible compressions using the exact test for paired proportions. For each reader, the proportion was not significantly different between the reversible (0-1%, 0/100 to 1/100) and irreversible 5:1 compression (0-3%). However, the proportion significantly increased with the irreversible 10:1 (95-99%) and 15:1 compressions (100%) versus reversible compression in all readers (P < 0.001); 100 and 95% of the 5:1 compressed images were rated indistinguishable from the original images by at least five of the six readers and all readers, respectively. Irreversibly 5:1 compressed abdominal CT images are visually lossless and, therefore, potentially acceptable for primary interpretation.

Isotropic CT examination of abdomen and pelvis diagnostic quality of reformat

RATIONALE AND OBJECTIVES

To evaluate the image quality of axial and coronal reformats obtained from isotropic resolution abdomino-pelvic computed tomography (CT) examinations.

MATERIALS AND METHODS

Thirty consecutive patients with intravenous contrast-enhanced abdomino-pelvic CT examinations (Brilliance 40, Philips Medical Systems, Cleveland, OH) were enrolled for the study. The raw data were reconstructed into two sets of source axial images: 0.9-mm slice widths with 0.45-mm reconstruction interval (isotropic resolution) and 4-mm slice widths with 3-mm reconstruction interval (anisotropic resolution: group A). Isotropic data set was reformatted into axial and coronal stacks (groups B and C, respectively) with 4-mm slice width and 3-mm interval. Three independent readers evaluated stacks A to C using a 3-point scale for resolution of hepatic vessels, edge sharpness of kidneys, respiratory motion artifact, reconstruction artifact, noise, and overall image quality.

RESULTS

There was no statistical difference among the groups A to C for vessel resolution, motion artifact, noise, and overall quality. The scores given to group C were significantly lower than those to groups A and B for reconstruction artifacts. There was no difference among groups A to C for overall impression of image quality. The interreader agreements were excellent for axial images (groups A and B) and moderate for coronal reformats.

CONCLUSION

Isotropic scanning of the abdomen and pelvis allows creation of reformats with similar image quality as similar thickness axial source images. These reformats are of sufficient quality to form the basis of clinical interpretation.

Plain abdominal radiographs: can we interpret them?

INTRODUCTION

Plain abdominal radiographs commonly form a part of medical assessments. Most of these films are interpreted by the clinicians who order them. Interpretation of these films plays an important diagnostic role and, therefore, influences the decision for admission and subsequent management of these patients. The aim of this study was to find out how well doctors in different specialties and grades interpreted plain abdominal radiographs.

MATERIALS AND METHODS

A total of 76 doctors from the Departments of Accident & Emergency, Medicine, Surgery and Radiology (17, 32, 23 and 4, respectively) participated in the study which involved giving a diagnosis for each of 14 plain abdominal radiographs (5 'normal' and 9 'abnormal'). They were also asked the upper limit of normal dimensions of small bowel and large bowel. One point was awarded for correctly identifying whether a radiograph was normal/abnormal, 1 point for the correct diagnosis and 1 point for the correct bowel dimensions, giving a total score of 30.

RESULTS

Mean scores out of 30 for specialties were as follows: Accident & Emergency 13.1 (range, 2-22), Medicine 11.2 (range, 2-23), Surgery 15.0 (range, 8-24) and Radiology 17.0 (range, 14-20; P = 0.241). Mean scores out of 30 for different grades of doctors were as follows: pre-registration house officers 10.8 (range, 4-20), senior house officers 13.0 (range, 2-22), registrars/staff grades 13.8 (range, 2-23) and consultants 17.3 (range, 12-24; P = 0.028). Fifteen out of 76 (19.7%) doctors correctly identified the upper limit of normal dimension of small bowel; 24 out of 76 (31.6%) correctly identified the upper limit of normal dimension of large bowel.

DISCUSSION

The level of seniority positively correlated with skills of plain abdominal radiograph interpretation. A large number of doctors were unable to give the correct upper limit of normal dimensions for small and large bowel.

CONCLUSIONS

All doctors could benefit from further training in the interpretation of plain abdominal radiographs. This could perhaps take place as formal teaching sessions and be included in induction programmes. Until then, plain abdominal films should ideally be reported by radiologists where there are clinical uncertainties; important management decisions made by junior doctors based on these films should at least be confirmed with a registrar, if not a consultant.

Radiation dose in pelvic imaging

OBJECTIVE

To compare the radiation dose during pelvic x-ray examinations using computed radiography (CR) and film-screen (FS) radiography at various x-ray tube voltages (kV) and tube-current time product (mAs) values.

METHODS

A pelvic phantom was imaged using FS and CR systems. The entrance surface dose was measured using an ionization chamber, and the gonadal dose and effective dose were calculated using the XDOSE program. The diagnostic quality of the images was assessed using a 5-point subjective scoring system.

RESULTS

At standard kV values, the image quality did not vary significantly between the CR and the FS system, but at higher kV values, the CR images werefound to be of better quality than FS images. In addition, the lower limit of entrance skin dose consistent with diagnostically acceptable CR images was 50% lower than that for FS images.

CONCLUSION

The gonadal dose and effective dose for pelvic x-ray examinations can be reduced by 50% when CR systems are used and appropriate exposure factors are established.

Is direct radiologist supervision of abdominal computed tomography (CT) scans necessary?

AIM

To determine the effect of direct radiological supervision of patients attending for abdominal CT by assessing the frequency of protocol alteration subsequent to radiologist review of the images obtained.

MATERIALS AND METHODS

A prospective questionnaire-based observational study was performed of 187 consecutive patients undergoing abdominal CT. The CT protocol was determined by a radiologist in advance, with reference to the request form. Any subsequent change in the prescribed study that was contingent on radiologist review of the images obtained was documented on the questionnaire. Comparison was made with a second (control) group of 100 patients undergoing cranial CT.

RESULTS

A protocol change was undertaken following radiologist review of the CT images of 17 (9%) of the group undergoing abdominal CT, compared with 14 (14%) of the group undergoing cranial CT. In the abdominal CT group, further scanning was performed for lesion characterization, to guide a subsequent interventional procedure, because of inadequate anatomical coverage or to evaluate an unexpected lung tumour. There was no significant difference in proportions between the two groups (p=0.23).

CONCLUSION

When abdominal and cranial CT studies were compared, there was no significant difference in the proportion of studies requiring a change in the prescribed protocol following radiologist review of the images obtained. There was no evidence to suggest that abdominal CT was any less suited to protocol.

Local diagnostic reference levels in standard X-ray examinations

The national diagnostic reference levels (NDRLs) form an efficient, concise and powerful standard for optimising radiation protection of a patient. However, in a large hospital, where many radiological departments are present, it is also possible to calculate and define lower dose values as local diagnostic reference levels (LDRLs). In our hospital there are eight radiological departments; in each of these, the entrance skin dose (ESD) distributions were determined for 10 standard projections (AP Abdomen, PA and LAT Chest, AP and LAT Lumbar Spine, LAT Lumbo-Sacral Joint, AP Pelvis, PA and LAT Skull and AP Urinary tract) and then the ESDs were compared with data previously published and with Italian NDRLs. All ESD values were below the corresponding NDRLs. The maximum/minimum ratio of ESDs ranged from 3.9 (LAT Skull) to 34.3 (AP Abdomen) for individual adult patients and from 2.1 (PA Skull) to 6.5 (Urinary tract) across the mean values of the radiological departments. Finally, it is shown how LDRLs can be proposed to obtain a more fully optimised radiation protection of patients.

Radiological parameters and radiation doses of patients undergoing abdomen, pelvis and lumbar spine X-ray examinations in three Nigerian hospitals

Thermoluminescent dosemeters (TLDs) have been used to measure the entrance surface doses (ESDs) of patients undergoing pelvis, abdomen and lumbar spine diagnostic X-ray examinations in Nigeria. A total of three public hospitals and 171 patients were included in this investigation. The ages of the patients involved were from 40 years to 85 years, while their weights ranged from 64 kg to 73 kg. Mean, median, first and third quartiles of ESDs are reported. The results showed that in most cases, for each of the examinations, the individual ESD values are found to be comparable with, and higher than, those from Ghana and Tanzania, respectively. The mean ESD values are also found to be within the range of mean ESD values that have been previously been reported from countries outside Africa. When compared with the European Community (EC) reference values, the mean ESDs were found to be below the reference values in only two of the hospitals. The ranges found in this work are high and this indicates more attention needs to be given to X-ray facilities in the country. This also suggests that radiographic departments need to review their radiographic practices in order to bring their doses to optimum levels. Effective doses were also calculated from the ESD values. The mean effective doses were found to be generally low when compared with those found in the literature from other countries including two African countries. The radiographic parameters used for all the patients were also compared with the European criteria. It is recommended that the tube filtration at one hospital be increased. The importance of good regulatory activities and trained personnel is stressed in this work. Apart from the fact that the data provided in this work will be useful for the formulation of national guidance levels, they also provide patient dosimetry information on healthcare level IV countries.

Nationwide Evaluation of X-ray Trends Survey of Abdomen and Lumbosacral Spine Radiography

Results of the 1995 Nationwide Evaluation of X-ray Trends (NEXT) survey of facilities that perform diagnostic radiographic examinations of the abdomen and lumbosacral spine were compared with those of previous NEXT surveys conducted in 1987 and 1989. A clinically validated radiographic phantom was used in the 1995 survey to capture data about radiation exposure and image quality. Additional data were obtained regarding clinical techniques, facility workloads, x-ray beam quality, film processing quality, and darkroom fog. Mean skin-entrance air kerma for the abdomen examination dropped from 3.2 mGy (in 1987) to 2.8 mGy at hospitals and from 3.4 mGy (in 1989) to 3.0 mGy at nonhospital facilities. Mean skin-entrance air kerma also decreased for the lumbosacral spine examination from 3.7 mGy (in 1987) to 3.3 mGy at hospitals and from 3.8 mGy (in 1989) to 3.2 mGy at nonhospital facilities. The quality of film processing improved, although 58 (18.3%) of 317 surveyed facilities did not meet the Mammography Quality Standards Act standard for film processing quality, compared with 185 (5.9%) of 3,120 mammography facilities inspected in 1995. Finally, 181 (58.0%) of 312 surveyed facilities had darkroom fog levels greater than the Mammography Quality Standards Act standard, compared with 1,426 (16.6%) of 8,605 mammography facilities inspected in 1995.

Management of patient dose and image noise in routine pediatric CT abdominal examinations

The aim was to propose a strategy for finding reasonable compromises between image noise and dose as a function of patient weight. Weighted CT dose index (CTDI(w)) was measured on a multidetector-row CT unit using CTDI test objects of 16, 24 and 32 cm in diameter at 80, 100, 120 and 140 kV. These test objects were then scanned in helical mode using a wide range of tube currents and voltages with a reconstructed slice thickness of 5 mm. For each set of acquisition parameter image noise was measured and the Rose model observer was used to test two strategies for proposing a reasonable compromise between dose and low-contrast detection performance: (1) the use of a unique noise level for all test object diameters, and (2) the use of a unique dose efficacy level defined as the noise reduction per unit dose. Published data were used to define four weight classes and an acquisition protocol was proposed for each class. The protocols have been applied in clinical routine for more than one year. CTDI(vol) values of 6.7, 9.4, 15.9 and 24.5 mGy were proposed for the following weight classes: 2.5-5, 5-15, 15-30 and 30-50 kg with image noise levels in the range of 10-15 HU. The proposed method allows patient dose and image noise to be controlled in such a way that dose reduction does not impair the detection of low-contrast lesions. The proposed values correspond to high- quality images and can be reduced if only high-contrast organs are assessed.

Survey of effective dose levels from typical paediatric CT protocols

Concern over reported large radiation doses leading to a high cancer risk for paediatric CT patients has prompted considerable investigation in paediatric CT. The recent release of software from Germany has allowed effective doses to be calculated from CT protocol information and radiation measurement for standard paediatric patient sizes for both sexes. An initial study has been undertaken in nine radiology departments, four of which were dedicated paediatric departments, for routine chest and abdominal CT procedures. The dose calculation software is based on Monte Carlo simulation of X-ray conditions during a CT procedure and utilized a 'tomographic' phantom model of a 7-year-old child and an 8-week-old baby to allow calculation of organ dose and hence effective dose. Results of the survey indicate that effective doses were higher for females than males, and higher for abdominal procedures. Slightly higher effective doses were calculated for the child compared to the baby. All centres but one recorded lower effective doses with their current protocols than if they had used recommended CT protocols found in the literature. Analysis of the survey data indicates that scan parameters are the main cause of dose variations, although the type of scanner can affect dose by a factor of 2 (when comparing different units) as well as variation in anatomy scanned in protocols. Dose reduction appears to be most closely linked with reduced mAs and increased pitch as expected. The calculation of effective dose appears to be a key factor in assessing CT protocols, particularly for paediatric patients.

Construction of an abdominal probabilistic atlas and its application in segmentation

There have been significant efforts to build a probabilistic atlas of the brain and to use it for many common applications, such as segmentation and registration. Though the work related to brain atlases can be applied to nonbrain organs, less attention has been paid to actually building an atlas for organs other than the brain. Motivated by the automatic identification of normal organs for applications in radiation therapy treatment planning, we present a method to construct a probabilistic atlas of an abdomen consisting of four organs (i.e., liver, kidneys, and spinal cord). Using 32 noncontrast abdominal computed tomography (CT) scans, 31 were mapped onto one individual scan using thin plate spline as the warping transform and mutual information (MI) as the similarity measure. Except for an initial coarse placement of four control points by the operators, the MI-based registration was automatic. Additionally, the four organs in each of the 32 CT data sets were manually segmented. The manual segmentations were warped onto the "standard" patient space using the same transform computed from their gray scale CT data set and a probabilistic atlas was calculated. Then, the atlas was used to aid the segmentation of low-contrast organs in an additional 20 CT data sets not included in the atlas. By incorporating the atlas information into the Bayesian framework, segmentation results clearly showed improvements over a standard unsupervised segmentation method.

Interpretation of normal anatomic structures on chest radiography: comparison of Fuji computed radiography (FCR) 5501D with FCR 5000 and screen-film system

The purpose of this study was to investigate the usefulness of Fuji Computed Radiography (FCR) 5501D by comparing it with FCR 5000 and a screen-film system (S/F). Posteroanterior chest radiographs of ten patients with no abnormality on chest CT scans were obtained with FCR 5501D, FCR 5000, and S/F. Six observers (three radiologists and three radio-technologists) evaluated the visibility of nine normal anatomic structures (including lungs, soft tissue, and bones) and overall visibility on each image. Observers scored using a five-point scale on each structure. FCR 5000 showed a significantly higher score in soft tissue and bone structures, and overall visibility compared with S/F, but, there was no significant difference between them in the visibility of all four normal lung structures. Compared with S/F, the score for FCR 5501D was higher in eight of the nine normal structures, including three of the four lung structures (unobscured lung, retrocardiac lung, and subdiaphragmatic lung), and overall visibility. Compared with FCR 5000, the score for FCR 5501D was higher in three normal structures, including two of the four lung structures (unobscured lung and subdiaphragmatic lung), and overall visibility. FCR 5501D was the best among the three techniques to visualize normal anatomic structures, particularly the obscured and unobscured lung.

The use of abdominal computed tomography scan decreases the frequency of misdiagnosis in cases of suspected appendicitis

BACKGROUND

Despite considerable experience the reported frequency of misdiagnosis in patients undergoing appendectomy continues in the range of 20% to 40% in some populations.

METHODS

We developed a clinical guideline that recommended abdominal computed tomography (CT) for all nonpregnant adults in whom the diagnosis of appendicitis was suspected unless the diagnosis could be ruled out clinically. The records of adult patients that underwent appendectomy from July 1998 through October 2001 were reviewed. The clinical guideline was developed in July 2000.

RESULTS

There were 194 appendectomies performed, 114 prior to the guideline and 80 after the development of the guideline. The rate of misdiagnosis decreased from 25% to 6% (P <0.05), the rate of CT use increased from 32% to 84% (P <0.05), and the perforation rate remained unchanged.

CONCLUSIONS

These results support the effectiveness of a clinical guideline that encourage the use of abdominal CT in decreasing the frequency of misdiagnosis in cases of suspected appendicitis.