Analysing the possibility of utilizing CBCT radiomics as an independent modality: a phantom study.

AIM: To verify if computed tomography (CT) radiomics were reproducible by cone beam CT (CBCT) radiomics by using Catphan® 504. MATERIALS AND METHODS: Catphan® 504 was imaged   using the default IGRT OBI  CBCT   imaging protocols and CT scanner. Seven known density image regions of the phantom were segmented and image feature was extracted by Imaging Biomarker Explorer (IBEX) software. The 49 selected features from four feature categories were analyzed by considering each region of interest (ROI) segment as individual image set. Correlation  was studies using interclass correlation coefficient (ICC) and Pearson's correlation coefficient. RESULTS: The ICC of the three feature categories, namely intensity, GLCM, and GLRLM was significant (p-value<0.05) in comparison with CT, while the ICC of the fourth feature category, NID, was no significant. The average absolute Pearson's correlation coefficient from the features of the images was as follows: CT: r=0.679±0.257, CBCThead: r=0.707±0.231, CBCTthorax: r=0.643±0.260, and CBCTpelvis: r=0.594±0.276. CONCLUSION:   It seems that the various densities of Catphan® 504 ROI image segments of the CT radiomics are reproducible with CBCT radiomics and CBCT radiomics can be used as an independent modality.

Variability of computed tomography radiomics features of fibrosing interstitial lung disease: A test-retest study.

OBJECTIVES: To investigate the intra- and inter-scanner repeatability and reproducibility of CT radiomics features (RF) of fibrosing interstitial lung disease (fILD). METHODS: For this prospective, IRB-approved test-retest study, CT data of sixty fILD patients were acquired. Group A (n = 30) underwent one repeated CT scan on a single scanner. Group B (n = 30) was scanned using two different CT scanners. All CT data were reconstructed using different reconstruction kernels (soft, intermediate, sharp) and slice thicknesses (one and three millimeters), resulting in twelve datasets per patient. Following ROI placement in fibrotic lung tissue, 86 RF were extracted. Intra- and inter-scanner RF repeatability and reproducibility were assessed by calculating intraclass correlation coefficients (ICCs) for corresponding kernels and slice thicknesses, and between lung-specific and non-lung-specific reconstruction parameters. Furthermore, test-retest lung volumes were compared. RESULTS: Test-retest demonstrated a majority of RF is highly repeatable for all reconstruction parameter combinations. Intra-scanner reproducibility was negatively affected by reconstruction kernel changes, and further reduced by slice thickness alterations. Inter-scanner reproducibility was highly variable, reconstruction parameter-specific, and greatest if either soft kernels and three-millimeter slice thickness, or lung-specific reconstruction parameters were used for both scans. Test-retest lung volumes showed no significant difference. CONCLUSION: CT RF of fILD are highly repeatable for constant reconstruction parameters in a single scanner. Intra- and inter-scanner reproducibility are severely impacted by alterations in slice thickness more than reconstruction kernel, and are reconstruction parameter-specific. These findings may facilitate CT data and RF selection and assessment in future fILD radiomics studies collecting data across scanners.

Diagnostic Reference Levels for computed tomography in Austria: A 2018 nationwide survey on adult patients.

PURPOSE: To define National Diagnostic Reference Levels (NDRLs) for computed tomography (CT) for Austria on adult patients. METHOD: In the course of a nationwide survey on common CT-examinations between June 2018 and November 2018, datasets were requested from all Austrian hospitals and radiology centers with CT-scanners. All facilities were asked to report a minimum sample of 10 representative dose length product (DLP) values per examination type and CT-scanner, including information about scan sequences, iterative reconstruction (IR) algorithms and, if available, patient data. Examination types included into the survey were the most common CT-indications for the anatomic regions head, facial bones, thorax, abdomen and pelvis. 3rd quartiles of CT-scanner median DLPs were calculated and compared to Austrian and international NDRLs. RESULTS: For 76 % of all operating CT-scanners, DLP data was submitted varying from 13 to 172 scanners per examination type. Mean year of manufacture of the CT-scanners was 2011, ranging from 2003 to 2018. In 66 % of the examinations, IR was used. 3rd quartile is on average 21 % lower for scanners using IR algorithms as opposed to scanners or protocols not using IR. In the case of gender differences, the DLP for females is on average 17 % lower than for males. CONCLUSIONS: The new recommendations for CT NDRLs for Austria based on a nationwide survey are on average 13 % lower than the current Austrian NDRLs and correspond well to recent German and Swiss NDRLs. 3rd quartiles for DLP are dependent on gender, the use of IR and year of manufacture of the CT-scanners.

Quantification and homogenization of image noise between two CT scanner models.

Feedback from radiologists indicated that differences in image appearance and noise impeded reading of post-contrast computed tomography (CT) scans from an updated CT scanner that was recently added to a fleet of existing scanners from the same vendor, despite using identically named reconstruction algorithms. The goals of this work were to quantify and possibly standardize image quality on the new and an existing scanner using phantom images. Three months of daily quality control images were analyzed to determine the mean CT number and noise magnitude in a water phantom. Next, subtraction images from the uniformity section of an American College of Radiology CT phantom were used to generate noise power spectra for both scanners. Then, a semi-anthropomorphic liver phantom was imaged with both scanners in triplicate using identical body protocols to quantify differences CT number and noise magnitude. Finally, the scanner dependence of CT number and noise magnitude on material attenuation was quantified using a multi-energy CT phantom with 15 material inserts. Significant differences between scanners were determined using a paired or Welch's t test as appropriate. In daily quality control images, the new scanner exhibited slightly higher CT number (0.697 vs. 0.412, P < 0.001, n = 85) and slightly lower noise magnitude (4.85 vs. 4.94, P < 0.001, n = 85). Measured NPS was not significantly different between the existing and new scanners. Interestingly, it was observed that the noise magnitude from the new scanner increased with increasing material attenuation in both the liver (P = 0.008) and multi-energy (P < 0.001) phantoms. Using an alternate reconstruction algorithm with the new scanner eliminated this deviation at high material attenuations. While standard noise evaluation in a water phantom was unable to discern differences between the scanners, more comprehensive testing with higher attenuation materials allowed for the characterization and homogenization of image quality.

Improved PET quantification and harmonization by adaptive denoising.

PURPOSE: Quantification in positron emission tomography (PET) is subject to bias due to physical and technical limitations. The goal of quantitative harmonization is to achieve comparable measurements between different scanners, thus enabling multicenter clinical trials. Clinical guidelines, such as those from the European Association of Nuclear Medicine (EANM), recommend harmonizing PET reconstructions to bring contrast recovery coefficients (CRCs) within specifications. However, these harmonized reconstructions can show quantitative biases. In this work we improve harmonization by using a novel adaptive filtering scheme. Our goal was to obtain low quantification bias and high peak signal to noise ratio (PSNR) values at the same time. METHODS: a novel three-stage adaptive denoising filter was implemented. Filter parameters were optimized to achieve both high PSNR in a digital brain phantom and low quantitative bias of maximum CRC values (CRCmax) obtained from a National Electrical Manufacturers Association (NEMA) PET image quality phantom. The NEMA phantom was scanned on several PET/CT scanners and reconstructed without postfilters. The optimal filter settings found for a training dataset were then applied to testing reconstructions from other scanners. Harmonization limits were defined using the 95% confidence intervals across reconstructions. RESULTS: Average CRCmax values close to unity (± 5%) were achieved for spheres with diameter equal or greater than 13 mm for the training dataset. PSNR values were comparable to other state-of-the-art filter results. Using the same optimal filter settings for the testing datasets, similar quantitative results were found. Lesion conspicuity was improved on clinical scans when compared with EANM reconstructions, with no visible artifacts. CONCLUSIONS: Our three-stage adaptive filter achieved state-of-the-art quantitative performance for PET imaging. Harmonization tolerances with lower bias and variance than EANM guidelines were achieved for a variety of scanner models. CRCmax values were close to unity and the quantification variability was reduced when compared with standard reconstructions.

Technical assessment of a mobile CT scanner for image-guided brachytherapy.

PURPOSE: The imaging performance and dose of a mobile CT scanner (Brainlab Airo®, Munich, Germany) is evaluated, with particular consideration to assessment of technique protocols for image-guided brachytherapy. METHOD: Dose measurements were performed using a 100-mm-length pencil chamber at the center and periphery of 16- and 32-cm-diameter CTDI phantoms. Hounsfield unit (HU) accuracy and linearity were assessed using materials of specified electron density (Gammex RMI, Madison, WI), and image uniformity, noise, and noise-power spectrum (NPS) were evaluated in a 20-cm-diameter water phantom as well as an American College of Radiology (ACR) CT accreditation phantom (Model 464, Sun Nuclear, Melbourne, FL). Spatial resolution (modulation transfer function, MTF) was assessed with an edge-spread phantom and visually assessed with respect to line-pair patterns in the ACR phantom and in structures of interest in anthropomorphic phantoms. Images were also obtained on a diagnostic CT scanner (Big Bore CT simulator, Philips, Amsterdam, Netherlands) for qualitative and quantitative comparison. The manufacturer's metal artifact reduction (MAR) algorithm was assessed in an anthropomorphic body phantom containing surgical instrumentation. Performance in application to brachytherapy was assessed with a set of anthropomorphic brachytherapy phantoms - for example, a vaginal cylinder and interstitial ring and tandem. RESULT: Nominal dose for helical and axial modes, respectively, was 56.4 and 78.9 mGy for the head protocol and 17.8 and 24.9 mGy for the body protocol. A high degree of HU accuracy and linearity was observed for both axial and helical scan modes. Image nonuniformity (e.g., cupping artifact) in the transverse (x,y) plane was less than 5 HU, but stitching artifacts (~5 HU) in the longitudinal (z) direction were observed in axial scan mode. Helical and axial modes demonstrated comparable spatial resolution of ~5 lp/cm, with the MTF reduced to 10% at ~0.38 mm-1 . Contrast-to-noise ratio was suitable to soft-tissue visualization (e.g., fat and muscle), but windmill artifacts were observed in helical mode in relation to high-frequency bone and metal. The MAR algorithm provided modest improvement to image quality. Overall, image quality appeared suitable to relevant clinical tasks in intracavitary and interstitial (e.g., gynecological) brachytherapy, including visualization of soft-tissue structures in proximity to the applicators. CONCLUSION: The technical assessment highlighted key characteristics of dose and imaging performance pertinent to incorporation of the mobile CT scanner in clinical procedures, helping to inform clinical deployment and technique protocol selection in brachytherapy. For this and other possible applications, the work helps to identify protocols that could reduce radiation dose and/or improve image quality. The work also identified areas for future improvement, including reduction of stitching, windmill, and metal artifacts.

Measurements of body surface area and volume in male Japanese White rabbits using a computed tomography scanner: comparison with male New Zealand White rabbits.

The body surface area (BSA) of animals has generally been estimated by multiplying the k value by the measured body weight (BW) raised to the power of 2/3 (Meeh's formula). In mathematical terms, the assumption that the density and body shape of animals are essentially constant means that the BSA is proportional to BW2/3. In this study, we measured the BSA and volume of 50 male Japanese White rabbits (JW) at 10 to 54 weeks of age using a computed tomography scanner, then calculated the k value, density, and sphericity. The variations in these parameters were then analyzed in relation to growth. The obtained results indicated that the k value was negatively correlated to BW, and that this negative correlation was mainly due to the variation in density. Based on the regression analysis, we propose the following linear regression equation for calculating the k value in male JW at 10-54 weeks of age: the k value = 14.602 - 0.959 × BW [kg]. The calculated values ranged from 10.9 to 12.7 (working BW range: 1.98 to 3.81 kg). The k value of male New Zealand White rabbits (NZW) determined in our previous study and that of male JW in the present study were compared. It was revealed that the k value of male JW was larger than that of male NZW. We concluded that different breeds of rabbits express different k values.

Dose of CT protocols acquired in clinical routine using a dual-layer detector CT scanner: A preliminary report.

PURPOSE: To assess the radiation dose associated with always-on dual-energy acquisitions in clinical practice over a broad range of clinical protocols using a dual-layer detector CT (DLCT; IQon spectral CT, Philips Healthcare) as compared to an otherwise technically equivalent single-layer detector CT (SLCT; Brilliance iCT, Philips healthcare). MATERIALS AND METHODS: Dose-length-product data for consecutive examinations over a six-month period acquired with DLCT were retrospectively collected and compared to consecutive examinations from an SLCT. Imaging protocols were optimized for diagnostic image quality for each system prior to data collection. Dose reports of CT protocols that were used at least 50 times on both systems were collected. After exclusion of statistical outliers, protocols were evaluated with regard to reported dose levels. RESULTS: In total, 4536 dose reports for DLCT and 5783 reports for SLCT were collected. All DLCT examinations were acquired at 120 kVp, enabling dual-energy analysis. With SLCT, 79% of examinations were acquired at 120 kVp, and 21% at 100/80 kVp. Protocols for 15 indications were used more than 50 times on both scanners. For seven protocols there was no significant difference between the two scanners (p > 0.05), whereas seven protocols were acquired with higher dose levels on SLCT compared to the DLCT (p < 0.03). For one protocol, the DLCT dose was significantly higher (p < 0.005) compared to the SLCT. CONCLUSION: Dual-layer detector CT enables acquisition of dual-energy information over a broad range of clinical indications without increasing radiation dose when compared to a conventional single-layer detector CT.

The use of 80 kV versus 100 kV in pulmonary CT angiography: An evaluation of the impact on radiation dose and image quality on two CT scanners.

INTRODUCTION: Use of CT in the investigation of pulmonary embolism in radiosensitive patients such as pregnant and young female patients entails the need for protocol optimization. The aim of this study was to analyze the dose reduction and image quality achieved by using 80 kV instead of 100 kV in CT pulmonary angiography protocols. METHODS: 80 examinations of non-obese patients were analyzed (40 consecutive patients for each protocol, equally distributed on two CT scanners). Objective image quality was assessed by measurements of HU values (average and standard deviation) in five ROIs in pulmonary arteries and calculations of signal-to-noise (SNR) and contrast-to-noise ratios (CNR). Subjective image quality was independently evaluated by two radiologists in terms of perceived noise, sharp reproduction of pulmonary arteries and overall diagnostic quality. Radiation dose parameters (CTDIvol, DLP, SSDE and effective dose) and effective risk were compared. Differences in radiation dose and objective measures of image quality for the two protocols were assessed using the independent t test; comparison of subjective grading of image quality was performed with the Mann-Whitney U test. RESULTS: Use of 80 kV significantly increased both arterial contrast enhancement and image noise. Differences in SNR and CNR between protocols were not statistically significant. Achieved dose reduction by using 80 kV was significant on both scanners (SSDE reduction 35% and 46%, p < 0.001; effective dose reduction 40% and 53%, p < 0.001). CONCLUSION: Use of 80 kV protocols for CT examinations of pulmonary arteries in non-obese patients with bodyweight below 80 kg results in significant reduction of radiation doses without compromising image quality.

Statistical analysis for obtaining optimum number of CT scanners in patient dose surveys for determining national diagnostic reference levels.

OBJECTIVES: To statistically determine an 'optimum number of CT scanners' for obtaining 'diagnostic reference levels' (DRLs) in CT examinations as close as possible to 'ideal DRLs' when all available CT scanners are considered. METHODS: First, six 'ideal DRLs' (CTDIVol and DLP) were determined for head, chest and abdomen/pelvis examinations by using patient-dose survey data of 100 CT scanners of different models in Tehran. Then, a 'random sampling method' was applied to different percent fractions of patient dose data of 100 CT scanners. The percent differences (PD) of the DRLs obtained from 'ideal DRLs' and their coefficients of variation (CVs) were calculated. The 'optimum number of CT scanners' determined met those of 'ideal DRL' criteria; i.e. precision (CV ≤ 10%) and accuracy (PD ≤ 10%). RESULTS: 'Optimum number of CT scanners' for determining DRLs as close as possible to 'ideal DRLs', fulfilling the stated criteria, is 43 instead of using 100. CONCLUSION: 'Optimum number of CT scanners' for obtaining DRLs as close as possible to 'ideal DRLs' was determined. This optimum number can be effectively applied in patient-dose survey situations with limited resources in a time- and cost-effective manner. KEY POINTS: • Ideal DRLs were determined by a CT patient-dose survey applied to available scanners. • 'Optimum number of CT scanners' statistically determined for DRLs is 43%. • Optimum number can be used for DRLs as if 'ideal DRLs' were determined by all scanners.

Association between years since manufacture and utilization of computed tomography scanner in South Korea: A cross-sectional study (a STROBE-compliant article).

Health care institutions that acquire an expensive, brand-new computed tomography (CT) scanner are likely to perform excessive scanning in an attempt to recover their investment as early as possible. We examined the association between the age of CT scanners and the number of CT scans at small-sized hospitals and clinics in Korea and assessed the notable increase in scanning quantity at health care institutions with a recently manufactured CT scanner.A cross-sectional study designed to analyze whether the age of CT scanners was associated with the number of scans at small-sized hospitals and clinics that were operating a CT scanner for the full year 2008 (n = 703). Data were obtained by linking the National Health Insurance Claims Database and Health Care Institution Statistics.A multiple regression analysis found that the older a CT scanner was, the fewer CT scans were performed in terms of annual total (ß = -34.8; P < .001) and patient average (ß = -0.0018; P = <.001).Health care institutions with newer CT scanners administered more CT scans in terms of annual total and scans per patient. Because this may indicate the practice of excessive scanning with newly acquired equipment, it is necessary to have a system of regularly monitoring the quantity and retake rate of CT scanning in these health care institutions so as to prevent unnecessary use of CT.

Over-scanning in chest CT: Comparison of practice among six hospitals and its impact on radiation dose.

OBJECTIVES: Compare incidence of over-scanning in chest CT among six hospitals and impact on effective and organ effective radiation dose. METHODS: Scout images of 600 chest CTs from six hospitals (A-F) were retrospectively reviewed using a radiation dose tracking software (RTS). Optimal scan range was determined and compared to the actual scan range. Incidence of cranial and caudal over-scanning was assessed and changes in total and organ effective dose were calculated. Descriptive statistics, Tukey- and Wilcoxon matched pairs test were applied. RESULTS: Simultaneous cranial and caudal over-scanning occurred in 29 of 600 scans (A = 0%, B = 1%, C = 12%, D = 3%, E = 11%, F = 2%). Effective radiation dose increased on average by 0.29 mSv (P < 0.001). Cranial over-scanning was observed in 45 of 600 scans (A = 0%, B = 8%, C = 2%, D = 15%, E = 17%, F = 3%) and increased organ effective dose by 0.35 mSv in the thyroid gland (P < 0.001). Caudal over-scanning occurred in 147 of 600 scans (A = 7%, B = 9%, C = 35%, D = 4%, E = 32%, F = 60%) and increased organ effective doses in the upper abdomen by up to 14% (P < 0.001 for all organs). CONCLUSIONS: Substantial differences in the incidence of over-scanning in chest CT exist among different hospitals. These differences result in excessive effective radiation dose and increased individual organ effective doses in patients.

Diagnostic performance of coronary CT angiography carried out with a novel whole-heart coverage high-definition CT scanner in patients with high heart rate.

BACKGROUND: Aim of the study was to evaluate image quality, radiation exposure and diagnostic accuracy of coronary CT angiography (CCTA) performed with a novel cardiac CT scanner in patients with very high heart rate (HR). METHODS: We prospectively enrolled 202 patients (111 men, mean age 66±8years) with suspected coronary artery disease who underwent CCTA with a whole-organ volumetric CT scanner. The HR during the scan was ≥80bpm in 100 patients (Group 1), while it was ≤65bpm in the remaining 102 patients (Group 2). In all patients, image quality score and coronary interpretability were evaluated and effective dose (ED) was recorded. In 86 of the 202 enrolled patients (40 patients in Group 1, 46 patients in Group 2) who were referred for a clinically indicated invasive coronary angiography (ICA) within 6months, diagnostic accuracy of CCTA vs. ICA was evaluated. RESULTS: Mean image quality and coronary interpretability were very high in both Groups (Likert=3.35 vs. 3.39 and 97.3% [1542/1584 segments] and 98% [1569/1600 segments] in Group 1 and Group 2, respectively). Mean ED was lower in Group 2 (1.1±0.5mSv) compared to Group 1 (2.9±1.6mSv). In Group 1, sensitivity and specificity of CCTA for detection of >50% stenosis vs. ICA were 95.2% and 98.9% in a segment-based analysis and 100% and 81.8% in a patient-based analysis, respectively. CONCLUSIONS: The whole organ high-definition CT scanner allows evaluating coronary arteries in patients with high HR with excellent image quality, coronary interpretability and low radiation exposure.

Doses from cervical spine computed tomography (CT) examinations in the UK.

OBJECTIVE: To review doses to patients undergoing cervical spine CT examinations in the UK. METHODS: A data collection form was developed and distributed to medical physicists and radiographers via e-mail distribution lists. The form requested details of CT scanners, exposure protocols and patient dose index information. RESULTS: Data were received for 73 scanners. It was seen that 97% of scanners used automatic exposure control, and 60% of scanners used an iterative reconstruction technique for cervical spine examinations. The majority of scans were taken at 120 kV. The average patient dose indicators in terms of CT dose index (CTDIvol) ranged from 3.5 to 39.7 mGy (mean value 16.7 mGy), and for the DLP, ranged from 87 to 1030 mGy cm (mean value 379 mGy cm) as quoted for the standard 32 cm phantom. CONCLUSION: The rounded third quartile value of the mean dose distributions from this study were a CT dose index (CTDIvol) of 20 mGy and a dose-length product of 440 mGy cm as quoted for a 32 cm body phantom. These are significantly higher than those in the 2011 Public Health England CT dose survey when adjusted for phantom size. It is suggested that the existing national diagnostic reference levels for cervical spine CT should be amended, both with the new values and also to quote according to the 32 cm phantom. Advances in knowledge: Proposed new national diagnostic reference levels are presented for cervical spine CT examinations.

Current CT practice in Germany: Results and implications of a nationwide survey.

PURPOSE: To assess patient doses and relative frequencies of standard CT examinations performed in Germany in 2013/14 as well as the effect of modern CT technology on patient exposure. METHODS: All known CT facilities in Germany were requested to complete a questionnaire on the frequency of 34 examinations and the respective parameter settings used. Taking into account type-specific properties of each scanner, effective doses were estimated for each reported examination. The mean and the percentiles of the CT dose index, scan length, dose length product, and effective dose were determined for each type of examination. RESULTS: According to the data provided for about 11% of all medical CT scanners operated in 2013/14, the effective dose was 4.6/5.9mSv per scan/examination. The effective dose was significantly reduced by about 15% compared to the CT practice before 2010. Modern CT technology, such as tube current modulation and iterative image reconstruction reduced the effective dose significantly by 6% and 13%, respectively. The mean effective dose applied at scanners produced by different manufacturers differed by 25%, at maximum. CONCLUSION: Patient exposure was reduced substantially in recent years. There is, however, still a considerable potential for further dose reduction by adapting scan protocols to the medical purpose and by a consequent exploitation of modern CT technologies.

Interventional management of necrotizing pancreatitis: an Australian experience.

BACKGROUND: The interventional management of necrotizing pancreatitis has evolved from early open surgery to delayed endoscopic or percutaneous intervention. However, few studies have directly compared the three treatment modalities. We aim to compare the outcomes of patients who had endoscopic, percutaneous or surgical interventions for necrotizing pancreatitis at our institution. METHODS: This is a retrospective cohort study of patients who had interventions for necrotizing pancreatitis at our institution from 2005 to 2014. Primary outcome was length of stay (LOS); secondary outcomes were complication rate and number of procedures required for resolution of necrosis. RESULTS: Thirty patients were included. Mortality rate was 13% (four patients). Median LOS and time to intervention was 88 and 28 days, respectively. There were no significant differences in the computed tomography severity indices and 48-h C-reactive protein levels among the three groups. Initial endoscopic intervention was associated with a median LOS of 62 days compared with 101 days in the percutaneous group and 91 days in the surgical group (P = 0.04). There were higher rates of pancreatic fistulae (40%) (P = 0.012) and new onset diabetes (30%) (P = 0.046) in the surgical group. Median number of procedures was similar among the three groups. Median LOS for patients with delayed intervention (fourth to sixth week of pancreatitis) was 66 days, compared with 137 days in patients with early intervention (first to third week) and 104 days in patients with late intervention (seventh week onwards) (P ≤ 0.001). CONCLUSION: A delayed, endoscopy first approach appears to be a reasonable strategy as it is associated with decreased LOS and low complication rate.

Study of the early management of acute pancreatitis.

BACKGROUND: Acute pancreatitis (AP) is a common acute surgical presentation with evidence-based guidelines for early management. The aim of this study was to assess the compliance to the published guidelines in patients presenting with AP in Western Sydney. METHODS: A retrospective case note audit was conducted for all patients with a confirmed diagnosis of AP from 2008 to 2011 in Western Sydney. RESULTS: There were 932 patients. The mortality was low for mild (0.7%) and severe (1.2%) AP. There was an under-utilization of ultrasound (U/S) with 239 (25.6%) patients not having a U/S. There was an over-utilization of early (within 72 h) computed tomography scanning for diagnosis (31.1%), assessment of severity (16.1%) and assessment for the presence of complications (7.3%). Inappropriate prophylactic antibiotic usage occurred in 15.3% patients. Of 373 cases of gallstone pancreatitis, only 231 (69.1%) had a cholecystectomy within 4 weeks of presentation. There was an under-utilization of early endoscopic retrograde cholangiopancreatography for associated cholangitis (12.5%). Only 16 (18.8%) patients with severe pancreatitis received enteric feeding. In patients with pancreatic necrosis, 50% had invasive intervention delayed beyond 4 weeks and 69% had minimally invasive procedures performed prior to necrosectomy. Patients having a minimally invasive procedure initially showed an improvement in mortality compared with those who had primary necrosectomy (0 versus 40%, P = 0.025). CONCLUSIONS: Although morbidity and mortality were acceptable, there was a failure to comply with evidence-based guidelines for the early management of pancreatitis. The results support for the development and auditing of protocols for the early assessment and treatment of AP in all hospitals.

Optimizing radiation exposure for CT localizer radiographs.

INTRODUCTION: The trend towards submillisievert CT scans leads to a higher dose fraction of localizer radiographs in CT examinations. The already existing technical capabilities make dose optimization of localizer radiographs worthwhile. Modern CT scanners apply automatic exposure control (AEC) based on attenuation data in such a localizer. Therefore not only this aspect but also the detectability of anatomical landmarks in the localizer for the desired CT scan range adjustment needs to be considered. MATERIALS AND METHODS: The effective dose of a head, chest, and abdomen-pelvis localizer radiograph with standard factory settings and user-optimized settings was determined using Monte Carlo simulations. CT examinations of an anthropomorphic phantom were performed using multiple sets of acquisition parameters for the localizer radiograph and the AEC for the subsequent helical CT scan. Anatomical landmarks were defined to assess the image quality of the localizer. CTDIvol and effective mAs per slice of the helical CT scan were recorded to examine the impact of localizer settings on a helical CT scan. RESULTS: The dose of the localizer radiograph could be decreased by more than 90% while the image quality remained sufficient when selecting the lowest available settings (80kVp, 20mA, pa tube position). The tube position during localizer acquisition had a greater impact on the AEC than the reduction of tube voltage and tube current. Except for the use of a pa tube position, all changes of acquisition parameters for the localizer resulted in a decreased total radiation exposure. CONCLUSION: A dose reduction of CT localizer radiograph is necessary and possible. In the examined CT system there was no negative impact on the modulated helical CT scan when the lowest tube voltage and tube current were used for the localizer.

Mucocele con expansión orbitaria / Mucocele with orbital expansion

El mucocele es una lesión quística benigna, que se desarrolla en el interior de los senos perinasales por la obstrucción de su drenaje natural en el curso de los procesos inflamatorios, traumas y cirugías. Se presentan tres casos con mucocele frontoetmoidal y expansión intraorbitaria, los cuales fueron atendidos en el Hospital Hermanos Ameijeiras entre los meses de febrero a diciembre del año 2013. El propósito del presente estudio es el análisis de los resultados terapéuticos obtenidos y determinar la posible influencia de la vía de abordaje utilizada sobre la efectividad terapéutica y la recidiva tumoral en cada uno de estos pacientes(AU)

Mucocele is a benign cystic lesion that emerges inside the perinasal sinuses due to the obstruction of their natural drainage in inflammatory processes, traumas and surgeries. Here are three cases with frontoethmoidal mucocele and intraorbital expansion, which were treated at Hermanos Ameijeiras hospital from February to December, 2013. The objective of this study was to analyze the therapeutic results and to determine the possible influence of the approach path on the therapeutic effectiveness and the tumor recurrence in each of the patients(AU)

Radiological mass casualty incident (MCI) workflow analysis: single-centre data of a mid-scale exercise.

OBJECTIVE: The aim of the study was to analyse and interpret radiological mass casualty incident workflow data. METHODS: In a mid-scale mass casualty incident exercise, the on-site triage assigned 12 cases to the investigated institution (11 included in the study). Two out of five institutional multislice-CT-scanners were used and the whole CT workflow and radiological service process chain were simulated as close to realistic as possible. The respective time intervals for reaching defined milestones were measured. RESULTS: The average CT in-room time, i.e. from entering to leaving the CT room was 9.43 min [(standard deviation) SD: 2.27 min; 95% (confidence interval) CI: 7.90-10.95 min]. Time spent on CT table was 6.75 min (SD: 1.67; CI: 5.63-7.87), and the pure scan time was 4.22 min (SD: 0.64; CI: 3.79-4.65). The first images after entering the CT room were available at a dedicated CT workstation after 5.85 min (SD: 2.20; CI: 4.37-7.32) and institution wide via picture archiving system (PACS) after 7.85 min (SD: 1.27; CI: 7.00-8.71). However, the PACS archiving process, that is, transfer of standard reconstruction set of CT images into the PACS was finished after 20.85 min (SD: 2.97; CI: 18.85-22.84). CONCLUSION: Up to six patients may be served per hour and per CT scanner by using a standard whole body CT polytrauma protocol. Dedicated CT triage protocols may even increase this number. The time portion until images were available at end points was relatively long. A solution has to be developed in order to avoid scenarios of patients being faster at end points than their images.