• Energy Research

We aimed to define the dual-energy CT characteristics of colorectal cancers and stool. Fifty consecutive patients were included who was referred for staging CT of a colorectal tumor between June 2011 and November 2012. Informed consent were obtained. Dual energy CT was performed by dual-source CT after insufflation of rectal air in supine position. Hounsfield units on 80kV, 140kV and virtual noncontrast images and iodine map were measured. DLP was measured. Statitistical analysis was performed by using Kruskal-Wallis, One-way Anova and Spearman?s rho correlation tests. Mean age of the patients was 60±13 years. Pathologic diagnoses were adenocarcinoma (n=47), squamus carcinoma (n=1), malignant melanoma (n=2). Mean DLP was 511 and estimated dose was 8.2mSv. CT density measurements on iodine map and virtual noncontrast images for tumors and stool were 56H (%95 CI: 61 ? 51H), and 32H (%95 CI: 37 ? 27) and 40H (%95 CI: 48 ? 32H) , -148 H (%95 CI: (-121H) ? (-175H)), respectively. Combination of Iodine map and VNC density values allowed differentiation of tumors from stool in all patients. There was no correlation between dual-energy characteristics and tumor grade, location, thickness and length. Eight polyps were detected on staging CT and density on iodine map and virtual noncontrast images were 70±8H and 16±5H. As an additional finding, liver metastases were found in 6 patients and renal cell cancer was detected in 2 patients. In conclusion, stool and tumors can be differentiated by combination of density measurements from iodine map and virtual noncontrast images. Dual-energy CT may allow diagnosis of coexisting polyps and other abdominal tumors. Bu çalışmada kolorektal kanserlerin ve gaytanın dual enerji BT özelliklerinin tanımlanması amaçlandı. Çalışmamıza Haziran 2011-Kasım 2012 tarihleri arasında BT çekilen kolon tümörlü 50 hasta dahil edildi. Hastalardan imzalanmış onam formu alındı. Hastalara evreleme BT'si için rektal yoldan hava verilerek supin pozisyonda çift tüplü BT ile dual-enerji BT kolonografi tetkiki yapıldı. 80kV, 140kV, sanal kontratsız görüntülerde ve iyot haritasında tümör ve gayta dansiteleri ölçüldü. DLP değerleri ölçüldü. İstatistiksel analizde Kruskal-Wallis, One-way Anova testleri ve Spearmans rho korelasyon katsayısı kullanıldı. Hastaların ortalama yaşı 60±13'tür. Patolojik tanılar kolon adenokanser (n=47), skuamöz kanser (n=1) ve malign melanomdu (n=2). Ortalama DLP 511 ve tahmini doz 8.2mSv'di. Kolon tümörlerinde iyot haritasında ve sanal kontrastsız görüntüde ölçülen dansite 56H (%95 CI : 61 ? 51H) ve 32H (%95 CI: 37 ? 27H) idi. Gaytadan yapılan ölçümlerde iyot haritasında dansite 40H (%95 CI: 48? 32H), sanal kontrastsız görüntüde dansite -148 H (%95 CI: (-121H) ? (-175H)) olarak ölçüldü. Dual-enerji özellikleri ile tümör grade, lokasyon, kalınlığı ve uzunluğu arasında korelasyon saptanmadı. Evreleme BT'sinde saptanan toplam 8 kolon polipin iyot haritasında ortalama dansitesi: 70±8H; sanal kontrastsız görüntüde ortalama dansite: 16±5H idi. Ek bulgu olarak 6 hastada karaciğer metastazı ve 2 hastada RCC saptandı. Çalışma sonuçları kolon tümörünün gaytadan dual enerji özellikleri kullanılarak ayırımının yapılabileceğini göstermektedir. Ayrıca eşlik eden abdominal tümörler ve kolon polipleri saptanabilir.

The bone mineral density(BMD) of the lumbar spine (L2-L4) was measured by using dual energy x-ray absorptiometry(Norland XR26 DEXA) in 80 children aged between 2months and 15years (group 1 : 2month-1years, group 2 : 1year-5years, group 3 : 6years-10years, group 4 : 11years-15years). The correlation coefficient of BMD with age, body weight, height and Tanner stage were 0.696, 0.693, 0.717 and 0.636 respectively. There were significant difference in BMD() between group 1(BMD : ) and group 2(BMD : ). and group 3(BMD : ) and group 4(BMD : )(P, Tanner stage 2 : , Tanner stage 3 : )(P

The purpose of this project was to explore the performance of methods for estimating stopping power ratio (SPR) from Hounsfield units (HU) using dual energy CT scans, rather than the standard single energy CT scans, with the aim of finding a method which could outperform the current single energy stoichiometric method. Such a method could reduce the margin currently added to the target volume during treatment which is defined as 3.5 % of the range to the target volume + 1 mm . Three such methods, by Taasti, Zhu, and, Lalonde and Bouchard, were chosen and implemented in MATLAB. A phantom containing 10 tissue-like inserts was scanned and used as a basis for the SPR estimation. To investigate the variation of the SPR from day-to-day the phantom was scanned once a day for 12 days. The resulting SPR of all methods, including the stoichiometric method, were compared with theoretical SPR values which were calculated using known elemental weight fractions of the inserts and mean excitation energies from the National Institute of Standards and Technology (NIST). It was found that the best performing method was the Taasti method which had, at best, an average percentage difference from the theoretical values of only 2.5 %. The Zhu method had, at best, 4.8 % and Lalonde-Bouchard 15.6% including bone tissue or 6.3 % excluding bone. The best average percentage difference of the stoichiometric method was 3.1 %. As the Taasti method was the best performing method and shows much promise, future work should focus on further improving its performance by testing more scanning protocols and kernels to find the ones yielding the best performance. This should then be supplemented with testing different pairs of energies for the dual energy scans. The fact that the Zhu and Lalonde-Bouchard method performed poorly could indicate problems with the implementation of those methods in this project. Investigating and solving those problems is also an important goal for future projects. Lastly the Lalonde-Bouchard method should be tested with more than two energy spectra.

PURPOSE A dual-energy (DE) phantom study was performed on two scanner types in order to evaluate (1) the stability and accuracy of CT numbers and iodine concentrations in function of object size; (2) the effect of beam hardening. METHOD AND MATERIALS Iodine concentrations of 3 and 6 mgI/ml were poured into two respective rows of cylindrical cavities with diameters ranging from 3 to 25.5 mm in an AAPM CT performance phantom. Besides this, a 16 mm diameter tube filled with 6 mgI/ml was placed in the main water-filled compartment, partly covered by a Teflon beam hardening ring. The phantom was scanned in standard 120 kVp and DE mode on a GE Healthcare Discovery HD750 and Siemens SOMATOM Definition Flash scanner at 3 CTDIvol's (9, 19 and 29 mGy). Iodine concentrations were determined for all cavities using the scanner's DE mode, and compared to their true concentrations. CT number stability was determined accordingly and a comparison was made between the DE acquisition and standard 120 kV scanning. RESULTS (1) Relatively constant (max VAR 14%) HU values for both scanners as a function of the object diameters were observed. The Siemens scanner showed a consistent overestimate of approximately 0.5 mgI/ml for both contrast concentrations. A significant decrease in concentration accuracy for object diameters smaller than 6 mm was present for both scanners. (2) A step-like increase of 10 HU upon transitioning out of the Teflon part was observed for both scanners at single energy 120 kV and the Siemens blended DE image, less for the GE DE image (AV 148 HU, max VAR 5 HU). CONCLUSION (1) Measured and true iodine concentrations were consistent down to 6 mm object size, notwithstanding an observed offset with one scanner type. (2) A step-like increase in HU highlights the effect of beam hardening, and is more prominent for classical scans compared to DE. CLINICAL RELEVANCE/APPLICATION DE CT techniques are being increasingly used in tumor imaging. Since iodine is a contrast agent commonly used in CT imaging, determining its detectable lower limit is a crucial factor. Iodine concentration estimations should be made with appropriate consideration.

Purpose: To assess the efficacy of dual-energy CT (DECT) in predicting the composition of urinary stones with a single index (dual energy ratio [DER]) and five indices. Methods: Patients undergoing...

Even outside of the instance of a global pandemic, the proper cleaning of professional work wear is crucial - thus, laundry technology becomes more and more efficient and automated. A bottleneck in the professional laundry process of working garments is the detection of foreign items in pockets and belts; undetected items may not only stain the clothes, but also harm the laundry machines and cause malfunctions or damages. However, the process of locating them is also potentially dangerous, as state-of-the-art is the manual scanning of every piece of garment to find items such as scissors, highlighters, syringes, screwdrivers, scalpels, paper notepads, and sweets. Some of the found objects are completely harmless, but several bare a high potential of injury for the worker involved in the laundry process. Due to the variety of the objects’ materials - plastics, paper, metal, and glass - the items are very challenging to detect with conventional sensors, such as cameras or metal detectors. In non-destructive testing, X-ray transmission (XRT) proved to be a powerful tool for detecting items inside of objects that can not be found by superficial sensors. Unfortunately, XRT does not allow for the distinction between thick objects with low X-ray mass attenuation coefficient and thin objects of stronger attenuation. Thus, similar gray values may be detected, for instance, for components of clothes, such as reflective stripes and pens. In this case, a segmentation by simple thresholding would be hopeless. In contrast, dual energy XRT allows for the obtainment of quantitative information concerning the chemical composition of the scanned materials, which helps to identify objects. In this study, different kinds of working garments were loaded with realistic foreign items in order to show the potential of dual energy XRT in the laundry industry.

This review aims to evaluate diagnostic performance of dual-energy computed tomography (DECT) in follow-up examinations after endovascular aneurysm repair (EVAR) and its radiation dose estimates compared to the standard triphasic protocol. A systematic search was conducted on 20th May 2018 on the following databases: MEDLINE, PubMed, and Scopus. Articles were screened against the inclusion and exclusion criteria. A narrative review of the literature was performed. A summary statistic table of the calculated mean effective dose (ED), percentages in dose reduction and diagnostic performance of DECT were pooled. Five original articles were included. Compared to the triphasic protocol being the reference standard, data from the DECT acquisitions were observed to have 98–100% overall accuracy for the detection of type I and II endoleaks. The cumulative EDs were significantly different (p<0.001) between the protocols. The ED delivered in the DECT protocol was approximately 61% lower than that delivered to the patient by the standard triphasic protocol (11.1 mSv compared with 27.8 mSv). A DECT protocol can replace the standard triphasic protocol in follow-up imaging after EVAR for the detection of type I and II endoleaks. This acquisition protocol also significantly reduces the ED to the patients. Refereed/Peer-reviewed

Heart CT has undergone substantial development from the use of calcium scores performed on electron beam CT to modern 256+-row CT scanners. The latest big step in its evolution was the invention of dual-energy scanners with much greater capabilities than just performing better ECG-gated angio-CT. In this review, we present the unique features of dual-energy CT in heart diagnostics.

Abstract PurposeVentilation-perfusion single photon emission computed tomography (VP SPECT) plays an important role in pulmonary embolism diagnosis. Rapid results may be obtained using same-day ventilation followed by perfusion imaging, but generally requires careful attention to achieving an optimal count rate ratio (P/V ratio) of ~3:1. This study investigated whether the ratio of counts simultaneously acquired in adjacent primary and Compton-scatter energy windows (E_ratio) on V SPECT was predictive of final normalised perfusion count rate (PCRnorm) on P SPECT using [99mTc]Tc-macroaggregated albumin (MAA), allowing optimisation of P/V ratio. MethodsSame-day VP SPECT studies acquired using standard protocols in adult patients during a 2-year period were assessed. Studies were included provided they were acquired with correct imaging parameters, and injection site imaging and laboratory records were available for quality control and normalised count rate corrections. Extraction of DICOM information, and linear regression were performed using custom Python and R scripts. A predictive tool was developed in Microsoft Excel.ResultsOf 643 studies performed, the scans of 343 participants (median age 30.4 years, 318 female) met inclusion criteria. A single outlier with high influence was excluded after an obvious cause was identified. Final analysis of the remaining 342 scans yielded a significant regression equation (F(1,340) = 1057.3, p <.000), with an adjusted R2 of .756 and MSE of 0.001089. A prediction tool designed for routine clinic use was developed for predicting final P/V ratio.ConclusionThe ratio of simultaneously acquired counts in adjacent energy windows on V SPECT is linearly related to perfusion count rate after administration of a known activity of [99mTc]Tc- MAA. A predictive tool based on this work may assist in optimising the dose and timing of [99mTc]Tc-MAA administration in same-day studies to the benefit of patients and workflows.