Computed Tomography Imaging Protocols Research Articles

CT Imaging as a Single Modality for Clinical Staging of Gastric Cancer in Limited Resource Centers: A Retrospective Pilot Study.

Gastric cancer disproportionately impacts populations in resource-limited settings. Within a safety-net network, we assessed the utility of computed tomography (CT) as a single staging modality. We utilized a clinical database of gastric cancer patients treated within the Los Angeles County safety-net hospital system from 2016 to 2023 in conjunction with retrospective imaging review by certified radiologists. We assessed agreement between clinical and pathological staging for patients who underwent curative gastrectomy using the Kappa coefficient. Of 107 patients with available CT imaging, 43.9% (n = 47) were staged with CT as a single modality. Most tumors displayed infiltrating (75%) or diffuse (28%) morphology, 41% displayed adequate gastric distention and regional lymphadenopathy was common (68%). Twenty-nine patients underwent curative gastrectomy. Overall agreement was minimal (κ = 0.29, 95% CI [0.071-0.51], p = 0.022), weak for T3/T4 tumors (κ = 0.50, 95% CI [0.17-0.82], p < 0.01), and weak for Hispanic/Latino patients (κ = 0.47, 95% CI [0.19-0.76], p < 0.01). There was minimal agreement between clinical and pathologic staging when assessing clinical stage by CT imaging alone, suggesting that CT is not adequate as a single modality staging tool. While every effort should be made to obtain multimodal staging, larger studies are warranted to improve CT imaging protocols for staging in resource-limited settings.

Task-based assessment for radiation dose optimization in CT abdominal examinations: A phantom study

Recent advancements in Computed Tomography (CT) imaging technology have significantly enhanced healthcare delivery. However, public concern regarding the safety and health risks associated with increased exposure to ionizing radiation has escalated. In response, this study performs a quantitative analysis comparing the image quality of the standard CT abdomen protocol (P1 protocols) with alternative optimization techniques. Adjustments to standard CT scan parameters, including tube potential (P2 protocols), effective mAs value (P3), and pitch factor (P4, P5, P6 protocols), were made to evaluate the effectiveness of these optimization strategies. A 64-slice CT scanner (Canon, Japan) and a polymethylmethacrylate (PMMA) textural water phantom was utilized in this study. CT dose descriptors, volume weighted CT Dose Index (CTDIvol) and dose-length product (DLP) alongside evaluation parameters such as Hounsfield Unit (HU) number, noise levels, Signal-to-Noise Ratio (SNR), and Contrast-to-Noise Ratio (CNR) were measured and analysed. Furthermore, this research introduced a Figure of Merit (FOM) based on the ratio of image quality parameters (SNR and CNR) to the CTDIvol, establishing a quantitative measure for optimization. A notable reduction in radiation dose—34.85% below the standard protocol (P1)—was observed in protocol P6, attributed to an increased pitch factor. Conversely, increase the effective mAs value has improved SNR and CNR values. The findings reveal that protocols P1 and P2 deliver the highest FOM for soft tissue and fat imaging, respectively. Protocol P1, with its higher attenuation factor, is optimal for abdominal examinations targeting soft tissues. Meanwhile, protocol P2's increase effective mAs value enhances beam intensity, improving CT numbers for fat tissues with their high-density composition. The study also found a strong correlation between FOM based on SNR and CNR values. In conclusion, adjustments to primary CT parameters significantly influence image quality. The FOM serves as an effective tool for measuring the overall performance of image quality, facilitating post-optimization assessment and contributing to the development of safer, more efficient CT imaging protocols.

Evaluation of overexposure risk when there is a space between the subject and the couch in computed tomography: a phantom study.

The purpose of this study was to investigate the risk of overexposure associated with automatic tube current modulation (ATCM) and automatic couch height positioning compensation mechanism (AHC) in computed tomography (CT) systems, particularly in scenarios involving a gap between the subject and the couch. Results revealed that when AHC was enabled, CT dose index volume (CTDIvol) increased by approximately 10% at 2.5cm, 20% at 5.0cm, and 40% at 10.0cm gaps compared to close contact conditions. While the AHC function ensures consistent exposure doses and image quality regardless of subject positioning relative to the CT gantry isocenter, the study highlights a potential risk of overexposure when a gap exists between the subject and the couch. These findings offer valuable insights for optimizing CT imaging protocols and underscore the importance of carefully considering subject positioning in clinical practice.

Diagnostic reference levels for common pediatric computed tomography studies: A retrospective study.

With the rapid increase in computed tomography (CT) examinations among pediatric patients, the concern about the effects of radiation exposure in this population has increased. Therefore, it is necessary to measure and regulate radiation exposure, which can be done using diagnostic reference levels (DRLs). This study aimed to calculate typical values for common pediatric studies at the radiology department of King Abdulaziz University Hospital Jeddah, Saudi Arabia. For a single institute, these are calculated as the median of computed tomography dose index (CTDIvol, mGy) or dose length product (DLP, mGy.cm) values. Pediatric patient data from January 2015 to December 2020 were collected, including CT examinations, dose descriptors, imaging protocols, and scanning parameters. A total of 8717 radiological studies were included in the sample. They were categorized into three age groups; more than half of the 5102 (58.5%) belonged to Group 1 (0–5 years), 1790 (20.5%) were in Group 2 (6–10 years), and 1826 (20.9%) were in Group 3 (11–15 years). Brain CT angiogram, non-enhanced brain CT, and Internal Auditory Canal (IAC) CT had the highest mean CTDI Vol and DLP, while virtual bronchoscopy contrast-enhanced chest and neck CT angiography had the lowest mean CTDI Vol. The values of DRLs in the current study were approximately lower than and comparable with those reported in other studies.

Automatic segmentation of large-scale CT image datasets for detailed body composition analysis

BackgroundBody composition (BC) is an important factor in determining the risk of type 2-diabetes and cardiovascular disease. Computed tomography (CT) is a useful imaging technique for studying BC, however manual segmentation of CT images is time-consuming and subjective. The purpose of this study is to develop and evaluate fully automated segmentation techniques applicable to a 3-slice CT imaging protocol, consisting of single slices at the level of the liver, abdomen, and thigh, allowing detailed analysis of numerous tissues and organs.MethodsThe study used more than 4000 CT subjects acquired from the large-scale SCAPIS and IGT cohort to train and evaluate four convolutional neural network based architectures: ResUNET, UNET++, Ghost-UNET, and the proposed Ghost-UNET++. The segmentation techniques were developed and evaluated for automated segmentation of the liver, spleen, skeletal muscle, bone marrow, cortical bone, and various adipose tissue depots, including visceral (VAT), intraperitoneal (IPAT), retroperitoneal (RPAT), subcutaneous (SAT), deep (DSAT), and superficial SAT (SSAT), as well as intermuscular adipose tissue (IMAT). The models were trained and validated for each target using tenfold cross-validation and test sets.ResultsThe Dice scores on cross validation in SCAPIS were: ResUNET 0.964 (0.909–0.996), UNET++ 0.981 (0.927–0.996), Ghost-UNET 0.961 (0.904–0.991), and Ghost-UNET++ 0.968 (0.910–0.994). All four models showed relatively strong results, however UNET++ had the best performance overall. Ghost-UNET++ performed competitively compared to UNET++ and showed a more computationally efficient approach.ConclusionFully automated segmentation techniques can be successfully applied to a 3-slice CT imaging protocol to analyze multiple tissues and organs related to BC. The overall best performance was achieved by UNET++, against which Ghost-UNET++ showed competitive results based on a more computationally efficient approach. The use of fully automated segmentation methods can reduce analysis time and provide objective results in large-scale studies of BC.

Micro Electromechanical System Navigation Assists Femoral Extramedullary Alignment Osteotomy in Total Knee Arthroplasty: A Single-Blind Randomizing Study.

A micro-electromechanical system (MEMS) was developed based on spatial alignment and navigation technology to assist femoral extramedullary alignment osteotomy (FEAO) in total knee arthroplasty (TKA). The system can locate and adjust the femoral distal condylar osteotomy (FDCO) to obtain a better femoral prosthesis placement. It is a portable navigation device and provides an innovative approach for FDCO. Sixty patients who suffered from severe knee osteoarthritis who underwent unilateral TKA from May 14, 2021 to May 30, 2022 were randomly divided into a MEMS-FEAO group and a conventional femoral intramedullary alignment osteotomy (FIAO) group, with 30 cases in each group for a controlled retrospective study. The hip-knee-ankle angle (HKAA) of the lower limb was measured before and after surgery, the femoral valgus angle (FVA) was measured preoperatively, and the femoral prosthesis valgus angle (FPVA) and the femoral prosthesis flexion angle (FPFA) were measured postoperatively following computed tomography imaging protocols. Measurement data is statistically described as mean ± standard deviation c. The count data is described by frequency (constituent ratio) using the rank sum test. A total of 6.7% (2/30) of FEAO compared to 20.0% (6/30) of FIAO cases were postoperative deviations where the HKAA exceeded ±3° of neutral alignment (p < 0.05). The postoperative HKAA was 178.74° ± 1.56° versus 176.64° ± 3.39° (p < 0.05), the HKAA deviation was 1.25° ± 1.56° versus 3.36° ± 3.40° (p < 0.05), and the FPFA was 4.85° ± 2.46° versus 6.60° ± 1.86°(p < 0.05). Therefore, the differences were all statistically significant between the two groups. However, the FPVA was -0.59° ± 2.73° versus -0.80° ± 2.85° (p > 0.05), and there was no statistical significance between the two groups. The MEMS-FEAO system can improve the accurate alignment and can be utilized as a locator to obtain the best femoral prosthesis placement in TKA and significantly reduce the rate of poor force line of the lower limb.

Laboratory X-ray computed tomography imaging protocol allowing the operando investigation of electrode material evolution in various environments

A robust imaging protocol utilizing laboratory XCT is presented. Hybrid 2D/3D imaging at different scales with real-time monitoring allowed to assess, in operation, the evolution of zinc electrodes within three environments, namely alkaline, near-neutral, and mildly acidic. Different combinations of currents were used to demonstrate various scenarios exhibiting both dendritic and smooth deposition of active material. Directly from radiograms, the volume of the electrode and therefore its growth/dissolution rate was estimated and compared against tomographic reconstructions and theoretical values. The protocol combines simplistic cell design with multiple three-dimensional and two-dimensional acquisitions at different magnifications, providing a unique insight into electrode's morphology evolution within various environments.

Comparison of Average Absorbed Dose Distributions of Organs in SPECT-CT Imaging Using Monte Carlo Simulation

Purpose: The use of ionizing radiation in medical research, treatment, and diagnosis is inevitable and expanding day by day. Meanwhile, in two modes of Computed Tomography (CT) and Single Photon Emission Computed Tomography (SPECT) imaging, the dose received by the organs is featured with limitations and problems, which are often referred to as the CT Dose Index volume (CTDIvol.) and the Dose Length Product (DLP). This study aimed to estimate the average dose of organs and compare them in each of these two modalities.&#x0D; Materials and Methods: Using the GATE code to simulate the SPECT-CT system and the International Commission on Radiological Protection (ICRP) voxelized phantom as the patient was investigated. The mean dose distribution in three groups of children, adults, and obese people with different body thicknesses was estimated. The dose received by each of the two systems was evaluated separately and results were discussed and analyzed comparatively.&#x0D; Results: In the kidney, bladder, intestine, colon, liver, and gallbladder, the dose received in CT is at least 10% more than nuclear medicine. For example, the ratio of the dose received in CT to the dose received in nuclear medicine in the lung was about 1.08 and in the esophagus was about 1.24. Subsequently, the ratio increased to 0.25 in the bladder and 0.19 in the colon and intestine. Moreover, the major organs that received the maximum dose, result in CT at least 10% more than nuclear medicine.&#x0D; Conclusion: The dose received in organs such as the esophagus, breast, and lung during CT imaging protocol and also maximum dose were at least ten percent more than nuclear medicine.

Stereolithography (STL) measurement rubric for the evaluation of craniomaxillofacial STLs

BackgroundFacial deformities often demand reconstructive surgery and the placement of three-dimensional (3D) printed craniomaxillofacial prostheses. Prostheses manufacturing requires patients’ computed tomography (CT) images. Poor quality images result in incorrectly sized prostheses, necessitating repeat imaging and refitting. The Centre for Rapid Prototyping and Manufacturing (CRPM) produces most facial prostheses in South Africa but does not have a prescribed optimised CT protocol. Therefore, this study was undertaken.MethodsA collection of CRPM STLs used in the design and manufacturing of craniomaxillofacial prostheses is available. The image quality of stereolithography (STL) files of CRPM CT scans was evaluated to determine what constitutes good image quality. This collection was scrutinised for inclusion in the image quality evaluation. After scrutiny, 35 STLs of individuals ≥15 years of age were selected and included metadata attached to the DICOM file. Furthermore, only STLs created without manipulation by the same designer were included in the collection. Before the qualitative evaluation of the STLs, eight different critical anatomical reference points (CARPs) were identified with the assistance of an expert team. A visual acuity rating scale of three categories was devised for each CARP, where 1 was allocated to poor visual acuity, 2 to partial, and 3 to good visual acuity. Similarly, rating scales were devised for the presence of concentric rings and the overall impression score awarded by the two designers involved in the design and manufacturing of the prostheses. This stereolithography measurement rubric (SMR) was then applied to the 35 STLs by a team of three experts, including the two designers, during a structured evaluation session. The scores were used to calculate summary and inferential statistics.ResultsScores grouped around the central rating of partial visual acuity. The three evaluators’ mean total CARP scores ranged from 13.1 to 14.4 (maximum possible score 24), while the mean total CARP + ring scores ranged from 15.8 to 17.1 (maximum possible score 27). No significant differences were detected between the evaluators’ scores.ConclusionThis SMR appears to be the first of its kind. This image quality assessment of STLs provides the groundwork for finer CT image quality evaluation to formulate a CT imaging protocol for the CRPM to design and manufacture accurate internal cranial prostheses.

Usefulness of a refined computed tomography imaging method to assess the prevalence of residual pulmonary thrombi in patients 1 year after acute pulmonary embolism: The Nagoya PE study

BackgroundPost‐pulmonary embolism (PE) syndrome is an important clinical condition that can affect the long‐term prognosis after acute PE. ObjectiveWe aimed to evaluate the prevalence of residual pulmonary thrombi and the thrombotic burden 1 year after acute PE, by using our refined computed tomography (CT) imaging method. Patients/MethodsIn this prospective study, patients diagnosed with acute PE were recruited and examinations were conducted at 1 month, 6 months, and 1 year. Especially at 1 year, patients were evaluated multifacetedly, including by laboratory tests, quality‐of‐life, 6‐min walking test, and enhanced CT. ResultsFifty‐two patients were enrolled. Two patients (3.8%) developed chronic thromboembolic pulmonary hypertension. A total of 43 patients completed evaluation at 1 year, among whom (74%) had residual thrombi, with a median modified CT obstruction index (mCTOI) of 10.7%. In multivariate analysis, residual thrombi at 1 month was the only factor significantly related to residual thrombi at 1 year (odds ratio, 103.4; 95% confidence interval, 4.2–2542.1). The tricuspid regurgitation pressure gradient ≥60 mmHg and left ventricular end‐diastolic dimension at diagnosis were significantly related to mCTOI at 1 year (β = 0.367, P = .003; and β = –0.435, P = .001, respectively). ConclusionsUsing our improved CT imaging protocol, we found a high prevalence of residual thrombi 1 year after acute PE. Furthermore, right ventricular overload was related to the thrombotic burden. The long‐term treatment strategy of acute PE could be modified to include precise CT imaging.

Towards the establishment of national imaging practice guidelines: A preliminary study of the basic computed tomography imaging protocols in Ghana

BackgroundThere is a need to harmonize imaging practices in computed tomography (CT) imaging. This study, therefore, investigated the variability of the basic imaging protocols used for CT imaging of common indications in Ghana in order to generate recommendations for the development of national imaging practice guidelines in CT imaging. MethodA cross-sectional study, utilizing a structured online questionnaire, was undertaken (between December 2018 to March 2019) to collect indication-based imaging protocol data (scan coverage, scan series, image quality requirement, slice thickness, reconstruction, scan mode and orientation, required window, AEC usage, scan and breath hold techniques etc.,) across the various CT facilities in the country. Data were analysed and with experts’ input, recommendations were made. ResultsThe imaging protocols used across the CT facilities in the country were largely similar, with a few variabilities for similar examinations. These variabilities were found in scan coverages, series and slice thicknesses. In particular, for a brain tumour examination, 92% of the 25 facilities used both non-contrast and contrast phases while 8% preferred only the IV contrast phase. Seventy percent of all the facilities (n=10) performing pulmonary angiograms in the country also used a two-sequence scan, and others (30%) worked with only the angiogram phase. A majority (89%) of the 19 facilities that were engaged in CT-IVU procedures also used 3-4 scan phases, while 11% preferred a split-bolus technique. None of the facilities employed the low-dose or ultra-low dose protocol for kidney stone examination. ConclusionsThe study's outcome provides an important preliminary roadmap that could lead to the development of imaging practice guidelines to ensure harmonization of imaging practices to improve the protection and safety of patients across the CT facilities.

High-Resolution CT Imaging of the Temporal Bone: A Cadaveric Specimen Study.

Objective Super-high and ultra-high spatial resolution computed tomography (CT) imaging can be advantageous for detecting temporal bone pathology and guiding treatment strategies. Methods Six temporal bone cadaveric specimens were used to evaluate the temporal bone microanatomic structures utilizing the following CT reconstruction modes: normal resolution (NR, 0.5-mm slice thickness, 512 2 matrix), high resolution (HR, 0.5-mm slice thickness, 1,024 2 matrix), super-high resolution (SHR, 0.25-mm slice thickness, 1,024 2 matrix), and ultra-high resolution (UHR, 0.25-mm slice thickness, 2,048 2 matrix). Noise and signal-to-noise ratio (SNR) for bone and air were measured at each reconstruction mode. Two observers assessed visualization of seven small anatomic structures using a 4-point scale at each reconstruction mode. Results Noise was significantly higher and SNR significantly lower with increases in spatial resolution (NR, HR, and SHR). There was no statistical difference between SHR and UHR imaging with regard to noise and SNR. There was significantly improved visibility of all temporal bone osseous structures of interest with SHR and UHR imaging relative to NR imaging ( p < 0.001) and most of the temporal bone osseous structures relative to HR imaging. There was no statistical difference in the subjective image quality between SHR and UHR imaging of the temporal bone ( p ≥ 0.085). Conclusion Super-high-resolution and ultra-high-resolution CT imaging results in significant improvement in image quality compared with normal-resolution and high-resolution CT imaging of the temporal bone. This preliminary study also demonstrates equivalency between super-high and ultra-high spatial resolution temporal bone CT imaging protocols for clinical use.

Magnetic resonance imaging in the assessment of acute stroke

Introduction: Stroke is the second leading underlying cause of death globally and the leading cause of disability in adults. Stroke diagnosis should be performed quickly and efficiently to eliminate other potential causes of neurological deficits and to assess the time since the onset of clinical symptoms. Computed tomography (CT) and magnetic resonance imaging (MRI) are essential methods of detecting and evaluating stroke type and treatmentoptions. Diffusion and perfusion MR imaging is recommended for early stroke diagnosis, as well as for the selection of patients for recanalization therapy, and is considered effective in assessing treatment outcomes. The objectives of this study were to demonstrate the diagnostic value of diffusion and perfusion imaging in the diagnosis of acute ischemic stroke, analyze the role of magnetic resonance imaging in the selection of patients with acute stroke for recanalization therapy, and assess the effect of acute stroke complicity.Material and methods: The research is designed as a systematic review of the primary scientific research literature, which was published in English in relevant scientific databases (PubMed, Google Scholar, Medline) from 2014 to 2021.Results: 14 scientific research papers were singled out and the general characteristics of the study were analyzed (country, authors, year of publication, title of the study, type of study, study objectives, research methods, results and conclusion). A quality assessment of the included studies with cohort design and randomized controlled studies was performed, and most belong to the category of high-quality studies with a smaller number of medium-quality studies. The overall percentage of detected AIS cases in isolated studies using the DWI and/or PWI sequence was 90.8%. At the same time, the outcome of recanalization therapy was assessed using MRI studies (the number of patients who developed adverse events with functional data outcome 30 or 90 days after the procedure was observed). Comparison of MRI and CT imaging protocols provided data on the total percentage of detected acute stroke cases using CT imaging protocols (68.9%) and MRI imaging protocols (88.5%), which is why MRI is considered a superior method.Conclusion: Although CT is a suitable method for visualizing bleeding and also for early differentiation of hemorrhagic from ischemic stroke, if MRI imaging is available, it is recommended to use DWI, PWI, MRA sequences for a more accurate diagnosis of stroke in the acute phase.

MEASUREMENT OF RADIATION DOSE TO THE EYE LENS IN NON-ENHANCED CT SCANS OF THE BRAIN.

Radiation can have undesirable effects on the eye, including a gradual loss of vision. Unnecessary radiation can reach the eye lens during non-enhanced computed tomography (CT) scans of the brain. The International Commission on Radiological Protection states the threshold for acute and chronic eye lens exposure is 500mGy and the equivalent dose limit for the eye lens for public exposure is 15mSv per year. Therefore, we measured the direct radiation dose to the eye lens during head CT scans using NanoDots in 216 adults. The mean absorbed dose to both eyes was 33.62mGy (standard deviation ±12.442). The averages for the other variables were: tube current-time product: 260 mAs; dose-length product: 708mGycm and CT dose index: 35.5mGy. Our findings encourage further study of radiation exposure and modifications in CT imaging protocols.

An Individualized Contrast-Enhanced Liver Computed Tomography Imaging Protocol Based on Body Mass Index in 126 Patients Seen for Liver Cirrhosis.

BackgroundComputed tomography (CT) imaging using iodinated contrast medium is associated with the radiation dose to the patient, which may require reduction in individual circumstances. This study aimed to evaluate an individualized liver CT protocol based on body mass index (BMI) in 126 patients investigated for liver cirrhosis.Material/MethodsFrom November 2017 to December 2020, in this prospective study, 126 patients with known or suspected liver cirrhosis were recruited. Patients underwent liver CT using individualized protocols based on BMI, as follows. BMI ≤24.0 kg/m2: 80 kV, 352 mg I/kg; BMI 24.1–28.0 kg/m2: 100 kV, 440 mg I/kg; BMI ≥28.1 kg/m2: 120 kV, 550 mg I/kg. Figure of merit (FOM) and size-specific dose estimates (SSDEs) were calculated and compared using the Mann-Whitney U test. Subjective image quality and timing adequacy of the late arterial phase were evaluated with Likert scales.ResultsThe SSDE was significantly lower in the 80 kV protocol, corresponding to a dose reduction of 36% and 50% compared with the others (all P<0.001). In the comparison of 80-, 100-, and 120-kV protocols, no statistically significant differences were found in FOMs (P=0.108~0.620). Of all the examinations, 95.2% (120 of 126) were considered as appropriate timing for the late arterial phase. In addition, overall image quality, hepatocellular carcinoma conspicuity, and detection rate did not differ significantly among the 3 protocols (P=0.383~0.737).ConclusionsThis study demonstrated the feasibility of using an individualized liver CT protocol based on BMI, and showed that patients with lower BMI should receive lower doses of iodinated contrast medium and significantly reduced radiation dose.

Normalization of multicenter CT radiomics by a generative adversarial network method

To reduce the variability of radiomics features caused by computed tomography (CT) imaging protocols through using a generative adversarial network (GAN) method. In this study, we defined a set of images acquired with a certain imaging protocol as a domain, and a total of four domains (A, B, C, and T [target]) from three different scanners was included. In data set#1, 60 patients for each domain were collected. Data sets#2 and #3 included 40 slices of spleen for each of the domains. In data set#4, the slices of three colorectal cancer groups (n = 28, 38 and 32) were separately retrieved from three different scanners, and each group contained short-term and long-term survivors. Seventy-seven features were extracted for evaluation by comparing the feature distributions. First, we trained the GAN model on data set#1 to learn how to normalize images from domains A, B and C to T. Next, by comparing feature distributions between normalized images of the different domains, we identified the appropriate model and assessed it, in data set#2 and data set#3, respectively. Finally, to investigate whether our proposed method could facilitate multicenter radiomics analysis, we built the least absolute shrinkage and selection operator classifier to distinguish short-term from long-term survivors based on a certain group in data set#4, and validate it in another two groups, which formed a cross-validation between groups in data set#4. After normalization, the percentage of aligned features between domains A versus T, B versus T, and C versus T increased from 10.4 %, 18.2% and 50.1% to 93.5%, 89.6% and 77.9%, respectively. In the cross-validation results, the average improvement of the area under the receiver operating characteristic curve achieved 11% (3%–32%). Our proposed GAN-based normalization method could reduce the variability of radiomics features caused by different CT imaging protocols and facilitate multicenter radiomics analysis.

Assessment of CT Imaging Protocols Impacts on Calculation of Point Dose in Water Phantom Using Radiotherapy Treatment Planning System

Purpose: Point dose calculation in the Treatment Planning System (TPS) is performed using Computed Tomography (CT) images because CT images data have the tissue electron density information. The effect of CT imaging protocols on the calculation of point doses in TPS is one of the most important subjects that was evaluated in this study. Materials and Methods: CT scan imaging was performed from cylindrical water phantom using three scanner systems and different imaging technical parameters. The CT images data were irradiated in TPS to delivering a 200 cGy radiation dose to the center of the phantom with 6 and 15MV X-Ray photon energy with multiple radiation fields and Monitor Unit (MU) were separately calculated. In the TPS, a virtual water phantom with the same characteristic as CT image phantom was simulated and irradiated with similar conditions. The difference in MU values obtained from two irradiation methods in TPS was compared with Wilcoxon nonparametric test. Results: Variations of mA, kV, Pitch, slice thickness, and kernel as CT imaging parameters have not significantly affected radiotherapy point dose calculation (&lt;2%). CT imaging protocols as a thin slice, 80 kV, and sharp kernel have the greatest difference between CT image-based calculation and designed phantom calculation in TPS where wedge field and 6 MV photon energy were used. Conclusion: The use of CT images obtained with multiple protocols can be used without having a significant effect on the dose calculations of the treatment planning system.

Intelligent 4D CT sequence scanning (i4DCT): First scanner prototype implementation and phantom measurements of automated breathing signal-guided 4D CT.

Four-dimensional (4D) computed tomography (CT) imaging is an essential part of current 4D radiotherapy treatment planning workflows, but clinical 4D CT images are often affected by artifacts. The artifacts are mainly caused by breathing irregularity during data acquisition, which leads to projection data coverage issues for currently available commercial 4D CT protocols. It was proposed to improve projection data coverage by online respiratory signal analysis and signal-guided CT tube control, but related work was always theoretical and presented as pure in silico studies. The present work demonstrates a first CT prototype implementation along with respective phantom measurements for the recently introduced intelligent 4D CT (i4DCT) sequence scanning concept (https://doi.org/10.1002/mp.13632). Intelligent 4D CT was implemented on the Siemens SOMATOM go platform. Four-dimensional CT measurements were performed using the CIRS motion phantom. Motion curves were programmed to systematically vary from regular to very irregular, covering typical irregular patterns that are known to result in image artifacts using standard 4D CT imaging protocols. Corresponding measurements were performed using i4DCT and routine spiral 4D CT with similar imaging parameters (e.g., mAs setting and gantry rotation time, retrospective ten-phase reconstruction) to allow for a direct comparison of the image data. Following technological implementation of i4DCT on the clinical CT scanner platform, 4D CT motion artifacts were significantly reduced for all investigated levels of breathing irregularity when compared to routine spiral 4D CT scanning. The present study confirms feasibility of fully automated respiratory signal-guided 4D CT scanning by means of a first implementation of i4DCT on a CT scanner. The measurements thereby support the conclusions of respective in silico studies and demonstrate that respiratory signal-guided 4D CT (here: i4DCT) is ready for integration into clinical CT scanners.

Changes in Approach to Solid Organ Injury: What the Radiologist Needs to Know.

This review aims to examine the challenges facing radiologists interpreting trauma computed tomography (CT) images in this era of a changing approach to management of solid organ trauma. After reviewing the pearls and pitfalls of CT imaging protocols for detection of traumatic solid organ injuries, we describe the key changes in the 2018 American Association for the Surgery of Trauma Organ Injury Scales for liver, spleen, and kidney and their implications for management strategies. We then focus on the important imaging findings in observed in patients who undergo nonoperative management and patients who are imaged post damage control surgery.

National Trends in CT Utilization and Estimated CT-related Radiation Exposure in the Evaluation and Follow-up of Stone Patients

ObjectiveTo describe trends in computed tomography (CT) use and estimate the radiation exposure among stone formers using a national insurance claims database. MethodsWithin MarketScan, adult stone patients from 2007 to 2013 were identified using International Classification of Diseases-Revision 9, International Classification of Diseases-Revision 10, and Current Procedural Terminology codes. Patients were classified as “active” (≥2 diagnosis codes for nephrolithiasis, or receipt of stone surgery) or “inactive” (1 stone diagnosis) and compared to age- and gender-matched controls. CT utilization was tracked over 3 years for each group. Annual CT-related radiation exposure was estimated using previously published dose values and compared using Kruskal-Wallis and χ2 tests. Demographic factors associated with greater CT exposure were identified on multivariate logistic regression. ResultsOf active stone patients, 112,140 underwent surgery and 215,376 were managed nonoperatively. There were 175,228 inactive stone patients and 502,744 controls. On average, active stone patients received nearly 10 times as many CTs as controls at 3 years (P <.001), and more acute imaging (P <.001). About 25% and 15% of operative and nonoperative patients, respectively, received ≥3 CTs in 3 years. This was associated with female gender. For nonoperative patients, this was also associated with age, residence in the North-Central or South regions, and inversely associated with metropolitan residence (all P <.01). Over 10% of active stone patients are estimated to receive >20 mSv in the first year alone. ConclusionCT use and nonsurgical radiation exposure for active stone patients is significant. Over 10% are estimated to exceed occupational limits in the first year. Judicious CT imaging and low-dose protocols are critical for stone patients.