1,265 results match your criteria thorax phantom

Dosimetric evaluation of different planning techniques based on flattening filter-free beams for central and peripheral lung stereotactic body radiotherapy.

Biomed Phys Eng Express 2021 Oct 12. Epub 2021 Oct 12.

Department of Radiotherapy, Government Medical College Patiala, Sangrur Road, Patiala, Punjab, 147001, INDIA.

This study aimed to dosimetrically compare and evaluate the flattening filter-free (FFF) photon beam-based three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) for lungstereotactic body radiotherapy (SBRT). RANDO phantom computed tomography (CT) images were used for treatment planning. Gross tumor volumes (GTVs) were delineated in the central and peripheral lung locations. Read More

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October 2021

Lung shunt fraction calculation using Tc-MAA SPECT/CT imaging for Y microsphere selective internal radiation therapy of liver tumors.

EJNMMI Res 2021 Sep 28;11(1):96. Epub 2021 Sep 28.

Department of Radiation Oncology, Miller School of Medicine, University of Miami, Miami, FL, USA.

Background: Tc-macroaggregated albumin (Tc-MAA) scintigraphy is utilized in treatment planning for Yttrium-90 (Y) Selective Internal Radiation Therapy (SIRT) of liver tumors to evaluate hepatopulmonary shunting by calculating the lung shunt fraction (LSF). The purpose of this study was to evaluate if LSF calculation using SPECT/CT instead of planar gamma camera imaging is more accurate and if this can potentially lead to more effective treatment planning of hepatic lesions while avoiding excessive pulmonary irradiation.

Results: LSF calculation was obtained using two different methodologies in 85 cases from consecutive patients intended to receive Y SIRT. Read More

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September 2021

Impact of Acquisition Protocols on Accuracy of Dose Calculation Based on XVI Cone Beam Computed Tomography.

J Med Phys 2021 Apr-Jun;46(2):94-104. Epub 2021 Aug 7.

SNIRM Laboratory, Faculty of Physics, University of Sciences and Technology Houari Boumediene, Algiers, ALGERIA.

Purpose: The objective of this work is to study the impact of acquisition protocols on the accuracy of cone beam computed tomography (CBCT)-based dose calculation and to determinate its limits from image characteristics such as image quality, Hounsfield numbers consistency, and restrictive sizes of volume acquisition, compared to the CT imaging for the different anatomy localizations: head and neck (H&N), thorax, and pelvis.

Materials And Methods: In this work, we used a routine on-board imaging CBCT of the XVI system (Elekta, Stockholm, Sweden). Dosimetric calculations performed on CT images require the knowledge of the Hounsfield unit-relative electron density (HU-ReD) calibration curve, which is determined for each imaging technology and must be adapted to the imaging acquisition parameters (filter/field of view). Read More

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Development and prospective validation of a spatial dose pattern based model predicting acute pulmonary toxicity in patients treated with volumetric arc-therapy for locally advanced lung cancer.

Radiother Oncol 2021 Sep 20;164:43-49. Epub 2021 Sep 20.

Department of Radiation Oncology, University Hospital, Brest, France; LaTIM UMR 1101 INSERM, University Brest, Brest, France.

Introduction: (Chemo)-radiotherapy is the standard treatment for patients with locally advanced lung cancer (LALC) not accessible to surgery. Despite strict application of dose constraints, acute toxicities such as acute pulmonary toxicity (APT) remain frequent, and may impact treatment's compliance and patients' quality of life. Previously, on a population treated with intensity-modulated photon therapy or passive scattering proton therapy, spatial dose patterns associated with APT were identified in the lower lungs, especially in the posterior right lung. Read More

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September 2021

On the interplay effect for moving targets treated with the CyberKnife static tracking system.

Phys Med 2021 Sep 13;90:30-39. Epub 2021 Sep 13.

Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland. Electronic address:

Purpose: To assess the interplay effect amplitude between different planned MU distributions and respiratory patterns in the CyberKnife system when treating moving targets with static tracking technique.

Methods: Small- and Large-Respiratory Motions (SRM and LRM) differing in amplitude and frequency were simulated in a semi-anthropomorphic dynamic thorax phantom. The interplay effect was evaluated for both respiration motions in terms of GTV coverage and conformity for three plans designed with an increasing range of MU per beam (small, medium and large). Read More

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September 2021

Validation of absolute point dosimetry by the analytical anisotropic algorithm and Acuros XB algorithm employing intensity-modulated radiotherapy technique on an in-house develop cost-effective heterogeneous thorax phantom.

J Cancer Res Ther 2021 Jul-Sep;17(4):859-864

School of Studies in Physics, Vikram University, Ujjain, Madhya Pradesh, India.

Introduction: Dose validation inside the human body needs a medium which can simulate the actual heterogeneities of a specific body site. The aim of the present work is to study the properties of a cost-effective heterogeneous thorax phantom (HTP) developed in-house by the author and its application for the evaluation of patient-specific absolute point dosimetry by employing analytic anisotropic algorithm (AAA) and Acuros XB (AXB) algorithm.

Materials And Methods: HTP was made from the dust of porous pinewood, rib cage, and honeybee's wax. Read More

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September 2021

Accuracy Evaluation of EPL and ETAR Algorithms in the Treatment Planning Systems using CIRS Thorax Phantom.

J Biomed Phys Eng 2021 Aug 1;11(4):483-496. Epub 2021 Aug 1.

PhD, Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.

Background: It is recommended for each set of radiation data and algorithm that subtle deliberation is done regarding dose calculation accuracy. Knowing the errors in dose calculation for each treatment plan will result in an accurate estimate of the actual dose achieved by the tumor.

Objective: This study aims to evaluate the equivalent path length (EPL) and equivalent tissue air ratio (ETAR) algorithms in radiation dose calculation. Read More

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Double-vertebral segment SBRT via novel ring-mounted Halcyon Linac: Plan quality, delivery efficiency and accuracy.

Med Dosim 2021 Aug 16. Epub 2021 Aug 16.

University of Kentucky, Department of Radiation Medicine, Lexington, KY, USA.

To evaluate the plan quality, treatment delivery efficiency, and accuracy of single-isocenter/multi-target (SIMT) volumetric modulated arc therapy (VMAT) of double-vertebral segments stereotactic body radiation therapy (SBRT) on Halcyon ring delivery system (RDS). In-house multi-target end-to-end phantom testing and independent dose verification using the MD Anderson's single-isocenter/multi-target (lung/spine targets) thorax phantom were completed. Six previously treated patients with 2-vertebral segments on thoracic and/or lumber spine were replanned on Halcyon RDS with 6MV-FFF beam using a single-isocenter placed between the vertebral segments. Read More

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Low dose cone beam CT for paediatric image-guided radiotherapy: Image quality and practical recommendations.

Radiother Oncol 2021 Jul 31;163:68-75. Epub 2021 Jul 31.

Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, UK.

Purpose: Cone beam CT (CBCT) is used in paediatric image-guided radiotherapy (IGRT) for patient setup and internal anatomy assessment. Adult CBCT protocols lead to excessive doses in children, increasing the risk of radiation-induced malignancies. Reducing imaging dose increases quantum noise, degrading image quality. Read More

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Dual flip-angle IR-FLASH with spin history mapping for B1+ corrected T1 mapping: Application to T1 cardiovascular magnetic resonance multitasking.

Magn Reson Med 2021 Jul 26. Epub 2021 Jul 26.

Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.

Purpose: To develop a single-scan method for -corrected T mapping and apply it for free-breathing (FB) cardiac MR multitasking without electrocardiogram (ECG) triggering.

Methods: One dual flip-angle (2FA) inversion recovery (IR)-FLASH scan provides two observations of (apparent T ) corresponding to two distinct combinations of the nominal FA α and . Spatiotemporally coregistered T and spin history maps are obtained by fitting the 2FA signal model. Read More

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Quantification of airway dimensions using a high-resolution CT scanner: A phantom study.

Med Phys 2021 Jul 20. Epub 2021 Jul 20.

Department of Radiological Sciences, University of California Irvine, Irvine, CA, USA.

Purpose: Small airways with inner diameters less than 2 mm are sites of major airflow limitations in patients with chronic obstructive pulmonary disease (COPD) and asthma. The purpose of this study is to investigate the limitations for accurate assessment of small airway dimensions using both high-resolution CT (HRCT) and conventional normal-resolution CT at low dose levels.

Methods: To model the normal human airways from the 3rd to 20th generations, a cylindrical polyurethane phantom with 14 airway tubes of inner diameters (ID) ranging from 0. Read More

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Correlation of image quality parameters with tube voltage in X-ray dark-field chest radiography: a phantom study.

Sci Rep 2021 07 8;11(1):14130. Epub 2021 Jul 8.

Department of Diagnostic and Interventional Radiology, School of Medicine and Klinikum Rechts Der Isar, Technical University of Munich, Ismaningerstr. 22, 81675, Munich, Germany.

Grating-based X-ray dark-field imaging is a novel imaging modality with enormous technical progress during the last years. It enables the detection of microstructure impairment as in the healthy lung a strong dark-field signal is present due to the high number of air-tissue interfaces. Using the experience from setups for animal imaging, first studies with a human cadaver could be performed recently. Read More

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Dose measurements in a thorax phantom at 3DCRT breast radiation therapy.

Rep Pract Oncol Radiother 2021 14;26(2):242-250. Epub 2021 Apr 14.

Department of Nuclear Engineering, Federal University of Minas Gerais, Belo Horizonte, Brazil.

Background: The anthropomorphic and anthropometric phantom developed by the research group NRI (Núcleo de Radiações Ionizantes) can reproduce the effects of the interactions of radiation occurring in the human body. The whole internal radiation transport phenomena can be depicted by film dosimeters in breast RT. Our goal was to provide a dosimetric comparison of a radiation therapy (RT) plan in a 4MV 3D-conformal RT (4MV-3DCR T) and experimental data measured in a breast phantom. Read More

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Computed Tomography Imaging in Simulated Ongoing Cardiopulmonary Resuscitation: No Need to Switch Off the Chest Compression Device during Image Acquisition.

Diagnostics (Basel) 2021 Jun 19;11(6). Epub 2021 Jun 19.

Department of Radiology, Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin, 12203 Berlin, Germany.

Computed tomography (CT) represents the current standard for imaging of patients with acute life-threatening diseases. As some patients present with circulatory arrest, they require cardiopulmonary resuscitation. Automated chest compression devices are used to continue resuscitation during CT examinations, but tend to cause motion artifacts degrading diagnostic evaluation of the chest. Read More

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Technical Note: End-to-end verification of an MR-Linac using a dynamic motion phantom.

Med Phys 2021 Sep 26;48(9):5479-5489. Epub 2021 Jul 26.

Department of Radiation Physics, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China.

Purpose: MR-Linac integrates an MRI scanner and a linear accelerator to provide adaptive radiation treatment. Superior tissue contrast and real-time imaging can give the clinicians confidence to reduce the margins of the planning target volume (PTV). The purpose of this study was to verify the dosimetric accuracy of an MR-Linac system in treating a moving target and assess the error with different motion patterns and adaptation methods. Read More

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September 2021

Assessing the reproducibility of CBCT-derived radiomics features using a novel three-dimensional printed phantom.

Med Phys 2021 Aug 11;48(8):4326-4333. Epub 2021 Jul 11.

Department of Radiation Oncology, NYU Langone Medical Center, New York, NY, USA.

Purpose: Radiomics modeling is an exciting avenue for enhancing clinical decision making and personalized treatment. Radiation oncology patients often undergo routine imaging for position verification, particularly using LINAC-mounted cone beam computed tomography (CBCT). The wealth of imaging data collected in modern radiation therapy presents an ideal use case for radiomics modeling. Read More

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Markerless Real-Time 3-Dimensional kV Tracking of Lung Tumors During Free Breathing Stereotactic Radiation Therapy.

Adv Radiat Oncol 2021 Jul-Aug;6(4):100705. Epub 2021 Apr 20.

Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, the Netherlands.

Purpose: Accurate verification of tumor position during irradiation could reduce the probability of target miss. We investigated whether a commercial gantry-mounted 2-dimensional (2D) kilo-voltage (kV) imaging system could be used for real-time 3D tumor tracking during volumetric modulated arc therapy (VMAT) lung stereotactic body radiation therapy (SBRT). Markerless tumor tracking on kV fluoroscopic images was validated using a life-like moving thorax phantom and subsequently performed on kV images continuously acquired before and during free-breathing VMAT lung SBRT. Read More

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On the evaluation of mobile target trajectory between four-dimensional computer tomography and four-dimensional cone-beam computer tomography.

J Appl Clin Med Phys 2021 Jul 3;22(7):198-207. Epub 2021 Jun 3.

Department of Radiation Oncology, School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.

Purpose: For mobile lung tumors, four-dimensional computer tomography (4D CT) is often used for simulation and treatment planning. Localization accuracy remains a challenge in lung stereotactic body radiation therapy (SBRT) treatments. An attractive image guidance method to increase localization accuracy is 4D cone-beam CT (CBCT) as it allows for visualization of tumor motion with reduced motion artifacts. Read More

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Dual-energy x-ray approach for object/energy-specific attenuation coefficient correction in single-photon emission computed tomography: effects of contrast agent.

J Med Imaging (Bellingham) 2021 Sep 31;8(5):052106. Epub 2021 May 31.

National University of Singapore, Center for Remote Imaging, Sensing and Processing and Department of Physics, Singapore.

To investigate the influence of radiographic contrast agent on the accuracy of the photon counts arising from the emission of gamma rays of radionuclides in single-photon emission computed tomography (SPECT), when dual-energy x-ray CT (DXCT) is employed for providing object/energy-specific attenuation coefficient correction in SPECT. Computer simulation was performed for three transmission CT approaches, namely, the conventional (single kVp, unimodal spectrum) x-ray CT, DXCT (single kVp, bimodal spectrum) with basis material decomposition (BMD), and DXCT with BMD followed by basis material coefficients transformation (BMT), to study the effects of these approaches on the accuracy of the photon counts from the SPECT image of a thorax-like phantom. All three CT approaches revealed that the error in the counts was both photon energy and iodine concentration-dependent. Read More

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September 2021

Proper Management of the Clinical Exposure Index Based on Body Thickness Using Dose Optimization Tools in Digital Chest Radiography: A Phantom Study.

Int J Environ Res Public Health 2021 05 13;18(10). Epub 2021 May 13.

Department of Health Sciences, Faculty of Health Sciences, Kyushu University, 774 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.

In radiography, the exposure index (EI), as per the International Electrotechnical Commission standard, depends on the incident beam quality and exposure dose to the digital radiography system. Today automatic exposure control (AEC) systems are commonly employed to obtain the optimal image quality. An AEC system can maintain a constant incident exposure dose on the image receptor regardless of the patient thickness. Read More

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Evaluating a calcium-aware kernel for CT CAC scoring with varying surrounding materials and heart rates: a dynamic phantom study.

Eur Radiol 2021 May 28. Epub 2021 May 28.

Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.

Objectives: The purpose of this study was twofold. First, the influence of a novel calcium-aware (Ca-aware) computed tomography (CT) reconstruction technique on coronary artery calcium (CAC) scores surrounded by a variety of tissues was assessed. Second, the performance of the Ca-aware reconstruction technique on moving CAC was evaluated with a dynamic phantom. Read More

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Commissioning and quality assurance of Euromechanics add-on multileaf collimator.

Biomed Phys Eng Express 2020 12 21;7(1). Epub 2020 Dec 21.

Department of Medical Physics, Tehran University of Medical Science, Tehran, Iran.

In this study, the beam characteristics of a Euromechanics add-on MLC that has been installed on a Varian CLINAC 2100 C/D linear accelerator are presented. This was the first installation of 60-leaf PMLC from Euromechanics Company worldwide and all mechanical and dosimetric parameters were measured before clinical use of this kind of MLC. Mechanical tests were executed for different gantry and collimator angles. Read More

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December 2020

SBRT treatment of abdominal and pelvic oligometastatic lymph nodes using ring-mounted Halcyon Linac.

J Appl Clin Med Phys 2021 Jun 25;22(6):162-171. Epub 2021 May 25.

Medical Physics Graduate Program, Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA.

Purpose/objectives: This work seeks to evaluate the plan quality, treatment delivery efficiency, and accuracy of single-isocenter volumetric modulated arc therapy (VMAT) of abdominal/pelvic oligometastatic lymph nodes (LNs) stereotactic body radiation therapy (SBRT) on Halcyon Linac.

Materials And Methods: After completing the in-house multitarget end-to-end phantom testing and independent dose verification using MD Anderson's single-isocenter/multi-target (lung and spine target inserts) thorax phantom, eight patients with two to three abdominal/pelvic oligometastatic LNs underwent highly conformal single-isocenter VMAT-SBRT treatment using the Halcyon Linac 6MV flattening filter free (FFF) beam. Targets were identified using an Axumin PET/CT scan co-registered with planning CT images and a single-isocenter was placed between/among the targets. Read More

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Automatic quantification package (Hone Graph) for phantom-based image quality assessment in bone SPECT: computerized automatic classification of detectability.

Ann Nucl Med 2021 Aug 24;35(8):937-946. Epub 2021 May 24.

Department of Radiology, Toyohashi Municipal Hospital, 50 Aza Hachiken Nishi, Aotake-Cho, Toyohashi, Aichi, 4418570, Japan.

Objective: We previously developed a custom-design thoracic bone scintigraphy-specific phantom ("SIM bone phantom") to assess image quality in bone single-photon emission computed tomography (SPECT). We aimed to develop an automatic assessment system for imaging technology in bone SPECT and demonstrate the validity of this system.

Methods: Four spherical lesions of 13-, 17-, 22-, and 28-mm diameters in the vertebrae of SIM bone phantom simulating the thorax were filled with radioactivity (target-to-background ratio: 4). Read More

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Conversion factors to derive organ doses for canine subjects undergoing CT examinations.

Vet Radiol Ultrasound 2021 Jul 14;62(4):421-428. Epub 2021 May 14.

Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA.

Although a large number of CT scans are being conducted on small animals, especially in Western countries, little is known of absorbed dose from veterinary CT scans. In the current retrospective analytical study, we estimated the radiation dose delivered to dogs from CT scans with various scan protocols and compared the results with those of human patients. We adopted a total of three computerized canine models with three sizes combined with a computer simulation model of a CT scanner. Read More

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Evaluation of novel AI-based extended field-of-view CT reconstructions.

Med Phys 2021 Jul 31;48(7):3583-3594. Epub 2021 May 31.

Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre+, Maastricht, 6229 ET, The Netherlands.

Purpose: Modern computed tomography (CT) scanners have an extended field-of-view (eFoV) for reconstructing images up to the bore size, which is relevant for patients with higher BMI or non-isocentric positioning due to fixation devices. However, the accuracy of the image reconstruction in eFoV is not well known since truncated data are used. This study introduces a new deep learning-based algorithm for extended field-of-view reconstruction and evaluates the accuracy of the eFoV reconstruction focusing on aspects relevant for radiotherapy. Read More

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Feasibility of equivalent performance of 3D TOF [F]-FDG PET/CT with reduced acquisition time using clinical and semiquantitative parameters.

EJNMMI Res 2021 May 1;11(1):44. Epub 2021 May 1.

Department of Nuclear Medicine and Endocrinology, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria.

Background: High-performance time-of-flight (TOF) positron emission tomography (PET) systems have the capability for rapid data acquisition while preserving diagnostic image quality. However, determining a reliable and clinically applicable cut-off of the acquisition time plays an important role in routine practice. This study aimed to assess the diagnostic equivalence of short acquisition time of 57 with routine 75 seconds per bed position (s/BP) of [F]-fluoro-deoxy-glucose (FDG) PET. Read More

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Fully automated quantification method (FQM) of coronary calcium in an anthropomorphic phantom.

Med Phys 2021 Jul 17;48(7):3730-3740. Epub 2021 May 17.

Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA.

Objective: Coronary artery calcium (CAC) score is a strong predictor for future adverse cardiovascular events. Anthropomorphic phantoms are often used for CAC studies on computed tomography (CT) to allow for evaluation or variation of scanning or reconstruction parameters within or across scanners against a reference standard. This often results in large number of datasets. Read More

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Monte Carlo simulation of enriched uranium in the lungs of thorax voxel phantom for assessment of enrichment and its effect on dose.

Appl Radiat Isot 2021 Jul 13;173:109721. Epub 2021 Apr 13.

Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.

In-vivo lung monitoring is an important technique for the assessment of internal dose of radiation workers handling actinides. At BARC, counting efficiencies (CEs) of detection systems used for estimation of natural uranium in the lungs are evaluated using realistic thorax physical phantoms or computational voxel phantoms. The quantification of U and U in lungs is done using CEs determined at 63. Read More

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Radiat Prot Dosimetry 2021 May;193(3-4):237-246

Department of Radiotherapy, West German Cancer Center, University Hospital Essen, Hufelandstrasse 55, Essen 45147, Germany.

The aim of this phantom study is to examine radiation doses of dual- and single-energy computed tomography (DECT and SECT) in the chest and upper abdomen for three different multi-slice CT scanners. A total of 34 CT protocols were examined with the phantom N1 LUNGMAN. Four different CT examination types of different anatomic regions were performed both in single- and dual-energy technique: chest, aorta, pulmonary arteries for suspected pulmonary embolism and liver. Read More

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