scholarly journals Influence of Different Arm Positions in the Localizer Radiograph(s) on Patient Dose during Exposure-Controlled CT Examinations of the Neck to Pelvis

Tomography ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 313-322
Author(s):  
Tony M. Svahn ◽  
Lovre Peric ◽  
Jennifer C. Ast
Keyword(s):  
Computed Tomography ◽  
Monte Carlo ◽  
Effective Dose ◽  
Patient Dose ◽  
Whole Body ◽  
Ct Scanner ◽  
Effective Doses ◽  
The Impact ◽  
Total Effective Dose

Our aim was to examine the impact of different arm positions during imaging of the localizer radiograph(s) on effective dose for exposure-controlled computed tomography (CT) (Siemens/Canon) scans of the neck to pelvis. An anthropomorphic whole-body phantom was scanned from the neck to pelvis with the arms positioned in three different ways during the acquisition of the localizer radiograph: (i) above the head, (ii) alongside the trunk, and (iii) along the trunk with the hands placed on the abdomen. In accordance with clinical routines, the arms were not included in the subsequent helical scans. Effective doses were computed to a standard-sized patient (male/female) using a dedicated system-specific Monte Carlo-based software. Effective doses for the Canon CT scanner for the different alternatives (male/female) were (a) 5.3/6.62 mSv, (b) 5.62/7.15 mSv and (c) 5.92/7.44 mSv. For the Siemens CT scanner, effective doses were (a) 4.47/5.59 mSv, (b) 5.4/6.69 mSv and (c) 5.7/6.99 mSv. Arms placed above the head during localizer radiograph imaging in the current CT procedures substantially reduced the total effective dose to the patient.

A Monte Carlo simulation for the estimation of patient dose in rest and stress cardiac computed tomography with a 320-detector row CT scanner

2015 ◽  
Vol 31 (8) ◽  
pp. 1029-1034 ◽  
Author(s):  
Jacob Geleijns ◽  
Raoul M.S. Joemai ◽  
Maria Cros ◽  
Irene Hernandez-Giron ◽  
Alfonso Calzado ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Cardiac Computed Tomography ◽  
Patient Dose ◽  
Ct Scanner

Effective doses in subjects undergoing computed tomography cardiac imaging with the 256-multislice CT scanner

2008 ◽  
Vol 65 (3) ◽  
pp. 442-448 ◽  
Author(s):  
Shinichiro Mori ◽  
Kanae Nishizawa ◽  
Chisato Kondo ◽  
Mari Ohno ◽  
Keiichi Akahane ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cardiac Imaging ◽  
Multislice Ct ◽  
Ct Scanner ◽  
Effective Doses

THE IMPACT OF HEAD POSITIONING ON THE IMAGE QUALITY OF MULTI-DETECTOR COMPUTED TOMOGRAPHY

2021 ◽  
pp. 2150050
Author(s):  
Yang-Ting Hsu ◽  
Jo-Chi Jao
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Control Group ◽  
Ct Scanner ◽  
Head Ct ◽  
Radiologic Technologists ◽  
Head Positioning ◽  
The Impact ◽  
Multi Detector Computed Tomography

Radiologic technologists face various types of patients during multi-detector computed tomography (CT) examinations. In emergency departments, it is common to have patients who cannot follow instructions for the examinations. The asymmetric axial view of the head CT might affect the correctness of the clinician’s diagnosis. This study aimed to assess the impact of head positioning on the image quality of head CT using two phantoms. All scans were performed on a 16-slice CT scanner. In the control group, the tilted angle of the phantoms was 0[Formula: see text], and no multiplanar reconstruction (MPR) was performed. In the experimental groups, the tilted angles of the phantoms were 5[Formula: see text], 10[Formula: see text] and 15[Formula: see text], respectively, and MPR was performed afterwards. The results showed that if the head was tilted during the head CT examinations, image asymmetry and artifacts appeared without MPR. After MPR, one phantom showed that there were significant differences and the other phantom showed no significant differences quantitatively in image symmetry and artifacts between experimental groups and the control group, while both phantoms showed no significant differences qualitatively in image symmetry and artifacts between experimental groups and the control group. Although MPR can correct the image asymmetry and artifacts caused by tilted head positioning to some extent, it consumes time. Therefore, technologists should position the head as exactly as possible when performing head CT examinations.

Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

2022 ◽  
Author(s):  
Yusuke Inoue ◽  
Yuka Yonekura ◽  
Kazunori Nagahara ◽  
Ayuka Uehara ◽  
Hideki Ikuma
Keyword(s):  
Computed Tomography ◽  
Effective Dose ◽  
Conversion Factor ◽  
Lower Extremities ◽  
Pulmonary Angiography ◽  
Ct Scanner ◽  
Dose Length Product ◽  
Ct Venography ◽  
Simplified Method ◽  
Imaging Conditions

Abstract For radiation dose assessement of computed tomography (CT), effective dose (ED) is often estimated by multiplying the dose-length product (DLP), provided automatically by the CT scanner, by a conversion factor. We investigated such conversion in CT venography of the lower extremities performed in conjunction with CT pulmonary angiography. The study subjects consisted of eight groups imaged using different scanners and different imaging conditions (five and three groups for the GE and Siemens scanners, respectively). Each group included 10 men and 10 women. The scan range was divided into four anatomical regions (trunk, proximal thigh, knee and distal leg), and DLP was calculated for each region (regional DLP). Regional DLP was multiplied by a conversion factor for the respective region, to convert it to ED. The sum of the ED values for the four regions was obtained as standard ED. Additionally, the sum of the four regional DLP values, an approximate of the scanner-derived DLP, was multiplied by the conversion factor for the trunk (0.015 mSv/mGy/cm), as a simplified method to obtain ED. When using the simplified method, ED was overestimated by 32.3%−70.2% and 56.5%−66.2% for the GE and Siemens scanners, respectively. The degree of overestimation was positively and closely correlated with the contribution of the middle and distal portions of the lower extremities to total radiation exposure. ED/DLP averaged within each group, corresponding to the conversion factor, was 0.0089−0.0114 and 0.0091−0.0096 mSv/mGy/cm for the GE and Siemens scanners, respectively. In CT venography of the lower extremities, ED is greatly overestimated by multiplying the scanner-derived DLP by the conversion factor for the trunk. The degree of overestimation varies widely depending on the imaging conditions. It is recommended to divide the scan range and calculate ED as a sum of regional ED values.

Etiology of Solitary Extrapulmonary Positron Emission Tomography and Computed Tomography Findings in Patients With Lung Cancer

2005 ◽  
Vol 23 (28) ◽  
pp. 6846-6853 ◽  
Author(s):  
Didier Lardinois ◽  
Walter Weder ◽  
Marina Roudas ◽  
Gustav K. von Schulthess ◽  
Michaela Tutic ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Lung Cancer ◽  
Positron Emission Tomography ◽  
Ct Imaging ◽  
Emission Tomography ◽  
Whole Body ◽  
Benign Tumors ◽  
Positron Emission ◽  
Pet Ct ◽  
The Impact

Purpose The aim of this prospective study was to assess the incidence and the nature of solitary extrapulmonary [18F] fluorodeoxyglucose (FDG) accumulations in patients with non–small-cell lung cancer (NSCLC) staged with integrated positron emission tomography and computed tomography (PET/CT) and to evaluate the impact on management. Patients and Methods A total of 350 patients with NSCLC underwent whole-body PET/CT imaging. All solitary extrapulmonary FDG accumulations were evaluated by histopathology, further imaging, or clinical follow-up. Results PET/CT imaging revealed extrapulmonary lesions in 110 patients. In 72 patients (21%), solitary lesions were present. A diagnosis was obtained in 69 of these patients, including 37 (54%) with solitary metastases and 32 (46%) with lesions unrelated to the lung primary. Histopathologic examinations of these 32 lesions revealed a second clinically unsuspected malignancy or a recurrence of a previous diagnosed carcinoma in six patients (19%) and a benign tumor or inflammatory lesion in 26 patients (81%). The six malignancies consisted of carcinoma of the breast in two patients, and carcinoma of the orbit, esophagus, prostate, and non-Hodgkin's lymphoma in one patient each. Benign tumors and inflammatory lesions included eight colon adenomas, four Warthin's tumors, one granuloma of the lower jaw, one adenoma of the thyroid gland, one compensatory muscle activity due to vocal chord palsy, two occurrences of arthritis, three occurrences of reflux esophagitis, two occurrences of pancreatitis, two occurrences of diverticulitis, one hemorrhoidal inflammation, and one rib fracture. Conclusion Solitary extrapulmonary FDG accumulations in patients with newly diagnosed lung cancer should be analyzed critically for correct staging and optimal therapy, given that up to half of the lesions may represent unrelated malignancies or benign disease.

scholarly journals Weightbearing CBCT, MDCT, and 2D imaging dosimetry of the foot and ankle

2014 ◽  
Vol 1 (2) ◽  
pp. 1 ◽  
Author(s):  
John B. Ludlow ◽  
Marija Ivanovic
Keyword(s):  
Effective Dose ◽  
Risk Estimation ◽  
Cone Beam Ct ◽  
Equivalent Material ◽  
Foot And Ankle ◽  
Tissue Equivalent ◽  
Effective Doses ◽  
2D Imaging ◽  
Imaging Dose ◽  
The Impact

Aims: This study compares effective doses associated with 2D lateral, oblique, and AP radiographs with 3D MDCT and Cone Beam CT images of the foot and ankle. Methods: An anthropomorphic phantom of the foot and ankle was constructed from an adult human skeleton and soft tissue equivalent material. Optical stimulated dosimeters were placed at 21 locations within and on tissues and anatomy of interest. Effective dose was calculated following 2007 ICRP recommendations. Three projections were exposed to simulate conventional 2D imaging. Standard and optimized dose MDCT scans were exposed to simulate typical CT options. Ten, 20, and 30cm fields of view, 100 and 120kVp and 4.5 and 6.8mAs exposures were tested using a PedCAT® CBCT device designed for weightbearing imaging. Dose was calculated for an adult as well as for a 5 and 10-year-old child to assess the impact of age on risk estimation. Results: Standard adult effective doses for single foot imaging were 0.6µSv for 2D, 3.8µSv for CBCT, and 25µSv for MDCT (p = 0.0013). Dose differed significantly with age (p = 0.0185). For a 5-year-old, doses rise to 0.8µSv for 2D, 18µSv for CBCT, and 200µSv for MDCT. Small and medium CBCT fields produced adult doses of 2.3 mSv and 0.9 mSv respectively. Conclusions: The effective dose for small FOV CBCT or conventional 2D series examinations is comparable to a few hours of equivalent background dose. Such doses are negligible; therefore, the dose of radiation should not be a concern when considering the use of CBCT imaging for foot/ankle examination. 

EFFECTS OF THE SCAN RANGE ON RADIATION DOSE IN THE COMPUTED TOMOGRAPHY COMPONENT OF ONCOLOGY POSITRON EMISSION TOMOGRAPHY/COMPUTED TOMOGRAPHY

2018 ◽  
Vol 185 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Yusuke Inoue ◽  
Kazunori Nagahara ◽  
Hiroko Kudo ◽  
Hiroyasu Itoh
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
Radiation Dose ◽  
Effective Dose ◽  
The Body ◽  
Emission Tomography ◽  
Whole Body ◽  
Computed Tomography Images ◽  
Positron Emission ◽  
Proximal Thigh

Abstract We performed phantom experiments to investigate radiation dose in the computed tomography component of oncology positron emission tomography/computed tomography in relation to the scan range. Computed tomography images of an anthropomorphic whole-body phantom were obtained from the head top to the feet, from the head top to the proximal thigh or from the skull base to the proximal thigh. Automatic exposure control using the posteroanterior and lateral scout images offered reasonable tube current modulation corresponding to the body thickness. However, when the posteroanterior scout alone was used, unexpectedly high current was applied in the head and upper chest. When effective dose was calculated on a region-by-region basis, it did not differ greatly irrespective of the scan range. In contrary, when effective dose was estimated simply by multiplying the scanner-derived dose-length product by a single conversion factor, estimates increased definitely with the scan range, indicating severe overestimation in whole-body imaging.

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