scholarly journals Radiation doses with various body weights of phantoms in brain 128-slice MDCT examination

2019 ◽  
Vol 60 (4) ◽  
pp. 466-475 ◽  
Author(s):  
Hung-Chih Lin ◽  
Te-Jen Lai ◽  
Hsien-Chun Tseng ◽  
Ching-Hsiang Wang ◽  
Yen-Ling Tseng ◽  
...  
Keyword(s):  
External Auditory Meatus ◽  
Weighting Factor ◽  
Parietal Bone ◽  
Dose Length Product ◽  
Thermoluminescent Dosimeters ◽  
The Public ◽  
Tissue Equivalent ◽  
Body Weights ◽  
Anthropomorphic Phantoms ◽  
Unnecessary Radiation

AbstractThe effective dose (HE) and organ or tissue equivalent dose (HT) for use in brain computed tomography (CT) examinations with various body weights were evaluated. Thermoluminescent dosimeters (TLD-100H) were inserted into Rando and five anthropomorphic phantoms. These phantoms were made of polymethylmethacrylate (PMMA), according to the specifications of ICRU 48, with masses from 10 to 90 kg. Brain CT examinations were conducted, scanning the maxillae from the external auditory meatus to the parietal bone using a 128-slice multi-detector CT (MDCT) scanner. To reduce errors, three independent trials were conducted. Calculated HE,TLD, based on the weighting factor recommended by ICRP 103, was 1.72 ± 0.28 mSv, which slightly exceeds the HE,DLP of 1.70 mSv, that was calculated from the dose–length product (DLP) of the Rando phantom. This experiment yielded HE,TLD values of ICRP 103 from the highest 1.85 ± 0.28 (90 kg) to the lowest 1.47 ± 0.22 (10 kg) mSv. HE,TLD (mSv) = 5.45×10−3 W(kg) + 1.361, with an R2 of 0.87667. Using the DLP protocol, HE,DLP was estimated from CTDIvol that was recorded directly from the console display of the CT unit and multiplied by the conversion coefficient (k) recommended by the ICRP 103. Finally, the experimental results obtained herein are compared with those in the literature. Physicians should choose and adjust protocols to prevent the exposure of patients to unnecessary radiation, satisfying the as low as reasonably achievable (ALARA) principle. These findings will be valuable to patients, physicians, radiologists and the public.

scholarly journals Extra radiation dose of lungs in male examinees during cardiac computed tomography

2017 ◽  
Vol 32 (4) ◽  
pp. 350-357
Author(s):  
Sung-Yi Tsai ◽  
Hsien-Chun Tseng ◽  
Zhipeng Ruan ◽  
Zumei Xu ◽  
Yonggui Liao ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cardiac Computed Tomography ◽  
Practical Method ◽  
The Body ◽  
Thermoluminescent Dosimeters ◽  
Tissue Equivalent ◽  
Body Weights ◽  
Computed Tomography Scans ◽  
The Relationship ◽  
Scanning Region

The use of multi-detector row computed tomography in cardiac examinations is increasing globally. Several hospitals are yet to establish a practical method for evaluating the extra scattering dose in the lungs (Dlung) of male examinees with different body-weights undergoing cardiac computed tomography. To measure the dose in each slice of a lung (Dlung,i), thermoluminescent dosimeters are inserted into Rando and tissue-equivalent phantoms made of polymethylmethacrylate and derived from ICRU 48 with masses from 10 to 90 kg. Dlung was evaluated by weighing the scanned volume of each slice. A practical method for determining Dlung involves 64-slice computed tomography scans using a Philips Brilliance computed tomography at 120 kV and 200 mAs, with a thickness of 1.0 mm. Dlung,i increased with distance from the scanning region. This experiment yielded Dlung values from 12.1 ? 2.1 mSv (90 kg) to 23.0 ? 3.8 mSv (10 kg). Finally, a simple equation can be used to derive the relationship between Dlung and the body-weights of a male examinee. Experimental results are compared with others in the literature.

scholarly journals Physical and Physiological Indicators of Welfare in Guinea Pigs (Cavia porcellus) Serving as Ambassador Animals

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 815 ◽  
Author(s):  
David M. Powell ◽  
Corinne P. Kozlowski ◽  
John Clark ◽  
Alice Seyfried ◽  
Eli Baskir ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Cavia Porcellus ◽  
Saint Louis ◽  
Physiological Indicators ◽  
The Public ◽  
Welfare Indicators ◽  
Glucocorticoid Response ◽  
Body Weights ◽  
Physiological Profiles ◽  
The Impact

Special encounters that allow contact between animals and guests are common in zoos and aquariums. Visitors to the Saint Louis Zoo may touch guinea pigs serving as ambassador animals. We evaluated two welfare indicators in ambassador guinea pigs by comparing glucocorticoid levels and body weights between periods when guinea pigs lived in a habitat accessible to the public and while off exhibit. Mean glucocorticoid levels did not differ between sexes or between on- and off-exhibit periods. There was significant individual variation, and females demonstrated greater variation than males. While on exhibit, glucocorticoid levels slightly but significantly increased in males and decreased in females. Moving guinea pigs between habitats only elicited a significant glucocorticoid response when females were moved off exhibit. Temporary closures of the exhibit had no effect on glucocorticoid levels in either sex. Analyses of the impact of handling rates on males found no impact on glucocorticoid levels. Guinea pigs’ body weights were lower while on exhibit. We conclude that guinea pigs serving as ambassador animals at the Saint Louis Zoo demonstrate comparable physiological profiles while on and off exhibit and, when used in a rotational schedule, are a suitable species for animal encounters involving contact with the public.

Dosimetry of transmission measurements in nuclear medicine: a study using anthropomorphic phantoms and thermoluminescent dosimeters

1998 ◽  
Vol 25 (10) ◽  
pp. 1435-1441 ◽  
Author(s):  
Pedro Almeida ◽  
Bernard Bendriem ◽  
Olivier de Dreuille ◽  
Arnaud Peltier ◽  
Claudine Perrot ◽  
...  
Keyword(s):  
Nuclear Medicine ◽  
Thermoluminescent Dosimeters ◽  
Anthropomorphic Phantoms ◽  
Transmission Measurements

scholarly journals A prospective feasibility study of a 1-mm bolus for postmastectomy radiotherapy

2020 ◽  
Author(s):  
Terufumi Kawamoto ◽  
Naoto Shikama ◽  
Chie Kurokawa ◽  
Naoya Hara ◽  
Masaki Oshima ◽  
...  
Keyword(s):  
Chest Wall ◽  
Medical Information ◽  
Skin Toxicity ◽  
University Hospital ◽  
In Vivo Dosimetry ◽  
Postmastectomy Radiotherapy ◽  
Thermoluminescent Dosimeters ◽  
Tissue Equivalent

Abstract BackgroundThere remains wide variation in the use of chest wall boluses for postmastectomy radiotherapy (PMRT). Therefore, we aimed to prospectively evaluate the use of a 1-mm-thick daily tissue-equivalent bolus in patients who received PMRT using thermoluminescent dosimeters (TLDs) and skin toxicity assessment.Materials and MethodsWe collected data from patients with a 1-mm-thick daily bolus during PMRT at The Juntendo University Hospital. The surface dose was measured in vivo under the 1-mm-thick bolus on the chest wall. We assessed the acute skin toxicity weekly during PMRT, and 1, 2, 4, and 12 weeks after the completion of PMRT.ResultsA total of 19 patients aged 32 − 79 years old received PMRT from July 2019 to January 2020. All patients completed the protocol treatment without interruptions, and the median follow-up was 32 weeks. In vivo dosimetry analysis revealed surface doses between 77% and 113% of the prescribed dose, with a mean of 92% of the prescribed radiation dose, and a standard deviation of 7% being delivered. Grade 2 dermatitis was found in 10 patients (53%), and Grade 3 dermatitis was found in one patient (5%). All cases of Grade 2 and 3 dermatitis were improved 4 weeks after PMRT. There were no cases of Grade 4 dermatitis and no chest wall recurrences during the treatment or follow-up period.ConclusionsThe 1-mm-thick daily bolus is a feasible regimen for PMRT, with appropriate dose buildup and acceptable skin toxicity without treatment interruptions.Trial registrationThe University Hospital Medical Information Network Clinical Trials Registry, UMIN000035773. Registered 1 July 2019, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000040622

Three-Dimensional Printing for Construction of Tissue-Equivalent Anthropomorphic Phantoms and Determination of Conceptus Dose

2018 ◽  
Vol 211 (6) ◽  
pp. 1283-1290 ◽  
Author(s):  
Matthew R. Hoerner ◽  
Matthew R. Maynard ◽  
Didier A. Rajon ◽  
Frank J. Bova ◽  
David E. Hintenlang
Keyword(s):  
Three Dimensional ◽  
Three Dimensional Printing ◽  
Tissue Equivalent ◽  
Anthropomorphic Phantoms ◽  
Dimensional Printing

scholarly journals Multimodal phantoms for clinical PET/MRI

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Eve Lennie ◽  
Charalampos Tsoumpas ◽  
Steven Sourbron
Keyword(s):  
Nuclear Medicine ◽  
Medical Physics ◽  
Tissue Equivalent ◽  
Simultaneous Acquisition ◽  
Positron Emission ◽  
Anthropomorphic Phantoms ◽  
Magnetic Resonance Imaging Mri ◽  
Materials Used ◽  
Phantom Design ◽  
Established Role

AbstractPhantoms are commonly used throughout medical imaging and medical physics for a multitude of applications, the designs of which vary between modalities and clinical or research requirements. Within positron emission tomography (PET) and nuclear medicine, phantoms have a well-established role in the validation of imaging protocols so as to reduce the administration of radioisotope to volunteers. Similarly, phantoms are used within magnetic resonance imaging (MRI) to perform quality assurance on clinical scanners, and gel-based phantoms have a longstanding use within the MRI research community as tissue equivalent phantoms. In recent years, combined PET/MRI scanners for simultaneous acquisition have entered both research and clinical use. This review explores the designs and applications of phantom work within the field of simultaneous acquisition PET/MRI as published over the period of a decade. Common themes in the design, manufacture and materials used within phantoms are identified and the solutions they provided to research in PET/MRI are summarised. Finally, the challenges remaining in creating multimodal phantoms for use with simultaneous acquisition PET/MRI are discussed. No phantoms currently exist commercially that have been designed and optimised for simultaneous PET/MRI acquisition. Subsequently, commercially available PET and nuclear medicine phantoms are often utilised, with CT-based attenuation maps substituted for MR-based attenuation maps due to the lack of MR visibility in phantom housing. Tissue equivalent and anthropomorphic phantoms are often developed by research groups in-house and provide customisable alternatives to overcome barriers such as MR-based attenuation correction, or to address specific areas of study such as motion correction. Further work to characterise materials and manufacture methods used in phantom design would facilitate the ability to reproduce phantoms across sites.

Replications can cause distorted belief in scientific progress

2018 ◽  
Vol 41 ◽  
Author(s):  
Michał Białek
Keyword(s):  
Real World ◽  
Scientific Progress ◽  
The Public ◽  
Psychological Science

AbstractIf we want psychological science to have a meaningful real-world impact, it has to be trusted by the public. Scientific progress is noisy; accordingly, replications sometimes fail even for true findings. We need to communicate the acceptability of uncertainty to the public and our peers, to prevent psychology from being perceived as having nothing to say about reality.

3-D optical transfer in excitation field synthesis microscopes

1995 ◽  
Vol 53 ◽  
pp. 64-65
Author(s):  
Vijay Krishnamurthi ◽  
Brent Bailey ◽  
Frederick Lanni
Keyword(s):  
Standing Wave ◽  
Spatial Information ◽  
3D Structure ◽  
Complete Recovery ◽  
Weighting Factor ◽  
Optical Transfer Function ◽  
Excitation Field ◽  
Optical Transfer ◽  
Set Up ◽  
Focus Plane

Excitation field synthesis (EFS) refers to the use of an interference optical system in a direct-imaging microscope to improve 3D resolution by axially-selective excitation of fluorescence within a specimen. The excitation field can be thought of as a weighting factor for the point-spread function (PSF) of the microscope, so that the optical transfer function (OTF) gets expanded by convolution with the Fourier transform of the field intensity. The simplest EFS system is the standing-wave fluorescence microscope, in which an axially-periodic excitation field is set up through the specimen by interference of a pair of collimated, coherent, s-polarized beams that enter the specimen from opposite sides at matching angles. In this case, spatial information about the object is recovered in the central OTF passband, plus two symmetric, axially-shifted sidebands. Gaps between these bands represent "lost" information about the 3D structure of the object. Because the sideband shift is equal to the spatial frequency of the standing-wave (SW) field, more complete recovery of information is possible by superposition of fields having different periods. When all of the fields have an antinode at a common plane (set to be coincident with the in-focus plane), the "synthesized" field is peaked in a narrow infocus zone.

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