HOW MANY DOSEMETERS ARE NEEDED FOR CORRECT MEAN ORGAN DOSE ASSESSMENT WHEN PERFOMING PHANTOM DOSIMETRY? A PHANTOM STUDY EVALUATING LIVER ORGAN DOSE AND INVESTIGATING TLD NUMBERS AND WAYS OF DOSEMETER PLACEMENT

2020 ◽  
Vol 189 (4) ◽  
pp. 475-488
Author(s):  
Peter H Pedersen ◽  
Asger G Petersen ◽  
Svend E Ostgaard ◽  
Torben Tvedebrink ◽  
Søren P Eiskjær
Keyword(s):  
Statistical Difference ◽  
Handling Time ◽  
Statistical Modelling ◽  
Organ Dose ◽  
Dose Assessment ◽  
Organ Doses ◽  
X Ray ◽  
Linear Effect ◽  
Organ Specific ◽  
Dose Measurements

Abstract This study evaluated repeated mean organ dose measurements of the liver by phantom dosimetry and statistical modelling in order to find a way to reduce the number of dosemeters needed for precise organ dose measurements. Thermoluminescent dosemeters were used in an adult female phantom exposed to a biplanar x-ray source at three different axial phantom rotations. Generalised mixed linear effect modelling was used for statistical analysis. A subgroup of five to six organ-specific locations out of 28 yielded mean liver organ doses within 95% confidence intervals of measurements based on all 28 liver-specific dosemeter locations. No statistical difference of mean liver dose was observed with rotation of the phantom either 10° clockwise or counter-clockwise as opposed to the coronal plane. Phantom dosimetry handling time during organ dose measurements can be markedly reduced, in this case the liver, by 79% (22/28), while still providing precise mean organ dose measurements.

scholarly journals Fluoroscopy X-Ray Organ-Specific Dosimetry System (FLUXOR) for Estimation of Organ Doses and Their Uncertainties in the Canadian Fluoroscopy Cohort Study

2021 ◽  
Vol 195 (4) ◽  
Author(s):  
A. Iulian Apostoaei ◽  
Brian A. Thomas ◽  
F. Owen Hoffman ◽  
David C. Kocher ◽  
Kathleen M. Thiessen ◽  
...  
Keyword(s):  
Cohort Study ◽  
Organ Doses ◽  
X Ray ◽  
Organ Specific ◽  
Dosimetry System

scholarly journals Image Quality and Patient-Specific Organ Doses in Stone Protocol CT: A Comparison of Traditional CT to Low Dose CT with Iterative Reconstruction

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Raghav Pai ◽  
Rishi Modh ◽  
Rebecca H. Lamoureux ◽  
Lori Deitte ◽  
David C. Wymer ◽  
...  
Keyword(s):  
Image Quality ◽  
Kidney Stone ◽  
Low Dose ◽  
Organ Dose ◽  
Patient Specific ◽  
Organ Doses ◽  
Low Dose Ct ◽  
Stone Burden ◽  
Stone Formers ◽  
Organ Specific

Objective. To compare organ specific radiation dose and image quality in kidney stone patients scanned with standard CT reconstructed with filtered back projection (FBP-CT) to those scanned with low dose CT reconstructed with iterative techniques (IR-CT). Materials and Methods. Over a one-year study period, adult kidney stone patients were retrospectively netted to capture the use of noncontrasted, stone protocol CT in one of six institutional scanners (four FBP and two IR). To limit potential CT-unit use bias, scans were included only from days when all six scanners were functioning. Organ dose was calculated using volumetric CT dose index and patient effective body diameter through validated conversion equations derived from previous cadaveric, dosimetry studies. Board-certified radiologists, blinded to CT algorithm type, assessed stone characteristics, study noise, and image quality of both techniques. Results. FBP-CT (n=250) and IR-CT (n=90) groups were similar in regard to gender, race, body mass index (mean BMI = 30.3), and stone burden detected (mean size 5.4 ± 1.2 mm). Mean organ-specific dose (OSD) was 54-62% lower across all organs for IR-CT compared to FBP-CT with particularly reduced doses (up to 4.6-fold) noted in patients with normal BMI range. No differences were noted in radiological assessment of image quality or noise between the cohorts, and intrarater agreement was highly correlated for noise (AC2=0.873) and quality (AC2=0.874) between blinded radiologists. Conclusions. Image quality and stone burden assessment were maintained between standard FBP and low dose IR groups, but IR-CT decreased mean OSD by 50%. Both urologists and radiologists should advocate for low dose CT, utilizing reconstructive protocols like IR, to reduce radiation exposure in their stone formers who undergo multiple CTs.

scholarly journals Dose assessment in dental cone beam computed tomography: comparison of optically stimulated luminescence dosimetry with the Monte Carlo method

2019 ◽  
Author(s):  
Chena Lee ◽  
Jeongmin Yoon ◽  
Sang-Sun Han ◽  
Ji Yeon Na ◽  
Jeong-Hee Lee ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Effective Dose ◽  
Organ Dose ◽  
Optically Stimulated Luminescence ◽  
Dose Assessment ◽  
High Dose ◽  
Organ Doses ◽  
Dose Evaluation ◽  
Luminescence Dosimetry ◽  
Mc Simulation

AbstractThe usage and the model variety of CBCT machine has been rapidly increasing, the dose evaluation of individual devices became an important issue. Patient dose from CBCT was assessed with two different methods, optically stimulated luminescence dosimeter (OSLD) measured and monte carlo (MC) simulation, in four different examination modes. Through the measurement process and obtained value, more practical and efficient method in acquiring CBCT effective dose would be suggested. Twenty-five OSLD were calibrated and equipped in human phantom of head and neck organs. This was exposed on 2 CBCT units, CS9300 (Carestream Dental LLC, Atlanta, Georgia) and RAYSCAN α+ (Ray Co. Ltd, Hwaseong-si, Korea) with 2 different examination modes. Dose recorded in dosimetry was obtained and organ dose as well as an effective dose were obtained in each units of examination modes. Those values were also calculated using MC software, PCXMC (STUK, Helsinki, Finland). The organ doses and effective doses from both methods were compared by each examination mode of individual unit. OSLD measured effective dose value was higher than that obtained with MC method in each examination mode, except dual jaw mode of CS9300. The percent difference of effective dose between the two methods were ranged from 4.0 to 14.3 %. The dose difference between the methods was decreased as the examination FOV decreased. Organ dose values were varied according to the method, while overall trend was similar in both methods. The organs showing high dose were mostly consistent in both methods. In this study, the effective dose obtained by OSLD measurement and MC simulation were compared and both methods were described in detail. Consequently, as relatively efficient and easy-handling method, we carefully suggest MC simulation for further dose evaluation.

scholarly journals Rapid switching kVp dual energy CT: Value of reconstructed dual energy CT images and organ dose assessment in multiphasic liver CT exams

2018 ◽  
Vol 102 ◽  
pp. 102-108 ◽  
Author(s):  
Usman Mahmood ◽  
Natally Horvat ◽  
Joao Vicente Horvat ◽  
Davinia Ryan ◽  
Yiming Gao ◽  
...  
Keyword(s):  
Organ Dose ◽  
Ct Images ◽  
Dual Energy ◽  
Dose Assessment ◽  
Dual Energy Ct ◽  
Liver Ct ◽  
Ct Value ◽  
Rapid Switching

scholarly journals The use of fricke dosimetry for low energy x-rays

2006 ◽  
Vol 49 (spe) ◽  
pp. 17-23 ◽  
Author(s):  
Carlos de Austerlitz ◽  
Viviane Souza ◽  
Heldio Pereira Villar ◽  
Aloisio Cordilha
Keyword(s):  
Ionization Chamber ◽  
Parallel Plate ◽  
Low Energy ◽  
Calibration Factor ◽  
X Rays ◽  
Measuring Systems ◽  
X Ray ◽  
Dose Measurements

The performance of four X-ray qualities generated in a Pantak X-ray machine operating at 30-100 kV was determined with a parallel-plate ionization chamber and a Fricke dosimeter. X-ray qualities used were those recommended by Deutsch Internationale Normung DIN 6809 and dose measurements were carried out with Plexiglas® simulators. Results have shown that the Fricke dosimeter can be used not only for soft X-ray dosimetry, but also for the maintenance of low-energy measuring systems' calibration factor.

scholarly journals Patient protection in dental radiology: Influence of exposure time on patient dose

2009 ◽  
Vol 6 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Danijela Arandjic ◽  
Dusko Kosutic ◽  
Djordje Lazarevic
Keyword(s):  
Exposure Time ◽  
Patient Dose ◽  
Dose Assessment ◽  
Dental Radiology ◽  
Reference Levels ◽  
X Ray ◽  
Patient Protection ◽  
Tube Output ◽  
Patient Doses

This paper shows the results of dose assessment for dental radiographic procedures. Entrance surface doses for 5 different procedures were assessed. More than 15 hospitals, twenty X-ray units in total, were encompassed in this research. Patient doses were estimated based on results of X-ray tube output measurements. Finally, doses were compared with Reference levels. Higher dose values were observed for X-ray units with 50 kVp. In comparison with digital units, doses from other procedures are significantly higher. .

scholarly journals Three-dimensional imaging of hold baggage for airport security

2014 ◽  
Vol XL-5 ◽  
pp. 331-336
Author(s):  
S. Kolokytha ◽  
R. Speller ◽  
S. Robson
Keyword(s):  
3D Imaging ◽  
Imaging System ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
Handling Time ◽  
Cost Effective ◽  
Airport Security ◽  
X Ray ◽  
Common System ◽  
Close Range

This study describes a cost-effective check-in baggage screening system, based on "on-belt tomosynthesis" (ObT) and close-range photogrammetry, that is designed to address the limitations of the most common system used, conventional projection radiography. The latter's limitations can lead to loss of information and an increase in baggage handling time, as baggage is manually searched or screened with more advanced systems. This project proposes a system that overcomes such limitations creating a cost-effective automated pseudo-3D imaging system, by combining x-ray and optical imaging to form digital tomograms. Tomographic reconstruction requires a knowledge of the change in geometry between multiple x-ray views of a common object. This is uniquely achieved using a close range photogrammetric system based on a small network of web-cameras. This paper presents the recent developments of the ObT system and describes recent findings of the photogrammetric system implementation. Based on these positive results, future work on the advancement of the ObT system as a cost-effective pseudo-3D imaging of hold baggage for airport security is proposed.

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