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 A new Monte Carlo tool for organ dose estimation in computed tomography

2020 ◽  
Vol 55 (2) ◽  
pp. 123-134
Author(s):  
C. Adrien ◽  
C. Le Loirec ◽  
S. Dreuil ◽  
J.-M. Bordy
Keyword(s):  
Computed Tomography ◽  
Monte Carlo ◽  
Organ Dose ◽  
Technical Note ◽  
Patient Specific ◽  
Organ Doses ◽  
Ct Dose ◽  
Dose Information ◽  
Ct Dose Index ◽  
Mc Simulation

The constant increase of computed tomography (CT) exams and their major contribution to the collective dose led to international concerns regarding patient dose in CT imaging. Efforts were made to manage radiation dose in CT, mostly with the use of the CT dose index (CTDI). However CTDI does not give access to organ dose information, while Monte Carlo (MC) simulation can provide it if detailed information of the patient anatomy and the source are available. In this work, the X-ray source and the geometry of the GE VCT Lightspeed 64 were modelled, based both on the manufacturer technical note and some experimental data. Simulated dose values were compared with measurements performed in homogeneous conditions with a pencil chamber and then in CIRS ATOM anthropomorphic phantom using both optically stimulated luminescence dosimeters (OSLD) for point doses and XR-QA Gafchromic® films for relative dose maps. Organ doses were ultimately estimated in the ICRP 110 numerical female phantom and compared to data reported in the literature. Comparison of measured and simulated values show that our tool can be used for a patient specific and organ dose oriented radiation protection tool in CT medical imaging.

scholarly journals Patient-Informed Organ Dose Estimation in Clinical CT: Implementation and Effective Dose Assessment in 1048 Clinical Patients

2021 ◽  
Vol 216 (3) ◽  
pp. 824-834
Author(s):  
Wanyi Fu ◽  
Francesco Ria ◽  
William Paul Segars ◽  
Kingshuk Roy Choudhury ◽  
Joshua M. Wilson ◽  
...  
Keyword(s):  
Effective Dose ◽  
Organ Dose ◽  
Dose Assessment ◽  
Dose Estimation

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 Japanese pediatric and adult atomic bomb survivor dosimetry: potential improvements using the J45 phantom series and modern Monte Carlo transport

2021 ◽  
Author(s):  
Keith T. Griffin ◽  
Tatsuhiko Sato ◽  
Sachiyo Funamoto ◽  
Konstantin Chizhov ◽  
Sean Domal ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Radiation Effects ◽  
Atomic Bomb ◽  
Radiation Transport ◽  
Organ Dose ◽  
Neutron Dose ◽  
Organ Doses ◽  
Atomic Bomb Survivors ◽  
Biological Effectiveness ◽  
Dosimetry System

AbstractThe radiation exposure estimates for the atomic bomb survivors at Hiroshima and Nagasaki have evolved over the past several decades, reflecting a constant strive by the Radiation Effects Research Foundation (RERF) to provide thorough dosimetry to their cohort. Recently, a working group has introduced a new series of anatomical models, called the J45 phantom series, which improves upon those currently used at RERF through greater age resolution, sex distinction, anatomical realism, and organ dose availability. To evaluate the potential dosimetry improvements that would arise from their use in an RERF Dosimetry System, organ doses in the J45 series are evaluated here using environmental fluence data for 20 generalized survivor scenarios pulled directly from the current dosimetry system. The energy- and angle-dependent gamma and neutron fluences were converted to a source term for use in MCNP6, a modern Monte Carlo radiation transport code. Overall, the updated phantom series would be expected to provide dose improvements to several important organs, including the active marrow, colon, and stomach wall (up to 20, 20, and 15% impact on total dose, respectively). The impacts were especially significant for neutron dose estimates (up to a two-fold difference) and within organs which were unavailable in the previous phantom series. These impacts were consistent across the 20 scenarios and are potentially even greater when biological effectiveness of the neutron dose component is considered. The entirety of the dosimetry results for all organs are available as supplementary data, providing confident justification for potential future DS workflows utilizing the J45 phantom series.

Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: Measurements and Monte Carlo simulations using voxel phantoms

2015 ◽  
Vol 42 (7) ◽  
pp. 3788-3800 ◽  
Author(s):  
Mariana Baptista ◽  
Salvatore Di Maria ◽  
Sílvia Barros ◽  
Catarina Figueira ◽  
Marta Sarmento ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Digital Breast Tomosynthesis ◽  
Organ Dose ◽  
Dose Assessment ◽  
Breast Tomosynthesis ◽  
Voxel Phantoms

Verification of organ doses calculated by a dose monitoring software tool based on Monte Carlo Simulation in thoracic CT protocols

2017 ◽  
Vol 59 (3) ◽  
pp. 322-326 ◽  
Author(s):  
Nika Guberina ◽  
Saravanabavaan Suntharalingam ◽  
Kai Naßenstein ◽  
Michael Forsting ◽  
Jens Theysohn ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Thyroid Gland ◽  
Effective Dose ◽  
Software Tool ◽  
Organ Doses ◽  
Dose Monitoring ◽  
Thoracic Ct ◽  
Monitoring Software

Background The importance of monitoring of the radiation dose received by the human body during computed tomography (CT) examinations is not negligible. Several dose-monitoring software tools emerged in order to monitor and control dose distribution during CT examinations. Some software tools incorporate Monte Carlo Simulation (MCS) and allow calculation of effective dose and organ dose apart from standard dose descriptors. Purpose To verify the results of a dose-monitoring software tool based on MCS in assessment of effective and organ doses in thoracic CT protocols. Material and Methods Phantom measurements were performed with thermoluminescent dosimeters (TLD LiF:Mg,Ti) using two different thoracic CT protocols of the clinical routine: (I) standard CT thorax (CTT); and (II) CTT with high-pitch mode, P = 3.2. Radiation doses estimated with MCS and measured with TLDs were compared. Results Inter-modality comparison showed an excellent correlation between MCS-simulated and TLD-measured doses ((I) after localizer correction r = 0.81; (II) r = 0.87). The following effective and organ doses were determined: (I) (a) effective dose = MCS 1.2 mSv, TLD 1.3 mSv; (b) thyroid gland = MCS 2.8 mGy, TLD 2.5 mGy; (c) thymus = MCS 3.1 mGy, TLD 2.5 mGy; (d) bone marrow = MCS 0.8 mGy, TLD 0.9 mGy; (e) breast = MCS 2.5 mGy, TLD 2.2 mGy; (f) lung = MCS 2.8 mGy, TLD 2.7 mGy; (II) (a) effective dose = MCS 0.6 mSv, TLD 0.7 mSv; (b) thyroid gland = MCS 1.4 mGy, TLD 1.8 mGy; (c) thymus = MCS 1.4 mGy, TLD 1.8 mGy; (d) bone marrow = MCS 0.4 mGy, TLD 0.5 mGy; (e) breast = MCS 1.1 mGy, TLD 1.1 mGy; (f) lung = MCS 1.2 mGy, TLD 1.3 mGy. Conclusion Overall, in thoracic CT protocols, organ doses simulated by the dose-monitoring software tool were coherent to those measured by TLDs. Despite some challenges, the dose-monitoring software was capable of an accurate dose calculation.

scholarly journals Organ doses of the fetus from external environmental exposures

2021 ◽  
Vol 60 (1) ◽  
pp. 93-113
Author(s):  
Nina Petoussi-Henss ◽  
Daiki Satoh ◽  
Helmut Schlattl ◽  
Maria Zankl ◽  
Vladimir Spielmann
Keyword(s):  
Monte Carlo ◽  
Dose Rate ◽  
Organ Dose ◽  
Pregnant Female ◽  
Rate Coefficients ◽  
Monte Carlo Code ◽  
Organ Doses ◽  
Organ Equivalent Dose ◽  
Specific Organ ◽  
External Exposures

AbstractThis article presents nuclide-specific organ dose rate coefficients for environmental external exposures due to soil contamination assumed as a planar source at a depth of 0.5 g cm−2 in the soil and submersion to contaminated air, for a pregnant female and its fetus at the 24th week of gestation. Furthermore, air kerma free-in-air coefficient rates are listed. The coefficients relate the organ equivalent dose rates (Sv s−1) to the activity concentration of environmental sources, in Bq m−2 or Bq m−3, allowing to time-integrate over a particular exposure period. The environmental radiation fields were simulated with the Monte Carlo radiation transport codes PHITS and YURI. Monoenergetic organ dose rate coefficients were calculated employing the Monte Carlo code EGSnrc simulating the photon transport in the voxel phantom of a pregnant female and fetus. Photons of initial energies of 0.015–10 MeV were considered including bremsstrahlung. By folding the monoenergetic dose coefficients with the nuclide decay data, nuclide-specific organ doses were obtained. The results of this work can be employed for estimating the doses from external exposures to pregnant women and their fetus, until more precise data are available which include coefficients obtained for phantoms at different stages of pregnancy.

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