• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1377-1384
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• 2018

Accurate measurement of the absorbed dose and the effective dose is required in dental panoramic radiography involving relatively low energy with a rotational X-ray tube system using long exposures. To determine the effectiveness of measuring the irradiation by using passive dosimetry, we compared the entrance skin doses by using a radiophotoluminescent glass dosimeter (RPL) and an optically stimulated luminescence detector (OSL) in a phantom model consisting of nine and 31 transverse sections. The parameters of the panoramic device were set to 80 kV, 4 mA, and 12 s in the standard program mode. The X-ray spectrum was applied in the same manner as the panoramic dose by using the SpekCalc Software. The results indicated a mass attenuation coefficient of $0.008226cm^2/g$, and an effective energy of 34 keV. The equivalent dose between the RPL and the OSL was calculated based on a product of the absorbed doses. The density of the aluminum attenuators was $2.699g/cm^3$. During the panoramic examination, tissue absorption doses with regard to the RPL were a surface dose of $75.33{\mu}Gy$ and a depth dose of $71.77{\mu}Gy$, those with regard to the OSL were surface dose of $9.2{\mu}Gy$ a depth dose of $70.39{\mu}Gy$ and a mean dose of $74.79{\mu}Gy$. The effective dose based on the International Commission on Radiological Protection Publication 103 tissue weighting factor for the RPL were $0.742{\mu}Sv$, $8.9{\mu}Sv$, $2.96{\mu}Sv$ and those for the OSL were $0.754{\mu}Sv$, $9.05{\mu}Sv$, and $3.018{\mu}Sv$ in the parotid and sublingual glands, orbit, and thyroid gland, respectively. The RPL was more effective than the OSL for measuring the absorbed radiation dose in low-energy systems with a rotational X-ray tube.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.1
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• pp.18-24
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• 2017

Patient-specific image-based internal dosimetry involves using the patient's individual anatomy and spatial distribution of radioactivity over time to obtain an absorbed dose calculation. Individual absorbed dose was calculated by accumulated activity multiply S-value of each organs. The aim of this study was to calculate the S-values using Monte Carlo simulation in monkey and mouse and evaluation of absorbed dose in each organ. Self-irradiation S-value of monkey heart self-irradiation was 3.15E-03 mGy-g/MBq-s, lung self-irradiation was 8.94E-04 mGy-g/MBq-s and liver self-irradiation S-value was 2.23E-03 mGy-g/MBq-s. Mouse heart self-irradiation S-value was 1.95E-01 mGy-g/MBq-s, lung was 9.59E-02 mGy-g/MBq-s, and liver was 1.40E-03 mGy-g/MBq-s. The results of this study show that the calculation protocol of image based individual absorbed dose of each organ using Monte Carlo simulation. Therefore, this study may be applied to calculate human specific absorbed dose.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.359-364
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• 2011

This study was aimed to investigate the effect of oxidants on biodegradability and decomposition of acetaminophen (ACT) by gamma ray. Three kinds of chemical, potassium persulfate, hydrogen peroxide and ferrous sulfate were selected as an oxidant. The absorbed dose was ranged from 0.2 to 10 kGy and the concentration of oxidants was from 0.1 to 10 mM and the initial concentration of acetaminophen was $30mg\;l^{-1}$ in this study. The concentration of ACT was gradually decreased corresponding to the increase of the absorbed dose. However, mineralization of ACT was not occurred by the increased of the absorbed dose. When the 10 mM of oxidants applied to the ACT aqueous solution, the concentration of ACT was rapidly decreased according to absorbed dose and the mineralization was observed in potassium persulfate. Biodegradability of ACT with potassium persulfate was higher than that of ACT without potassium persulfate in lower absorbed dose and decreased according to higher absorbed dose.

• Journal of radiological science and technology
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• v.47 no.3
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• pp.213-218
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• 2024

The myocardial nuclear medicine examination is widely performed to diagnose myocardium disease using various radionuclides. Although image quality according to radionuclides has improved, the radiation exposure for target organ as well as peripheral organs should be considered. Here, the aim of this study was to evaluate absorbed dose (Gy) for peripheral organs in myocardial nuclear medicine scan from myocardium according to various scan environments based on Monte Carlo simulation. The simulation environment was modeled 5 cases, which were considered by radionuclides, number of injections, and radiodosage. In addition, the each radionuclide simulation such as distribution fraction was considered by recommended standard protocol, and the mesh computational female phantom, which is provided by International Commission on Radiological Protection (ICRP) 145, was used using the particle and heavy ion transport code system (PHITS) version 3.33. Based on the results, the closer to the myocardium, the higher the absorbed dose values. In addition, application for dual injection for radionuclides leaded to high absorbed dose compared with single injection for radionuclide. Consequently, there is difference for absorbed dose according to radionuclides, number of injections, and radiodosage. To detect the accurate diseased area, acquisition for improved image quality is crucial process by injecting radionuclides, however, we need to consider absorbed dose both target and peripheral inner organs from radionuclides in terms radiation protection for patient.

• Archives of Pharmacal Research
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• v.18 no.6
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• pp.427-433
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• 1995

A microscopic mass balance approach has hsown that the initial saturation (Is), absorption number (An), dose number (Do), and dissolution number (Dn) are four fundamental dimensionless parameters that can be used to estimate the fraction dose absorbed (F)l of suspensions of poorly soluble drugs in humans. The dissolution number of a drug increases with decreasing its particle size. The effect of micronization on F for suspensions was investigated in terms of Dn. About 90% of maximal F can be achieved at $Dn{\approx}2$. Increasing the solubility of a drug results in better oral absorption through increasing Dn and decreasing the solubility of a drug results in better oral absorption through increasing Dn and decreasing Do. The fractions dose absorbed of digoxin, griseofulvin, and benoxaprofen agree with predicted F values sorbed by reducing particle size, while absorption of drugs with high Do and low Dn is limited by solubility and requires higher solubility to enhance the fraction dose absorbed in addition to micronization. Solubility at the physiological pH should be used for the estimation of the fraction dose absorbed.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.248-253
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• 2023

Directly, it is not possible to measure the absorbed dose of radiopharmaceuticals in the organs of the human body. Therefore, simulation methods are utilized to estimate the dose in distinct organs. In this study, individual organs were separately considered as the source organ or target organ to calculate the mean absorption dose, which SAF and S factors were then calculated according to the target uptake via MIRD method. Here, ^99mTc activity distribution within the target was analyzed using the definition and simulation of ideal organs by summing the fraction of cumulative activities of the heart as source organ. Thus, GATE code was utilized to simulate the Zubal humanoid phantom. To validate the outcomes in comparison to the similar results reported, the accumulation of activity in the main organs of the body was calculated at the moment of injection and cardiac rest condition after 60 min of injection. The results showed the highest dose absorbed into pancreas was about 21%, then gallbladder 18%, kidney 16%, spleen 15%, heart 8%, liver 8%, thyroid 7%, lungs 5% and brain 2%, respectively, after 1 h of injection. This distinct simulation model may also be used for different periods after injection and modifying the prescribed dose.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.273-279
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• 2022

In order to reduce the absorbed dose given to the patient during dental radiography, a sensor that inserts a shield into the intraoralsensor was designed. Using the designed sensor, the change in absorbed dose depending on whether or not a shield was used was evaluated. The system used to evaluate the absorbed dose is VEX-S300C from Vatech, and the energy spectrum of X-rays was obtained through SPEKTR simulation based on the irradiation conditions of 65 kV, 3 mA, and 0.15 sec, and the number of photons for each energy was derived. After designing the system through Genat4 Application for Tomographic Emission(GATE) simulation, the energy spectrum obtained was used as a radiation source to calculate the absorbed dose. Lead was used for the shield, and simulations were performed at 0.1 mm thickness intervals from 0.1 mm to 0.5 mm was evaluated. In the case of using an X-ray field with a diameter of 60 mm, the decrease in absorbed dose according to the presence or absence of a shield decreased exponentially as the thickness of the shield increased. In addition, when a 20 mm × 30 mm field was used, the absorbed dose was significantly reduced even when no shield was used, and it was confirmed that the absorbed dose was further reduced when a shield was used.

• Progress in Medical Physics
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• v.24 no.3
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• pp.140-144
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• 2013

In this research, the glass dosimeter was calibrated to measure the standard absorbed dose of the Cs-137 irradiator and absorbed dose in a biological sample. Absorbed dose in water for Cs-137 gamma ray was determined by the IAEA TRS-277 protocol. The PTW-TM30013 ion chamber and the PTW-TM41023 water phantom were utilized for measuring absorbed dose and the value was compared with the reading from DoseAce GD-302M glass dosimeter from Asahi Techno Glass Corporation for its calibration. The uncertainty of measurement ($1{\sigma}$) of the calibrated glass dosimeter was 2.7% and this result would be applied to improve the accuracy in measurement of absorbed dose in a biological sample.

• Progress in Medical Physics
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• v.18 no.4
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• pp.187-193
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• 2007

In an effort to assess the internal absorbed dose of radionuclides that is suitable to Koreans' physiological characteristics, we asked 28 male Koreans to take $^{131}|$ orally, determined the thyroidal uptake and daily urination ratio, and assessed the absorbed dose by organ. As a result, first, 24 hours after administering, the average thyroidal uptake and the daily urination ratio registered 19.70% and 71.12%, respectively. Second, the whole body effective dose according to the thyroidal uptake calculated herein and the existing ICRP-suggested thyroidal uptake of 30% offered 1.464E-08 Sv and 2.189E-08 Sv, respectively, showing a 1.5 times difference. To evaluate the quantity of the absorbed dose of radioactive iodine, we can better reduce the error in assessing the body exposure dose by conducting measurement according to human races rather than depending on the existing ICRP data.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.50-56
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• 2012

Purpose: Those who access to the nuclear medicine department are classified as radiation workers, temporarily access group, and occasional access group as defined by the atomic energy law. The radiation workers and temporarily access people wear a personal radiation dosimeter for checking their own radiation absorbed dose periodically. However, because of the sanitation workers, classified as temporarily access group, who are working in the nuclear medicine department are moved in a cycle with other departments and their works are changeful, it is hard to control their radiation absorbed dose. Thus, this study is going to examine the state of the sanitation worker's radiation absorbed dose, and then make sure whether they are classified as temporarily access group or not. Materials and methods: In the first instance, the first sanitation worker who works in vitro laboratory and PET room and the second sanitation worker who works in gamma camera rooms (invivo room) wore radiation dosimeter-OSL(Optically Stimulated Luminescence)- to measure their own radiation absorbed dose during work time from May to June 2011. Secondly, this study was taken place 5 places in gamma camera rooms, 2 places in PET bed room, operating room, waiting room and cyclotron room in PET and 4 places in vitro laboratory. And then to measure the radiation space dose rate, it is measured 10 times each of places as sanitation worker's work flow by using radiation survey meter. Results: The radiation absorbed dose on OSL of the first c who works in vitro laboratory and PET room and the second one who works in gamma camera rooms are 0.04, 0.02 mSv per month respectively. That means the estimated annual radiation absorbed doses are less than 1mSv as 0.48, 0.24 mSv/yr respectively. The radiation space dose rates as sanitation worker's work flow using survey meter are 0.0037, 0.0019 mSv/day, so the estimated annual radiation absorbed dose are 0.93, 0.47 mSv/yr respectively. The weighted exposure dose of first sanitation worker of each places are 1.62% in cyclotron room, 3.88% in waiting room, 2.39% in operating room, 81.01% in bed room of PET and 11.01% in vitro laboratory. The weighted exposure dose of second sanitation worker of each places are 45.22% in radiopharmaceutical laboratory, gamma 30.64% in camera rooms, 15.65% in waiting room, 8.49% in reading room. Conclusion: The annual radiation absorbed doses on OSL of both sanitation workers are less than 1 mSv per year and the annual radiation absorbed doses by using survey meter are less than 1mSv either, but close up to 1 mSv. Thus, to clarify whether the sanitation workers are temporarily access group or not, and to be lessen their s radiation absorbed dose, they should be educated about management of radiation and modified their work flow or work time appropriately, their radiation absorbed dose would be lessen certainly.