• Journal of radiological science and technology
• /
• v.39 no.4
• /
• pp.565-570
• /
• 2016

Radioactive iodine($^{131}I$) treatment reduces recurrence and increases survival in patients with differentiated thyroid cancer. However, it is important in terms of radiation safety management to measure the radiation dose rate generated from the patient because the radiation emitted from the patient may cause the exposure. Research methods, it measured radiation dose-rate according to the elapsed time from 1 m from the upper abdomen of the patient by intake of radioactive iodine. Directly comparing the changes over time, high dose rate sensitivity and efficiency is statistically significant, and higher chamber than GM counter(p<0.05). Low dose rate sensitivity and efficiency in the chamber had lower levels than gm counter, but not statistically significant(p>0.05). In this study confirmed the characteristics of calibrated ionization chamber and GM counter according to the radiation intensity during high-dose radioactive iodine therapy by measuring the accurate and rapid radiation dose rate to the patient explains, discharged patients will be reduced to worry about radiation hazard of family and others person.

• Journal of radiological science and technology
• /
• v.39 no.4
• /
• pp.509-516
• /
• 2016

A dental panoramic radiography which usually uses low level X-rays is subject to the Nuclear Safety Act when it is installed for the purpose of education. This paper measures radiation dose and spatial dose rate by usage and thereby aims to verify the effectiveness of radiation safety equipment and provide basic information for radiation safety of radiation workers and students. After glass dosimeter (GD-352M) is attached to direct exposure area, the teeth, and indirect exposure area, the eye lens and the thyroid, on the dental radiography head phantom, these exposure areas are measured. Then, after dividing the horizontal into a $45^{\circ}$, it is separated into seven directions which all includes 30, 60, 90, 120 cm distance. The paper shows that the spatial dose rate is the highest at 30 cm and declines as the distance increases. At 30 cm, the spatial dose rate around the starting area of rotation is $3,840{\mu}Sv/h$, which is four times higher than the lowest level $778{\mu}Sv/h$. Furthermore, the spatial dose rate was $408{\mu}Sv/h$ on average at the distance of 60 cm where radiation workers can be located. From a conservative point of view, It is possible to avoid needless exposure to radiation for the purpose of education. However, in case that an unintended exposure to radiation happens within a radiation controlled area, it is still necessary to educate radiation safety. But according to the current Medical Service Act, in medical institutions, even if they are not installed, the equipment such as interlock are obliged by the Nuclear Safety Law, considering that the spatial dose rate of the educational dental panoramic radiography room is low. It seems to be excessive regulation.

• Tuberculosis and Respiratory Diseases
• /
• v.61 no.3
• /
• pp.207-213
• /
• 2006

기존의 폐암 발생의 고위험군(나이. 흡연력, $FEV_1$, 가족력, 직업적 발암물질의 노출력, 기존의 폐암 및 두경부 종양)에 대한 저선량 나선식 CT와 기관지 내시경 검사로 선별 검사 시 폐암의 유병률은 높아야 2%내외이고 대부분 그보다 낮은 것으로 알려져 있다. 특이도는 49-90%, 양성예측률은 10%이하로 선별검사 시 불필요한 검사를 초래하고 그에 따른 이환률과 사망률을 증가시키며 비용적인 문제를 야기하는 것으로 알려져 있다. 이에 기존의 고위험군에 대해 대상 환자를 더욱 더 좁힐 필요가 있으며, 이는 실제 임상적으로 이용 가능한 생물학적 표지자의 개발의 필요성이 있다고 하겠다. 그러나 현재까지 알려진 폐암조기검진에 대한 각종 진단 수기 중애서 상기의 3가지 방법(저선량 MDCT, 자가형광기관지경 및 객담내 MAGE)을 한꺼번에 시행하는 program은 비용적인 문제는 있지만 시도해 볼 만한 방법이라고 생각된다.

• Journal of Radiation Protection and Research
• /
• v.16 no.2
• /
• pp.67-74
• /
• 1991

Parameter uncertainty and sensitivity of KFOOD model for calculating the ingestion dose via terrestrial food-chain pathway was analyzed with using Monte-Carlo approach. For the rice ingestion pathway, estimated values from KFOOD code were very conservative. Most sensitive input parameters in model were deposition velocities and soil-to-plant transfer coefficient of radionuclides.

• Journal of radiological science and technology
• /
• v.47 no.4
• /
• pp.263-270
• /
• 2024

The objective of this study was to evaluate the accuracy and impact of leaf open time (LOT) and pitch using various machine learning models on EBT film-based delivery quality assurance (DQA) performed on 211 patients of helical tomotherapy (HT). We randomly selected passed (n=191) and failed (n=20) DQA measurements to evaluate the accuracy of the k-nearest neighbor (KNN), support vector machine (SVM), naive Bayes (NB) and logistic regression (LR) models using scale-dependent metrics such as the coefficient of determination (R2), mean squared error (MSE), and root MSE (RMSE). We evaluated the performance of the four prediction models in terms of the accuracy, precision, sensitivity, and F1-score using a confusion matrix, finding the NB and LR models to achieve optimal results. The results of this study are expected to reduce the workload of medical physicists and dosimetrists by predicting DQA results according to LOT and pitch in advance.

• Radiation Oncology Journal
• /
• v.21 no.3
• /
• pp.238-244
• /
• 2003

Purpose: The Planning of High-Dose-Rate (HDR) brachytherapy treatments are becoming individualized and more dependent on the treatment planning system. Therefore, computer software has been developed to perform independent point dose calculations with the integration of an isodose distribution curve display into the patient anatomy images. Meterials and Methods: As primary input data, the program takes patients'planning data including the source dwell positions, dwell times and the doses at reference points, computed by an HDR treatment planning system (TPS). Dosimetric calculations were peformed in a $10\times12\times10\;Cm^3$ grid space using the Interstitial Collaborative Working Group (ICWG) formalism and an anisotropy table for the HDR Iridium-192 source. The computed doses at the reference points were automatically compared with the relevant results of the TPS. The MR and simulation film images were then imported and the isodose distributions on the axial, sagittal and coronal planes intersecting the point selected by a user were superimposed on the imported images and then displayed. The accuracy of the software was tested in three benchmark plans peformed by Gamma-Med 12i TPS (MDS Nordion, Germany). Nine patients'plans generated by Plato (Nucletron Corporation, The Netherlands) were verified by the developed software. Results: The absolute doses computed by the developed software agreed with the commercial TPS results within an accuracy of $2.8\%$ in the benchmark plans. The isodose distribution plots showed excellent agreements with the exception of the tip legion of the source's longitudinal axis where a slight deviation was observed. In clinical plans, the secondary dose calculations had, on average, about a $3.4\%$ deviation from the TPS plans. Conclusion: The accurate validation of complicate treatment plans is possible with the developed software and the qualify of the HDR treatment plan can be improved with the isodose display integrated into the patient anatomy information.

• Journal of the Korean Society of Radiology
• /
• v.7 no.2
• /
• pp.121-129
• /
• 2013

In this study measured patient exposure dose for purpose exposure area and peripheral critical organs by using optically stimulated luminescence dosimeters (OSLDs) from computed tomography (CT), based on the measurement results, we predicted the radiobiological effects, and would like to advised ways of reduction strategies. In order to experiment, OSLDs received calibration factor were attached at left and right lens, thyroid, field center, and sexual gland in human body standard phantom that is recommended in ICRP, and we simulated exposure dose of patients in same condition that equal exposure condition according to examination area. Average calibration factor of OSLDs were $1.0058{\pm}0.0074$. In case of left and right lens, equivalent dose was measure in 50.49 mGy in skull examination, 0.24 mGy in chest, under standard value in abdomen, lumbar spine and pelvis. In case of thyroid, equivalent dose was measured in 10.89 mGy in skull examination, 7.75 mGy in chest, 0.06 mGy in abdomen, under standard value in lumber spine and pelvis. In case of sexual gland, equivalent dose was measured in 21.98 mGy, 2.37 mGy in lumber spine, 6.29 mGy in abdomen, under standard value in skull examination. Reduction strategies about diagnosis reference level (DRL) in CT examination needed fair interpretation and institutional support recommending international organization. So, we met validity for minimize exposure of patients, systematize influence about exposure dose of patients and minimize unnecessary exposure of tissue.

• Journal of radiological science and technology
• /
• v.26 no.3
• /
• pp.7-11
• /
• 2003

Currently, many hospitals are hastening to introduce digital radiography systems. This is a direct result of the intentions to improve medical services and to digitalize radiology information systems, and is also leading to the improvement of medical imaging technology. Throughout F/S system's long history, many people have researched the image quality and dosage concerning these systems, and as a result, huge improvements in the dosage of patients were possible. Similarly, I believe that DR systems need the same kind of effort. Of course, decreases in dosage that ignore image quality are unthinkable. The results of experiments conducted by five hospitals during a period of 3 months brought to us the conclusions listed below. 1. Based on the comparison and analysis of the exposure control of F/S systems and DR systems, DR systems generally showed higher exposure control for parts of the phantom that became thicker, and the exposure control improved rapidly as the thickness increased. 2. DR systems still proved to be somewhat deficient in resolution measurements compared to existing F/S systems. The image processing part of DR systems contributed much to these result. 3. Under conditions used clinically, the dosage measurements of DR systems were generally higher regardless of region. 4. According to the evaluation of image quality, DR systems showed a higher degree of satisfaction as the thickness of the region became thinner. As mentioned above and based on the mutual relationship experiments between the dosage and image quality of F/S systems and DR systems, research to increase the satisfaction of DR systems must be considered.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.2 no.2
• /
• pp.113-124
• /
• 2004

A computer software program, called BIDAS (BIoassay Data Analysis Software) is developed to interpret the bioassay measurement data in terms of intakes and the committed effective dose using the human respiratory tract model (HRTM), gastrointestinal tract (GI-tract) model and biokinetic models currently recommended by the International Commission on Radiological Protection (ICRP) to describe the behavior of the radioactive materials within the body. The program consists of three modules; first, a database module to manage the bioassay data, second, another databasee module to store the predicted bioassay quantities of each radionuclide and finally, a computational module to estimate the intake and committed effective dose calculated with the bioassay quantity measurement values from either an acute or chronic exposure of the radionuclies within the body. This paper describes the features of the program as well as the quality assurance check results of the BIDAS software program.

• Korean Journal of Veterinary Research
• /
• v.41 no.2
• /
• pp.203-210
• /
• 2001

Here, we compared the effectiveness of 50 MeV($p{\to}RBe^+$) cyclotron fast neutrons versus $^{60}Co$ ${\gamma}$-rays by the apoptotic fragment frequency in both rat peripheral lymphocytes and crypt cells to check a radiobiological endpoint. The incidence of apoptotic cell death was increased in all irradiated groups, and radiation at all doses trigger rapid changes in both crypt cells and peripheral lymphocytes. These data suggest that apoptosis may play an important role in homeostasis of damaged radiosensitive target organ by removing damaged cells. The curve of dose-effect relationship for these data of apoptotic fragments frequencies was $y=0.3+(6.512{\pm}0.279)D(r^2=0.975)$ after neutrons, while $y=0.3+(4.435{\pm}0.473)D+(-1.300{\pm}0.551)D^2(r^2=0.988)$ after ${\gamma}$-rays. In addition, $y=3.5+(118.410{\pm}10.325)D+(-33.548{\pm}12.023)D^2(r^2=0.992)$ after ${\gamma}$-rays in rat lymphocytes. A significant dose-response relationship was found between the frequency of apoptotic cell and dose. These data show a trend towards increase of the numbers of apoptotic cells with increasing dose. Dose-response curves for high and low linear energy transfer (LET) radiation modalities in these studies were different. The relative biological effectiveness (RBE) value for crypt cells was 1.919. In addition, there were significant peaks on apoptosis induction at 4 and 6h after irradiation, and the morphological findings of the irradiated groups were typical apoptotic fragments in crypt cells that were hardly observed in the control group. Thus, apoptosis induction in both crypt cells and peripheral lymphocytes could be a useful endpoint of rat model for studying screening test and microdosimetic indicator to evaluate the biological effects of radiation-induced cell damage.