• Communications for Statistical Applications and Methods
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• 제29권3호
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• pp.287-299
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• 2022

In radiation epidemiology, the excess relative risk (ERR) model is used to determine the dose-response relationship. In general, the dose-response relationship for the ERR model is assumed to be linear, linear-quadratic, linear-threshold, quadratic, and so on. However, since none of these functions dominate other functions for expressing the dose-response relationship, a Bayesian semiparametric method using splines has recently been proposed. Thus, we improve the Bayesian semiparametric method for the selection of the tuning parameters for splines as the number and location of knots using a Bayesian knot selection method. Equally spaced knots cannot capture the characteristic of radiation exposed dose distribution which is highly skewed in general. Therefore, we propose a nonparametric Bayesian knot selection method based on a Dirichlet process mixture model. Inference of the spline coefficients after obtaining the number and location of knots is performed in the Bayesian framework. We apply this approach to the life span study cohort data from the radiation effects research foundation in Japan, and the results illustrate that the proposed method provides competitive curve estimates for the dose-response curve and relatively stable credible intervals for the curve.

• 대한디지털의료영상학회논문지
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• 제13권2호
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• pp.63-69
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• 2011

Table strapis patient fixture for securing the patient movements and falls. if it designed to measure the abdominal circumference and used as an indicator of dose selection at CT scan. it will prevent the overexposure of dose without degradation of image quality and efficiently manage dose of each type of body to technician to deal with CT. First, in order to compare the dose used in CT image and qualitative characteristics. reference image is obtained by examining the abdominal phantom in same conditions with the hospital 120 kVp, 200 mAs, D-Dom (Dynamic Dose Of Modulation). SNR, PSNR, RMSE, MAE, CTDIvol of CT images are compared with reference image. for comparing with reference image, the image that Umbilicus level image of Abdomen CT is stored in the PACS were used. For comparison, the top 12 o'clock portion of the air drawn from the same ROI was measured. CTDIvol, mAs, etc. In order to analyze the characteristics of the image, by measuring the length of the umbilicus circumference, pattern of the dose was analyzed. by using the analyzed perimeter and dose information, To be identified visually, fixed band that scale marked were produced. Use them, If the length of circumference of less than 60 cm 100 mAs, Case of 61~80 cm 120 mAs, Case of 80~100 cm 150 mAs, more than 100 cm 200 mAs, dose selection based on the perimeter, the image was applied. by compare analyzed with the Reference Image, image quality was assessed. by compare with existing tests that equally 200 mAs applied, How much was confirmed that the dose reduction. 1. Depending on the Abdominal circumference, the average PSNR(dB) of the image that differently dose applied was 45.794. 2. Comparing with existing test. the dose of scan that adjusted the mAs depending on the circumference was decreased about 40%. SNR and PSNR of the image that obtained by adjusting the standard mAs based on dose modulation were not much different. Therefore, By choosing a low mAs. dose reduction can be obtained. and the dose selection method that measured Abdominal circumference using a fixed band can protect the overexposure and uniformly apply dose of each type of body to technician to deal with CT.

• 한국콘텐츠학회논문지
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• 제13권8호
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• pp.275-283
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• 2013

자동노출제어장치를 사용하는 흉부 후전 검사는 이온전리조의 선택에 따라 환자가 받는 피폭선량이 달라진다. 본 논문에서는 자동노출제어장치의 이온전리조의 선택에 따른 최적의 진단 영상을 획득하면서 피폭선량을 최소화하는 방안에 대해 연구하였다. 실험방법은 흉부 후전 검사와 동일한 조건으로 자동노출제어장치의 이온전리조 선택과 감도변화에 따라 실험하였다. 이온전리조의 상단 2개, 하단 1개의 센서를 on/off 선택에 따라 7가지의 경우로 나누어 각각 5회씩 측정하여 평균값을 구하고 피폭선량을 산출하였다. 영상평가는 변조전달함수, 최대신호 대 잡음비, 평균제곱근, 신호 대 잡음비, 대조도 대 잡음비, 평균대표준편차비를 각각 측정하여 평가를 시행하였다. 실험결과 피폭선량 평가에서 이온전리조 상단 2개를 선택한 경우가 다른 조합에 비해 가장 낮은 선량을 나타내었고, 해상력 평가결과로는 감도 625(High)에서 상단2개를 선택한 영상이 두 번째로 높은 공간주파수 1.343 lp/mm를 나타내었다. 상단 2개를 선택한 영상의 평균제곱근 결과값이 두 번째로 낮게 나타났으며, 신호 대 잡음비, 대조도 대 잡음비, 평균 대 표준편차비는 두 번째로 높은 결과값을 나타내었다. 그리고 감도가 증가함에 따라 피폭선량은 감소하였으며, 영상품질 측면에서도 보다 우수한 영상을 얻을 수 있었다. 따라서 피폭선량을 최소화하고, 최적의 의료 영상을 얻기 위해서는 감도 625(High)에서 이온전리조 상단 2개를 선택하는 것이 임상적으로 유용할 것으로 사료된다.

• 대한디지털의료영상학회논문지
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• 제15권2호
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• pp.45-53
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• 2013

Purpose : Fixed way of mAs previously Low Extremity Computed Tomography Angiography(LECTA) examination were used. Automatic Current Selection(ACS) to use for the purpose of reducing the dose when Low Extremity Computed Tomography Angiography examining patients. Materials and methods : Were analyzed from July 2011 to July 2012 MDCT examination of Dose Length Product(DLP) LECTA 116 Case. It was defined as previous inspection methods(Old protocol). CT workstation is set to 100 mAs and 150 mAs protocol based on the patient's weight 70kg examined by LECTA. We defined as 'New protocol' that applies to ACS. The data collection period are 76 cases from October 2012 to January 2013 Results : 1. Average Total DLP of 'Old protocol' is 3602.943 $mGy^*cm$. 2. Average Total DLP of 'New protocol' is 1762.977 $mGy^*cm$. 3. Due to the 'New Protocol' use of Total DLP was reduced by approximately 51 %. Phase-specific dose reduction is as follows. Pre(33.62 %), Artery(64.63 %), Delay(49.0 %) 4. Using One way ANOVA Analysis of fluctuations obtained DLP is as follows. 'Old protocol', 'New protocol' a value of P < 0.001, P = 0.882 values were obtained. Conclusions : Dose reduction of 51 % is a useful study that proves. The results obtained using the ACS, the effects of a dose reduction of 51 % was obtained. Therefore, it has been proven to be a useful way. Statistics using SPSS version came out of the 'Old protocol' P-value P < 0.0001. This result means that the DLP a large difference values. On the other hand, The results of the 'New protocol' was P = 0.882. These results means to that small and regularly was fluctuations of the dose. The use of ACS, you can get a reduction of the dose and will able to get the effect of reducing the dose errors.

• 대한임상약리학회:학술대회논문집
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• 대한임상약리학회 2001년도 제10차 추계학술대회
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• pp.18-18
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• 2001

• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2004년도 KSOT/KEMS Fall Annual Meeting
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• pp.41-47
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• 2004

• 한국독성학회:학술대회논문집
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• 한국독성학회 2004년도 KSOT/KEMS fall annual meeting
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• pp.41-47
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• 2004

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4189-4200
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• 2021

In this study, the relationship between the environmental radiation dose rate and meteorological variables was investigated with multiple regression analysis and big data of those variables. The environmental radiation dose rate and 36 different meteorological variables were measured on Ulleung Island, Republic of Korea, from 2011 to 2015. Not all meteorological variables were used in the regression analysis because the different meteorological variables significantly affect the environmental radiation dose rate during different periods, and the degree of influence changes with time. By applying the Pearson correlation analysis and stepwise selection methods to the big dataset, the major meteorological variables influencing the environmental radiation dose rate were identified, which were then used as the independent variables for the regression model. Subsequently, multiple regression models for the monthly datasets and dataset of the entire period were developed.

• 한국의학물리학회지:의학물리
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• 제1권1호
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• pp.23-29
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• 1990

In order to explane the stereotactic procedure, the three steps of the procedure (target localization, dose planning, and radiation treatment) must be examined separately. The ultimate accuracy of the full procedure is dependent on each of these steps and on the consistancy of the approach The concern in this article was about dose planning, which is a important factor to the success of radiation treatment. The major factor in dose planning is a dosimetry system to evaluate the dose delivered to the target and normal tissues in the patient, while it generates an optimal dose distribution that will satisfy a set of clinical criteria for the patient. A three-dimensional treatment planning program is a prerequisite for treatment plan optimization. It must cover 3-D methods for representing the patient, the dose distributions, and beam settings. The major problems and possible modelings about 3-D factors and optimization technique were discussed to simplify and solve the problems associatied with 3-D optimization, with relative ease and efficiency. These modification can simplify the optimization problem while saving time, and can be used to develop reference dose planning system to prepare standard guideline for the selection of optimum beam parameters, such as the target position, collimator size, arc spacing, the variation in arc length and weight. The method yields good results which can then be simulated and tailored to the individual case. The procedure needed for dose planning in stereotactic radiosurgery is shown in figure 1.

• 대한방사선기술학회지:방사선기술과학
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• 제21권2호
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• pp.19-25
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• 1998

By analyzing each part of expsure condition and the status of an entrance dose which is exposed to patients, this study reached the following conclusion. Since there is no standard in setting up an exposure condition, the technology practiced in each facility varies tremendously, and the entrance dose increased especially due to the improper selection of screen and grid and the shortage of a total amount of filtration in leaching the standard filtration amount. Entrance dose was, generally, turned out to be $2{\sim}3$ times as much as that of advanced countries, and there was big difference between facilities ; approximately 52 times inlateral of cervical vertebrae, 35 times in A-P of femur, 33 times in chest A-P, and 11 times in lumber A-P. Therefore, to minimize the entrance dose of a patient with thegreatest amount of image information, acquirement of technological know-how necessary for standardization of exposure condition for each part can be an important research task.