Earticle

Protective behavior of radiological technologists against radiation exposure is important to achieve reduction of the patientdoses without compromising medical achievements. This study attempts to provide a basic model for the sophisticatedintervention strategy that increases the level of the protective behavior of the technologists. The model was applied to realsituations in Korea to demonstrate its utility. The results of this study are summarized as follows: First, the protectiveenvironment showed the highest relationship in the factors considered, r=0.637 (p<0.01). Secondly, the important factorswere protective environment in environment characteristics, expectation for the protective behavior 0.228 (p<0.001), self-efficacy 0.142 (p<0.001), and attitude for the protective behavior 0.178 (p<0.001) in personal characteristics, and dailypatient -0.112 (p<0.001) and number of the participation in the education session for the protective behavior 0.074 (p<0.05).Thirdly, the final protective behavior model by a path analysis method had direct influence on the attitude 0.171 (p<0.01)and environment 0.405 (p<0.01) for the protective behavior, self efficacy 0.122 (p<0.01), expectation for the protectivebehavior 0.16 (p<0.01), and self-efficacy in the specialty of projects 0.154 (p<0.01). The acceptance of the modeldetermined by the absolute fit index (GFI), 0.969, and by the incremental fit index (CFI), 0.943, showed very significantlevels. Value of 2/df that is a factor applied to verify the acceptance of the model was 37, which implies that the resultcan be accepted in the desirable range. In addition, the parsimonious fit index configured by AGFI (0.890) and TLI(0.852) was also considered as a scale that accepts the model in practical applications. In case of the establishment of some specific intervention strategies based on the protective behavior model againstharmful radiation effects proposed in this study, the strategy will provide an effective way to prevent medical harmfulradiation effects that could cause severe injuries to people.

We exposed ICR mice to low-dose (0.2 Gy) and low-dose-rate (0.7 mGy/h) -radiation (137Cs) in the Low-dose-rateIrradiation Facility at the Radiation Health Research Institute to evaluate systemic effects of low-dose radiation. Wecompared the body and organ weights, number of blood cells (white and red blood cells and platelets), levels of biochemicalmarkers in serum, and frequency of micronuclei in polychromatic erythrocytes between low-dose irradiated and non-irradiated control mice. The ICR mice irradiated with total doses of 0.2 and 2 Gy showed no changes in body and organweights, number of blood cells (white and red blood cells), or frequency of micronuclei in the polychromatic erythrocytesof peripheral blood. However, the number of platelets (P = 0.002) and the liver weight (P < 0.01) were significantlyincreased in mice exposed to 0.2 and 2 Gy, respectively. These results suggest that a low-dose-rate of 0.7 mGy/h does notinduce systemic damage. This dose promotes hematopoiesis in the bone marrow microenvironment and the proliferationof liver cells. In the future, the molecular biological effects of lower doses and dose rates need to be evaluated.

A Compton camera, which is based on Compton kinematics, is a very promising gamma-ray imaging device in that it couldovercome the limitations of the conventional gamma-ray imaging devices. In the present study, the image quality of a rotating Comptoncamera was evaluated by using 4-D Monte Carlo simulation technique and the applicability to nuclear industrial applications wasexamined. It was found that Compton images were significantly improved when the Compton camera rotates around a gamma-raysource. It was also found that the 3-D imaging capability of a Compton camera could enable us to accurately determine the 3-D locationof radioactive contamination in a concrete wall for decommissioning purpose of nuclear facilities. The 4-D Monte Carlo simulationtechnique, which was applied to the Compton camera fields for the first time, could be also used to model the time-dependent geometryfor various applications.

Since 1990s, some events - detection of a dirty bomb in a Russian nation park in 1995, 9/11 terrorist attack to WTC in 2001,discovery of Al-Qaeda’s experimentation to build a dirty bomb in 2003 etc - have showed that nuclear or radiological terrorism relatingto radioactive materials (hereinafter “radioactive materials” is referred to as “nuclear material, nuclear spent fuel and radioactive source”)isnot incredible but serious and credible threat. Thus, to respond to the new threat, the international community has not only strengthenedsecurity and physical protection of radioactive materials but also established prevention of and response to illicit traffickingof radioactivematerials. In this regard, our government has enacted or revised the national regulatory framework with a view to improving security ofradioactive materials and joined the international convention or agreement to meet this international trend. For the purpose of preventionofnuclear/radiological terrorism, this paper reviews physical characteristics of nuclear material and existing detection instruments used forprevention of illicit trafficking. Finally, national detection regime against nuclear/radiological terrorism based on paths of the smuggledradioactive materials to terrorist’s target building/area, national topography and road networks, and defence-in-depth concept is suggestedin this paper. This study should contribute to protect people's health, safety and environment from nuclear/radiological terrorism.

During the maintenance period at Korean nuclear power plants, internal exposure of radiation workers occurred by theinhalation of 131I released to the reactor building when primary system was opened. The internal radioactivity of radiation workerscontaminated by 131I was immediately measured using a whole body counter and the whole body counting was performed again after afew days. In this study, the intake estimated from the record history of entrance to radiation control areas and the measurement resultsof air sampling for 131I in those areas, were compared with that from the results of whole body counting. As a result, it was concludedthat the intake estimation using whole body counting and air sampling showed similar results.

During the maintenance period at Korean nuclear power plants, internal exposure of radiation workers occurred by theinhalation of 131I released to the reactor building when primary system opened. The internal radioactivity of radiation workers contaminatedby 131I was measured using a whole body counter. Intake estimation and the calculation of committed effective dose were also conductedconforming to the guidance of internal dose assessments from publications of International Commission on Radiological Protection.Because the uptake and excretion of 131I in a body occur quickly and 131I is accumulated in the thyroid gland, the estimated intakes showeddifferences depending on the counting time after intake. In addition, since ICRP publications do not provide the intake retention fraction(IRF) for whole body of 131I, the IRF for thyroid was substitutionally used to calculate the intake and subsequently this caused moreerror in intake estimation. Thus, intake estimation and the calculation of committed effective dose were conducted by manual calculation.In this study, the IRF for whole body was also calculated newly and was verified. During this process, the estimated intake and committedeffective dose were reviewed and compared using several computer codes for internal dosimetry.

This study was conducted to evaluate the accuracy of CyberKnife SynchronyTMrespiratory tracking system which wasapplied to Stereotactic Radiosurgery (SRS) for moving tumors in chest and abdomen with breathing motion. For accurate evaluation, gold fiducial marks were implanted into a moving phantom. The moving phantom was a cube imbedding an acryl ball as a target. Theacryl ball was prescribed to 20 Gy at 70% of isodose curve in a virtual treatment and radiochromic films were inserted into the acrylball for dose verification and tracking accuracy evaluation. The evaluation of position tracking consists of two parts: fiducial marktracking in a stationary phantom and SynchronyTMrespiratory tracking in a moving phantom. Each measurement was done in threedirections and was repeated to 5 times. Range of position error was 0.1957 mm to 0.6520 mm in the stationary phantom and 0.4405 mmto 0.7665 mm in the moving phantom. Average position error was 0.3926 mm and 0.5673 mm in the stationary phantom and themoving phantom respectively. This study evaluates the accuracy of CyberKnife SynchronyTMRespiratory tracking system, and confirmsthe usefulness when it’s used for Stereotactic Radiosurgery of body organs.

This study examines how much the radiation dose rate around it varies if a crack occurs on the spent nuclear fuel rod. Thespent nuclear fuel rod to be examined is that of Kori unit 3&4. The source terms are evaluated using the ORIGEN-ARPthat is part of the version 5.1 of the SCALE package. The radiation dose rate is assessed using the TORT. To check if thestructure of a fuel rod is appropriately modeled in the TORT calculation, the calculation results by the TORT arecompared with those by the ANISN for the same case. From the code simulation, it is known that if a crack occurs on thespent nuclear fuel rod, the neutron dose rate varies depending on what material is the crack filled with, but the gammadose rate varies irrespective of type of the material that the crack is filled with.

The Radiation Emergency Plan (REP) can be divided into a technical and an administrative responses. The domestic NPP'sREPs are reviewed from the viewpoint of the administrative response and improvement methods are also suggested in this treatise. Thefields of the reviews are the composition of the emergency response organizations, the activation criteria of the organizations, theselection of the staffings and the reasonableness of the REP’s volume. In addition, the limitations of the current radiation exercises arereviewed and the improvement method of the exercise is presented. It is expected that the suggested recommendations will be helpful inestablishing useful REPs and making practical radiation exercises in Korea.