• Journal of the Korean Society of Radiology
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• v.11 no.3
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• pp.117-122
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• 2017

With the increase in leisure life, the population of ski resorts is rapidly increasing. The activity at the ski resort is likely to receive a direct chance of natural sunlight or space ray. Because it is located in the mountains where altitude exists. As a general rule, it is widely known that the higher the elevation rate, the more increasing the natural radiation dose. However, the natural radiation dose rate for the ski slopes has not been reported yet. Various ski resorts exist in Korea, but this study had chose 4 ski resorts to measure the natural dose of natural radiation. As a result, the natural radiation dose for the ski slope was measured at a relatively high dose of ordinary living areas. However, the level of natural radiation dose was not worrisome. It is recommended to wear ski wear or goggles to minimize natural radiation exposure at the ski slopes.

• Journal of radiological science and technology
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• v.35 no.1
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• pp.35-44
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• 2012

The goal of this study is to awaken about risk occurred by CT examination. For radio-technologists working at 'S medical center' located in Seoul, we investigated a recognition about dose and risk CT and normal X-ray examination according by working experience in hospital, experience about CT examination and radiation source. For subjects of investigation, radio-technologists working at 'S medical center' located in Seoul helped us. We collected 131 questionnaires for a test of hypothesis. Cronbach @ coefficients of questionnaires were 0.825988 and 0.767161 and a rejection rate of p-value was below 0.05. SAS 9.1(SAS Institute Inc., Cary, NC, USA.) statistic package was used for hypothesis test. We used Mann-Whitney test, Kruskai-Wallis test, Two sample T-test, Two sample T-test with Bonferroni's Correction and One-way ANOVA methods. P-values of hypothesis about dose of CT and normal X-ray examination were 0.2291 ~ 0.9663. p-values of hypothesis about risk were 0.1924 ~ 1.0000. All of hypothesis is over rejection rate(<0.05). This study shows that radio-technologists of S medical center recognized that CT has higher dose and risk than general X-ray examination.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.127-133
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• 2014

Purpose: Low dose of PET/CT is important because of Patient's X-ray exposure. The aim of this study was to evaluate the effectiveness of low-dose PET/ CT image through the CTAC and QAC of patient study and phantom study. Materials and Methods: We used the discovery 710 PET/CT (GE). We used the NEMA IEC body phantom for evaluating the PET data corrected by ultra-low dose CT attenuation correction method and NU2-94 phantom for uniformity. After injection of 70.78 MBq and 22.2 MBq of 18 F-FDG were done to each of phantom, PET/CT scans were obtained. PET data were reconstructed by using of CTAC of which dose was for the diagnosis CT and Q. AC of which was only for attenuation correction. Quantitative analysis was performed by use of horizontal profile and vertical profile. Reference data which were corrected by CTAC were compared to PET data which was corrected by the ultra-low dose. The relative error was assessed. Patients with over weighted and normal weight also underwent a PET/CT scans according to low dose protocol and standard dose protocol. Relative error and signal to noise ratio of SUV were analyzed. Results: In the results of phantom test, phantom PET data were corrected by CTAC and Q.AC and they were compared each other. The relative error of Q.AC profile was been calculated, and it was shown in graph. In patient studies, PET data for overweight patient and normal weight patient were reconstructed by CTAC and Q.AC under routine dose and ultra-low dose. When routine dose was used, the relative error was small. When high dose was used, the result of overweight patient was effectively corrected by Q.AC. Conclusion: In phantom study, CTAC method with 80 kVp and 10 mA was resulted in bead hardening artifact. PET data corrected by ultra- low dose CTAC was not quantified, but those by the same dose were quantified properly. In patients' cases, PET data of over weighted patient could be quantified by Q.AC method. Its relative difference was not significant. Q.AC method was proper attenuation correction method when ultra-low dose was used. As a result, it is expected that Q.AC is a good method in order to reduce patient's exposure dose.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.653-659
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• 2019

The purpose of this study is to measure the (air dose rate of radiation dose) the discharged patient who was administrated high dose $^{131}I$ treatment, and to predict exposure radiation dose in public person. The dosimetric evaluation was performed according to the distance and angle using three copper rings in 30 patients who were treated with over 200mCi high dose Iodine therapy. The two observer were measured using a GM surverymeter with 8 point azimuth angle and three difference distance 50, 100, 150cm for precise radion dose measurement. We set up three predictive simulations to calculate the exposure dose based on this data. The most highest radiation dose rate was showed measuring angle $0^{\circ}$ at the height of 1m. The each distance average dose rate was used the azimuth angle average value of radiation dose rate. The maximum values of the external radiation dose rate depending on the distance were $214{\pm}16.5$, $59{\pm}9.1$ and $38{\pm}5.8{\mu}Sv/h$ at 50, 100, 150cm, respectively. If high dose Iodine treatment patient moves 5 hours using public transportation, an unspecified person in a side seat at 50cm is exposed 1.14 mSv radiation dose. A person who cares for 4days at a distance of 1 meter from a patient wearing a urine bag receives a maximum radiation dose of 6.5mSv. The maximum dose of radiation that a guardian can receive is 1.08mSv at a distance of 1.5m for 7days. The annual radiation dose limit is exceeded in a short time when applied the our developed radiation dose predictive modeling on the general public person who was around the patients with Iodine therapy. This study can be helpful in suggesting a reasonable guideline of the general public person protection system after discharge of high dose Iodine administered patients.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.345-351
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• 2020

In this study, a dose assessment was conducted on the exposure dose of thyroid, breast and sexual gland using a personal dosimeter in multiple CT examinations currently being conducted in health examinations. The dose assessment was measured by attaching TLD and EPD to the locations of the thyroid, breast and sexual gland during CT examinations of Brain, Brain + C-S, Brain + Low lung, Brain + L-S among CT items. The generated dose of equipment, CTDI_vol and DLP, was measured. The study found that effective doses were rated 41.7% higher for thyroid TLD in Brain + C-S CT examinations than for the general public, 156% higher for EPD, 10% for breast EPD in Brain + Low Lung CT examinations, 124.4% higher for reproductive TLD and 339.8% higher for Brain + L-S CT examinations. The CTDI_vol and DLP analysis results showed that C-S CTDI_vol values were higher than the diagnostic reference levels at 0.6%, Low Lung CTDI_vol values at 5.7%, DLP values at 11.8% and L-S CTDIvol values at 1.2%. In order to reduce the exposure dose of patients, indiscriminate examination is reduced and dose limit setting is needed in health examination.

• Journal of Radiation Protection and Research
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• v.29 no.2
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• pp.141-150
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• 2004

Dose rate characteristics of cosmic radiation field at flight altitudes were analyzed and the route doses to the personnels on board due to cosmic-ray were calculated for Korean-based commercial international airline routes using CARI-6. Annual individual doses to aircrew and the collective effective dose of passengers were estimated by applying the calculated route doses to the flight schedules of aircrew and the air travel statistics of Korea. The result shows that the annual doses to aircrew, around 2.62 mSv, exceed the annual dose limit of public and are comparable to doses of the group of workers occupationally exposed. Therefore it is necessary to consider the frequent flyers as well as the aircrew as the occupational exposure group. The annual collective dose to 11 million Korean passengers in 2001 appeared to be 136 man-Sv. The results should be modified when the dose rates of cosmic radiation at high altitude are revised by taking into account the changes in the radiation weighting factors for protons and neutrons as given in ICRP 92.

• Journal of Radiation Protection and Research
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• v.27 no.2
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• pp.77-80
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• 2002

A more practice approach for the determination of monetary values of the unit collective dose for intervention against long-term exposure following a nuclear accident was proposed. In addition, she monetary values of the unit collective dose estimated from the proposed approach were compared with those estimated from the previous model, which are derived from assumptions of routine exposure and the same values are applied in a nuclear accident without modification, using Korean economic data. The monetary values based on the proposed approach showed a distinct difference depending on inequity in the distribution of individual doses. The discounting rate was also an important factor in determination of monetary values of the unit collective dose.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.3
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• pp.273-279
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• 2012

Purpose : This study was aimed to calculate effective dose from cone beam CT and compare effective dose from periapical and panoramic radiography for mesiodens. Materials and Methods : Upper anteiror periapical, panoramic radiography and cone-beam CT were taken for diagnosis of mesiodens. The effective dose were calculated by using an anthropomorphic phantom loaded with thermoluminescent dosimeters at the 23 sites related to sensitive organs. Results : The highest absorbed doses were received by the mandibular body, parotid gland and cheek from periapical, panoramic and cone-beam CT, respectively. The effective doses for periapical, panoramic radiography and cone-beam CT measured 2, 18 and 48 ${\mu}Sv$. Conclusion : Cone-beam CT, although providing additional diagnostic benefits, exposes patients to higher levels of radiation than conventional periapical and panoramic radiography.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.253-259
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• 2020

Mammography has the advantage of being economical, simple and effective in detecting microcalcification, but breast is a highly sensitive organ and is accompanied by the risk of an over-exposure. While accurate dose assessments are important to prevent this, current breast dose assessments are limited to breast implant patients. This purpose of this study was to identify dose variations due to tube voltages by forming a mock-up with breast implants for an accurate dosimetric assessment on breast implant patients. As a result, doses from the presence of breast implants were smaller than those from the absence of the mammal. As the result of the change of the voltage to 26, 28, 30, and 32 kV, the imcreased tube voltage included larger dose regardless of the presence of Breast implant. Therefore, it is believed that diagnosis recommendations for breast implants will be possible if further studies on internal and external bioretical imaging and quality assessment are carried out as the basis for this study.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.283-289
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• 2015

Recently, high energy photon radiotherapy is a growing trend for increasing therapy results. Commonly, if you use high energy photons above 6~8 MeV nominal accelerator voltage, It lead the photo-nuclear reaction and the generation of photo-neutron are accompanied and these problematic factors are issued in the view of radiation protection. Therefore, in this study analyzed for dose distribution of photo-neutron in radiotherapy room based on MCNPX. As a result, absorbed dose is increased sharply from 10 MV to 12 MV. It was founded that the rapid increasement of photoneutron fluence was related to the absorbed dose at above 10 MV. Also, in case of the recommendation of ICRP 103, the outcome of an exchanged equivalent dose which based on calculated an absorbed dose, showed lower equivalent dose than ICRP 60 by reflecting the contribution of secondary photon for absorbed dose of human body in the low energy band.