• Analytical Science and Technology
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• v.20 no.6
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• pp.460-467
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• 2007

Dose rate conversion factor was calculated to estimate the absorbed effective annual doses for soils for the beta-rays and gamma-rays, which were emitted from $^{238,235}U$, $^{232}Th$, and $^{40}K$ isotopes. The most recent data of the emitted energies per decay, half-lifes, and branching ratios, which were obtained from National Nuclear Data Center, were used. When this factor and the effective annual doses for the beta-rays and the gamma-rays of natural radioisotopes were compared with those of Aitken, these of $^{238}U$, $^{232}Th$ and $^{40}K$ are estimated to have good agreements but a large difference is shown in this for $^{235}U$. Through the calculations of effective annual doses by using these factor and the measurements of gamma-ray spectra for soils, which were extracted from prehistoric remains (Mansuri) on Osong, Chungchengbuk-do, The annual effective doses were obtained to be 3.8~5.9 mGy/yr. Also, when these doses including decay elements upper Rn were compared with those on all isotopes, the differences within 9~30 % were obtained. The analysis method of the annual effective doses for the beta-rays and the gamma-rays of the natural isotopes of soils was established by this dose rate conversion factor.

• Radiation Oncology Journal
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• v.19 no.2
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• pp.118-126
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• 2001

Purpose : In this study, it was investigated whether dose response relation existed or not in local radiotherapy for primary hepatocellular carcinoma. Materials and Methods : From January 1992 to March 2000, 158 patients were included in present study. Exclusion criteria included the presence of extrahepatic metastasis, liver cirrhosis of Child's class C, tumors occupying more than two thirds of the entire liver, and performance status on the ECOG scale of more than 3. Radiotherapy was given to the field including tumor with generous margin using 6, 10-MV X-ray. Mean tumor dose was $48.2{\pm}7.9\;Gy$ in daily 1.8 Gy fractions. Tumor response was based on diagnostic radiologic examinations such as CT scan, MR imaging, hepatic artery angiography at $4\~8$ weeks following completion of treatment. Statistical analysis was done to investigate the existence of dose response relationship of local radiotherapy when it was applied to the treatment of primary hepatocellular carcinoma. Results : An objective response was observed in 106 of 158 patients, giving a response rate of $67.1\%$. Statistical analysis revealed that total dose was the most significant factor in relation to tumor response when local radiotherapy was applied to the treatment of primary hepatocellular carcinoma. Only $29.2\%$ showed objective response in patients treated with dose less than 40 Gy, while $68.6\%\;and\;77.1\%$ showed major response in patients with $40\~50\;Gy$ and more than 50 Gy, respectively. Child-Pugh classification was significant factor in the development of ascites, overt radiation induced liver disease and gastroenteritis. Radiation dose was an important factor for development of radiation induced gastroduodenal ulcer. Conclusion : Present study showed the existence of dose response relationship in local radiotherapy for primary hepatocellular carcinoma. Only radiotherapy dose was a significant factor to predict the objective response. Further study is required to predict the maximal tolerance dose in consideration of liver function and non-irradiated liver volume.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.17-21
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• 2015

Recently, As people's interest in the health of teeth is increased in the medical field changed into aging society, the number of times for the radiological diagnosis is increased. It can be said that the radiation exposure dose of Korean population is increased. It is also growing concern about radiation exposure. Therefore, the basic data for the dental panoramic X-ray system, its investigation and measuring the radiation dose is needed. In this study, we used ALOKA PDM-117 dosimeter and estimated a two-dimensional dose distribution of the dental panoramic X-ray system (VATEC Pax-400). Dose evaluation about the distribution is confirmed from the point of radiation exposure of a patient. Dose distribution of the dental panoramic X-ray system irradiated chin and the facial region to high dose as well as the parts of teeth. It was founded that the eye lens which are sensitive to radiation are exposed to unnecessary radiation, considering the effect of scattered radiation. The results of this study will be used more accurate dose assessment in a variety of object size and location of measuring dose.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.173-178
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• 2010

In projection radiography, two types of digital imaging systems are currently available, computed radiography (CR) and digital radiography (DR): a difference between them can be stated in terms of dose and image quality. In the Department of Radiology our hospital, a flat-panel DR equipment (Digital diagnost, Philips) and two CR systems (ADC Compact plus digitizer, AGFA) are employed. Eight standard radiographic examinations (Skull AP, Skull LAT, Chest PA, Chest LAT, Abdomen AP, L-spine AP, L-spine LAT, Pelvis AP) were considered: doses delivered to patients in terms of both entrance skin dose (ESD) were calculated and compared in order to study the dosimetric discrepancies between CR and DR. Assessment of image quality is undertaken by Consultant Radiologists to ensure that the quality criteria for diagnostic radiographic images of the European guidelines were met. Results showed that both ESD in DR are lower than that in CR; all images met the criteria in the European Guidelines for both modalities and were used for reporting by the radiologists. Since the operators are the same and the image quality is comparable in both modalities, this study shows that in the considered examinations, DR can perform better than CR from a dosimetric point of view.

• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.741-746
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• 2020

To investigate the radiation dose sensitivity in extremity radiatioin therapy depending on rice cultivar which have different size and shape of grains, plan results are compared that used rice bolus Korean and Thai rice. Phantoms that are each no bolus, Korean rice bolus, Thai rice bolus were used and prescribed 100 cGy to isocenter and checked the point dose of 12 points of interest of each phantoms. The meane dose are 103.57±1.98 cGy in Thai rice bolus using, 104.27±2.12 cGy in Korean rice bolus and 104.99±6.40 cGy in phantom without bolus. Dose distribution of Thai and Korean rice bolus differed significantly in Wilcoxon's Signed Rank test (p=.011). It has been confirmed that that the bolus using Thai rice, which has a small grain size, shows a more even dose distribution.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.121-124
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• 2015

Digital Mammography is very important for the early diagnosis of breast cancer. but excessive radiation dose to the patient may increase the probability of occurrence of breast cancer. absorbed dose rate and signal, noise, and contrast in accordance with the change of the filter, and analyzed the signal-to-noise ratio. absorbed dose rate GE Equipment is higher than that of Siemens and Hologic. using the material of Mo / Mo was lower than the other target-filter combination. SNR of Siemens equipment is high and measured high when Mo / Mo selected, the other two devices was measured high when Mo / Rh selected. when you choose a target-filter combination our results will be a good indicator.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.889-894
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• 2019

Upper gastrointestinal series is an examination that uses X-rays. It is important to defend against exposure to radiation during upper gastrointestinal examination because the organs, such as thyroid gland, lens, breasts, and gonads, with relatively high biological sensitivity to radiation are distributed on the examination area. We have made a whole body phantom that can change the depth of organs. radiation dose of eye, thyroid gland, breast and gonads were measured by the same procedure as the actual upper gastrointestinal examination. When performed only fluoroscopy the mean dose reduction of lens, thyroid gland, breast and gonads was 62.2%. The mean dose reduction of lens, thyroid gland, breast and gonads was 59.0% when both fluoroscopy and spot shoot were performed. Therefore, when performed upper gastrointestinal examination it was confirmed that shielding of the lens, thyroid gland, breast and gonads was effective in decreasing the exposure dose. The manufactured human phantom can be used in measuring radiation dose for deep organ because it can adjust the height corresponding to the organs located in the human body.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.21-28
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• 1988

Absorbed dose in water was analyzed by Burlin's general cavity theory for medium X-ray energy region (HVL : 0.29, 0.84, 1.60, 2.62mm Cu) using LiF : PTFE TL dosimeter(0.4 mm ${\times}\;{\phi}$ 12.5mm, hot-pressed LiF TLD-700) which was enclosed in lucite capsule. The absorbed dose rate at 5cm depth in water phantom was determined with measurement error of ${\pm}5%$. This result was compared to that of the ionization method, indirectly absolute measurement method, of which measurement error of ${\pm}2%$. The difference between these two results lies within measurement error of LiF : PTFE method. Therefore, the absorbed dose in water obtained by LiF: PTFE is reliable, and this result suggests the base to estimate dose-equivalent for medium X-rays.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.519-526
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• 2022

Electronic personal dosimeter (EPD) provide real time monitoring and a direct indication of the accumulated dose or dose rate in terms of personal dose. Most EPD do not perform well in low energy photon radiation fields present in medical radiation environments. It has poor responsibility and large error rate for low energy photon radiation of medical radiation environments. This study evaluated to optimal additional filtration for EPD using silicon PIN photodiode detector form 40 to 120 kVp range in medical radiation environments. From 40 to 80 kVp energy range, Al 0.2 mm and Sn 1.0 mm overlapped filtration showed good responsibility to dose rate and from 80 kVp to 120 kVp energy range, Al 0.2 mm and Sn 1.6 mm overlapped filtration showed good responsibility to dose rate.

• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.909-916
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• 2019

Radiation therapy of oral and head and neck cancers often involves skin in the therapeutic range, and the use of bolus is frequently used. Dose irregularities provide dose uncertainty in patient application. In this study, the physical properties of patients with gel bolus, poly lactic acid (PLA), and silicon using 3D printing were fabricated. Dose uncertainties arising from the actual radiation dose delivery were measured. As a result, PLA bolus was stable in the Common irregularities. Silicon bolus may be useful for patients with severe irregularities or frequent changes in patient's body shape.