• Analytical Science and Technology
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• 제20권6호
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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.

• Proceedings of the Korean Nuclear Society Conference
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• 한국원자력학회 1996년도 춘계학술발표회논문집(4)
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• pp.23-27
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• 1996

$\beta$-선 흡수선량의 1차 표준이 확립되지않은 상황에서 측정표준이 이미 확립된 외국의 표준기관에서 검증되어 도입된 $\beta$-선 흡수선량 조사시설에 대해 ISO-6980에서 명시한 항목에 대해 성능실험을 수행하였고, 외삽형전리함을 사용하여 측정된 이온화전류로 부터 흡수선량률을 재평가하여 외국의 검증결과와 비교하였다. 조사시설의 성능실험 결과 Sr$^{90}$ +Y$^{90}$ 선원에 대해 선원으로부터 30cm거리에서 빔 균일도, 제동복사선 기여도 및 $\beta$-선 최대잔여에너지가 기준에 적합한 것으로 나타났다. 그리고 흡수선량 평가결과는 '96. 4. 1을 기준으로하여 20 $^{\circ}C$,1기압에서 2.686 ($\pm$2.73%)$\mu$Gy/sec로 외국표준기관의 측정치와 1.8%이내에서 일치하는 것으로 나타났다.

• Journal of Radiation Protection and Research
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• 제16권2호
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• pp.17-26
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• 1991

Beta ray $(^{90}Sr+^{90}Y)$ absorbed dose at tissue surface was measured from the distance of 30cm by use of extrapolation chamber. In the measurement, following factors were considered: effective area of collecting electrode, polarity effect, ion recombination and window attenuation. The measured absorbed dose rate at tissue surface was $1.493{\mu}Gy/sec$ with ${\pm}2.9%$.

• Proceedings of the Korean Nuclear Society Conference
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• 한국원자력학회 1995년도 춘계학술발표회논문집(2)
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• pp.895-898
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• 1995

베타선 흡수선량의 정밀측정에 사용되는 평판형전리함의 일종인 외삽형전리함(Extrapolation Chamber)으로 베타선 이온화전류의 정확한 측정을 위하여는 이온수집 단면적의 정화한 평가가 필요하다. 이를 위하여 표준 폴리축전기와 표준전압원을 이용한 충전용량 측정법으로 실제 유효 단면적을 구하였으며 측정결과는 기계적 측정치와 약 10.5%의 차이가 있음이 밝혀졌다.

• The Korean Journal of Nuclear Medicine
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• 제31권4호
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• pp.433-439
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• 1997

$^{166}Ho$-chitosan complex, or $^{166}Ho$-CHICO, is a candidate pharmaceutical for intracavitary radiation therapy of cystic brain tumors because of the desirable nuclear characteristics of $^{166}Ho$ for therapeutic use and the suitable biological and chemical characteristics of chitosan, not to mention its ready producibility The amount of $^{166}Ho$-CHICO to be administered to obtain the goal therapeutic effect can be suggested by predicting the dose to the cyst wall for a varying pharmaceutical dose. When $^{166}Ho$-CHICO is infused into the cyst, the major part of the energy delivery by beta particles emitted from $^{166}Ho$ occurs in the cyst wall within 4mm in depth from the cyst wall surface. Also, realizing the attachment of $^{166}Ho$-CHICO to the cyst wall surface would change the predictions of dose to the cyst wall.

• Progress in Medical Physics
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• 제13권4호
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• pp.187-194
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• 2002

In this work we investigated through Monte Carlo calculations the physical characteristics of the absorbed dose from the Ir-192 source used in brachytherapy The Monte Carlo calculations were performed using the code EGS4, which was extensively modified in order to handle cylindrical sources, phantoms, and energy distributions to suit out own purpose. From the results of the calculations for the $\beta$ -rays, it was found that they contribute on the average 0.02% to The total absorbed dose in the distance range of 0.5-5.0 cm from the source. This is due to the face that, although most of the primary $\beta$ -rays are absorbed in the source and encapsulation material, the resulting low energy braking radiation from them contribute to such a distance. The absorbed dose in the encapsulation material varied on the average from 2.8% for platinum down to 1.1% for iron. The radial dose functions obtained by our Monte Carlo calculations were consistent within $\pm$3% with those of the TG-43 report for the radial distance interval 0.5-10.0 cm from the source. The user code we wrote in this work can be used for other sources of different sizes and so it can be very useful in designing and producing the sources for brachytherapy.

• Journal of Radiation Protection and Research
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• 제21권4호
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• pp.255-262
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• 1996

This paper describes the results of intercomparison measurements of KAERI reference photon and beta radiation fields between the KAERI and the PNNL(Pacific Northwest National Laboratory), recently performed at KAERI radiation calibration and dosimetry laboratory on the basis of the ANSI N13.11 criteria for personal dosimeter performance test. Each laboratory used her own radiation detectors or measurement devices traceable to her national primary standard in measuring the exposure rates for photon fields, the absorbed dose rates for beta radiation fields. The agreements in reference radiation measurements between two laboratories were found to be less than ${\pm}2.0%$ for photon fields, ${\pm}1.0%$ for beta radiation fields. Therefore, it could be concluded that KAERI reference radiation fields comply well with the international standard and thus can further serve as a national basis for the researches and developments in radiation protection dosimetry in Korea.

• Progress in Medical Physics
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• 제9권3호
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• pp.155-162
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• 1998

Ho-l66 was produced by neutron reaction in a reactor at the Korea Atomic Energy Institute (Taejon, Korea). Ho-l66 emits a high energy beta particles with a maximum energy of 1.85 MeV and small proportion of gamma rays (80 keV). Therefore, the radiation absorbed dose estimation could be based on the in-vivo quantification of the activity in tumors from the gamma camera images. Approximately 1 mCi of Ho-l66 in solution was mixed into the flood phantom and planar scintigraphic images were acquired with and without patient interposed between the phantom and scintillation camera. Transmission factor over an area of interest was calculated from the ratio of counts in selected regions of the two images described above. A dual-head gamma camera(Multispect2, Siemens, Hoffman Estates, IL, USA) equipped with medium energy collimators was utilized for imaging(80 keV${\pm}$10%). Fifty-nine year old female patient with hepatoma was enrolled into the therapeutic protocol after the informed consent obtained. Thirty millicuries(110MBq) of Ho-166-CHICO was injected into the right hepatic arterial branch supplying hepatoma. When the injection was completed, anterior and posterior scintigraphic views of the chest and pelvic regions were obtained for 3 successive days. Regions of interest (ROIs) were drawn over the organs in both the anterior and posterior views. The activity in those ROIs was estimated from geometric mean, calibration factor and transmission factors. Absorbed dose was calculated using the Marinelli formula and Medical Internal Radiation Dose (MIRD) schema. Tumor dose of the patient treated with 1110 MBq(30 mCi) Ho-l66 was calculated to be 179.7 Gy. Dose distribution to normal liver, spleen, lung and bone was 9.1, 10.3, 3.9, 5.0 % of the tumor dose respectively. In conclusion, tumor dose and absorbed dose to surrounding structures were calculated by daily external imaging after the Ho-l66 therapy for hepatoma. In order to limit the thresholding dose to each surrounding organ, absorbed dose calculation provides useful information.

• Journal of the Korean Society of Radiology
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• 제16권7호
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• pp.1007-1014
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• 2022

Targeted radionuclide therapy (TRT) is a method of treating tumor cells using radiopharmaceuticals. Cells and nuclei constituting tissues of the human body are composed of spherical and oval shapes, but cancer cells are composed of various cell types. Therefore, this study analyzed the absorbed dose for each organelle according to the change in the size of the cell nucleus for beta-emitting nuclides during targeted radionuclide therapy through the Monte Carlo method. Cells were set in two sphere shapes, 5 ㎛ and 10 ㎛, and the internal structure was divided into cell nucleus, cytoplasm, and cell surface. Next, the absorbed dose according to the increase in the size of the cell nucleus was evaluated. As a result, ¹⁷⁷Lu among the target radionuclides showed the highest dose in all cell compartments. As the ratio of the nucleus in the cell increased, the absorbed dose on the cell surface increased, but the absorbed dose in the cytoplasm and nucleus tended to decrease. Accordingly, it is judged that it is important to select a radionuclide considering the size of cancer cells and determine an appropriate amount of radioactivity during targeted radionuclide treatment.

• Progress in Medical Physics
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• 제10권3호
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• pp.151-157
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• 1999

The GafChromic film was used for the dosimetry of a balloon angio catheter filled with the radioisotope HO-166 for endovascular irradiation. The balloon angio catheter was 2 cm long and 3 mm in diameter when inflated. The isotope, Ho-166, was produced by the neutron bombardment using the research reactor in Korea Atomic Energy Research Insititute. Co-60 teletherapy beam was used for making H-D curve for the Gaf-Chromic film. The film dosimetry was measured with a videodensitometer. The radial dose distribution indicated that the absorbed dose dropped to about 20% of the surface dose at the 1 mm away from the balloon surface and at 5 mm position the dose decreased to below 1% of the surface dose. The result also shows that with the specific activity of Ho-l66, 250 mCi/ml it takes 230 seconds to deliver 1200 cGy to the region where is 1mm away from the balloon surface. The concentric isodose curves were also presented. The Ho-166 is an another alternative for endovascualr irradiation to prevent restenosis after PTCA (Percutaneous Trans Coronary Angioplasty)