• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.115-118
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• 2004

Respiratory motion in the thorax and abdomen is an important limiting factor in high-precision radiation therapy. The lung tumor and tumor(pancreas, stomach) in abdomen therefore are internal motion due to breathing. We will perform to measurement of dose distributions for these moving tumors. In preliminary study, we investigated displacement of moving tumor such as liver, lung tumor in abdomen with previously reported papers. With reference data, internal movements of tumor are displayed with phantom and moving control device(MCD), which appear three dimension (3-D) motion such as x, y and z axis. These devices are used to access dose delivered in tumor with and without internal motion. The MCD and phantom were used to evaluate a delivered dose under similar condition, although there are not same internal tumor motion. In future, we will obtain the exact evaluation of dose if improved in programed software of moving control device and measure precise internal motion using image modality such as fluoroscopy, simulator in based on this study.

• Journal of Radiation Protection and Research
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• v.34 no.3
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• pp.129-136
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• 2009

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

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.313-319
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• 2018

In radiation treatment, it is unavoidable to block the influence of scattered ray on a skin and prevent internal normal organs from being exposed to radiation. It is fair to say that radiation therapy aims to reduce an absorbed dose of normal tissues. In particular, in radiation therapy of left-sided breast cancer, the internal neighboring organs are normal breast tissues, the heart, and the lung. The side effects on the heart include cardioplegy and myocardial infarction. This study tried to observe changes in the volume and dose of the heart in general radiation therapy plan and respiratory control based radiation therapy plan for patients with left-sided breast cancer, and to find the heart's volume and dose generated by respiration. According to the 4D computer tomography (CT), a volume of the heart had $12.8{\pm}8.7cc$ on average, and its dose had $17.3{\pm}12.1cGy$ on average. The differences in the volume and dose may cause side effects in radiation treatment. Therefore, it is necessary to apply respiratory control technique to establish the radiation treatment plan based on an accurate position of the heart.

• Radiation Oncology Journal
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• v.36 no.1
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• pp.79-84
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• 2018

Deep inspiration breathing hold (DIBH) compared to free-breathing (FB) during radiotherapy (RT) has significantly decreased radiation dose to heart and has been one of the techniques adopted for patients with breast cancer. However, patients who are unable to make suitable deep inspiration breath may not be eligible for DIBH, yet still need to spare the heart and lung during breast cancer RT (left-sided RT in particular). Continuous positive airway pressure (CPAP) is a positive airway pressure ventilator, which keeps the airways continuously open and subsequently inflates the thorax resembling thoracic changes from DIBH. In this report, authors applied CPAP instead of FB during left-sided breast cancer RT including internal mammary node in a patient who was unable to tolerate DIBH, and substantially decreased radiation dose the heart and lung with CPAP compared to FB.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.333-338
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• 2016

Background: In case of radiation emergencies, internal exposure monitoring for the members of public will be required to confirm internal contamination of each individual. In-vivo monitoring technique using portable gamma spectrometer can be easily applied for internal exposure monitoring in the vicinity of the on-site area. Materials and Methods: In this study, minimum detectable doses (MDDs) for $^{134}Cs$, $^{137}Cs$, and $^{131}I$ were calculated adjusting minimum detectable activities (MDAs) from 50 to 1,000 Bq to find out the optimal in-vivo counting condition. DCAL software was used to derive retention fraction of Cs and I isotopes in the whole body and thyroid, respectively. A minimum detect-able level was determined to set committed effective dose of 0.1 mSv for emergency response. Results and Discussion: We found that MDDs at each MDA increased along with the elapsed time. 1,000 Bq for $^{134}Cs$ and $^{137}Cs$, and 100 Bq for $^{131}I$ were suggested as optimal MDAs to provide in-vivo monitoring service in case of radiation emergencies. Conclusion: In-vivo monitoring program for emergency response should be designed to achieve the optimal MDA suggested from the present work. We expect that a reduction of counting time compared with routine monitoring program can achieve the high throughput system in case of radiation emergencies.

• Journal of Radiation Protection and Research
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• v.37 no.4
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• pp.226-230
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• 2012

The gross alpha analysis of nasal smear samples for the radiation emergency and the additional follow-up steps were established. Cotton swab sticks using in local hospitals for nasal smear in Korea were used for the verification. The measurement results of standard samples spiked with certified reference source were well agreed within ${\pm}20%$ compared with reference values. The clearance ratio of smear samples conducted with wet smear condition showed higher value. To eliminate the quenching effect of liquid scintillation samples, dry of smear samples should be followed up before counting samples. Based on the measurement results, medical decision levels and internal dose assessment were established for the victims in the beginning of radiation emergency.

• The Journal of Korean Society for Radiation Therapy
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• v.1 no.1
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• pp.79-83
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• 1985

Carcinoma of the breast has been treated by surgery followed by irradiation of the chest wall and regional lymphatics treatment planning of the breast cancer is required that lung must be spared as much as possible. However megavoltage irradiation of the internal mammary chain results in high dose to underlying heart, esophagus and spinal cord. Electron beam can be used for the irradiation of the internal mammary chain instead of megavoltage beam. We studied dose distribution of single anterior electron field, compared with traditional treatment methods. 12 and 15MeV electron beam with bolus has good dose distribution to spare underlying lung tissue and other organs.

• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.12-20
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• 2010

In a primary system at nuclear power plants (NPPs), various radionuclides including fission products and corrosion products are generated due to the complex water conditions. Particularly, $^3H,\;^{14}C,\;^{58}Co,\;^{60}Co,\;^{137}Cs,\;and^{131}I$ are important radionuclides in respect of dose assessment for radiation workers and management of radioactive effluents. In this paper, the dominant contributors of radiation exposure for radiation workers and the member of public adjacent to NPPs were reviewed and the process of dose assessment attributable to those contributors were introduced. Furthermore, the analysis for some examples of radiation exposure to radiation workers and the public during the NPP operation was carried out. This analysis included the notable precedents of internal radiation exposure and contamination of demineralized water occurred in Korean NPPs. Particularly, the potential issue about the dose assessment of tritium and carbon-14 was also reviewed in this paper.

• Radiation Oncology Journal
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• v.2 no.1
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• pp.149-153
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• 1984

Postoperative radiotherapy of breast cancer makes it possible to reduce loco-regional recurrence of breast cancer. The treatment technique, which can reduce the low-dose region at the junction and lung, is required. To produce proper dose distribution of internal mammary chain and chest wall, authors tried to find the method to expose $^{60}Co\;\gamma-ray$ on internal mammary region and 7MeV electron on chest wall. Exposure time of $^{60}Co\;\gamma$ and monitor unit of 9MeV were selected so that dose of $^{60}Co$ at 4cm depth was the same as that of 7Mev electron at $80\%$ dose depth. The position and direction of electron beam were changed for $^{60}Co$ beam: $0^{\circ},\;5^{\circ}$ for 0cm seperation; $0^{\circ},\;5^{\circ},\;10^{\circ}$ for 0.5cm seperation; $5^{\circ},\;10^{\circ},\;15^{\circ}$ for 1cm seperation. The results are as followings. 1. When the seperation of two fields was increased, dose on the axis of $^{60}Co$ beam was increased and dose at the junction region decreased while the volume of lung to be exposed to high dose and hot spot size were irregularly changed. 2. The dose distribution in the target volume of internal mammary and chest wall was most ideal when the seperation of two fields was $0\~0.5cm$ and the direction of electron beam was parallel to $^{60}Co$ beam.

• Journal of Radiation Protection and Research
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• v.36 no.2
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• pp.64-70
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• 2011

The intercomparison exercise on internal dose assessment has been carried out for the purpose of the evaluation for harmonization of internal dosimetry between the nuclear-related institutes in Korea. The exercises of 9 items on internal dose assessment have been developed for the unknown internal dosimetric parameters such as the intake pathway, absorption type, AMAD, and intake time of a radionuclide. Solutions to these exercises were reported by 7 participants from 5 institutes. The range of the ratio between the individual values and the geometric mean value of the evaluated doses for the exercises was $5.75{\times}10^{-4}$ ~ 9.81. But without the extreme partial solution, the range of the ratio was 0.216 ~ 3.12.