• 대한방사선치료학회지
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• 제1권1호
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• pp.63-69
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• 1985

High energy electron beams took effect for tumor radio-therapy, however, had a lot of problems in clinical application because of various conversion factors and complication of physical reactions. Therefore, we had experimentally studied the important properties of high energy electron beams from the linear accelerator, LMR-13, installed in Yonsei Cancer Center. The results of experimental studies on the problems in the 8, 10, 12 Mev electron beam therapy were reported as following. 1. On the measurements of the outputs and absorbed does, the ionization type dosimeters that had calibrated by $^{90}Sr$ standard source were suitable as under $3\%$ errors for high energy electrons to measure, but measuring doses in small field sizes and the regions of rapid fall off dose with ionization chambers were difficult. 2. The electron energy were measured precisely with energy spectrometer consisted of magnet analyzer and tele-control detector and the practical electron energy was calculated under $5\%$ errors by maximum range of high energy electron beam in the water. 3. The correcting factors of perturbated dose distributions owing to radiation field, energy and material of the treatment cone were checked and described systematically and variation of dose distributions due to inhomogeneous tissues and sloping skin surfaces were completely compensated. 4. The electron beams, using the scatters; i.e., gold, tin, copper, lead, aluminium foils, were adequately diffused and minimizing the bremsstrahlung X-ray induced by the electron energy, irradiation field size and material of scatterers, respectively. 5. Inproving of the dose distribution from the methods of pendulum, slit, grid and focusing irradiations, the therapeutic capacity with limited electron energy could be extended.

• Radiation Oncology Journal
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• 제20권3호
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• pp.274-282
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• 2002

목적 : 방사선치료시 환자에 조사되는 방사선량을 매 치료시마다 간편하게 확인하기 위한 생체내(in vivo) 선량측정의 한 방법으로 투과선량을 이용하는 새로운 시스템에 필요한 알고리즘을 이미 개발한 바 있다. 본 연구에서는 조사면 일부가 차폐된 부정형 조사면에서 적용하기 위한 보정 알고리즘을 개발하고자 하였다. 재료 및 방법 : 알고리즘을 개발하기 위한 기본 자료를 마련하기 위하여 투과선량 측정을 시행하였다. 측정에는 선형가속기의 6 MV 및 10 MV의 X선을 이용하였고, 이온함형 측정기 및 전위계를 사용하였다. 측정조건으로는 조사면의 크기(collimator opening)는 $2\times2\;cm^2$에서 $32\times32\;cm^2$까지 한 변을 2 cm씩 증가시켜 16단계로 하였고, 팬톰 두께(phantom thickness; Tp)는 0, 10, 20 및 30 cm, 팬톰과 측정기간의 거리(phantom chamber distance; PCD)는 10, 30 및 50 cm으로 하였다. 이 때 조사면의 일부를 차폐하였으며 차폐되지 않은 유효조사면(effective field size)의 크기를 $5\times5,\;10\times10,\;15\times15$ 및 $20\times20\;cm^2$으로 하였다. 결과 : 조사면의 일부가 차폐체에 의하여 차폐된 경우 종양선량이 감소되며 동시에 투과선량도 감소된다는 물리학적인 추론을 이용하여 방사선조사면 일부 차폐가 투과선량에 미치는 영향을 보정하기 위한 알고리즘을 개발하였으며 조사면 일부가 차폐된 여러 측정 조건에서 알고리즘을 이용한 계산치와 실제측정치 간의 오차는 ${\pm}1.0\%$ 이내이었다. 결론 : 투과선량 계산 알고리즘은 조사면 일부가 차폐된 불규칙 조사면의 경우 ${\pm}1.0\%$ 이하의 오차 범위로 정확히 투과선량을 계산할 수 있음을 확인하였다.

• 대한방사선치료학회지
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• 제17권1호
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• pp.33-40
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• 2005

목적 : 3D conformal, IMRT와 같은 치료기술의 개발로 인하여 CT를 이용한 최신의 치료들이 적용되어지고 있는 것이 지금의 현실이지만, 유방암 환자에서는 일반 CT의 hole size의 제약으로 인하여 일부의 경우는 기존의 환자고 정기구들이 사용되어지지 못하고 있다. 또한 simulation 시에 수술한 팔을 장시간 올리고 있는 자세를 유지함으로써 환자들이 pain을 호소하고, SCL (supraclavicular Imphnodes) 치료 시에 skin reaction의 문제점이 제기되었다. 이에 본원에서는 이러한 문제점을 개선하기 위하여 Ewha Breast device (EBD)를 자체 제작하여 사용하였으며, 이번 논제에서는 EBD의 제작과 유용성의 평가에 대하여 논하고자 한다. 대상 및 방법 : CT data를 이용하여 머리의 크기를 분석하였으며, 일반 CT의 hole size, 자세의 안정성, SCL field에서의 피부의 겹침(fold) 등을 고려하여 아크릴로 device를 제작하였으며 기존의 device를 사용하였을 경우와 set-up의 재현성, RTP상의 dose분포, SCL field에서의 skin reaction 등을 비교 분석하여 EBD의 유용성에 대하여 평가하였다. 결과 : 제작한 EBD를 사용 시 CT simulator가 아닌 hole size가 작은 일반 CT에서도 팔의 부딪힘이 없이 자세를 유지할 수 있었고, 위로 올린 팔의 pain도 많이 감소하였다. 그리고, 기존의 device와 비교하였을 경우에 set-up의 재현성에서 큰 차이를 보이지 않았으며, RTP상에서는 3D segment field를 이용한 plan으로 device의 tilting이 되지 않은 문제점은 해결할 수 있었으나 기존보다 팔을 많이 위로 올리지 않는 관계로 axillary region에서 이전보다 약$10\%$ 정도의 선량이 더 들어감을 알 수 있었다. SCL field에서의 skin reaction은 접힌 부분(fold)을 펼치기 위해 팔을 조정하여 위치를 잡는 관계로 이전보다 월등히 적은 skin reaction이 발생함을 알 수 있었다. 결론 : 비용이 저렴한 EBD의 제작으로 유방암 환자에서 CT를 이용한 3D 치료가 용이하게 되었으며, simulation 시에 팔의 pain을 경감시킬 수 있었고, skin reaction의 감소 등으로 치료에 EBD를 유용하게 사용할 수 있었다. 앞으로 EBD를 사용하여 나타난 device의 문제점 등을 보완 수정한다면 치료에 더 많은 도움이 되리라 생각된다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.267-270
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• 2000

The feasibility of small linear antenna for near range wireless communications was studied. The requirement of the system are frequency range 9∼12 MHz and antenna size 15 cm. The communication range is about 15 m. The antenna input impedance is very small radiation resistance and very large capacitive reactance. The lossless impedance matching is nearly impossible, therefore lossy matching is considered. The antenna has very low radiation efficiency. The near field calculation has a large uncertainty, but the results can be used as the guideline of a small linear antenna system for a near range wireless communication.

• 한국의학물리학회지:의학물리
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• 제25권4호
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• pp.255-263
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• 2014

소조사면을 이용하는 방사선치료기법들은 소조사면내의 측면 전자 비평형, 급격한 선량 변화, 그리고 조사면 크기에 대한 검출기의 기하학적 크기 영향으로 정확한 선량의 평가가 어렵다. 본 연구의 목적은 사이버나이프의 6개의 조사면(5 mm~30 mm)에 대해서 소조사면 선량측정용으로 새롭게 출시되어 상업적으로 이용되고 있는 마이크로다이아몬드(PTW 60019 microDiamond) 검출기의 유용성을 평가하고자 한다. 이를 위해 선량선형성, 선량률의존성, 출력선량계수, 깊이선량백분율 및 축바깥선량비 등의 선량측정인자를 측정하였고, 0.015 cc 부피의 이온전리함(PTW 31014 PinPoint chamber), 다이아몬드 검출기(PTW 60003 diamond), 액체이온함(PTW 31018 microLion), 그리고 다이오드 검출기(PTW 60008 diode)의 측정 결과와 비교 및 평가를 하였다. 그 결과 마이크로다이아몬드 검출기는 선량선형성이 우수하며, 선량률의존성이 적게 나타났다. 또한 사이버나이프 소조사면 측정용으로 상업적으로 권고되고 있는 다이오드 검출기와의 선량측정인자 측정값 3.8%의 차이를 보였다. 또한 깊이선량백분율도 다이오드 검출기의 결과와 유사한 결과를 얻었다. 마이크로다이아몬드 검출기는 유효체적이 작으므로 반음영이 작게 평가되었으며, 다른 검출기들보다도 공간분해능이 높은 것으로 생각된다. 연구 결과 마이크로다이아몬드 검출기는 조직등가물질로 이루어져 있으며, 작은 유효체적으로 광자선 소조사면선량측정 검출기로서 매우 유용한 것으로 판단된다.

• Radiation Oncology Journal
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• 제2권2호
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• pp.271-280
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• 1984

The peripheral dose, defined as the dose outside therapeutic photon fields, which is responsible for the functional damage of the critical organs, fetus, and radiation. induced carcinogenesis, has been investigated for $^{60}Co\;\gamma$ ray and 10 MV Xray. It was measured by silicon diode controlled by semiautomated water phantom without any shielding or with lead plate of HVL thickness put horizontally or vertically to shield stray radiations. Authors could obtain following results. 1. The peripheral dose was larger than $0.7\%$ of central axis maximum dose even at 20cm distance from field margin. That is clinically significant, so it should be reduced. 2. Even for square fields of 10 MV Xray, radial peripheral dose distribution did not coincide with transverse distribution, because of the position of collimator jaws. 3. Between surface and $d_m$, the peripheral dose distributions show a pattern of the dose distribution of electron beams and the maximum doss was approximately proportional to the length of a side of square field. 4. The peripheral doses depended on radiation quality, field size, distance from field margin and depth in water. Distance from field margin was the most important factor. 5. Except for near surface, the peripheral dose from phantom was approximately equal to that from therapy unit. 6. To reduce the surface dose outside fields, therapist should shield stray radiations from therapy unit by lead plate of at least one HVL for 10 MV X-ray and by bolus equivalent to tissue of 0.5cm thickness for $^{60}Co$. 7. To reduce the dose at depth deeper than $d_m$, it is desirable to shield stray radiations from therapy unit by lead.

• Radiation Oncology Journal
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• 제2권2호
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• pp.287-297
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• 1984

The normal intracranial structures are relatively resistant to therapeutic radiation, but may react adversely in a variety of ways, and the damage to nerve tissue may be slow in making its appearance, and once damage has occured the patient recovers slowly and incompletly. Therefore, it is important to consider the possibility of either recurrent tumor or late adverse effect in any patient who has had radiotherapy. The determination o( rnorphological/pathological correlation is very important to the therapeutic radiologist who uses CT scans to define a treatment volume, as well as to the clinician who wishes to explain the patient's clinical state in terms of regress, progression, persistence, or recurrence of tumor or radiation-induced edema or necrosis, The authors are obtained as following results ; 1. The field size(whole CNS, large, intermediate, small field) was variable according to the location and extension of tumor and histopathologic diagnosis, and the tatal tumor dose was 4,000 to 6,000 rads except one of recurred case of 9,100 rads. The duration of follow up CT scan was from 3 months to 5 year 10 months. 2, The histopathologic diagnosis of 9cases were glioblastoma multiforme(3 cases), pineal tumor (3), oligodendroglioma (1), cystic astrocytoma (1), pituitary adenoma (1) and their adverse effects after radiation therapy were brain atrophy (4 cases) , radiation necrosis(2), tumor recurrence with or without calcification (2), radiation·induced infarction (1). 3. The recurrent symptoms after radiation therapy of brain tumor were not always the results of regrowth of neoplasm, but may represent late change of irradiated brain. 4. It must be need that we always consider the accurate treatment planning and proper treatment method to reduce undesirable late adverse effects in treatment of brain tumors.

• 천문학논총
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• 제27권4호
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• pp.325-329
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• 2012

We will report our recent study on the properties of more than 1,600 galaxies detected by the AKARI All-Sky Survey with physical quantities based on optical and 21-cm observations, to understand the physics determining the infrared spectral energy distribution (Totani et al., 2011). We discover a tight linear correlation for normal star-forming galaxies between the radiation field strength of dust heating (corresponding to dust temperature) and the galactic-scale infrared radiation field, $L_{TIR}/R^2$. This is the tightest correlation of dust temperature ever known, and the dispersion along the mean relation is 13% in dust temperature. This relation can be explained physically by a thin layer of heating sources embedded in a thicker, optically-thick dust screen. We also find that the number of galaxies sharply drops when galaxies become optically thin against dust-heating radiation, indicating that a feedback process to galaxy formation (e.g., by the photoelectric heating) is working when dust-heating radiation is not self-shielded on a galactic scale. We discuss implications from these findings for the $M_{H_I}$ -size relation, the Kennicutt-Schmidt relation, and galaxy formation in the cosmological context.

• 한국의학물리학회지:의학물리
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• 제29권1호
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• pp.8-15
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• 2018

This work reports the acceptance testing and commissioning experience of the Robotic Intensity-Modulated Radiation Therapy (IMRT) M6 system with a newly released $InCise^{TM}2$ Multileaf Collimator (MLC) installed at the Yonsei Cancer Center. Acceptance testing included a mechanical interdigitation test, leaf positional accuracy, leakage check, and End-to-End (E2E) tests. Beam data measurements included tissue-phantom ratios (TPRs), off-center ratios (OCRs), output factors collected at 11 field sizes (the smallest field size was $7.6mm{\times}7.7mm$ and largest field size was $115.0mm{\times}100.1mm$ at 800 mm source-to-axis distance), and open beam profiles. The beam model was verified by checking patient-specific quality assurance (QA) in four fiducial-inserted phantoms, using 10 intracranial and extracranial patient plans. All measurements for acceptance testing satisfied manufacturing specifications. Mean leaf position offsets using the Garden Fence test were found to be $0.01{\pm}0.06mm$ and $0.07{\pm}0.05mm$ for X1 and X2 leaf banks, respectively. Maximum and average leaf leakages were 0.20% and 0.18%, respectively. E2E tests for five tracking modes showed 0.26 mm (6D Skull), 0.3 mm (Fiducial), 0.26 mm (Xsight Spine), 0.62 mm (Xsight Lung), and 0.6 mm (Synchrony). TPRs, OCRs, output factors, and open beams measured under various conditions agreed with composite data provided from the manufacturer to within 2%. Patient-specific QA results were evaluated in two ways. Point dose measurements with an ion chamber were all within the 5% absolute-dose agreement, and relative-dose measurements using an array ion chamber detector all satisfied the 3%/3 mm gamma criterion for more than 90% of the measurement points. The Robotic IMRT M6 system equipped with the $InCise^{TM}2$ MLC was proven to be accurate and reliable.

• 방사선산업학회지
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• 제6권2호
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• pp.139-145
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• 2012

Gold nanoparticles (GNPs) have led to the development of a new field in the diagnosis and treatment of diseases such as cancer. An efficient synthesis of gold nanoparticles within the range of 8~57 nm was established by ${\gamma}-ray$ irradiation. The good point of a radiation-based method is the production of gold nanoparticles with a higher concentration and narrower size distribution compared with conventional methods. The size of gold nanoparticles was controlled using two methods. : (i) varying the ${\gamma}-ray$ irradiation dose of 10 to 25 kGy and (ii) varying the concentration of $HAuCl_4$ solution from 4 to 40 mM. In addition, the GNPs were radiolabeled using $[^{125}I]NaI$ in a simple and fast manner with high yields. The produced gold nanoparticles were characterized using a transmission electron microscopy (TEM), a UV-visible spectrophotometer, and a radio-TLC imaging scanner. From these results, these radiolabeled GNPs can be applicable for a radioisotope tag of biomolecules.