• Journal of Magnetics
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• 제19권1호
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• pp.15-19
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• 2014

In this study, for 6-20 MeV electron beam energy occurring in a linear accelerator, the authors attempted to investigate the relation between the effective source-skin distance and the relation between the radiation field and the effective source-skin distance. The equipment used included a 6-20 MeV electron beam from a linear accelerator, and the distance was measured by a ionization chamber targeting the solid phantom. The measurement method for the effective source-skin distance according to the size of the radiation field changes the source-skin distance (100, 105, 110, 115 cm) for the electron beam energy (6, 9, 12, 16, 20 MeV). The effective source-skin distance was measured using the method proposed by Faiz Khan, measuring the dose according to each radiation field ($6{\times}6$, $10{\times}10$, $15{\times}150$, $20{\times}20cm^2$) at the maximum dose depth (1.3, 2.05, 2.7, 2.45, 1.8 cm, respectively) of each energy. In addition, the effective source-skin distance when cut-out blocks ($6{\times}6$, $10{\times}10$, $15{\times}15cm^2$) were used and the effective source-skin distance when they were not used, was measured and compared. The research results showed that the effective source-skin distance was increased according to the increase of the radiation field at the same amount of energy. In addition, the minimum distance was 60.4 cm when the 6 MeV electron beams were used with $6{\times}6$ cut-out blocks and the maximum distance was 87.2 cm when the 6 MeV electron beams were used with $20{\times}20$ cut-out blocks; thus, the largest difference between both of these was 26.8 cm. When comparing the before and after the using the $6{\times}6$ cut-out block, the difference between both was 8.2 cm in 6 MeV electron beam energy and was 2.1 cm in 20 MeV. Thus, the results showed that the difference was reduced according to an increase in the energy. In addition, in the comparative experiments performed by changing the size of the cut-out block at 6 MeV, the results showed that the source-skin distance was 8.2 cm when the size of the cut-out block was $6{\times}6$, 2.5 cm when the size of the cut-out block was $10{\times}10$, and 21.4 cm when the size of the cut-out block $15{\times}15$. In conclusion, it is recommended that the actual measurement is used for each energy and radiation field in the clinical dose measurement and for the measurement of the effective source-skin distance using cut-out blocks.

• 대한방사선치료학회지
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• 제6권1호
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• pp.89-93
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• 1994

Authors have measured virtual source distance of electron beam from CL/1800 medical linear accelerator, with newly designed method. Beam scanning was performed with the direction of beam axis in the air. Compared results between this study and well established in phantom measurement shows good agreement with in experimental error. And we have found that build-up cap plays very important role in air measurement because of charge build up. The method of in-air measurement of virtual source distance is very easy to set-up and generate accurate results.

• 한국정보통신학회논문지
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• 제20권10호
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• pp.2001-2006
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• 2016

감마선 공간 탐지 장치는 감마선원을 스캔하여 영상화 한 후 스테레오 영상처리기술을 적용하여 탐지선원까지의 거리를 측정한다. 또한 실제 공간의 방사선원에 대한 분포 정보를 제공해 준다. 본 논문에서는 감마선 탐지장치가 3차원 공간상에서 장치로부터 선원을 찾기 위해 스캔하는 탐지 시간을 단축 시킬 수 있도록 감마선 탐지 고속화 알고리즘을 구현하였다. 그리고 감마선 조사 시험장에서 실험을 통해 그 성능을 검증하였다. 탐지시험 결과 고속 탐지를 위한 알고리즘을 적용할 경우 단일선원을 탐지할 경우 좌 우 스테레오 영상 획득 시보다 약 35% 의 탐지 시간을 단축시킬 수 있음을 확인하였다. 또한 사용자에게 방사선 공간분포 정보를 효율적으로 전달하기 위한 감마선원 분포의 입체 가시화를 구현하여 방사선원에 대한 정보를 제공할 수 있도록 하였다.

• 한국의학물리학회지:의학물리
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• 제5권1호
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• pp.67-74
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• 1994

선량분포특성은 거리의 제곱에 반비례하기 때문에 근접조사에서 선원의 조그마한 오차는 선량계산에서 큰 차이를 초래할 수 있어서 선원의 정확한 거리 이동과 그에 따른 critical organ에 조사되는 선량의 정확도는 자궁경부암 환자의 치료성적에 결정적인 역할을 할 수가 있다. 특히 High Dose Rate의 RALS(Remote After Loading System)에서 선원의 정확한 calibration은 자궁경부암 환자의 치료에서 선량분포에 지대한 영향을 미치며 나아가 이 선량분포는 치료후 나타나는 재발 및 합병증이나 휴유증의 발생에도 큰 영향을 미치게 된다. 본 연구에서는 실제 RALS시 선원의 거리 이동을 측정하여 치료계획용 computer에서 계산된 선원간의 거리 이동과 비교 검토하였으며 Rectum 위치에 chamber를 삽입하여 실제 Rectum에 조사되는 선량과 computer에서 계산된 값들을 비교검토하였다. Tandem Source을 1cm 간격으로 거리를 이동하면서 실험을 되풀이 한 결과 처음 monitor로 1cm을 이동할 때 측정치가 0.8cm 이동한 것으로 나타났으며, 2번째부터 5번째까지의 거리 이동에서는 monitor의 값과 측정치의 값이 정확하게 일치하였다. 또한 12명의 환자를 대상으로 실시한 Rectum dose의 측정치는 computer계산치보다 평균 8%로 낮게 나타났다.

• 한국의학물리학회지:의학물리
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• 제29권4호
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• pp.137-142
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• 2018

This study aimed to evaluate and verify a process for correcting the extended source-to-imager distance (SID) in portal dosimetry (PD). In this study, eight treatment plans (four volumetric modulated arc therapy and four intensity-modulated radiation therapy plans) at different treatment sites and beam energies were selected for measurement. A Varian PD system with portal dose image prediction (PDIP) was used for the measurement and verification. To verify the integrity of the plan, independent measurements were performed with the MapCHECK device. The predicted and measured fluence were evaluated using the gamma passing rate. The output ratio was defined as the ratio of the absolute dose of the reference SID (100 cm) to that of each SID (120 cm or 140 cm). The measured fluence for each SID was absolutely and relatively compared. The average SID output ratios were 0.687 and 0.518 for 120 SID and 140 SID, respectively; the ratio showed less than 1% agreement with the calculation obtained by using the inverse square law. The resolution of the acquired EPIDs were 0.336, 0.280, and 0.240 for 100, 120, and 140 SID, respectively. The gamma passing rates with PD and MapCHECK exceeded 98% for all treatment plans and SIDs. When autoalignment was performed in PD, the X-offset showed no change, and the Y-offset decreased with increasing SID. The PD-generated PDIP can be used for extended SID without additional correction.

• 대한의용생체공학회:의공학회지
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• 제38권5호
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• pp.256-263
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• 2017

By using the buildup characteristics of the radiophotoluminescence glass dosimeter(RPLGD), it is aimed to help the measurement of the accurate dose by measuring the radiation dose according to the time of the glass element. Five glass elements were arranged on the table and the source to image receptor distance(SID) was set to 100 cm for the build-up radiation dose measurement of the fluorescent glass dosimeter glass element(GD-352M). Radiation doses and saturation rates were measured over time according to irradiation time, with the tube voltage (30, 60, 90 kVp) and tube current (50, 100 mAs) Repeatability test was repeated ten times to measure the coefficient of variation. The radiation dose increased from 0.182 mGy to 12.902 mGy and the saturation rate increased from 58.3% with increasing exposure condition and time. The coefficient of variation of the glass elements of the fluorescent glass dosimeter was ranged from 0.2 to 0.77 according to the X - ray exposure conditions. X - ray exposure showed that the radiation dose and saturation rate were increased with buildup characteristics, and degeneration of glass elements was not observed. The reproducibility of the variation coefficient of the radiation generator was included within the error range and the reproducibility of the radiation dose was excellent.

• 분석과학
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• 제5권1호
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• pp.57-61
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• 1992

중성자 스펙트럼을 측정하기 위해 $^6Li$ 중성자 분광계를 설치하고 $^{137}Cs$과 $^{207}Bi$ 점선원을 사용하여 $^6Li$ 검출관의 특성을 파악하고 $^{241}Am-Be$ 중성자 선원을 사용하여 중성자 포획피이크를 측정하였으며, $^6Li$ (n, ${\alpha}$) T 반응에 의한 에너지 파고스펙트럼을 측정하였다. 또한 중성자 선원의 조사 시간의 변화, 선원과 검출관 사이의 거리의 변화, 파고분석기의 문턱조절자를 미세하게 변환시키는 경우에 파고스펙트럼을 측정하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.323-327
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• 2002

In order to control the railway noise, the radiation characteristic of the noise during the train passage should be analyzed. Generally, the major noise sources for Korean Train Express are the rolling noise and power unit noise up to 300km/h. In this paper, we describe on a train model that is considered to be a row of point sources to calculate the radiation characteristic. The calculation results are compared with short distance measurement. It is shown that the radiation characteristic of the rolling noise is dipole type. The noise generated by the power unit is radiated as the cosine type. The noise level at an observer is increased in the direction of motion and reduced in the direction opposite to the motion with increasing of the train speed. The calculation results including the moving effect of the noise source at 300km/h show in good agreement.

• Journal of Radiation Protection and Research
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• 제28권1호
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• pp.59-63
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• 2003

Purpose : Measurement of transmission dose is useful for in vivo dosimetry of QA purpose. The objective of this study is to develope an algorithm for estimation of tumor dose using measured transmission dose for open radiation field. Materials and Methods : Transmission dose was measured with various field size (FS), phantom thickness (Tp), and phantom chamber distance (PCD) with a acrylic phantom for 6 MV and 10 MV X-ray Source to chamber distance (SCD) was set to 150 cm. Measurement was conducted with a 0.6 cc Farmer type ion chamber. Using measured data and regression analysis, an algorithm was developed for estimation of expected reading of transmission dose. Accuracy of the algorithm was tested with flat solid phantom with various settings. Results : The algorithm consisted of quadratic function of log(A/P) (where A/P is area-perimeter ratio) and tertiary function of PCD. The algorithm could estimate dose with very high accuracy for open square field, with errors within ${\pm}0.5%$. For elongated radiation field, the errors were limited to ${\pm}1.0%$. Conclusion : The developed algorithm can accurately estimate the transmission dose in open radiation fields with various treatment settings.

• 한국기계가공학회지
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• 제11권3호
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• pp.166-173
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• 2012

This study is about comparison of thermal and flow characteristics on the wind & radiant heat shield with STS mesh type screen for offshore. Numerical analysis was conducted to find transmission coefficient in the mesh and then analyse the flow characteristics about wind & radiant heat shield. The experiment method of solar radiation has been used as thermal radiation source to get the performance of radiant heat shield measurement. The sensor radiation device has been used to measure the reduction of solar radiation with various size of cells and at a distance of 0.5m and 1m from the cold face of the wind & radiant heat shield.