• 제목/요약/키워드: Beam profile

검색결과 471건 처리시간 0.036초

Profile and Dose Distribution for Therapeutic Heavy Ion Beams

  • Sasaki, Hitomi;Komori, Masataka;Kohno, Toshiyuki;Kanai, Tatsuaki;Hirai, Masaaki;Urakabe, Eriko;Nishio, Teiji
    • 한국의학물리학회:학술대회논문집
    • /
    • 한국의학물리학회 2002년도 Proceedings
    • /
    • pp.211-213
    • /
    • 2002
  • The purpose of this work is acquiring some parameters of therapeutic heavy ion beams after penetrating a thick target. The experiments were performed using a pencil-like $\^$12/C beam of about 3 mm in diameter from NIRS-HIMAC, and the data were taken at several points of the target thickness for $\^$12/C beam of 290 MeV/u and 400 MeV/u. By the simultaneous measurements using some detectors, the atomic number of each fragment particle was identified, and the beam profile, the dose distribution and the LET spectrum for each element were derived.

  • PDF

집속 이온빔 가공변수에 따른 Au 에칭 특성 연구 (The ocused Ion Beam Etching Characteristic of Au)

  • 박진주;김성동
    • 한국공작기계학회논문집
    • /
    • 제16권5호
    • /
    • pp.129-133
    • /
    • 2007
  • Focused Ion Beam(FIB) systems is a useful tool for the fabrication of micro-nano scale structures. In this study, the effects of FIB etching on the Au microstructure are systematically investigated. As the fabrication parameters, ion dose, dwell time and beam overlap ratio are studied. First, the increases of Ga ion dose makes the milling yield higher and the sidewall of milling profile steeper. Dwell time is found to have little effects on the milling profile due to the relatively large milling area of $1\times1{\mu}m^2$ used in this study. However, beam overlap significantly affects not only milling rate but also milling profile. As the beam overlap ratio changes from positive to negative, the development of regular cross-stripe patterns at the bottom with low milling rate is observed.

빔셰이퍼 마스크를 이용한 레이저 빔의 강도 분포 제어 (Control of Intensity Distribution Profile of Laser Beam using Beam Shaping Mask with Random Array Slits)

  • 오재용;박덕수;신보성
    • 한국레이저가공학회지
    • /
    • 제15권2호
    • /
    • pp.11-14
    • /
    • 2012
  • In this paper, we have made a proposal concerning the beam shaping mask(BSM) using random-array slits to control intensity distribution profile of laser beam and demonstrated its proprieties experimentally. When a lot of slits are set out irregularly, diffraction patterns of light does not appear but granularity patterns as a bundle of fibers appear. Intensity distribution profile is controlled by densities distribution of circular slits arrayed randomly because the number of slits and its area means amount of light energy through BSM. Namely as the number of slits in high intensity area is increased and that in low intensity area decreased, amount of light energy is same over all local parts. So gaussian intensity distribution could be changed to flat-top.

  • PDF

ML-6M LINAC에 장착한 Radiosurgery Cone의 Beam 특성에 대한 고찰 (Dose Characteristics of Stereotatic Radiosurgery CONE used for ML-6M Linear Accelerator)

  • 문언철;김현진;김영석
    • 대한방사선치료학회지
    • /
    • 제7권1호
    • /
    • pp.15-31
    • /
    • 1995
  • The radiosurgery treatment is one time, non surgical approach to the treatment of patients with intracranial disorders whose conditions would be difficult or dangerous to treat with conventional sugical procedures. The LINAC based radiosurgery is based on the combination of multiple isocentric arc irradiation with small fields centered in the stereotactic target. The absorption of the beam in a tissue equivalent medium, such as water, as well as the uniformity, or profile, of the beam must be precisely documented. The beam characteristics and dosimetric measurememts of the 6MV X-ray beam from a ML-6M linear accelerator are examined. The percent depth dose (PDD) and beam profile (including flatness, symmetry and penumbra) is calibrated with the radiosurgery cone in water phantom. The cone is made of lead which size is from $10{\times}10mm{\phi}$ to $30{\times}30mm{\phi}$ All of these dosimetric measurements sufficiently characterized the beam to permit safe clinical use.

  • PDF

Characterization of a Neutron Beam Following Reconfiguration of the Neutron Radiography Reactor (NRAD) Core and Addition of New Fuel Elements

  • Craft, Aaron E.;Hilton, Bruce A.;Papaioannou, Glen C.
    • Nuclear Engineering and Technology
    • /
    • 제48권1호
    • /
    • pp.200-210
    • /
    • 2016
  • The neutron radiography reactor (NRAD) is a 250 kW Mark-II Training, Research, Isotopes, General Atomics (TRIGA) reactor at Idaho National Laboratory, Idaho Falls, ID, USA. The East Radiography Station (ERS) is one of two neutron beams at the NRAD used for neutron radiography, which sits beneath a large hot cell and is primarily used for neutron radiography of highly radioactive objects. Additional fuel elements were added to the NRAD core in 2013 to increase the excess reactivity of the reactor, and may have changed some characteristics of the neutron beamline. This report discusses characterization of the neutron beamline following the addition of fuel to the NRAD. This work includes determination of the facility category according to the American Society for Testing and Materials (ASTM) standards, and also uses an array of gold foils to determine the neutron beam flux and evaluate the neutron beam profile. The NRAD ERS neutron beam is a Category I neutron radiography facility, the highest possible quality level according to the ASTM. Gold foil activation experiments show that the average neutron flux with length-to-diameter ratio (L/D) = 125 is $5.96{\times}10^6n/cm^2/s$ with a $2{\sigma}$ standard error of $2.90{\times}10^5n/cm^2/s$. The neutron beam profile can be considered flat for qualitative neutron radiographic evaluation purposes. However, the neutron beam profile should be taken into account for quantitative evaluation.

Geant4 코드를 이용한 선형가속기 6 MV 광자선의 선량분포에 관한 연구 (Geant4 Code Based Simulation of 6 MV Photon Beam for Analysis of Dose Distribution)

  • 이준성;김양수;이선영
    • 대한방사선기술학회지:방사선기술과학
    • /
    • 제45권5호
    • /
    • pp.449-455
    • /
    • 2022
  • This study is to present a Geant4 code for the simulation of the absorbed dose distribution given by a medical linac for 6 MV photon beam. The dose distribution was verified by comparison with calculated beam data and beam data measured in water phantom. They were performed for percentage depth dose(PDD) and beam profile of cross-plane for two field sizes of 10 × 10 and 15 × 15 cm2. Deviations of a percentage and distance were obtained. In energy spectrum, the mean energy was 1.69 MeV. Results were in agreement with PDD and beam profile of the phantom with a tolerance limit. The differences in the central beam axis data 𝜹1 for PDD had been less than 2% and in the build up region, these differences increased up to 4.40% for 10 cm square field. The maximum differences of 𝜹2 for beam profile were calculated with a result of 4.35% and 5.32% for 10 cm, 15 cm square fields, respectively. It can be observed that the difference was below 4% in 𝜹3 and 𝜹4. For two field sizes of 𝜹50-90 and RW50, the results agreed to within 2 mm. The results of the t-test showed that no statistically significant differences were found between the data for PDD of 𝜹1, p>0.05. A significant difference on PDD was observed for field sizes of 10 × 10 cm2, p=0.041. No significant differences were found in the beam profile of 𝜹3, 𝜹4, RW50, and 𝜹50-90. Significant differences on beam profile of 𝜹2 were observed for field sizes of 10 × 10 cm2, p=0.025 and for 15 × 15 cm2, p=0.037. This work described the development and reproducibility of Geant4 code for verification of dose distribution.

레이저 빔 반사 패턴을 이용한 표면 프로파일 추정 (Estimation of Surface Profile Using Reflected Laser Beam Pattern)

  • 서영호;김화영;안중환
    • 한국정밀공학회:학술대회논문집
    • /
    • 한국정밀공학회 2002년도 춘계학술대회 논문집
    • /
    • pp.263-266
    • /
    • 2002
  • An optical method for surface roughness estimation based on statistical analysis of the light intensity of a scattered laser beam pattern. The method is very simple but has a disadvantage that no more information than the averaged roughness is estimated. In this study a new try was conducted to derive more advanced surface information from the details of the light intensity distribution. Some periodic ripples among the light intensity distribution being assumed to relate with scratch left on the machined surface, a corresponding surface profile is estimated from the ripples using FFT and IFFT algorithm. IFFT technique is used to extract some dominant signal components among the intensity distribution. Compared to the measured profiles by a stylus type surf-tester, the profiles obtained through the proposed method are probably acceptable in a sense of the profile shape. Calibration of the amplitude needs more works in the future.

  • PDF

Si V-groove를 이용한 광섬유와 Photodiode결합에서의 Beam Profile과 결합효율에 대한 이론적 연구 (Theoretical Study of the Beam Profile and Coupling Efficiency for Fiber-Photodiode Coupling using Si V-grooves)

  • 금동인;민성욱;이병호
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 1995년도 하계학술대회 논문집 C
    • /
    • pp.1265-1267
    • /
    • 1995
  • In the fiber-photodiode(PD) coupling module using v-groove, the paraxial approximation is no longer valid because the beam enters obliquely the PD substrate with the angle of $20^{\circ}$ after being reflected from the $55^{\circ}$ mirror formed by anisotropically etching of the (100) silicon wafer. In this paper, we study the beam profile incident on the PD active area and fiber-PD coupling efficiency for this case.

  • PDF

Laser Beam Shaping Using Hollow Optical Fiber and Its Application in Laser Induced Thermal Printing

  • Yi, Jong-Hoon;Lee, Kang-In;Park, Ill-Hyun;Kwon, Jin-Hyuk
    • Journal of the Optical Society of Korea
    • /
    • 제13권1호
    • /
    • pp.146-151
    • /
    • 2009
  • A Gaussian beam of single mode fiber laser was changed into a ring-shaped pattern after it was transmitted through the hollow optical fiber. The ring-shaped beam was focused on a plane by an f-. lens and it was scanned by a Galvano-mirror. The spatial profile of laser energy incident on a plane had two peaks at both sides of the scanned linear track. The profile was compared with the result obtained when the Gaussian beam was dithered transversely by an acousto-optic modulator. It is found that hollow optical fiber beam shaper can replace acousto-optic beam dithering device which is employed in a laser induced thermal printing system.