• Title/Summary/Keyword: Beam verification

Search Result 327, Processing Time 0.021 seconds

Experimental Verification of Flexible Multibody Dynamic Simulations for A Rotating Beam (회전 외팔보에 대한 유연 다물체 동역학 시뮬레이션의 실험적 검증)

  • Kim, Seong-Su;Gang, Yeon-Jun;Lee, Gyu-Il
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.26 no.2
    • /
    • pp.267-274
    • /
    • 2002
  • Using a flexible rotating beam test bed, experimental verification of a flexible multibody dynamic simulations for a rotating beam model has been carried out. The test bed consists of a flexible arm, harmonic driver reducer, AC servo motor and DSP board with PC. The mechanical ports of the test bed has been designed using 3D CAD program. For the simulation model, mass and moment of inertia of each part of the flexible rotating beam test bed are also obtained from 3D CAD model. In the flexible multibody dynamic simulations, the substructuring model has been established to capture nonlinear effects of the flexible rotating beam. Through the experimental verification, substructuring model provides better results than those from the linear model in the high speed rotation.

Comparison of knife-edge and multi-slit camera for proton beam range verification by Monte Carlo simulation

  • Park, Jong Hoon;Kim, Sung Hun;Ku, Youngmo;Lee, Hyun Su;Kim, Chan Hyeong;Shin, Dong Ho;Jeong, Jong Hwi
    • Nuclear Engineering and Technology
    • /
    • v.51 no.2
    • /
    • pp.533-538
    • /
    • 2019
  • The mechanical-collimation imaging is the most mature technology in prompt gamma (PG) imaging which is considered the most promising technology for beam range verification in proton therapy. The purpose of the present study is to compare the performances of two mechanical-collimation PG cameras, knife-edge (KE) camera and multi-slit (MS) camera. For this, the PG cameras were modeled by Geant4 Monte Carlo code, and the performances of the cameras were compared for imaginary point and line sources and for proton beams incident on a cylindrical PMMA phantom. From the simulation results, the KE camera was found to show higher counting efficiency than the MS camera, being able to estimate the beam range even for $10^7$ protons. Our results, however, confirmed that in order to estimate the beam range correctly, the KE camera should be aligned, at least approximately, to the location of the proton beam range. The MS camera was found to show lower efficiency, being able to estimate the beam range correctly only when the number of the protons is at least $10^8$. For enough number of protons, however, the MS camera estimated the beam range correctly, errors being less than 1.2 mm, regardless of the location of the camera.

Upgrade of gamma electron vertex imaging system for high-performance range verification in pencil beam scanning proton therapy

  • Kim, Sung Hun;Jeong, Jong Hwi;Ku, Youngmo;Jung, Jaerin;Cho, Sungkoo;Jo, Kwanghyun;Kim, Chan Hyeong
    • Nuclear Engineering and Technology
    • /
    • v.54 no.3
    • /
    • pp.1016-1023
    • /
    • 2022
  • In proton therapy, a highly conformal proton dose can be delivered to the tumor by means of the steep distal dose penumbra at the end of the beam range. The proton beam range, however, is highly sensitive to range uncertainty, which makes accurately locating the proton range in the patient difficult. In-vivo range verification is a method to manage range uncertainty, one of the promising techniques being prompt gamma imaging (PGI). In earlier studies, we proposed gamma electron vertex imaging (GEVI), and constructed a proof-of-principle system. The system successfully demonstrated the GEVI imaging principle for therapeutic proton pencil beams without scanning, but showed some limitations under clinical conditions, particularly for pencil beam scanning proton therapy. In the present study, we upgraded the GEVI system in several aspects and tested the performance improvements such as for range-shift verification in the context of line scanning proton treatment. Specifically, the system showed better performance in obtaining accurate prompt gamma (PG) distributions in the clinical environment. Furthermore, high shift-detection sensitivity and accuracy were shown under various range-shift conditions using line scanning proton beams.

The Verification of Dosimetric Characteristics of the 3-D Compensator with the Exit Beam Dose Profile (Exit Beam Dose Profile을 이용한 3차원 보상체의 성능확인)

  • 이상훈;이병용;권수일;김종훈;장혜숙
    • Progress in Medical Physics
    • /
    • v.7 no.2
    • /
    • pp.3-17
    • /
    • 1996
  • Dose compensators have been widely used in radiotherapy fields. But, few reliable verification methods have been reported. We have developed the verification method for the evaluation of the effect of dose compensator using exit beam dose profile. The exit beam dose profiles were measured with and without dose compensator. For this purpose X-Omat V films and lead screened cassettes are used and dose distibutions are compared. Phantom data are collected using CT simulator(Picker, AcQ Sim) and compensator information can be obtained from Render Plan 3-D planning System. Aluminum Compensators are generated by computer controlled milling machine. The real dose distribution in the phantom and the exit beam dose profile can be obtained simultaneously with the films in the phantom and the opposite site of the beam. Dose compensations effects for oblique beam, parallel opposing beam and inhomogeneous human phantom can be obtained using above tools. And we could simate those effects with exit beam dose profile using the method that we have developed in this study.

  • PDF

Performance prediction of gamma electron vertex imaging (GEVI) system for interfractional range shift detection in spot scanning proton therapy

  • Kim, Sung Hun;Jeong, Jong Hwi;Ku, Youngmo;Jung, Jaerin;Kim, Chan Hyeong
    • Nuclear Engineering and Technology
    • /
    • v.54 no.6
    • /
    • pp.2213-2220
    • /
    • 2022
  • The maximum dose delivery at the end of the beam range provides the main advantage of using proton therapy. The range of the proton beam, however, is subject to uncertainties, which limit the clinical benefits of proton therapy and, therefore, accurate in vivo verification of the beam range is desirable. For the beam range verification in spot scanning proton therapy, a prompt gamma detection system, called as gamma electron vertex imaging (GEVI) system, is under development and, in the present study, the performance of the GEVI system in spot scanning proton therapy was predicted with Geant4 Monte Carlo simulations in terms of shift detection sensitivity, accuracy and precision. The simulation results indicated that the GEVI system can detect the interfractional range shifts down to 1 mm shift for the cases considered in the present study. The results also showed that both the evaluated accuracy and precision were less than 1-2 mm, except for the scenarios where we consider all spots in the energy layer for a local shifting. It was very encouraging results that the accuracy and precision satisfied the smallest distal safety margin of the investigated beam energy (i.e., 4.88 mm for 134.9 MeV).

Test of a Multilayer Dose-Verification Gaseous Detector with Raster-Scan-Mode Proton Beams

  • Lee, Kyong Sei;Ahn, Sung Hwan;Han, Youngyih;Hong, Byungsik;Kim, Sang Yeol;Park, Sung Keun
    • IEIE Transactions on Smart Processing and Computing
    • /
    • v.4 no.5
    • /
    • pp.297-304
    • /
    • 2015
  • A multilayer gaseous detector has been developed for fast dose-verification measurements of raster-scan-mode therapeutic beams in particle therapy. The detector, which was constructed with eight thin parallel-plate ionization chambers (PPICs) and polymethyl methacrylate (PMMA) absorber plates, is closely tissue-equivalent in a beam's eye view. The gas-electron signals, collected on the strips and pad arrays of each PPIC, were amplified and processed with a continuous charge.integration mode. The detector was tested with 190-MeV raster-scan-mode beams that were provided by the Proton Therapy Facility at Samsung Medical Center, Seoul, South Korea. The detector responses of the PPICs for a 190-MeV raster-scan-mode proton beam agreed well with the dose data, measured using a 2D ionization chamber array (Octavius model, PTW). Furthermore, in this study it was confirmed that the detector simultaneously tracked the doses induced at the PPICs by the fast-oscillating beam, with a scanning speed of 2 m s-1. Thus, it is anticipated that the present detector, composed of thin PPICs and operating in charge.integration mode, will allow medical scientists to perform reliable fast dose-verification measurements for typical dynamic mode therapeutic beams.

Experimental Verification of a Structural Damage Identification Method for Beam Structures (보 구조물에 대한 손상검출기법의 실험적 검증)

  • 조국래;이우식
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1997.10a
    • /
    • pp.837-840
    • /
    • 1997
  • This paper provides an experimental verification of an FRF-based structural damage identification method (SDIM) developed by the authors for beam structures. The FRF-based SDIM requires the following data : (1) natural frequencies and mode shapes measured at the intact state and (2) the FRF-data measured at the damaged state. Experiments are conducted for the cantilevered beam with one slot and three slots. It is shown that the FRF-based SDIM developed by the authors provide very successful damage identification results which agree well with true damage state.

  • PDF

Fire Resistance Evaluation of SLIM AU Composite Beam (슬림 AU 합성보 내화성능 평가)

  • Oh, Myoung-Ho;Kim, Myeong-Han
    • Journal of Korean Association for Spatial Structures
    • /
    • v.16 no.4
    • /
    • pp.53-58
    • /
    • 2016
  • SLIM AU(A plus U-shaped) composite beam was developed for reducing the story height in the residential buildings, and saving the cosrtuction cost of floor structures. Structural performance and economic feasibility of the composite beam have been sufficiently approved through the structural experiments and the analytical studies. However, the verification for fire safety is necessary for the practical application of the composite beam. The fire resistance tests with and without loading were performed for the fire safety verification, and the test results were summarized in this paper.

The Properties of Beam Intensity Scanner(BInS) in IMRT with Phantom for Three Dimensional Dose Verification

  • Young W. Vahc;Park, Kwangyl;Byung Y. Yi;Park, Kyung R.;Lee, Jong Y.;Ohyun Kwon;Park, Kwangyl;Kim, Keun M.
    • Proceedings of the Korean Society of Medical Physics Conference
    • /
    • 2003.09a
    • /
    • pp.64-64
    • /
    • 2003
  • Objectives: Patient dose verification is clinically the most important parts in the treatment delivery of radiation therapy. The three dimensional(3D) reconstruction of dose distribution delivered to target volume helps to verify patient dose and determine the physical characteristics of beams used in intensity modulated radiation therapy(IMRT). We present Beam Intensity Scanner(BInS) system for the pre treatment dosimetric verification of two dimensional photon intensity. The BInS is a radiation detector with a custom made software for relative dose conversion of fluorescence signals from scintillator. Methods: This scintillator is fabricated by phosphor Gadolinium Oxysulphide and is used to produce fluorescence from the irradiation of 6MV photons on a Varian Clinac 21EX. The digitized fluoroscopic signals obtained by digital video camera will be processed by our custom made software to reproduce 3D relative dose distribution. For the intensity modulated beam(IMB), the BInS calculates absorbed dose in absolute beam fluence, which are used for the patient dose distribution. Results: Using BInS, we performed various measurements related to IMRT and found the followings: (1) The 3D dose profiles of the IMBs measured by the BInS demonstrate good agreement with radiographic film, pin type ionization chamber and Monte Carlo simulation. (2) The delivered beam intensity is altered by the mechanical and dosimetric properties of the collimating of dynamic and/or static MLC system. This is mostly due to leaf transmission, leaf penumbra, scattered photons from the round edges of leaves, and geometry of leaf. (3) The delivered dose depends on the operational detail of how to make multileaf opening. Conclusions: These phenomena result in a fluence distribution that can be substantially different from the initial and calculative intensity modulation and therefore, should be taken into account by the treatment planing for accurate dose calculations delivered to the target volume in IMRT.

  • PDF

Dosimetric Characteristic of Digital CCD Video Camera for Radiation Therapy

  • Young Woo. Vahc;Kim, Tae Hong.;Won Kyun. Chung;Ohyun Kwon;Park, Kyung Ran.;Lee, Yong Ha.
    • Progress in Medical Physics
    • /
    • v.11 no.2
    • /
    • pp.147-155
    • /
    • 2000
  • Patient dose verification is one of the most important parts in quality assurance of the treatment delivery for radiation therapy. The dose distributions may be meaningfully improved by modulating two dimensional intensity profile of the individual high energy radiation beams In this study, a new method is presented for the pre-treatment dosimetric verification of these two dimensional distributions of beam intensity by means of a charge coupled device video camera-based fluoroscopic device (henceforth called as CCD-VCFD) as a radiation detecter with a custom-made software for dose calculation from fluorescence signals. This system of dosimeter (CCD-VCFD) could reproduce three dimensional (3D) relative dose distribution from the digitized fluoroscopic signals for small (1.0$\times$1.0 cm$^2$ square, ø 1.0 cm circular ) and large (30$\times$30cm$^2$) field sizes used in intensity modulated radiation therapy (IMRT). For the small beam sizes of photon and electron, the calculations are performed In absolute beam fluence profiles which are usually used for calculation of the patient dose distribution. The good linearity with respect to the absorbed dose, independence of dose rate, and three dimensional profiles of small beams using the CCD-VCFD were demonstrated by relative measurements in high energy Photon (15 MV) and electron (9 MeV) beams. These measurements of beam profiles with CCD-VCFD show good agreement with those with other dosimeters such as utramicro-cylindrical (UC) ionization chamber and radiographic film. The study of the radiation dosimetric technique using CCD-VCFD may provide a fast and accurate pre-treatment verification tool for the small beam used in stereotactic radiosurgery (SRS) and can be used for verification of dose distribution from dynamic multi-leaf collimation system (DMLC).

  • PDF