Constancy checks of a well-type ionization chamber should be performed regularly as part of a quality assurance regime. The goal of this work was to test the feasibility of using a linear accelerator and an orthovoltage unit to check the constancy of a well-type chamber's response to an external radiation source. The reproducibility, linearity with dose, variation with dose-rate, and variation ...

BACKGROUND In this study, dosimetric aspects of TSEI consisting of a 4 MeV beam with no spoiler were investigated in comparison to a nominal 6 MeV beam with spoiler, and the potential for clinical applications was evaluated. METHODS The TSEI technique is based on the Stanford technique, which utilizes a beam configuration of six-dual fields. MOSFETs were used to measure the optimal gantry ang...

Daily morning quality assurance (QA) for all available beams using conventional phantom measures only output and beam quality. PTW QUICKCHECKwebline (PTW QCw) is a compact movable light-weight dosimetry equipment used daily QA, capable of measuring flatness, symmetry, constancy given in single exposure. The purpose this study was to analyze monitor the medical linear accelerator QCw assess over...

The purpose of this study was to evaluate beam attenuation by treatment couch and build a treatment couch model in TPS to check for beam-couch intersection at the planning stage and deal with beam attenuation by treatment couch in dose calculation. In this study, a standard treatment couch, Siemens ZXT couch, has been incorporated into Pinnacle3 8.0 TPS, based on an existing TPS tool, model-bas...

The purpose of this study was to introduce a three-field monoisocentric inverse treatment planning method without half-beam blocks for breast cancer radiation treatments. Three-field monoisocentric breast treatment planning with half-beam blocks limits the tangential field length to 20 cm. A dual-isocenter approach accommodates patients with larger breasts, but prolongs treatment time and may i...

Collimators are used as lateral beam shaping devices in proton therapy with passive scattering beam lines. The dose contamination due to collimator scattering can be as high as 10% of the maximum dose and influences calculation of the output factor or monitor units (MU). To date, commercial treatment planning systems generally use a zero-thickness collimator approximation ignoring edge scatteri...

Guang-Hong Chen University of Wisconsin–Madison Department of Medical Physics Madison, Wisconsin 53704 and University of Wisconsin–Madison Department of Radiology Madison, Wisconsin 53792 E-mail: [email protected] Abstract. We present a cone-beam image reconstruction algorithm for helical CT scanning with a tilted gantry and N-PI data acquisition. When the gantry is tilted, the effective source t...

In this investigation, the multi-objective selection and optimization of a gantry machine tool is achieved by analytic hierarchy process, multi-objective genetic algorithm, and Pareto-Edgeworth-Grierson–multi-criteria decision-making method. The objectives include maximum static deformation, the first four natural frequencies, mass, and fabrication cost of the gantry. Further structural optimiz...

This article presents the design system for high efficiency gantry crane system using elevator and conveyor system. The basic concept for the proposed gantry crane system can be used with modification of the classical gantry crane instead of changing lots of them. However, the proposed crane system can reduce the cycle time more than the classical gantry crane. The high efficiency gantry crane ...

Recently, the MRI-linac prototype at UMC Utrecht was upgraded with a ring-based gantry, where all linac components are mounted on a ring around the MR scanner. Although adaptations have been made to both linac and MR magnets in order to account for mutual magnetic interference, interference problems cannot be ruled out completely. Therefore, in this paper the impact of gantry position dependent...