A method of evaluating the performance of computed tomography (CT) with equivalent resolution images was investigated. Generally, in performance evaluations of CT, the resolution property is measured by the wire method, and the noise property is measured from noise images of a cylindrical water phantom. The signal-to-noise ratio (SNR) is then calculated for the integrated evaluation. Our propos...

In the estimation of additional shielding requirements for primary beam apart from that provided by patient and hardware in the x-ray beam, there is the need to distinguish between attenuation and hardening properties of materials in comparison. In this work, numerical comparison of attenuation and hardening properties of phantom (Lucite, soft tissue, water) and hardware (aluminum and steel) ma...

New technologies in cancer radiotherapy need a more accurate computation of the dose delivered in the radiotherapeutical treatment plan, and it is important to integrate sophisticated mathematical models and advanced computing knowledge into the treatment planning (TP) process. We present some results about using Monte Carlo (MC) codes in dose calculation for treatment planning. A distributed c...

Introduction. Conventional gradient calibration procedures do not exclude significant bias in the diffusion-weighted (DW) signal during MR experiments. The error, arising from imperfections in the DW gradients, varies among the different gradient directions and exhibits different extent of offsets. We propose a calibration method for DW imaging using a homogeneous water phantom, presuming that ...

Introduction: The commercial 252Cf sources are too large in size and clinical applications of neutron brachytherapy (NBT) are limited to a small number of intracavitary treatments of cervical cancers. Recently, under the Cooperative Research and Development Agreement (CRADA) with Isotron Inc., the Oak Ridge National Laboratory (ORNL) encapsulated a new medical 252Cf sources, c...

BACKGROUND We developed a cardiac SPECT system (X-ACT) with low dose volume CT transmission-based attenuation correction (AC). Three solid-state detectors are configured to form a triple-head system for emission scans and reconfigured to form a 69-cm field-of-view detector arc for transmission scans. A near mono-energetic transmission line source is produced from the collimated fluorescence x-r...

For the purpose of dose measurement using a high-dose rate (192)Ir source, four methods of thermoluminescent dosimeter (TLD) calibration were investigated. Three of the four calibration methods used the (192)Ir source. Dwell times were calculated to deliver 1 Gy to the TLDs irradiated either in air or water. Dwell time calculations were confirmed by direct measurement using an ionization chambe...

Several national and international protocols have been established for the dosimetry of x-ray beams used in radiotherapy. For the very low energy x-rays (0.035 mm1.0 mm Al HVL) only two codes are available: the UK IPEMB Code of Practice and the German standard, DIN 6809 Part 4. The measurement of very low energy x-ray beams is normally performed with parallel plate ionization chambers calibrate...

Background: Most of the current brachytherapy treatment planning systems (TPS) use the TG-43U1 recommendations for dosimetry in water phantom, not considering the heterogeneity effects.Objective: The purpose of this study is developing a method for obtaining correction factors for heterogeneity for Cs-137 brachytherapy sources based on pre-calculated MC simulations and interpolation.Method: To ...