Recent advances in collimator design and detector size, combined with radiopharmaceuticals having high photon yield, have resulted in diagnostic tests that may deliver photon fluxes in excess of the levels at which scintillation cameras can process the data. Moreover, these high rates of photon input may im pair certain parameters of image quality (1 ,2). For certain diagnostic tests, such as c...

This work quantified differences between recommendations of the TG-51 and TG-51 addendum reference dosimetry protocols. Reference dosimetry was performed for flattened photon beams with nominal energies of 6, 10, 15, and 23 MV, as well as flattening-filter free (FFF) beam energies of 6 and 10 MV, following the recommendations of both the TG-51 and TG-51 addendum protocols using both a Farmer® i...

Certain defects in the explosive charge of an artillery shell can cause the projectile to explode prematurely in the barrel of the launcher from which it is fired. The sensitivity of the radiographic technique presently used is limited by the large influence of the steel shell casing on the transmitted radiation. A filmless radiometric technique utilizing the basic radiation principle of Compto...

PURPOSE To develop a collimator trajectory optimization paradigm for volumetric modulated arc therapy (VMAT) and evaluate this technique in paraspinal stereotactic body radiation therapy (SBRT). METHOD AND MATERIALS We propose a novel VMAT paradigm, Coll-VMAT, which integrates collimator rotation with synchronized gantry rotation, multileaf collimator (MLC) motion, and dose-rate modulation. A...

UNLABELLED Myocardial perfusion imaging with SPECT remains critically important for diagnosing, assessing, and evaluating treatment of coronary artery disease. However, conventional rotational SPECT suffers from prolonged study times because of relatively low detection efficiency. We therefore have investigated a multipinhole collimator that could improve the detection efficiency in cardiac SPE...

PURPOSE To calculate an optimal collimator angle at each of sectional arcs in a full-arc volumetric modulated arc therapy (VMAT) plan and evaluate dosimetric quality of these VMAT plans comparing full-arc VMAT plans with a fixed collimator angle. METHODS Seventeen patients who had irregularly-shaped target in abdominal, head and neck, and chest cases were selected retrospectively. To calculat...

Rotation modulation collimators (RMC) are a class of nuclear imaging devices that are found in various applications. RMC are used for far-field applications, as in astronomy, and in near-field applications, as in environmental, medical and military uses. The typical detectors used in RMC system are scintillators and semi-conductors, which detect γ radiation only. This work investigates the util...

The aim of this study was to determine the shuttle dose for all collimator helmets (4, 8, 14 and 18 mm) of the Gamma Knife, model B, in Vienna, Austria. The additional dose accumulated during the transport of the patient in and out of the treatment position should be considered in the dose planning procedure of multicentre treatment regimens and in fractionated stereotactic Gamma Knife radiothe...

abstract background: coherent scattering leads to diffraction effects and especially constructive interferences. theseinterferences carry some information about the molecular structure of the tissue. as breast cancer isthe most widespread cancer in women, this project evaluated the application of small anglex-ray scattering (saxs) for differentiation between normal and cancerous breast tissues....