background: a set of hardware stereotactic radiosurgery is designed and constructed. the scope of this article is to describe how we have designed and developed stereotactic collimation assembly for a 9 mv neptun 10 pc linac. materials and methods: one collimator holder and six collimators were made, with their radiation field diameter between 12.5 mm to 25 mm at isocenter level. beam data, suc...

background: radiosurgery is a focal brain irradiation technique that delivers, usually in a single session, high dose of ionizing radiation. the presence of lateral electronic disequilibrium and steep dose gradients in small fields demands special attention to the selection of a suitable detector with respect to its size, composition and response. materials and methods : small circular fields w...

The applicability of the dual-wavelength reflectance-ratio (DWR) method to emissivity-free radiation thermometry electromagnetically levitated high-temperature liquid metals was investigated. To establish measurement technique, DWR applied Ni in a static magnetic field, which suppresses surface oscillation and translational motion. In previous study, temperature measured by showed deviations ab...

PURPOSE The purpose of this study is to investigate the dose-volume variations of planning target volume (PTV) and organs-at-risk (OARs) in prostate volumetric modulated arc therapy (VMAT) when using different collimator angles. It is because collimator angle awareness is essential for planner to produce an optimal prostate VMAT plan in a rational time. METHODS Single-arc VMAT plans at differ...

Simultaneous acquisition of dual-isotope SPECT data offers a number of advantages over separately acquired data; however, simultaneous acquisition can result in cross-contamination between isotopes. In this work we propose and evaluate two frameworks for iterative model-based compensation of cross-contamination in dual-isotope SPECT. The methods were applied to cardiac imaging with technetium-9...

In this study, an airborne alpha detection system, which consists of a passivated implanted planar silicon (PIPS) detector and air filter, was developed. A collimator applied to the system showed enhancement in resolution degradation efficiency. The efficiency were compared analyzed evaluate performance collimator. Thus, found be more important than as determining factor performance, from viewp...

Angulation errors in collimator septa degrade tomographic resolution in SPECT due to mispositioning of events in the projection data. These errors should be small compared to other contributions to SPECT system resolution, such as intrinsic camera and collimator resolution, gantry alignment, and algorithmic smoothing. We describe a radioisotope technique to measure septal angulation errors over...

A slat collimator in single photon emission computed tomography consists of a set of parallel slats. As the collimator spins, the detector measures a one-dimensional projection data set. A complete data set can be obtained by rotating the detector/collimator assembly around the object (patient) while the collimator spins continuously. The measured projection data are assumed to be weighted plan...

UNLABELLED Our objective was to optimize the quality of (123)I-metaiodobenzylguanidine (MIBG) scans by using a medium-energy collimator to reduce high-energy-photon septal penetration. METHODS In addition to the 159-keV γ-ray, (123)I has a small abundance of energies above 400 keV that can compromise the image quality of MIBG studies because of septal penetration. Using a low-energy ultrahigh...

Prolonged treatment execution time is a concern in CyberKnife robotic radiosurgery. Beam reduction and node reduction technique, and monitor unit optimization methods are adopted to reduce the treatment time. Usage of single collimator in the CyberKnife treatment plan can potentially reduce collimator exchange time. An optimal single collimator, which yields an acceptable dose distribution alon...