INTEC, Ghent University/iMinds, Ghent, Belgium Combining Single Photon Emission Computed Tomography (SPECT) with Magnetic Resonance Imaging (MRI) results in an interaction of the time-varying magnetic field gradients with the highly conducting tungsten collimator, which generates a secondary magnetic field causing spatial distortions in reconstructed MR images. Accurate simulations are importan...

Introduction: We have investigated cardiac SPECT with slant hole collimator in which the holes are slanted towards the target organ, to provide greater sensitivity over the parallel hole collimator. In addition, parallel hole collimator was used to obtain a comparison in FWHM, sensitivity, Compton and photoelectric area values in the simulations. Materials and Methods...

OBJECTIVE To determine accurately the relative output factors, defined as the ratio of the nominal dose rate for a given collimator to that of the 60-mm collimator. This is particularly important for radiosurgical treatment of functional disorders, such as trigeminal neuralgia, in which a single large radiation dose is delivered to the target with a small collimator, such as the 5-mm collimator...

Accurate determination of the head scatter factor Sc is an important issue, especially for intensity modulated radiation therapy, where the segmented fields are often very irregular and much less than the collimator jaw settings. In this work, we report an Sc calculation algorithm for symmetric, asymmetric, and irregular open fields shaped by the tertiary collimator (a multileaf collimator or b...

This paper presents the first determination of spatial resolution ANET Compact Neutron Collimator, obtained with a measuring campaign at LENA Mark-II TRIGA reactor in Pavia. novel collimator consists sequence collimating and absorbing channels organised chessboard-like geometry. It has scalable structure both length field view. is characterized by an elevated collimation power within limited le...

multileaf collimator (mlc) is among the radiation field shaping systems used for conformal radiotherapy and intensity modulation radiation therapy techniques. the mlc system that has been designed and fabricated in this study includes 52 leaves, 52 stepper motors, 2 dc motors, 16 programmable logic controllers (plcs) and one human machine interface (hmi). this system can be mounted on conventio...

Poor resolution of single photon emission computed tomography (SPECT) has degraded its use in clinical practice. Collimator correction has been shown to improve the reconstructed resolution, but the correction can generate ringing artefacts, which lower image quality. This paper investigates whether Bayesian reconstruction methods could reduce these artefacts. We have applied and tested three B...

An a irradiation device is described that utilises a commercially available disc-shaped americium-241 source of 8 cm diameter. The a particles traverse a moving collimator and the source is rotated to reduce the influence of source inhomogeneities. Source, collimator and a shutter disc are mounted in a container which is flushed with helium to reduce energy losses of the a particles before reac...

the aim of this study is to provide a control software system, based on monte carlo simulation, and calculations of dosimetric parameters of standard and wedge radiation fi elds, using a monte carlo method. gate version 6.1 (opengate collaboration), was used to simulate a compact 6 mv linear accelerator system. in order to accelerate the calculations, the phase-space technique and cluster compu...