We consider diffraction by pixelated lenses when the lens size is significantly smaller than the diffraction pattern of single pixels. In that case, the diffraction orders show shapes that have not been identified in earlier studies and that are quite sensitive to the pixel filling ratio as well as to decentering.

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...

“Camouflage” is a natural or nature identical phenomenon where the sensory route of vision delayed toavoid visual detection. Reducing detection capability and hiding in background environment critical for Army vehicles, equipment, soldiers. This research aims to implement process that will generate digital camouflage patterns specific terrain. The adapted pattern helps an object blend symmetric...

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...

Introduction The ZAP-X is a novel self-contained and first-of-its-kind self-shielded therapeutic radiation device dedicated to brain and head and neck radiosurgery. By utilizing a 2.7-MV linear accelerator and incorporating a design in which a beam stop and major mechanical elements serve a radiation shielding function, the Zap-X does not typically require a radiation bunker. The unique collima...

In order to have highly flexible secondary beamlines collimation is crucial. Collimators are blocks of material placed along the beamline that let main beam pass within collimator aperture limits, while most particles beyond it interact in and gets absorbed or loses enough energy be deflected away from core by magnets downstream. Some can at edge collimators accepted beam, creating background f...

A rotatable collimator is proposed for the LHC phase II collimation upgrade. When the beam crosses the collimator, it will excite trapped modes that can contribute to the beam energy loss and power dissipation on the vacuum chamber wall. Transverse trapped modes can also generate transverse kicks on the beam and may thus affect the beam quality. In this paper, the parallel eigensolver code Omeg...