PURPOSE Investigation of a reduced source to target distance to improve organ at risk sparing during stereotactic irradiation (STX). METHODS The authors present a planning study with perfectly target-volume adapted collimator compared with multi-leaf collimator (MLC) at reduced source to virtual isocentre distance (SVID) in contrast to normal source to isocentre distance (SID) for stereotacti...

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introduction: multileaf collimator (mlc) is state of the art among the radiation field shaping systems for conformal radiotherapy techniques. some advantages of this system are as follow: reduction of treatment time, higher precision in conforming the radiation field to the projection of the target volume and lowering the chance of errors made by technologists. the purpose of this research was ...

We have designed a new type of curved deformable mirror with 3000 actuators. It will be used at the 6.5 m MMT telescope in an adaptive optics system to correct the wavefront on a scale of 12 cm, for di raction limited images in visible light ( 0.02 arcsec) and for high contrast imaging with a coronagraph in the near infrared. The mirror's 51 cm diameter glass faceplate, 400 microns thick, will ...

A serial homogeneity test based on Indonesian Standard SNI 8506:2018 were undertaken to investigate 12 manufactured collimators by using double wall single image radiography (DWSI) technique with an x-ray machine ranging from 120 150 kV. The standard stated that the film density should be measured seven different points, and result obtained must not exceed ± 0.05 average density. This paper out...

Wakefields excited in the small aperture collimators may damage the beam. As pointed out by K. Bane and P. Morton the wakefields can be reduced considerably by tapering the steps and using the “step+taper” collimator geometry. The optimisation of this kind of geometry for TTF 2 collimators with different apertures is carried out in the paper. For the optimal geometries the nonlinear near-wall w...

Based on realistic Monte-Carlo simulations a two-stage beam collimation system is designed to minimize the beam loss in the Fermilab Tevatron for fixed target and collider Run II. Thin primary collimators are used to increase particle amplitude and their impact parameter on the downstream secondary collimators. This results in a significant reduction of the total beam loss in the machine, decre...

Simulations have been performed in Omega3P to study both trapped modes and impedance contributions of a rotatable collimator for the LHC phase II collimation upgrade. Bench-top stretched coil probe impedance methods are also being implemented for measurements on prototype components to directly measure the low frequency impedance contributions. The collimator design also calls for a RF contact ...

This paper considers Scintimammography (SM) imaging using two different image acquisition/formation methods: Low Energy High Resolution (LEHR) collimator and a Modified Uniformly Redundant Array (MURA) coded aperture (CA) systems. Using Monte Carlo simulation, the effectiveness and performance of both systems were evaluated by quantitative comparison of lesion contrast and Full-Width-Half-Maxim...