Introduction: Stereotactic radiosurgery (SRS) is one of the conformal radiotherapy methods and Gamma Knife is a non-invasive SRS technique to treat intracranial lesions with 201 Co- 60 sources without need to surgery and bleeding. Beam penumbra phenomenon leads to irradiation outside the field and normal tissues. Therefore, considering it is momentous to attain the acceptable t...

Using a recently developed time domain numerical approach we calculate the short-range geometric wakefields of 3D collimators and compare with analytical models. We find, in the diffractive regime, that the transverse mode kick factor can be approximated from the change in field energy between the beam pipe and the collimator if the collimator is long, or using a “field clipping” estimate if it...

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...

Intensity-modulated radiation therapy (IMRT) plans for the treatment of large and complex volumes may contain a relatively large contribution from multileaf collimator (MLC) transmission. In such cases, comprehensive characterization of direct and scatter MLC transmission is important. We designed a set of tests (open beam, closed static MLC, and dynamic MLC gap) to determine dosimetric MLC pro...

introduction: scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. accurate estimation of scatter in projection data of spect is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. methods: the objective of this paper is to develop and validate a scatter correction technique ...

Purpose: Most of the nuclear imaging systems, especially those that are based on single photon emission detection, require the use of a collimatorusually made out of lead (Pb) or some other high Z material such as tungsten (W). Even some PET systems employ some sort of slat-septa collimation, although the important part of PET image formation is done electronically via coincidence detection. Mu...