UNLABELLED This study was performed to investigate the usefulness of a general-purpose medium-energy (ME) collimator for the accurate localization of the sentinel lymph node (SLN) in breast cancer patients. METHODS We compared phantom images and lymphoscintigraphy images obtained under different conditions for a patient with breast cancer. Comparisons were performed between 2 cameras, between...

introduction: image quality and accuracy of in vivo activity quantification in spect are affected by collimator penetration and scatter components, especially in high energy imaging. these phenomena highly depend on the collimator characteristic and photon energy. the presence of penetrated and scattered photons from collimator in spect images degrades spatial resolution, contrast and image qua...

The importance of collimator R&D with test beam facilities is demonstrated with the example of ILC collimator studies at SLAC End Station A. Related LHC collimator aspects and longer term plans are addressed. Presented at IDTB07, ILC Detector Test Beam workshop, Fermilab, USA, 2007.

Because background radiation in an irradiation room creates a problem with the PG-SPECT (Prompt Gamma-ray Single Photon Emission Computed Tomography) system, which evaluates the absorbed dose for the Boron Neutron Capture Therapy treatment, optimization of a collimator system was performed while taking the shielding of background gamma-rays into consideration. Assuming that a parallel-beam coll...

Collimator systems used in Intensity Modulated Radiation Therapy can form different geometric aperture shapes depending on their physical capabilities. We compare the efficiency of using regular, rotating and dual multileaf collimator (MLC) systems under different combinations of consecutiveness, interdigitation and rectangular constraints. We also create a virtual freeform collimator, which ca...

To more easily estimate accurate values of collimator scatter facor, S(c), we suggest a two-component saturation model that accounts for scatter from the primary collimator and flattening filter and from the collimator jaws. This model, which assumes an exponential distribution of scatter intensity, was tested by in-air measurements using a mini-phantom for 4 MV and 10 MV X-rays of a Clinac 210...

As for the optical measurement, the longer the focal length of collimator is, the less the measurement error is. However, the longer the focal length is, the more difficult the optical design is. It's higher application value to design long focal length collimator with wide-view. The paper designs a collimator with 2000mm focal length, 4 degree field of view and its wavelength range is from 480...

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...

PURPOSE The use of the low-energy high-resolution (LEHR) collimator for lymphoscintigraphy causes the appearance of star-shaped artifacts at injection sites. The aim of this study was to confirm whether the lower resolution of the low- to medium-energy general-purpose (LMEGP) collimator is compensated by decrease in the degree of septal penetration and the reduction in star-shaped artifacts. ...

The Leksell Gamma Knife is a standard radiosurgical tool for treating brain lesions by directing beams of gamma radiation to a specific region. The diameter of the gamma beams is confined by collimator systems and available collimator sizes are 4, 8, 14 and 18 mm. The reduction in dose rate for each collimator helmet is called the output factor (OPF). Experimental determination of OPFs is diffi...