For scintigraphic instruments such as scanners and scintillation cameras, collimatore with greatly dif ferent characteristics have become available during recent years. In general little information is given concerning the performance of focused collimatore to the physician or physicist who has to select the proper collimator for a particular application.! Only the number of holes, the focal le...

Gamma-ray spectrometry is widely applied in several science fields, and particular non-destructive gamma scanning emission tomography of irradiated nuclear fuel. Often, a collimator used the experimental setup, to selectively interrogate region interest For optimization instrument design, as well for planning measurement campaigns, predictive models transmitted gamma-ray intensity through are n...

Abstract Purpose The quantitative accuracy of Nuclear Medicine images, acquired for both planar and SPECT studies, is influenced by the isotope-collimator combination as well image corrections incorporated in iterative reconstruction process. These factors can be investigated optimised using Monte Carlo simulations. This study aimed to evaluate quantification 123 I with low-energy high resoluti...

attached to an external detector system, the thyroid uptake of iodine was measured at 6 and 24 hr. The external detector consisted of a 1Â1⁄4x 1 in. NaI(Tl) scintillation crystal and a flat-field lead collimator. A Lucite extension of the collimator was shaped to fit the neck and assure good geometry with a neck-to crystal distance of 20 cm. A standard neck phantom was used with standard capsul...

INTRODUCTION One of the important input factors in the commissioning of the radiotherapy treatment planning systems is the phantom scatter factor (Sp) which requires the same collimator opening for all radiation fields. In this study, we have proposed an analytical method to overcome this issue. METHODS The measurements were performed using Siemens Primus Plus with photon energy 6 MV for fiel...

We present an example when profile measurement and modeling of an Elekta Agility multileaf collimator (MLC) had a large effect specifically on arc therapy plan quality assurance (QA) results using ArcCheck. ArcCheck absolute dose measurements of these plans were systematically lower than planned by 3-10%. Failing QA results were seen even with unmodulated static and conformal arcs. Furthermore,...

We are developing an acceptance measurement system to evaluate the matching of the emittance of an injection beam to the acceptance of the AVF cyclotron. The system is composed of a phase-space collimator in the low energy section and beam intensity monitors which are installed just after the phase space collimator and in the high energy section. The phase-space collimator, which consists of tw...

Super-collimation is the propagation of a light beam without spreading that occurs when the light beam is guided by the dispersion properties of a photonic crystal, rather than by defects in the photonic crystal. Super-collimation has many potential applications, the most straight-forward of which is in the area of integrated optical circuits, where super-collimation can be utilized for optical...

The accuracy of the dose planning system (Leksell GammaPlan) used in Gamma Knife (model-B) radiosurgery was verified using both the GafChromic films MD-55 (improved) and the EGS4 Monte Carlo technique. The Monte Carlo technique was employed to calculate the dose distribution along the x-, y- and z-axes when a single shot with opening of all 201 sources was delivered at the centre of a simulated...