نتایج جستجو برای: geometric phantom equivalent body
تعداد نتایج: 957899 فیلتر نتایج به سال:
Introduction: This study, evaluate pediatric digital radiography. Due to the high rates of this test and the high sensitivity of children to ionizing radiation in comparison with adults, it is attempted to achieve near optimal conditions by reducing the dose and maintaining the image quality. The object of the study is to change the irradiation parameters such as kV and mA and ...
Simplified Dynamic Phantom for Pediatric Renography: A Description of Instrument and Its Performance
Objective(s): Renography is used for the diagnostic evaluation of pediatric patients with a suspected obstruction of urinary tract or impaired renal function. The recommended dose for children have been released by the European Association of Nuclear Medicine, Society of Nuclear Medicine and Molecular Imaging, and Japanese Society of Nuclear Medicine. Since acquisition counts in dynamic scintig...
Background and purpose: The human body is composed of various inhomogenous tissues with a variety of physical and radiological properties. These inhomogeneities could change isodose distributions, increase the probability of geometric errors, and eventually lead to missing of the target irradiation or incorrect isodose coverage in conformal radiation therapy (CRT) due to the uncertainties resul...
Background: High-energy linear accelerator (linac) is a valuable tool and the most commonly device for external beam radiation treatments in cancer patients. In the linac head, high-energy photons with energies above the threshold of interaction produce photoneutrons. These photoneutrons deliver the extra dose to the patients in the planning treatment and increase the risk of secondary cancer.O...
background: in nuclear medicine application often it is required to use computational methods for evaluation of organ absorbed dose. monte carlo simulation and phantoms have been used in many works before. the shape, size and volume in organs are varied, and this variation will produce error in dose calculation if no correction is applied. materials and methods: a computational framework for co...
For determining the absorbed dose of ionizing radiation is tissues, it is essential to have materials which behave like tissues. These kinds of materials are usually called phantom. Up to now many different compounds like water, rubber, Perspex etc have been used. Unfortunately, the practical use of each of them has had its own problems. Our suggested gelatin phantom is very similar to soft...
At our institution the standard delivery quality assurance (DQA) procedure for tomotherapy plans is accomplished with a water equivalent phantom, EDR2 film, and ion chamber point-dose measurements. Most plans deliver at most 5 Gy to the dose plane; however, recently a stereotactic body radiotherapy (SBRT) protocol has produced plans delivering upwards of 12 Gy to the film plane. EDR2 film satur...
• Geometric Distortion • Spatial Resolution • Slice thickness and position • Interslice Gap • Estimate of Image Bandwidth • Low Contrast Detectability • Image Uniformity • Signal-to-Noise Ratio (SNR) • Physical and Electronic Slice Offset • Landmark This document contains phantom specifications and materials and a brief description of image analysis. For a more complete description of the ACR M...
background: in vivo dosimetry is a method for estimation of overall error in the delivered dose to the patients at the end of radiotherapy process. in this research, two methods for target dose calculation were evaluated on midline and central axis of photon beams in in vivo dosimetry of thorax fields. materials and methods: entrance and exit doses for anterior and lateral fields of thorax were...
Comparison of radiation shields of different thicknesses and structures (especially different particle sizes of their constituents) is helpful to select an appropriate shield for patient protection in medical imaging tests particularly CT-scan. In this study micro- and nano-powders of bismuth were mixed with silicone matrix to make composite radiation shields for breast. The shields were provid...
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