MR images are known to be distorted because of both gradient nonlinearity and imperfections in the B0 field, the latter caused either by an imperfect shim or sample-induced distortions. This paper describes in detail a method for correcting the gradient warp distortion, based on a direct field mapping using a custom-built phantom with three orthogonal grids of fluid-filled rods. The key advance...

Cone-beam CT (CBCT) has shown to be a useful imaging modality for various dentomaxillofacial applications. However, optimization and quality control of dental CBCT devices is hampered due to the lack of an appropriate tool for image quality assessment. To investigate the application of different image quality parameters for CBCT, a prototype polymethyl methacrylate (PMMA) cylindrical phantom wi...

OBJECTIVE The purpose of this study was to assess the accuracy and measurement variability of automated lesion measurement on CT colonography in comparison with manual 2D and 3D techniques under varying scanning conditions. MATERIALS AND METHODS The study included phantoms (23 phantom objects) and patients (16 polyps). Measurement with sliding calipers served as the reference for the phantom ...

Radiotherapy of lung and liver lesions has changed from normofractioned 3D-CRT to stereotactic treatment in a single or few fractions, often employing volumetric arc therapy (VMAT)-based techniques. Potential unintended interference of respiratory target motion and dynamically changing beam parameters during VMAT dose delivery motivates establishing 4D quality assurance (4D QA) procedures to as...

Introduction Dosimetric accuracy is a major issue in the quality assurance (QA) program for treatment planning systems (TPS). An important contribution to this process has been a proper dosimetry method to guarantee the accuracy of delivered dose to the tumor. In brachytherapy (BT) of gynecological (Gyn) cancer it is usual to insert a combination of tandem and ovoid applicators with a complicat...

background: dose assessment using proper dosimeters is especially important in radiation protection optimization and imaging justification in diagnostic radiology. objective: the aim of this study is to obtain the entrance skin dose (esd) of patients undergoing lumbar spine imaging using two thermoluminescence dosimeters tld-100 (lif: mg, ti) and gr-200 (lif: mg, cu, p) and also to obtain the a...

Background: In radiation therapy, water is the phantom material of choice, both for reference and for relative dosimetry measurements. Solid phantoms, however, are more useful for routine measurements because they tend to be more robust and easier to set up than water phantoms. Materials and Methods: FLUKA input data cards have been arranged in sequential order. A simple cylindrical geometry wi...

Space radiation is known to be key hazard of manned space mission. To estimate accurately radiation health risk detailed study of dose distribution inside human body by means of human phantom is conducted. In the space experiment MATROSHKA-R, the tissue-equivalent spherical phantom (32 kg mass, 35 cm diameter and 10 cm central spherical cave) made in Russia has been used on board the ISS for mo...

Introduction: Accuboost is a HDR brachytherapy system in early stages breast cancer treatment. This device provides a completely noninvasive procedure with parallel-opposed radiation from two immobilizing peripheral applicators that caused it a preferred option of modalities to choose. In most commercial treatment planning systems, tissues are considered as a simple water phan...