Image fusion of reconstructed digital tomosynthesis volumes from a frontal and a lateral acquisition
Digital tomosynthesis (DTS) has been used in chest imaging as a low radiation dose alternative to computed tomography (CT). Traditional DTS shows limitations in the spatial resolution in the out-of-plane dimension. As a first indication of whether a dual-plane dual-view (DPDV) DTS data acquisition can yield a fair resolution in all three spatial dimensions, a manual registration between a frontal and a lateral image volume was performed. An anthropomorphic chest phantom was scanned frontally and laterally using a linear DTS acquisition, at 120 kVp. The reconstructed image volumes were resampled and manually co-registered. ...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Arvidsson, J., Söderman, C., Allansdotter Johnsson, A., Bernhardt, P., Starck, G., Kahl, F., Bath, M. Tags: Paper Source Type: research
Parallelisation of the model-based iterative reconstruction algorithm dira
New paradigms for parallel programming have been devised to simplify software development on multi-core processors and many-core graphical processing units (GPU). Despite their obvious benefits, the parallelisation of existing computer programs is not an easy task. In this work, the use of the Open Multiprocessing (OpenMP) and Open Computing Language (OpenCL) frameworks is considered for the parallelisation of the model-based iterative reconstruction algorithm DIRA with the aim to significantly shorten the code's execution time. Selected routines were parallelised using OpenMP and OpenCL libraries; some routines were conve...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Örtenberg, A., Magnusson, M., Sandborg, M., Alm Carlsson, G., Malusek, A. Tags: Paper Source Type: research
Automatic segmentation of pelvis for brachytherapy of prostate
Advanced model-based iterative reconstruction algorithms in quantitative computed tomography (CT) perform automatic segmentation of tissues to estimate material properties of the imaged object. Compared with conventional methods, these algorithms may improve quality of reconstructed images and accuracy of radiation treatment planning. Automatic segmentation of tissues is, however, a difficult task. The aim of this work was to develop and evaluate an algorithm that automatically segments tissues in CT images of the male pelvis. The newly developed algorithm (MK2014) combines histogram matching, thresholding, region growing,...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Kardell, M., Magnusson, M., Sandborg, M., Alm Carlsson, G., Jeuthe, J., Malusek, A. Tags: Paper Source Type: research
Volumetric localisation of dense breast tissue using breast tomosynthesis data
This study attempted to use combined data from reconstructed digital breast tomosynthesis (DBT) volumes and density estimation of projection images to localise dense tissue inside the breast, using the assumption that the breast can be treated as consisting of only two types of tissue: fibroglandular (dense) and adipose (fatty). To be able to verify results, software breast phantoms generated using fractal Perlin noise were employed. Projection images were created using the PENELOPE Monte Carlo package. Dense tissue volume was estimated from the central projection image. The density image was used to determine the number o...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Dustler, M., Petersson, H., Timberg, P. Tags: Paper Source Type: research
Validation of a simulation procedure for generating breast tomosynthesis projection images
In order to achieve optimal diagnostic performance in breast tomosynthesis (BT) imaging, the parameters of the imaging chain should be evaluated. For the purpose of such evaluations, a simulation procedure based on the Monte Carlo code system Penelope and the geometry of a Siemens BT system has been developed to generate BT projection images. In this work, the simulation procedure is validated by comparing contrast and sharpness in simulated images with contrast and sharpness in real images acquired with the BT system. The results of the study showed a good agreement of sharpness in real and simulated reconstructed image p...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Petersson, H., Warren, L. M., Tingberg, A., Dustler, M., Timberg, P. Tags: Paper Source Type: research
Customisation of a monte carlo dosimetry tool for dental cone-beam ct systems
A versatile EGSnrc Monte Carlo (MC) framework, initially designed to explicitly simulate X-ray tubes and record the output data into phase space data files, was modified towards dental cone-beam computed tomography (CBCT) dosimetric applications by introducing equivalent sources. Half value layer (HVL) measurements were conducted to specify protocol-specific energy spectra. Air kerma measurements were carried out with an ionisation chamber positioned against the X-ray tube to obtain the total filtration attenuation characteristics. The framework is applicable to bowtie and non-bowtie inherent filtrations, and it accounts f...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Stratis, A., Zhang, G., Lopez-Rendon, X., Jacobs, R., Bogaerts, R., Bosmans, H. Tags: Paper Source Type: research
A monte-carlo simulation framework for joint optimisation of image quality and patient dose in digital paediatric radiography
In paediatric radiography, according to the as low as reasonably achievable (ALARA) principle, the imaging task should be performed with the lowest possible radiation dose. This paper describes a Monte-Carlo simulation framework for dose optimisation of imaging parameters in digital paediatric radiography. Patient models with high spatial resolution and organ segmentation enable the simultaneous evaluation of image quality and patient dose on the same simulated radiographic examination. The accuracy of the image simulation is analysed by comparing simulated and acquired images of technical phantoms. As a first application ...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Menser, B., Manke, D., Mentrup, D., Neitzel, U. Tags: Paper Source Type: research
Investigation of partial volume effect in different pet/ct systems: a comparison of results using the madeira phantom and the nema nu-2 2001 phantom
In this study, a new phantom, MADEIRA (Minimising Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations) for activity quantification in PET and single photon emission computed tomography (SPECT) was used to investigate the influence on the PVE by lesion size and tumour-to-background activity concentration ratio (TBR) in four different PET/CT systems. These measurements were compared with data from measurements with the NEMA NU-2 2001 phantom. The results with the MADEIRA phantom showed that the activity concentration (AC) values were closest to the true values at low ratios of TBR (<10) an...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Chipiga, L., Sydoff, M., Zvonova, I., Bernhardsson, C. Tags: Paper Source Type: research
Assessing the usefulness of the quasi-ideal observer for quality control in fluoroscopy
The aim of this work was to evaluate the reliability of the square of the signal-to-noise ratio rate, SNRrate2, as a precise measurement for quality control test in a digital fluoroscopy system. The quasi-ideal model observer was used to measure SNRrate2. The dose rate, pulse rate and field of view were varied, and their effect on dose efficiency, defined as SNRrate2/PKA,rate, was evaluated (where PKA,rate is the air kerma-area product rate). Measurements were repeated to assess reproducibility. The relative standard deviation in SNRrate2/PKA,rate over seven consecutive measurements was 5 %. No significant variation in SNR...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Tesselaar, E., Sandborg, M. Tags: Paper Source Type: research
Accurate kap meter calibration as a prerequisite for optimisation in projection radiography
Modern X-ray units register the air kerma–area product, PKA, with a built-in KAP meter. Some KAP meters show an energy-dependent bias comparable with the maximum uncertainty articulated by the IEC (25 %), adversely affecting dose-optimisation processes. To correct for the bias, a reference KAP meter calibrated at a standards laboratory and two calibration methods described here can be used to achieve an uncertainty of <7 % as recommended by IAEA. A computational model of the reference KAP meter is used to calculate beam quality correction factors for transfer of the calibration coefficient at the standards laborat...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Malusek, A., Sandborg, M., Carlsson, G. A. Tags: Paper Source Type: research
Beam quality correction factors for kap meters for lightly and heavily filtered x-ray beams
Kerma-area product (KAP) meters have a pronounced energy dependence when measuring air KAP for lightly filtered X-ray beams (RQR). Today, it is also common with more heavily filtered beams. In this work, the energy dependence for lightly as well as heavily filtered beams (RQC) was investigated for several KAP meter models. The relative energy dependence of the readings of an external and an internal KAP meter was determined relative to an ionisation chamber, which had been calibrated at the primary standards laboratory. As a complement to the measurements, the sensitivity of a KAP meter for various X-ray beam qualities was...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Herrnsdorf, L., Petersson, H. Tags: Paper Source Type: research
Clinical audit of image quality in radiology using visual grading characteristics analysis
The aim of this work was to assess whether an audit of clinical image quality could be efficiently implemented within a limited time frame using visual grading characteristics (VGC) analysis. Lumbar spine radiography, bedside chest radiography and abdominal CT were selected. For each examination, images were acquired or reconstructed in two ways. Twenty images per examination were assessed by 40 radiology residents using visual grading of image criteria. The results were analysed using VGC. Inter-observer reliability was assessed. The results of the visual grading analysis were consistent with expected outcomes. The inter-...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Tesselaar, E., Dahlström, N., Sandborg, M. Tags: Paper Source Type: research
Simple surface plasmon resonance-based dosemeter
The interest to application of various surface plasmon resonance (SPR)-based sensors for the investigation of chemical and biological processes in thin layers deposited on the grating's surface/media is developing. Characterisation of processes as well as specimen's features might be performed analysing variations in optical properties (refraction index) of these thin layers. SPR sensors by default are characterised by high resolution and small uncertainties, and measurements might be performed in situ. High-resolution, low-cost, SPR-based dosemeter concept has been proposed and realised depositing dose-sensitive nPAG gel ...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Urbonavicius, B. G., Adliene, D. Tags: Paper Source Type: research
Image-guided treatment using an x-ray therapy unit and gold nanoparticles: test of concept
Gold nanoparticles (GNPs) have the potential to enhance the radiation dose locally in conjunction with kV X-rays used for radiation therapy. As for other radiotherapy modalities, the absorbed dose needs to be controlled. To do that, it is an advantage to know the distribution of GNPs. However, no effective imaging tool exists to determine the GNP distribution in vivo. Various approaches have been proposed to determine the concentration of GNPs and its distribution in a tumour and in other organs and tissues. X-ray fluorescence computed tomography (XFCT) is a promising imaging technique to do that. A new experimental device...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Le Loirec, C., Chambellan, D., Tisseur, D. Tags: Paper Source Type: research
Multicentre comparison of image quality for low-contrast objects and microcatheter tips in x-ray-guided treatment of arteriovenous malformation in the brain
The treatment of brain arteriovenous malformations (AVMs) can be performed as a minimally invasive X-ray-guided procedure using a microcatheter for navigation to reach the target site. The performance of the interventional vascular surgery devices used for AVM was compared in four hospitals. The relation between image quality and the entrance surface air kerma (ESAK) was assessed for the default protocols for digital subtraction angiography (DSA) and fluoroscopy. A custom phantom, built with PMMA and aluminium plates was used to mimic the attenuation properties of the patient head. Image quality was assessed using low-cont...
Source: Radiation Protection Dosimetry - June 6, 2016 Category: Radiology Authors: Hernandez-Giron, I., Mourik, J. E. M., Overvelde, M. L., Veldkamp, W. J. H., Zweers, D., Geleijns, J. Tags: Paper Source Type: research
