Abstract：
:The standard Fourier metrics used for assessing image quality in computed tomography (CT) use a planar (2D) formulation of the noise equivalent quanta (NEQ) without a specific concept to manage the influence of longitudinal resolution variations, thus create a bias in the comparison of image quality for different reconstructed slice thicknesses. For this work, we designed a 'slice NEQ' that takes the longitudinal resolution into account and provides a volumetric indication of the scanner imaging performance. We also developed a specific formulation for the system DQE at the CT isocentre. A cylindrical water phantom with three different inserts for three contrast levels (-100, 120 and 1000 HU) was used for the task-based transfer functions (TTF) and noise power spectra (NPS) measurements. The longitudinal TTF was measured using the point source of the Catphan® 600 phantom. Images of the phantoms were acquired on two scanners (GE Discovery 750 HD and Siemens SOMATOM Force) and reconstructed using different slice thicknesses between 1 and 5 mm and algorithms (FBP for both systems, ASIR 50 and ASIR-V 50 for the GE). The slice NEQ correctly compared the imaging performance for different longitudinal resolutions whereas the 2D NEQ increased proportionally with the reconstructed slice thickness. The system DQE peaked at 0.70 (at 0.1 mm-1) for the Siemens and at 0.50 (at 0.1 mm-1) for the GE for FBP reconstructions. The validity of these Fourier-based metrics was restricted to a limited range of contrast due to nonlinearities introduced when dealing with iterative reconstructions (IR).
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Monnin P,Viry A,Verdun FR,Racine Ddoi
10.1088/1361-6560/ab807asubject
Has Abstractpub_date
2020-06-09 00:00:00pages
105009issue
10eissn
0031-9155issn
1361-6560journal_volume
65pub_type
杂志文章abstract：:A new thin-target method (patent pending) is described for portal imaging with low-energy (tens of keV) photons from a medical linear accelerator operating in a special mode. Low-energy photons are usually produced in the accelerator target, but are absorbed by the target and flattening filter, both made of medium- or...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/43/8/016
更新日期：1998-08-01 00:00:00
abstract：:In addition to being a powerful clinical tool, Positron emission tomography (PET) is also used in small laboratory animal research to visualize and track certain molecular processes associated with diseases such as cancer, heart disease and neurological disorders in living small animal models of disease. However, dosi...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/58/1/169
更新日期：2013-01-07 00:00:00
abstract：:We propose a hybrid multiobjective (MO) evolutionary optimization algorithm (MOEA) for intensity-modulated radiotherapy inverse planning and apply it to optimize the number of incident beams, their orientations and intensity profiles. The algorithm produces a set of efficient solutions, which represent different clini...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/49/5/007
更新日期：2004-03-07 00:00:00
abstract：:Recently, deep learning technology has achieved various successes in medical image analysis studies including computer-aided diagnosis (CADx). However, current CADx approaches based on deep learning have a limitation in interpreting diagnostic decisions. The limited interpretability is a major challenge for practical ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aaef0a
更新日期：2018-12-04 00:00:00
abstract：:Technical advances towards high resolution PET imaging try to overcome the inherent physical limitations to spatial resolution. Positrons travel in tissue until they annihilate into the two gamma photons detected. This range is the main detector-independent contribution to PET imaging blurring. To a large extent, it c...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/58/15/5127
更新日期：2013-08-07 00:00:00
abstract：:This study aims at investigating in real-time the structural and dynamical changes occurring in an ex vivo tissue during a microwave thermal ablation (MTA) procedure. The experimental set-up was based on ex vivo liver tissue inserted in a dedicated box, in which 3 fibre-optic (FO) temperature probes were introduced to...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab1a67
更新日期：2019-05-31 00:00:00
abstract：:For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron stor...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/57/24/8231
更新日期：2012-12-21 00:00:00
abstract：:The purpose of this work was to study and quantify the differences in dose distributions computed with some of the newest dose calculation algorithms available in commercial planning systems. The study was done for clinical cases originally calculated with pencil beam convolution (PBC) where large density inhomogeneit...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/52/13/002
更新日期：2007-07-07 00:00:00
abstract：:The signal-to-noise ratio (SNR) in x-ray imaging can be increased using a photon counting detector which could allow for rejecting electronics noise and for weighting x-ray photons according to their energies. This approach, however, was not feasible for a long time because photon counting x-ray detectors with very hi...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/16/009
更新日期：2009-08-21 00:00:00
abstract：:In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of H...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/50/7/013
更新日期：2005-04-07 00:00:00
abstract：:Ring artifacts in cone beam computed tomography (CBCT) images are caused by pixel gain variations using flat-panel detectors, and may lead to structured non-uniformities and deterioration of image quality. The purpose of this study is to propose a method of general ring artifact removal in CBCT images. This method is ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/aa7017
更新日期：2017-07-07 00:00:00
abstract：:Monte Carlo simulation with PENELOPE (version 2003) is applied to calculate Leksell Gamma Knife dose distributions for heterogeneous phantoms. The usual spherical water phantom is modified with a spherical bone shell simulating the skull and an air-filled cube simulating the frontal or maxillary sinuses. Different sim...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/50/23/018
更新日期：2005-12-07 00:00:00
abstract：:We recently started orthogonal two-port carbon ion therapy for choroidal melanoma with the intent to reduce the incidence of radiation complications that occur with mono-port therapy. Treatment planning techniques involving therapeutic beam characteristics are described here. The vertical (140 MeV/u) and horizontal (1...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/52/17/016
更新日期：2007-09-07 00:00:00
abstract：:This study investigated the integration of the Calypso real-time tracking system, based on implanted ferromagnetic transponders and a detector array, into the current process for image-guided radiation treatment (IGRT) of prostate cancer at our institution. The current IGRT process includes magnetic resonance imaging ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/17/N03
更新日期：2009-09-07 00:00:00
abstract：:All available imaging devices in nuclear medicine have finite energy resolution. This leads to inclusion of scattered radiation, which in turn degrades the image quality. Different scatter correction schemes therefore try to eliminate the effect of scattered radiation. On the other hand, improvement of the camera's in...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/34/1/008
更新日期：1989-01-01 00:00:00
abstract：:Beam tracking with scanned carbon ion radiotherapy achieves highly conformal target dose by steering carbon pencil beams to follow moving tumors using real-time magnetic deflection and range modulation. The purpose of this study was to evaluate the robustness of target dose coverage from beam tracking in light of posi...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/60/4/1717
更新日期：2015-02-21 00:00:00
abstract：:Ho-166 is a combined beta-gamma emitter of which the betas can be used therapeutically. From the 81 keV gammas of Ho-166, SPECT images can be obtained, which give opportunities to guide Ho-166 therapy. Accurate reconstruction of Ho-166 images is currently hampered by photopeak-scatter in the patient, down-scatter in t...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/51/19/004
更新日期：2006-10-07 00:00:00
abstract：:We present a method based on spectral theory for the shape analysis of carpal bones of the human wrist. We represent the cortical surface of the carpal bone in a coordinate system based on the eigensystem of the two-dimensional Helmholtz equation. We employ a metric--global point signature (GPS)--that exploits the sca...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/59/4/961
更新日期：2014-02-21 00:00:00
abstract：:It is important to assess the viability of extremity soft tissues, as this component is often the determinant of the final outcome of fracture treatment. Microwave tomography (MWT) and sensing might be able to provide a fast and mobile assessment of such properties. MWT imaging of extremities possesses a complicated, ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/52/18/015
更新日期：2007-09-21 00:00:00
abstract：:A theoretical analysis and numerical solutions are presented for viscosity-dominated flow through a uniform, highly distensible tube with a slit-shaped cross section undergoing peristalsis. At flow rates below an intrinsic upper limit to the peristaltic carrying capacity of the tube, provided that there is always at l...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/32/7/002
更新日期：1987-07-01 00:00:00
abstract：:Induction cookers are a type of cooking appliance that uses an intermediate-frequency magnetic field to heat the cooking vessel. The magnetic flux density produced by an induction cooker during operation was measured according to the EN 62233 standard, and the measured values were below the limits set in the standard....
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/56/19/001
更新日期：2011-10-07 00:00:00
abstract：:This work describes the dosimetric commissioning of the treatment planning system (TPS) RayStation v6.1 from RaySearch Laboratories (Stockholm, Sweden) for a synchrotron-based scanned proton beam delivery with isocentric and non-isocentric setups at MedAustron. Focus was on the comparison of the pencil beam (PBv4.1) a...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/1361-6560/ab3557
更新日期：2019-08-28 00:00:00
abstract：:The dosimetrical characteristics of a new miniature multileaf collimator (ModuLeaf MLC, MRC Systems GmbH, Heidelberg, Germany) attached to the accessory holder of a Siemens accelerator with 6 MV x-rays (PRIMUS, Siemens OCS, Concord, California, USA) have been investigated. In particular, those parameters which are imp...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/47/12/402
更新日期：2002-06-21 00:00:00
abstract：:In order to analyse the respective roles of ion concentration and fractional volume of the interstitial compartment as determinants of the impedance, Z, of renal medullary tissue, a model was needed in which both these factors could be varied independently. An array of blood cell suspensions ions in saline (different ...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/35/11/011
更新日期：1990-11-01 00:00:00
abstract：:An in vivo probe was compared with a gamma camera for the task of detecting radiolabelled tumour models in a water phantom. The probe, which contained a 1 cm diameter NaI(T1) detector, was designed and used by us for surgical staging studies of gynaecological patients. Tumours were spherical sources of different sizes...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/34/6/008
更新日期：1989-06-01 00:00:00
abstract：:A novel radiation targeted therapy is investigated for HER-2 positive breast cancers. The proposed concept combines two known approaches, but never used together for the treatment of advanced, relapsed or metastasized HER-2 positive breast cancers. The proposed radiation binary targeted concept is based on the anti HE...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/51/6/001
更新日期：2006-03-21 00:00:00
abstract：:Single energy x-ray analysis is explored in the context of computed tomography (CT), whereby Hounsfield numbers (HN) are used to estimate electron density N(e) and parameters that describe composition. We examine measurements with tissue substitute materials and theoretical HN for a broad range of tissues. Results are...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/57/23/8079
更新日期：2012-12-07 00:00:00
abstract：:Planning of radiotherapy is often difficult due to restrictions on morphological images. New imaging techniques enable the integration of biological information into treatment planning and help to improve the detection of vital and aggressive tumour areas. This might improve clinical outcome. However, nowadays morphol...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/50/17/020
更新日期：2005-09-07 00:00:00
abstract：:We investigated the physical characteristics of two complementary metal oxide semiconductor (CMOS) mammography detectors. The detectors featured 14-bit image acquisition, 50 microm detector element (del) size and an active area of 5 cm x 5 cm. One detector was a passive-pixel sensor (PPS) with signal amplification per...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/54/6/022
更新日期：2009-03-21 00:00:00
abstract：:This study was carried out to investigate whether the electronic portal imaging (EPI) acquisition process could be optimized, and as a result tolerance and action levels be set for the PIPSPro QC-3V phantom image quality assessment. The aim of the optimization process was to reduce the dose delivered to the patient wh...
journal_title：Physics in medicine and biology
pub_type： 杂志文章
doi：10.1088/0031-9155/52/23/006
更新日期：2007-12-07 00:00:00
