Abstract:
:A circular scanning trajectory is and will likely remain a popular choice of trajectory in computed tomography (CT) imaging because it is easy to implement and control. Filtered-backprojection (FBP)-based algorithms have been developed previously for approximate and exact reconstruction of the entire image or a region of interest within the image in circular cone-beam and fan-beam cases. Recently, we have developed a 3D FBP-based algorithm for image reconstruction on PI-line segments in a helical cone-beam scan. In this work, we demonstrated that the 3D FBP-based algorithm indeed provided a rather general formulation for image reconstruction from divergent projections (such as cone-beam and fan-beam projections). On the basis of this formulation we derived new approximate or exact algorithms for image reconstruction in circular cone-beam or fan-beam scans, which can be interpreted as special cases of the helical scan. Existing algorithms corresponding to the derived algorithms were identified. We also performed a preliminary numerical study to verify our theoretical results in each of the cases. The results in the work can readily be generalized to other non-circular trajectories.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Pan X,Xia D,Zou Y,Yu Ldoi
10.1088/0031-9155/49/18/011subject
Has Abstractpub_date
2004-09-21 00:00:00pages
4349-69issue
18eissn
0031-9155issn
1361-6560journal_volume
49pub_type
杂志文章abstract::An accurate, low noise estimate of photon attenuation in the subject is required for quantitative microPET studies of molecular tracer distributions in vivo. In this work, several transmission-based measurement techniques were compared, including coincidence mode with and without rod windowing, singles mode with two d...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/51/16/008
更新日期:2006-08-21 00:00:00
abstract::The sensitivity and detection limit for measurements of the concentration of cadmium in the kidney cortex of man in vivo have been investigated using the technique of X-ray fluorescence. An 11 GB1 241Am source was used to generate the characteristic K alpha X-rays of cadmium. The variation in the sensitivity for the d...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/26/1/004
更新日期:1981-01-01 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::Proton therapy with active scanning beam delivery has significant advantages compared to conventional radiotherapy. However, so far only static targets have been treated in this way, since moving targets potentially lead to interplay effects. For 4D treatment planning, information on the target motion is needed to cal...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/7/1779
更新日期:2012-04-07 00:00:00
abstract::A new multiplicative correction factor for tissue heterogeneities based on an exact expression for homogeneous non-unit-density media is proposed. O'Connor's density scaling theorem is invoked to evaluate the medium-specific tissue-maximum ratios used in the exact formulation. Monte Carlo calculations were performed a...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/31/10/005
更新日期:1986-10-01 00:00:00
abstract::Complex intra-fractional motion and deformation of the liver significantly impacts the accuracy of delivered dose in radiotherapy. It limits margin reduction, dose escalation and normal tissue sparing. A critical component of motion management is to accurately reconstruct tumor motion. In this study, we developed a si...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab4c0d
更新日期:2019-11-21 00:00:00
abstract::The purpose of this work is to develop a validated Geant4 simulation model of a whole-body prototype PET scanner constructed from the four-layer depth-of-interaction detectors developed at the National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Japan. T...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/abaa24
更新日期:2020-12-18 00:00:00
abstract::Multileaf collimators (MLCs) have been in clinical use for many years and meanwhile are commonly used to deliver intensity-modulated radiotherapy (IMRT) beams. For this purpose it is important to know their dosimetric properties precisely, one of them being inter- and intraleaf leakage. The Siemens 160 MLC features a ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/2/N02
更新日期:2011-01-21 00:00:00
abstract::In order to optimize external-beam conformal radiotherapy, patient movement during treatment must be minimized. For treatment on the upper torso, the target organs are known to move substantially due to patient respiration. This paper deals with the technical aspects of gating the radiotherapy beam synchronously with ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/41/1/007
更新日期:1996-01-01 00:00:00
abstract::Various forms of GAFChromic film have been used for several years as radiographic media for measuring dose distributions of brachytherapy sources and small radiation fields. Upon irradiation the film changes colour and darkens with time post-irradiation. The darkening is most rapid in the first 24 h, and it has been s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/43/10/001
更新日期:1998-10-01 00:00:00
abstract::As a new method, x-ray diffraction enhanced imaging (DEI) has extremely high sensitivity for weakly absorbing low-Z samples in medical and biological fields. Conventional performance parameters, such as spatial resolution and low-contrast resolution, are not enough to describe the characteristics of a DEI system. This...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/51/12/002
更新日期:2006-06-21 00:00:00
abstract::Cylindrical homogenous phantoms for magnetic resonance (MR) elastography in biomedical research provide one way to validate an imaging systems performance, but the simplified geometry and boundary conditions can cloak complexity arising at tissue interfaces. In an effort to develop a more realistic gel tissue phantom ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/18/6821
更新日期:2016-09-21 00:00:00
abstract::A multicentre phase II trial of stereotactic body radiotherapy for T1N0M0 non-small cell lung cancer was initiated in Japan as the Japan Clinical Oncology Group trial (JCOG0403). Before starting the trial, a decision was made to evaluate the treatment machine and treatment planning in participating institutions to min...
journal_title:Physics in medicine and biology
pub_type: 杂志文章,多中心研究
doi:10.1088/0031-9155/51/21/002
更新日期:2006-11-07 00:00:00
abstract::A comprehensive set of measurements and calculations has been conducted to investigate the accuracy of the Dose Planning Method (DPM) Monte Carlo code for electron beam dose calculations in heterogeneous media. Measurements were made using 10 MeV and 50 MeV minimally scattered, uncollimated electron beams from a racet...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/47/11/301
更新日期:2002-06-07 00:00:00
abstract::It is a challenging problem to resolve and identify drug (or non-specific fluorophore) distribution throughout the whole body of small animals in vivo. In this article, an algorithm of unmixing multispectral fluorescence tomography (MFT) images based on independent component analysis (ICA) is proposed to solve this pr...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/17/5025
更新日期:2014-09-07 00:00:00
abstract::Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regul...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/4/1452
更新日期:2016-02-21 00:00:00
abstract::The development of alpha-emitting radiopharmaceuticals using 211At requires quantitative determination of the time-dependent nature of the 211At biodistribution. However, imaging-based methods for acquiring this information with 211At have not found wide-spread use because of its low abundance of decay emissions suita...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aaaa95
更新日期:2018-02-21 00:00:00
abstract::A new function to treat tetrahedral-mesh geometry was implemented in the particle and heavy ion transport code systems. To accelerate the computational speed in the transport process, an original algorithm was introduced to initially prepare decomposition maps for the container box of the tetrahedral-mesh geometry. Th...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa6b45
更新日期:2017-06-21 00:00:00
abstract::The 0.35 T 60Co MRIdian system (ViewRay Inc., Mountain View) has been in clinical use in our institution since May 2016. For quality assurance (QA) of dose delivery and end-to-end testing for this machine, a reliable dosimeter is required. However, it is possible that a magnetic field may cause perturbations to dosime...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aad58d
更新日期:2018-08-20 00:00:00
abstract::Droplets of liquid perfluorocarbon (PFC) are under study as the next generation of contrast agents for ultrasound (US). These droplets can be selectively vaporized into echogenic gas bubbles in situ by externally applied US, with numerous applications to diagnosis and therapy. However, little is known about the mechan...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/21/7205
更新日期:2012-11-07 00:00:00
abstract::Changes in the relative biological effectiveness (RBE) of the radiation-induced cell killing of human salivary glands (HSG) were assessed along the Bragg peak of a 60 MeV clinical proton beam by means of coupling biophysical models with the results of Monte Carlo radiation transport simulations and experimental measur...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab491f
更新日期:2020-01-10 00:00:00
abstract::W (the average energy to form an ion pair) for 5.4 MeV 241Am alpha particles in a Rossi-type tissue-equivalent (TE) gas, argon and methane was determined to an accuracy better than 0.2% using a new automated data handling system. A vibrating reed electrometer and current digitiser were used to measure the current prod...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/24/2/005
更新日期:1979-03-01 00:00:00
abstract::Although x-ray mammography is widely developed for breast tumour detection, it suffers from spatial superposition in its two-dimensional (2D) representation of a three-dimensional (3D) breast structure. Accordingly, 3D breast imaging, such as cone-beam computed tomography (CT), arises at the historic moment. In this p...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/48/14/312
更新日期:2003-07-21 00:00:00
abstract::The objective of this work is to test analytical models to calculate the luminescence efficiency of Al(2)O(3):C optically stimulated luminescence detectors (OSLDs) exposed to heavy charged particles with energies relevant to space dosimetry and particle therapy. We used the track structure model to obtain an analytica...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/2/437
更新日期:2012-01-21 00:00:00
abstract::Monte Carlo simulation techniques are applied to track the annihilation photons from positron decay, and store the photon histories. Reasonably realistic models of the isotope distribution in the brain and heart during typical PET studies, as well as the traditional phantoms used for measuring PET scanner performance ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/37/3/017
更新日期:1992-03-01 00:00:00
abstract::We investigate the effect of multiple scattering on the optical coherence tomography (OCT) signal and the Doppler OCT signal of flowing blood. Doppler OCT measurements at 1300 nm are performed on flowing diluted porcine blood with hematocrit ranging between 0% and 15%. Measured blood hematocrit and mean red blood cell...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/7/1907
更新日期:2012-04-07 00:00:00
abstract::Voltage-sensitive dyes are an important tool in visualizing electrical activity in cardiac tissue. Until today, they have mainly been applied in cardiac electrophysiology to subsurface imaging. In the present study, we assess different imaging methods used in optical tomography with respect to their effectiveness in v...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/2/003
更新日期:2005-01-21 00:00:00
abstract::The goal of this study was to assess the impact of set-up uncertainty on compliance with the objectives and constraints of an intensity modulated radiation therapy protocol for early stage cancer of the oropharynx. As the convolution approach to the quantitative study of set-up uncertainties cannot accommodate either ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/15/003
更新日期:2005-08-07 00:00:00
abstract::Corrections for room scatter, [ksc(d, H)]RM, were derived using Monte Carlo methods for rooms of various sizes, including the brachytherapy treatment room, in which primary air kerma strength standardization of a remote afterloading microSelectron 192Ir HDR source was carried out, using a 60 cm3 spherical graphite ion...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/46/9/303
更新日期:2001-09-01 00:00:00
abstract::Proton therapy potentially offers excellent dose conformality and reduction in integral dose. The superior dose distribution is, however, much more sensitive to the radiological depth along the beam path than for photon fields. Variations in this depth due to inaccurate planning calculation, setup uncertainty, respira...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/5/016
更新日期:2008-03-07 00:00:00