Abstract:
:Single photon emission computed tomography (SPECT) is an important technology for molecular imaging studies of small animals. In this arena, there is an increasing demand for high performance imaging systems that offer improved spatial resolution and detection efficiency. We have designed a multipinhole small animal imaging system based on position sensitive avalanche photodiode (PSAPD) detectors with the goal of submillimeter spatial resolution and high detection efficiency, which will allow us to minimize the radiation dose to the animal and to shorten the time needed for the imaging study. Our design will use 8 x 24 mm2 PSAPD detector modules coupled to thallium-doped cesium iodide [CsI(Tl)] scintillators, which can achieve an intrinsic spatial resolution of 0.5 mm at 140 keV. These detectors will be arranged in rings of 24 modules each; the animal is positioned in the center of the 9 stationary detector rings which capture projection data from the animal with a cylindrical tungsten multipinhole collimator. The animal is supported on a bed which can be rocked about the central axis to increase angular sampling of the object. In contrast to conventional SPECT pinhole systems, in our design each pinhole views only a portion of the object. However, the ensemble of projection data from all of the multipinhole detectors provide angular sampling that is sufficient to reconstruct tomographic data from the object. The performance of this multipinhole PSAPD imaging system was simulated using a ray tracing program that models the appropriate point spread functions and then was compared against the performance of a dual-headed pinhole SPECT system. The detection efficiency of both systems was simulated and projection data of a hot rod phantom were generated and reconstructed to assess spatial resolution. Appropriate Poisson noise was added to the data to simulate an acquisition time of 15 min and an activity of 18.5 MBq distributed in the phantom. Both sets of data were reconstructed with an ML-EM reconstruction algorithm. In addition, the imaging performance of both systems was evaluated with a uniformity phantom and a realistic digital mouse phantom. Simulations show that our proposed system produces a spatial resolution of 0.8 mm and an average detection efficiency of 630 cps/MBq. In contrast, simulations of the dual-headed pinhole SPECT system produce a spatial resolution of 1.1 mm and an average detection efficiency of 53 cps/MBq. These results suggest that our novel design will achieve high spatial resolution and will improve the detection efficiency by more than an order of magnitude compared to a dual-headed pinhole SPECT system. We expect that this system can perform SPECT with submillimeter spatial resolution, high throughput, and low radiation dose suitable for in vivo imaging of small animals.
journal_name
Med Physjournal_title
Medical physicsauthors
Funk T,Després P,Barber WC,Shah KS,Hasegawa BHdoi
10.1118/1.2190332subject
Has Abstractpub_date
2006-05-01 00:00:00pages
1259-68issue
5eissn
0094-2405issn
2473-4209journal_volume
33pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract::The measurement of the radioactivity administered to the patient is one of the major components of 90Y microsphere liver brachytherapy. The activity of 90Y microspheres in a glass delivery vial was measured in a dose calibrator. The calibration value to use for 90Y in the dose calibrator was verified using an activity...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2731034
更新日期:2007-06-01 00:00:00
abstract::The immediate goal of clinically based x-ray-transmission computed tomography (CT) is to provide a measurement of the x-ray linear attenuation coefficient in cross section with the ultimate goal of impacting on patient management and care. To do this with the accuracy needed for clinical goals requires the careful int...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.594381
更新日期:1977-03-01 00:00:00
abstract:PURPOSE:Theoretical models of the detective quantum efficiency (DQE) of x-ray detectors are an important step in new detector development by providing an understanding of performance limitations and benchmarks. Previous cascaded-systems analysis (CSA) models accounted for photoelectric interactions only. This paper des...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4794495
更新日期:2013-04-01 00:00:00
abstract:PURPOSE:In CT-guided liver tumor ablation interventions, registration of a preoperative contrast-enhanced CT image to the intraoperative CT image is hypothesized to improve guidance. This is a highly challenging registration task due to differences in patient poses and large deformations, and therefore high registratio...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12332
更新日期:2017-07-01 00:00:00
abstract:PURPOSE:Repeated brain MRI scans are performed in many clinical scenarios, such as follow up of patients with tumors and therapy response assessment. In this paper, the authors show an approach to utilize former scans of the patient for the acceleration of repeated MRI scans. METHODS:The proposed approach utilizes the...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4928148
更新日期:2015-09-01 00:00:00
abstract::Neutron and photon energy spectra were measured in different depths and lateral positions in tissue-equivalent phantoms exposed to a therapeutical 14.1 MeV neutron beam. Intensity weighted mass energy absorption coefficients were derived for application in ionization chamber dosimetry in mixed neutron-gamma fields. Th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594744
更新日期:1980-09-01 00:00:00
abstract::A quality assurance protocol has been developed to assess the relative accuracy of computerized monitor unit calculations. Results from this testing reveal that errors (defined as the difference between the computer results and those obtained using a standard formula with manual calculation) in monitor unit calculator...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596539
更新日期:1990-01-01 00:00:00
abstract::The concept of the radiological depth is central to all algorithms which calculate radiation dose in a heterogeneous medium. For a discrete heterogeneous medium, consisting of regions of inhomogeneity, the radiological depth is usually presented as the sum over segments of the product of the segment length and the inh...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595739
更新日期:1985-01-01 00:00:00
abstract::In order to understand the role of water desorption, i.e., the opposite of water adsorption, in optical clearing of biological tissue created by the application of hyperosmotic agents, dynamics of water loss in fresh porcine muscle tissue administrated with glycerol or ethylene glycol was investigated with the near-in...
journal_title:Medical physics
pub_type:
doi:10.1118/1.1576228
更新日期:2003-06-01 00:00:00
abstract::In a series of in vivo experiments on five adult canines, a small cylindrical permanent magnet (approximately 5-mm diameter x 5 mm long) was magnetically moved under fluoroscopic guidance from an occipital-lobe burr hole to a predetermined destination within the brain and then removed. On three of the animals, dorsal ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596520
更新日期:1990-05-01 00:00:00
abstract:PURPOSE:Radiotherapy is an effective treatment for many types of cancer in clinical settings. Gel dosimetry has the potential to record three-dimensional (3D) dose distribution compared to a conventional ion chamber. As the elasticity of the gel is altered after irradiation due to gel polymerization, we aim to measure ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14020
更新日期:2020-03-01 00:00:00
abstract:PURPOSE:Digital breast tomosynthesis (DBT) is becoming an important part of breast cancer screening and diagnosis. Compared to two-dimensional mammography, tomosynthesis introduces limited three-dimensional (3D) resolution, but maintains high in-plane resolution, low dose, and allows for similar clinical protocols. The...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13116
更新日期:2018-10-01 00:00:00
abstract:PURPOSE:The lateral edge of a proton therapy beam is commonly used to achieve conformality to the treatment volume where critical structures reside close to the target. However, when treating shallow depths, the lateral edge of a pencil beam scanning (PBS) system may be broader than that of a double scattered (DS) syst...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4941957
更新日期:2016-03-01 00:00:00
abstract:PURPOSE:To show that Cherenkov emission is generated by external radiotherapy beam in tissue, and could serve as optical source to excite an oxygen sensitive phosphor, Oxyphor G4, within tissue. The intensity and lifetime of the phosphorescence was measured with a time-gated system and reveals the oxygenation levels in...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734811
更新日期:2012-06-01 00:00:00
abstract::In this study, BrachyDose, a recently developed EGSnrc Monte Carlo code for rapid brachytherapy dose calculations, has been benchmarked by reproducing previously published dosimetry parameters for three brachytherapy seeds with varied internal structure and encapsulation. Calculations are performed for two 125I seeds ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2400843
更新日期:2007-02-01 00:00:00
abstract::It is known that motion of an object imaged by magnetic resonance imaging leads to errors and artifacts in the image. This effect is especially important when a pulse sequence with long echo time (TE) and long TR is used to provide T2-weighted images. We have modified the usual spin warp imaging pulse sequence in a wa...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596026
更新日期:1987-07-01 00:00:00
abstract::Using superior localization and immobilization methods, stereotactic radiosurgery is capable of delivering spheres of dose as small as a few millimetres in diameter to intracranial targets. For targets abutting critical structures, the most conformal treatments minimize adverse radiation side effects and it is importa...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2965910
更新日期:2008-07-01 00:00:00
abstract:PURPOSE:To use Cone Beam CT scans obtained just prior to treatments of head and neck cancer patients to measure the setup error and cumulative dose uncertainty of the cochlea. METHODS:Data from 10 head and neck patients with 10 planning CTs and 52 Cone Beam CTs taken at time of treatment were used in this study. Patie...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4830427
更新日期:2013-12-01 00:00:00
abstract:PURPOSE:To investigate the effect of energy (kVp) and filters (no filter, half Bowtie, and full Bowtie) on the dose response curves of the Gafchromic XRQA2 film and nanoDot optical stimulated luminescence dosimeters (OSLDs) in CBCT dose fields. To measure surface and internal doses received during x-ray volume imager (...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4803466
更新日期:2013-06-01 00:00:00
abstract::Seeds containing radioactive Ytterbium-169 (169Yb) have recently been manufactured for possible application to brachytherapy. Ytterbium-169 emits photons with an average energy of 93 keV (excluding energies less than 10 keV), and decays with a half-life of 32 days. Analytic and Monte Carlo computations have been used ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.596813
更新日期:1992-05-01 00:00:00
abstract:PURPOSE:To evaluate plan quality of a novel MRI-compatible direction modulated brachytherapy (DMBT) tandem applicator using 192 Ir, 60 Co, and 169 Yb HDR brachytherapy sources, for various cervical cancer high-risk clinical target volumes (CTVHR ). MATERIALS AND METHODS:The novel DMBT tandem applicator has six periphe...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12598
更新日期:2017-12-01 00:00:00
abstract::Monte Carlo simulations of x-ray beams typically take parameters of the electron beam in the accelerating waveguide to be free parameters. In this paper, a methodology is proposed and implemented to determine the energy, spectral width, and beam divergence of the electron source. All treatment head components were rem...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3070547
更新日期:2009-03-01 00:00:00
abstract:PURPOSE:Cherenkov light during MV radiotherapy has recently found imaging and therapeutic applications but is challenged by relatively low fluence. Our purpose is to investigate the feasibility of increasing Cherenkov light production during MV radiotherapy by increasing photon energy and applying specialized beam-hard...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12927
更新日期:2018-07-01 00:00:00
abstract:PURPOSE:Efficient and accurate segmentations of 3D end-firing transrectal ultrasound (TRUS) images play an important role in planning of 3D TRUS guided prostate biopsy. However, poor image quality of the input 3D TRUS images, such as strong imaging artifacts and speckles, often makes it a challenging task to extract th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4906129
更新日期:2015-02-01 00:00:00
abstract::Transthoracic electrical impedance Z consists of a constant baseline component Z0 and the time variable component delta Z such that Z = Z0 + delta Z. The first time derivative of Z has a negative peak, the magnitude of which is (dZ/dt)min. Measurements of 170 volunteers show that (dZ/dt)min is a function of the consta...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.594910
更新日期:1981-01-01 00:00:00
abstract::Simultaneous rest 99mTc-Sestamibi/ 123I-BMIPP cardiac SPECT imaging has the potential to replace current clinical 99mTc-Sestamibi rest/stress imaging and therefore has great potential in the case of patients with chest pain presenting to the emergency department. Separation of images of these two radionuclides is diff...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3063544
更新日期:2009-02-01 00:00:00
abstract:BACKGROUND:X-ray dark-field radiography could enhance mammography by providing more information on imaged tissue and microcalcifications. The dark field signal is a measure of small angle scattering and can thus provide additional information on the imaged materials. This information can be useful for material distinct...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14043
更新日期:2020-04-01 00:00:00
abstract:PURPOSE:The purpose of the paper was to use a virtual phantom to identify a set of radiomic features from T1-weighted and T2-weighted magnetic resonance imaging (MRI) of the brain which is stable to variations in image acquisition parameters and to evaluate the effect of image preprocessing on radiomic features stabili...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.13834
更新日期:2019-11-01 00:00:00
abstract::Recently, the clinical application of electronic portal imaging devices has enabled more frequent verification of patient setup for radiation treatment. However, the image quality has sometimes proven to be inadequate, motivating the investigation of alternative sensors with better image quality. Amorphous selenium (a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598219
更新日期:1998-04-01 00:00:00
abstract:PURPOSE:Scatter contamination in cone-beam computed tomography (CBCT) degrades the image quality by introducing shading artifacts. A moving-blocker-based approach has been proposed to simultaneously estimate scatter and reconstruct the complete volume within field of view (FOV) from a single CBCT scan. Promising result...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4811086
更新日期:2013-07-01 00:00:00