Abstract:
:Histotripsy is an ultrasound ablation method that depends on the initiation of a cavitation bubble cloud to fractionate soft tissue. Although previous work has provided significant insight into the process of intrinsic threshold histotripsy, the majority of these studies have used highly focused (i.e. f-number < 0.6) transducers. In this study, we investigate the effects of f-number on the histotripsy intrinsic threshold and cavitation bubble cloud behavior using a 500 kHz array transducer, with the effective f-number of the transducer varied from 0.51 to 0.89. The intrinsic threshold did not significantly change with f-number, with the threshold remaining ~27-30 MPa for all conditions. The predictability of intrinsic threshold histotripsy was further demonstrated by experiments comparing the predicted and experimentally measured bubble cloud dimensions, with results showing close agreement for all f-numbers. Finally, the effects of f-number on 'bubble density' and tissue fractionation efficiency were investigated, with results supporting the hypothesis that the density of the bubbles within the bubble cloud significantly decreases at higher f-numbers, resulting in decreased fractionation efficiency. Overall, this study provides significant insight into the effects of f-number on intrinsic threshold histotripsy that will help to guide the development of histotripsy for specific clinical applications.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Vlaisavljevich E,Gerhardson T,Hall T,Xu Zdoi
10.1088/1361-6560/aa54c7subject
Has Abstractpub_date
2017-02-21 00:00:00pages
1269-1290issue
4eissn
0031-9155issn
1361-6560journal_volume
62pub_type
杂志文章abstract::Raman spectroscopy is a potentially important clinical tool for real-time diagnosis of disease and in situ evaluation of living tissue. The purpose of this article is to review the biological and physical basis of Raman spectroscopy of tissue, to assess the current status of the field and to explore future directions....
journal_title:Physics in medicine and biology
pub_type: 传,历史文章,杂志文章,评审
doi:10.1088/0031-9155/45/2/201
更新日期:2000-02-01 00:00:00
abstract::The UK and European protocols for mammographic dosimetry use conversion factors that relate incident air kerma to the mean glandular dose (MGD) within the breast. The conversion factors currently used were obtained by computer simulation of a model breast with a composition of 50% adipose and 50% glandular tissues by ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/45/11/308
更新日期:2000-11-01 00:00:00
abstract::New values of the factors required to convert the reading of a radiation dosemeter calibrated in terms of air kerma (or exposure) into absorbed dose to water for medium-energy x-radiation were given in a code of practice published by the IAEA in 1987. These are not considered to possess sufficient support from other s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/36/8/001
更新日期:1991-08-01 00:00:00
abstract::This paper presents a compressed sensing (CS)-inspired reconstruction method for limited-angle computed tomography (CT). Currently, CS-inspired CT reconstructions are often performed by minimizing the total variation (TV) of a CT image subject to data consistency. A key to obtaining high image quality is to optimize t...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/7/2119
更新日期:2013-04-07 00:00:00
abstract::Breast cancer is one of the leading causes of female cancer deaths. Early diagnosis with prophylactic may improve the patients' prognosis. So far ultrasound (US) imaging is a popular method in breast cancer diagnosis. However, its accuracy is bounded to traditional handcrafted feature methods and expertise. A novel me...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/abc5c7
更新日期:2020-10-29 00:00:00
abstract::Factors influencing the precision of measuring changes in the calcium content of sections of bone, including vertebrae, using reactor neutrons for partial body in vivo activation analysis have been examined and quantified. These factors include (a) the choice of incidient neutron spectrum, (b) the uniformity of activa...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/20/1/007
更新日期:1975-01-01 00:00:00
abstract::Quantification of nuclear medicine image data is a prerequisite for personalized absorbed dose calculations and quantitative biodistribution studies. The spatial response of a detector is a governing factor affecting the accuracy of image quantification, and the aim of this work was to model this impact. To simulate s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/6/013
更新日期:2010-03-21 00:00:00
abstract::To monitor and strategically control energy deposition in magnetic resonance imaging (MRI), measured as a specific absorption rate (SAR), numerical methods using generic human models have been employed to estimate worst-case values. Radiofrequency (RF) sequences are therefore often designed conservatively with large s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/24/8153
更新日期:2012-12-21 00:00:00
abstract::Transverse image truncation can be a serious problem for human imaging using cone-beam transmission CT (CB-CT) implemented on a conventional rotating gamma camera. If this problem can be solved, CB-CT will be useful for attenuation compensation of SPECT images. This paper presents a reconstruction method to reduce or ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/37/3/004
更新日期:1992-03-01 00:00:00
abstract::Microbeam radiation therapy (MRT) is a treatment approach in radiation therapy where the treatment field is spatially fractionated into arrays of a few tens of micrometre wide planar beams of unusually high peak doses separated by low dose regions of several hundred micrometre width. In preclinical studies, this treat...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa8d63
更新日期:2017-10-19 00:00:00
abstract::A mammogram is the standard modality used for breast cancer screening. Computer-aided detection (CAD) approaches are helpful for improving breast cancer detection rates when applied to mammograms. However, automated analysis of a mammogram often leads to inaccurate results in the presence of the pectoral muscle. There...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/23/8493
更新日期:2013-12-07 00:00:00
abstract::Effects of different scatter compensation methods incorporated in fully 3D iterative reconstruction are investigated. The methods are: (i) the inclusion of an 'ideal scatter estimate' (ISE); (ii) like (i) but with a noiseless scatter estimate (ISE-NF); (iii) incorporation of scatter in the point spread function during...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/42/8/011
更新日期:1997-08-01 00:00:00
abstract::In this work we present a new 3D numerical model for heat transfer in the human eye, which takes into account the aqueous humour flow in the anterior chamber. We show that consideration of this phenomenon in the calculations alters the temperature distribution on the corneal and lens surfaces, without, however, notice...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/19/003
更新日期:2010-10-07 00:00:00
abstract::To generate large thermal lesions in ultrasound thermal therapy, cooling intermissions are usually introduced during the treatment to prevent near-field heating, which leads to a long treatment time. A possible strategy to shorten the total treatment time is to eliminate the cooling intermissions. In this study, the t...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/48/9/307
更新日期:2003-05-07 00:00:00
abstract::We propose and evaluate the performance of an improved preclinical positron emission tomography (PET) scanner design, referred to as Polaroid-PET, consisting of a detector equipped with a layer of horizontal Polaroid to filter scintillation photons with vertical polarization. This makes it possible to improve the spat...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/abaeb8
更新日期:2020-12-02 00:00:00
abstract::It is well known that the experimental dosimetry of brachytherapy sources presents a challenge. Depending on the particular-dosimeter used, measurements can suffer from poor spatial resolution (ion chambers), lack of 3D information (film) or errors due to the presence of the dosimeter itself distorting the radiation f...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/44/10/305
更新日期:1999-10-01 00:00:00
abstract::To achieve accurate and fast deformable image registration (DIR) for pulmonary CT, we proposed a Multi-scale DIR framework with unsupervised Joint training of Convolutional Neural Network (MJ-CNN). MJ-CNN contains three models at multi-scale levels for a coarse-to-fine DIR to avoid being trapped in a local minimum. It...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab5da0
更新日期:2020-01-13 00:00:00
abstract::The Studsvik thermal-neutron facility was originally designed for neutron capture radiography (NCR) at high thermal-neutron fluence and low fast-neutron contamination. It has now been modified to permit irradiation of living cells and animals without the need for stopping and restarting the R2-0 reactor. Previous calc...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/38/8/006
更新日期:1993-08-01 00:00:00
abstract::In recent years, particle therapy has become a widely accepted form of cancer treatment and technological advances in beam delivery technology (i.e. pencil beam scanning (PBS)) have enabled the application of highly conformal dose distributions to static targets. Current research focuses on the possibilities for the t...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/22/7905
更新日期:2013-11-21 00:00:00
abstract::Experimental radiobiological investigations of fast neutron beams involve irradiation of thin cell layers. The irradiation of cells is done either in free air or with a material such as graphite, TE plastic or bone-equivalent plastic covering the cells. This paper discusses the computed dose distributions in LET at sh...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/24/5/007
更新日期:1979-09-01 00:00:00
abstract::It is not feasible to define very small or complex organs and tissues in the current voxel-type adult reference computational phantoms of the International Commission on Radiological Protection (ICRP), which limit dose coefficients for weakly penetrating radiations. To address the problem, the ICRP is converting the v...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa5b72
更新日期:2017-03-21 00:00:00
abstract::Intraoperative x-ray radiography/fluoroscopy is commonly used to assess the placement of surgical devices in the operating room (e.g. spine pedicle screws), but qualitative interpretation can fail to reliably detect suboptimal delivery and/or breach of adjacent critical structures. We present a 3D-2D image registratio...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa62c5
更新日期:2017-04-21 00:00:00
abstract::Quantifying the retention or washout of (99m)Tc-Sestamibi (MIBI) in breast tumours in vivo may provide a basis for predicting the chemotherapy response. The aim of this study is to investigate the variations and limitations of the different methods used to quantify these parameters. A phantom was developed that allowe...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/9/013
更新日期:2005-05-07 00:00:00
abstract::Recent acute shortage of medical radioisotopes prompted investigations into alternative methods of production and the use of a cyclotron and ¹⁰⁰Mo(p,2n)(99m)Tc reaction has been considered. In this context, the production yields of (99m)Tc and various other radioactive and stable isotopes which will be created in the ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/17/002
更新日期:2011-09-07 00:00:00
abstract::There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values....
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/19/7637
更新日期:2015-10-07 00:00:00
abstract::Several applications in nuclear medicine require absolute activity quantification of single photon emission computed tomography images. Obtaining a repeatable calibration factor that converts voxel values to activity units is essential for these applications. Because source preparation and measurement of the source ac...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/3/1325
更新日期:2015-02-07 00:00:00
abstract::In (19)F MRI oximetry, a method used to image tumour hypoxia, perfluorocarbons serve as oxygenation markers. The goal of this study is to evaluate the impact of perfluorocarbon distribution and concentration in (19)F MRI oximetry through a computer simulation. The simulation studies the correspondence between (19)F me...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/8/013
更新日期:2011-04-21 00:00:00
abstract::The dosimetric measurement and modeling of small radiation treatment fields (<2 × 2 cm2) are difficult to perform and prone to error. Measurements of small fields are often adversely influenced by the properties of the detectors used to make them. The dosimetric properties of small fields have been difficult to accura...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/12/015
更新日期:2011-06-21 00:00:00
abstract::Positron emission tomography (PET) iterative 3D reconstruction is a very computational demanding task. One of the main issues of the iterative reconstruction concerns the management of the system response matrix (SRM). The SRM models the relationship between the projection and the voxel space and its memory footprint ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aae12b
更新日期:2018-09-28 00:00:00
abstract::The cerebral arteries are difficult to reproduce from first principles, featuring interwoven territories, and intricate layers of grey and white matter with differing metabolic demand. The aim of this study was to identify the ideal configuration of arteries required to sustain an entire brain hemisphere based on mini...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab2479
更新日期:2019-06-21 00:00:00