Abstract：
:This paper examines the distributions of the SAR (specific absorption rate) ratio and temperature elevation when an ultrasound beam propagates through the interface of muscle and bone. This interface is regarded as a flat boundary to partition the energy of the ultrasound beam, and the analytical solution of temperature distribution is based on the steady-state bio-heat transfer equation. The parameters considered are the incident angle of ultrasound beam, the ultrasound frequency, the acoustic attenuation coefficients of refracted longitudinal and shear waves in bone, and the blood perfusion in muscle. The results show that the peak of the SAR ratio is always at the interface of muscle and bone, while the peak of temperature is located in the bone region beyond the interface. A muscle with lower perfusion or a bone with higher acoustic attenuation results in the shifting of the temperature peak closer to the interface. It is more difficult to heat a higher perfused muscle in front of a bone using a lower frequency ultrasound since the temperature elevation for bone relative to muscle is greater.
journal_name
Med Physjournal_title
Medical physicsauthors
Lin WL,Liauh CT,Chen YY,Liu HC,Shieh MJdoi
10.1118/1.598979subject
Has Abstractpub_date
2000-05-01 00:00:00pages
1131-40issue
5eissn
0094-2405issn
2473-4209journal_volume
27pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：:A clamp-on current probe utilizing the Hall effect was used to determine x-ray tube current. This noninvasive technique was compared to two other methods of mA measurement: the Machlett Dynalyzer and the mR/mAs linearity method. Three diagnostic x-ray units were used in the comparison; two modern three-phase rooms and...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596080
更新日期：1987-03-01 00:00:00
abstract：PURPOSE:This report describes upgrades and performance characterization of an experimental benchtop cone-beam x-ray fluorescence computed tomography (XFCT) system capable of determining the spatial distribution and concentration of metal probes such as gold nanoparticles (GNPs). Specifically, a high-power (~3 kW) indus...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13138
更新日期：2018-10-01 00:00:00
abstract：:In external beam radiotherapy, electronic portal imaging becomes more and more an indispensable tool for the verification of the patient setup. For the safe clinical introduction of high dose conformal radiotherapy like intensity modulated radiation therapy, on-line patient setup verification is a prerequisite to ensu...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1668391
更新日期：2004-04-01 00:00:00
abstract：:Functional single photon emission computed tomography (SPECT) images of brain activation are based on a comparison of base line and activation images. The correctness of the functional images depends, among other factors, on the accurate spatial registration (alignment) of the base line and activation image data. The ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597412
更新日期：1994-10-01 00:00:00
abstract：:Current MRI nonuniformity correction techniques are reviewed and investigated. Many approaches are used to remedy this artifact, but it is not clear which method is the most appropriate in a given situation, as the applications have been with different MRI coils and different clinical applications. In this work four w...
journal_title：Medical physics
pub_type： 杂志文章,评审
doi：10.1118/1.598357
更新日期：1998-09-01 00:00:00
abstract：PURPOSE:To evaluate a simple, semi-automated lung mass estimation method on CT scans from a variety of acquisition techniques for mass correction of MIRD dose estimates. METHODS:CT scans from ten patients undergoing stereotactic body radiation therapy treatment planning on a GE DST PET/CT scanner were analyzed retrosp...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734654
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:The objectives of this study were (a) to devise a technique for measuring quantum noise in clinical body computed tomography (CT) images and (b) to develop a model for predicting that noise with high accuracy. METHODS:The study included 83 clinical image sets at two dose levels (clinical and 50% reduced dose l...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4938588
更新日期：2016-01-01 00:00:00
abstract：:Preclinical experiments are carried out with approximately 20-30 microm wide, approximately 10 mm high parallel microbeams of hard, broad-"white"-spectrum x rays (approximately 50-600 keV) to investigate microbeam radiation therapy (MRT) of brain tumors in infants for whom other kinds of radiotherapy are inadequate an...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1562169
更新日期：2003-04-01 00:00:00
abstract：:The purpose of this work is to investigate algorithms for the delivery of intensity-modulated fields using independent collimators (IC). Two heuristic algorithms are proposed to calculate jaw-setting sequences for arbitrary 2D intensity distributions. The first algorithm is based on searching the whole intensity matri...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598794
更新日期：1999-12-01 00:00:00
abstract：PURPOSE:The pulse line ion accelerator (PLIA) is a low-cost accelerator concept originally designed to accelerate heavy ions. Our group has been investigating the use of PLIA to accelerate light ions and believe a multi-stage PLIA could be useful for short half-life PET isotope production. The goal of this work was to ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13875
更新日期：2019-12-01 00:00:00
abstract：PURPOSE:To investigate how the setting of optimization parameters, fractional dose and tuning structure in tomotherapy treatment planning affects plan dosimetric quality and treatment efficiency. METHODS:A digital phantom to simulate head and neck radiotherapy was constructed for this study. Tumor was 10cm long C-shap...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735724
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:To construct a Monte Carlo (MC)-based simulation model for analyzing the dependence of tumor oxygen distribution on different variables related to tumor vasculature [blood velocity, vessel-to-vessel proximity (vessel proximity), and inflowing oxygen partial pressure (pO2)]. METHODS:A voxel-based tissue model c...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4892386
更新日期：2014-09-01 00:00:00
abstract：PURPOSE:Silicon photodetectors are of significant interest for use in positron emission tomography (PET) systems due to their compact size, insensitivity to magnetic fields, and high quantum efficiency. However, one of their main disadvantages is fluctuations in temperature cause strong shifts in gain of the devices. P...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4903889
更新日期：2015-01-01 00:00:00
abstract：PURPOSE:Traditionally, unidirectional leaf-sweeping schemes have been employed to deliver IMRT plans using the dynamic multileaf collimator (DMLC) technique. The goal of this research is to investigate the potential impact of relaxing the leaf-motion restrictions in DMLC IMRT on the beam-modulation quality and the deli...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13158
更新日期：2018-11-01 00:00:00
abstract：PURPOSE:To improve image quality and reduce imaging dose in CBCT for radiation therapy applications and to realize near real-time image reconstruction based on use of a fast convergence iterative algorithm and acceleration by multi-GPUs. METHODS:An iterative image reconstruction that sought to minimize a weighted leas...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735747
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:The goals of stereotactic radiosurgery (SRS) are the ablation of target tissue and sparing of critical normal tissue. We develop tools to aid in the selection of collimation and prescription (Rx) isodose line to optimize the dose gradient for single isocenter intracranial stereotactic radiosurgery (SRS) with Ga...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735542
更新日期：2012-06-01 00:00:00
abstract：:This study presents experimental results about the effective depth of penetration and about the radiofrequency (rf) power absorption in humans as a function of frequency. The frequency range investigated covers 10 up to 220 MHz. For the main part, the results were derived from bench measurements of the quality factor ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595995
更新日期：1987-11-01 00:00:00
abstract：PURPOSE:The GammaPod is a novel dedicated prone breast stereotactic radiosurgery (SRS) device recently developed at the University of Maryland Medical Center. This device utilizes multiple rotating Co-60 sources to create highly conformal dose distributions for breast treatments, including boosts, partial breast irradi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14197
更新日期：2020-08-01 00:00:00
abstract：:A high sensitivity (HS) model of radiochromic film is receiving increasing use. The film's linear sensitometric response in the range of 0.5-40 Gy would make this film an ideal candidate for complex dosimetry applications that require tissue equivalence. This study investigates the potential use for clinical dosimetry...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.1883565
更新日期：2005-04-01 00:00:00
abstract：PURPOSE:The depth dose of a monoenergetic broad parallel proton beam has been modeled in a number of ways, but evidently not yet for oblique incidence. The purpose of this investigation is to find an accurate analytic formula for this case, which can then be used to model the depth dose of a broad beam with an initial ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3495969
更新日期：2010-11-01 00:00:00
abstract：:In the presence of intrafraction organ motion, target localization uncertainty can greatly hamper the advantage of highly conformal dose techniques such as intensity modulated radiation therapy (IMRT). To minimize the adverse dosimetric effect caused by tumor motion, a real-time knowledge of the tumor position is requ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2842072
更新日期：2008-04-01 00:00:00
abstract：PURPOSE:Hip fracture is a serious health problem and textural methods are being developed to assess bone quality. The authors aimed to perform textural analysis at femur on high-resolution digital radiographs compared to three-dimensional (3D) microarchitecture comparatively to bone mineral density. METHODS:Sixteen ca...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3528125
更新日期：2011-01-01 00:00:00
abstract：PURPOSE:Discuss optimised Accelerated Partial Breast Irradiation (APBI) using a Strut-Adjused Volume Implant (SAVI) applicator for patients with implanted pacemeker, without overdosing or relocating the pacemaker. METHODS:A right breast cancer patient with an in situ pacemaker (Medtronic model ADDR01) on the right sid...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735299
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:To present EBT2 film verification of treatment planning with the eXtend System, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery. METHODS:A human head shaped phantom simulated the verification process for fractionated Gamma Knife (GK) treatment. Phantom preparation for e...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735487
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Efficacy of tuberculosis (TB) treatment is often monitored using chest radiography. Monitoring size of cavities in pulmonary tuberculosis is important as the size predicts severity of the disease and its persistence under therapy predicts relapse. The authors present a method for automatic cavity segmentation i...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4881096
更新日期：2014-07-01 00:00:00
abstract：PURPOSE:In intensity-modulated proton therapy (IMPT), protons are used to deliver highly conformal dose distributions, targeting tumors, and sparing organs-at-risk. However, due to uncertainties in both patient setup and relative stopping power (RSP) calculation, margins are added to the treatment volume during treatme...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14347
更新日期：2020-09-01 00:00:00
abstract：:Gd2O2S phosphor screens between 250 and 1000 mg/cm2 thick were evaluated for use in megavoltage imaging systems. The phosphor layers were placed on brass plates ranging from 1 to 5 mm thick, each with and without an optical back reflector (white paint). Light output and spatial resolution were measured at 6- and 23-MV...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597209
更新日期：1994-08-01 00:00:00
abstract：PURPOSE:To introduce video surface imaging guidance in synchronization with 4D cone-beam CT (CBCT) scans, and in combination with respiration- gated or target-tracked dose delivery to treat mobile tumors, without collaterally damaging nearby critical structures. METHODS:The approach uses the concept that the integral ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734688
更新日期：2012-06-01 00:00:00
abstract：:Tissue absorbed dose (D) is a computed result for internal emitters. For fixed geometries, D is calculated by a matrix (S) multiplication of the integrated activity vector (Ã). The last quantity is usually measured by nuclear imaging of activity in various source organs and performing a temporal integration. Ã is the ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735750
更新日期：2012-06-01 00:00:00
abstract：PURPOSE:Anomalous pixels may be defined as those pixels whose exposure response relationship is deviant from the typical, expected or calibrated response. A group of anomalous pixels may Result in visible correlated artifacts. Here we demonstrate an approach to identify anomalous pixels and correlated artifacts using f...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734820
更新日期：2012-06-01 00:00:00
