Abstract：
:A method for finding optimal primary fluence profiles for multiple field external beam radiation therapy techniques has been developed using a radiobiologically based objective function that quantifies the probability of achieving complication-free tumor control, P+. The objective function P+ has the valuable property of giving the highest possible dose to the tumor without causing severe damage to normal tissues at risk. This radiobiologically based objective function selects suitable dose levels but also takes into account the dose homogeneity in the target volume to the extent that it is not causing an excessive risk of local recurrence or damage to surrounding normal tissues. The biological parameters used can either be patient specific, as determined by a predictive assay on biopsy specimens, or taken from a library of radiobiological parameter values characteristic for different tissue types of a reference patient. In its present form the method can be used to determine the optimum incident photon fluence profiles for each beam. The method has been used to investigate for a given target volume a large number of combinations of beam entry directions to find the best beam orientations with respect to the probability of achieving complication-free tumor control. It is demonstrated that when nonuniform dose delivery is available it is unsuitable to combine parallel opposed beams in two-beam techniques and to a lesser extent also to use perpendicular beams. In two-beam techniques the best angle between the beams is generally in the 100 degrees-120 degrees range. The major symmetry characteristics of the P+ phase space for two-beam techniques are also identified. The method can easily be extended from two to three dimensions and noncoplanar geometry, but it is presented here in its two-dimensional form for clarity and speed of calculation.
journal_name
Med Physjournal_title
Medical physicsauthors
Södertröm S,Brahme Adoi
10.1118/1.596971subject
Has Abstractpub_date
1993-07-01 00:00:00pages
1201-10issue
4eissn
0094-2405issn
2473-4209journal_volume
20pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract：PURPOSE:To evaluate a model which can predict patient's Entrance Skin Exposure (ESE) from height and weight and a single kVp mR/mAs measurement for radiographic. METHODS:Patient height, weight and post exposure mAs are obtained to assess ESE based on IAEA model. Patient's thickness is obtained by assuming a cylindrica...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4734825
更新日期：2012-06-01 00:00:00
abstract：:Because of complex dose distributions and dose gradients that are created in three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), photon- and electron-energy spectra might change significantly with spatial locations and doses. This study examined variations in photon- and...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2710550
更新日期：2007-04-01 00:00:00
abstract：PURPOSE:In the practice code of dosimetry, humidity effect is assumed to be constant as far as the measurements are performed in the relative humidity (RH) range of (20-80)%; thus, the humidity effect can be ignored with a dose uncertainty of 0.15%. This assumption is based on the previous experimental results by Niate...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.13665
更新日期：2019-09-01 00:00:00
abstract：:Computed tomography colonography (CTC) is a minimally invasive method that allows the evaluation of the colon wall from CT sections of the abdomen/pelvis. The primary goal of CTC is to detect colonic polyps, precursors to colorectal cancer. Because imperfect cleansing and distension can cause portions of the colon wal...
journal_title：Medical physics
pub_type： 临床试验,杂志文章
doi：10.1118/1.1796171
更新日期：2004-10-01 00:00:00
abstract：:In this paper, two new boundary tracing algorithms for segmentation of breast masses are presented. These new algorithms are based on the dynamic programming-based boundary tracing (DPBT) algorithm proposed in Timp and Karssemeijer, [S. Timp and N. Karssemeijer, Med. Phys. 31, 958-971 (2004)] The DPBT algorithm contai...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2791034
更新日期：2007-11-01 00:00:00
abstract：PURPOSE:In this study the Octavius detector 729 ionization chamber (IC) array with the Octavius 4D phantom was characterized for flattening filter (FF) and flattening filter free (FFF) static and rotational beams. The device was assessed for verification with FF and FFF RapidArc treatment plans. METHODS:The response o...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4817482
更新日期：2013-09-01 00:00:00
abstract：PURPOSE:Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckl...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4922206
更新日期：2015-07-01 00:00:00
abstract：:A commercial optical system developed by Solid Photography, Inc., has been used to generate precise paraffin--polyethylene tissue compensators. A program with the objective of constructing a medical facility has been undertaken to access patient topology for treatment planning, tissue-compensator fabrication, and pati...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.594447
更新日期：1978-11-01 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：10.1118/1.597228
更新日期：1994-12-01 00:00:00
abstract：:We discuss a formalism for clinical proton beam dosimetry based on the use of ionization chamber absorbed dose-to-water calibration and beam quality correction factors. A quantity kQ, the beam quality correction factor, is defined which corrects the absorbed dose-to-water calibration factor ND,w in a reference beam of...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597768
更新日期：1996-01-01 00:00:00
abstract：PURPOSE:A dosimetry evaluation model for treatment planning of esophageal radiation therapy is developed using a deep learning model. The model predicts dose volume histogram (DVH) from distance to target histogram (DTH) based on stacked de-noise auto-encoder (SDAE) and one-dimensional convolutional network (1D-CN). M...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14434
更新日期：2020-10-01 00:00:00
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 temperatu...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598979
更新日期：2000-05-01 00:00:00
abstract：:Accurate segmentation of microcalcifications in mammography is crucial for the quantification of morphologic properties by features incorporated in computer-aided diagnosis schemes. A novel segmentation method is proposed implementing active rays (polar-transformed active contours) on B-spline wavelet representation t...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2991286
更新日期：2008-11-01 00:00:00
abstract：PURPOSE:To evaluate the availability and performance of pencil beam algorithm for fast neutrons radiotherapy dose calculations and to achieve improvements in universality, speed and inhomogeneities corrections. METHODS:Pencil beam (PB) method uses integration of dose kernel cross field size to estimate dose distributi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4735630
更新日期：2012-06-01 00:00:00
abstract：:An automated technique for the alignment of right and left breast images has been developed for use in the computerized analysis of bilateral breast images. In this technique, the breast region is first identified in each digital mammogram by use of histogram analysis and morphological filtering operations. The anteri...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.597307
更新日期：1994-03-01 00:00:00
abstract：PURPOSE:To investigate how x-ray tube projection angle affects organ and effective doses to patients undergoing a CT examination on a cone beam scanner. METHODS:The authors investigated two cone beam CT systems that use a flat panel detector to capture the x-ray pattern transmitted through patients. One system had the...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3397458
更新日期：2010-05-01 00:00:00
abstract：PURPOSE:High-quality radiation therapy using highly conformal dose distributions and image-guided techniques requires optimum machine delivery performance. In this work, a monitoring system for multileaf collimator (MLC) performance, integrating semiautomated MLC quality control (QC) tests and statistical process contr...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4901520
更新日期：2014-12-01 00:00:00
abstract：:In order to investigate the relationship between diagnostic accuracy and radiographic image quality, we have developed a dual-film cassette which produces two radiographs simultaneously with a single exposure. One of these radiographs is of standard quality; the second is of lower quality because of degraded spatial r...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595546
更新日期：1984-09-01 00:00:00
abstract：PURPOSE:Elastography using computer tomography (CT) is a promising methodology that can provide patient-specific regional distributions of lung biomechanical properties. The purpose of this paper is to investigate the feasibility of performing elastography using simulated lower dose CT scans. METHODS:A cohort of eight...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14112
更新日期：2020-08-01 00:00:00
abstract：PURPOSE:To validate GPUMCD, a new package for fast Monte Carlo dose calculations based on the GPU (graphics processing unit), as a tool for low-energy single seed brachytherapy dosimetry for specific seed models. As the currently accepted method of dose calculation in low-energy brachytherapy computations relies on sev...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.3598441
更新日期：2011-07-01 00:00:00
abstract：:A formulation of the single energy photon transport problem is cast in the form of a series of convolutions over the primary fluence distribution with invariant kernels. A method is developed for compensating for the variant intervoxel attenuation in the scattered dose distribution by means of an invariant correction ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.595964
更新日期：1986-07-01 00:00:00
abstract：:A nondestructive and noninvasive method for numeric characterization (quantification) of the structural composition of human bone tissue has been developed and tested. In order to quantify and to compare the structural composition of bones from 2D computed tomography (CT) images acquired at different skeletal location...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2336501
更新日期：2006-10-01 00:00:00
abstract：PURPOSE:Total and regional body composition are important indicators of health and mortality risk, but their measurement is usually restricted to controlled environments in clinical settings with expensive and specialized equipment. A method that approaches the accuracy of the current gold standard method, dual-energy ...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.14492
更新日期：2020-12-01 00:00:00
abstract：:The measurement of output factors for small fields is challenging and can lead to large dose errors in patient treatments if corrections for detector size and scatter from high-Z material are not applied. Due to its high spatial resolution and near tissue equivalence, GAFCHROMIC® film potentially provides a correction...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4740095
更新日期：2012-07-01 00:00:00
abstract：:The effectiveness of film-screen mammography is limited by tradeoffs between latitude and contrast, film granularity, and the need to increase dose when antiscatter methods are used. We are currently developing a scanned-projection digital mammography (SPDM) system to overcome these limitations. The system consists of...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.596147
更新日期：1987-09-01 00:00:00
abstract：PURPOSE:Given its sensitivity to anatomical variations, proton therapy is expected to benefit greatly from integration with magnetic resonance imaging for online anatomy monitoring during irradiation. Such an integration raises several challenges, as both systems mutually interact. The proton beam will experience quasi...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1002/mp.12961
更新日期：2018-07-01 00:00:00
abstract：PURPOSE:In C-arm computed tomography (CT), the field of view (FOV) is often not sufficient to acquire certain anatomical structures, e.g., a full hip or thorax. Proposed methods to extend the FOV use a fixed detector displacement and a 360° scan range to double the radius of the FOV. These trajectories are designed for...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4915542
更新日期：2015-05-01 00:00:00
abstract：:A multislit collimator was designed and fabricated for basic studies on microbeam radiation therapy (MRT) with an x-ray energy of about 100 keV. It consists of 30 slits that are 25 microm high, 30 mm wide, and 5 mm thick in the beam direction. The slits were made of 25 microm-thick polyimide sheets that were separated...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.2940157
更新日期：2008-07-01 00:00:00
abstract：:Two new liquid ionization chamber (LIC) designs, consisting of cylindrical and plane-parallel configurations, are presented. They are designed to be suitable for high-precision measurements of absorbed dose-to-water at dose rates and photon energies typical for LDR intermediate photon energy brachytherapy sources. The...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.598268
更新日期：1998-06-01 00:00:00
abstract：PURPOSE:To simplify the often complex and user-dependent manual region of interest (ROI) selection process for head motion monitoring, an automatic ROI selection method was developed. METHODS:The automatic ROI selection algorithm calculated the displacements and velocities of 3D surface points between a temporally cor...
journal_title：Medical physics
pub_type： 杂志文章
doi：10.1118/1.4711805
更新日期：2012-06-01 00:00:00
