SU-E-T-567: Improve Dose Conformity with IMRT Using Shorter Source to Tumor Distance.

Abstract:

PURPOSE:To reduce the potential of late toxicity (tissue necrosis and cognitive function loss) from brain radiotherapy, we studied a novel planning technique for MLC-equipped linear accelerators (LINACS) that reduces the high doses delivered outside the PTV, enhancing radiation dose conformity. METHODS:The feasibility of improving dose conformity by using variable source-to-tumor distances was tested on brain CT datasets with tumor contours representing solitary lesions and an example with two lesions. For the single tumor cases, different tumor volumes from 2 to 83 cc were explored, while an example double lesion had a total volume of 13 cc. Three different source-to-axis distances (SADs), 100, 80 and 65 cm, were used to create separate 5-field IMRT plans with the same beam angles for all SADs. For each example, the PTV dose coverage and critical organ doses were constrained to be the same, except for the normal brain doses that were determined by the dose conformity. High dose spillage outside the PTV was quantified by R50 (the ratio between the 50% isodose volume and the PTV), and the V12 (volume of normal brain receiving 12Gy or higher). RESULTS:R50 decreased monotonically with shorter SAD for all examples. Compared with 100 cm SAD, average R50 reductions of 13% and 19% were observed with 80 and 65 cm SAD respectively. Improved conformity was more notable on smaller lesions and the multiple lesion case. V12 also decreases significantly with shorter SAD. CONCLUSIONS:Improvement in dose conformity can be achieved on existing LINACS by reducing the treatment distance for each IMRT field. Sharper beam penumbra and smaller projected MLC leaf width contribute to the improvement. Precise delivery of non- isocentric beams can be challenging on traditional LINACS, but the problem is much more manageable on machines with precise robotic gantry and couch capabilities.

journal_name

Med Phys

journal_title

Medical physics

authors

Yang W,Sandler H,Fraass B

doi

10.1118/1.4735656

subject

Has Abstract

pub_date

2012-06-01 00:00:00

pages

3836

issue

6Part19

eissn

0094-2405

issn

2473-4209

journal_volume

39

pub_type

杂志文章
  • Subvoxel precise skeletons of volumetric data based on fast marching methods.

    abstract::The accurate calculation of the skeleton of an object is a problem not satisfactorily solved by existing approaches. Most algorithms require a significant amount of user interaction and use a voxel grid to compute discrete and often coarse approximations of this representation of the data. We present a novel, automati...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2409238

    authors: Van Uitert R,Bitter I

    更新日期:2007-02-01 00:00:00

  • Improving the calibration of radiochromic films by the use of uncertainties in optical density and dose.

    abstract:PURPOSE:To compare how the inclusion of the uncertainties in dose and optical density affects the results of the calibration of Gafchromic(®) EBT3 radiochromic films. METHODS:Five methods of least square minimization were compared for calibration of radiochromic films. These differed in the way in which the uncertaint...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4811238

    authors: Garcia LI,Azorin JF

    更新日期:2013-07-01 00:00:00

  • Development of a dynamic quality assurance testing protocol for multisite clinical trial DCE-CT accreditation.

    abstract:PURPOSE:Credentialing can have an impact on whether or not a clinical trial produces useful quality data that is comparable between various institutions and scanners. With the recent increase of dynamic contrast enhanced-computed tomography (DCE-CT) usage as a companion biomarker in clinical trials, effective quality a...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4812429

    authors: Driscoll B,Keller H,Jaffray D,Coolens C

    更新日期:2013-08-01 00:00:00

  • Thermoacoustic molecular tomography with magnetic nanoparticle contrast agents for targeted tumor detection.

    abstract:PURPOSE:The primary feasibility steps of demonstrating the ability of microwave-induced thermoacoustic (TA) in phantoms have been previously reported. However, none were shown to target a diseased site in living subjects in thermoacoustic tomography (TAT) field so far. To determine the expressions of oncogenic surface ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3466696

    authors: Nie L,Ou Z,Yang S,Xing D

    更新日期:2010-08-01 00:00:00

  • Measurement of the replacement correction factor for parallel-plate chambers in electron fields.

    abstract::When parallel-plate chambers are used for dosimetry in electron fields, the AAPM dosimetry protocol recommends a value of 1.0 for the replacement correction factor, P(repl),pp,E, until further data become available. Here, P(repl),pp,E for five commercially available parallel-plate chambers was measured as a function o...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.596740

    authors: Reft CS,Kuchnir FT

    更新日期:1991-11-01 00:00:00

  • Practical dosimetric considerations of a 10-MV photon beam.

    abstract::An overall practical dosimetric study of a 10-MV photon beam produced by a Varian Clinac-18 linear accelerator is presented. In particular measurements were made to provide data which could be utilized in computerized dosage calculations using the concept of dividing the radiation beam into primary and scatter compone...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.594311

    authors: Van Dyk J

    更新日期:1977-03-01 00:00:00

  • Iterative algebraic reconstruction algorithms for emission computed tomography: a unified framework and its application to positron emission tomography.

    abstract::In this paper, a unified framework of iterative algebraic reconstruction for emission computed tomography (ECT) and its application to positron emission tomography (PET) is presented. The unified framework is based on an algebraic image restoration model and contains conventional iterative algebraic reconstruction alg...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.596954

    authors: Xu XL,Liow JS,Strother SC

    更新日期:1993-11-01 00:00:00

  • SU-D-213CD-03: Live Video-Guided Volumetric Tracking of Respiration Motion.

    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

    authors: Li S,Haiti B,Serratore D,Neicu T,Chan P,Valakh V,Bizhan M,Miyamoto C,Geng J

    更新日期:2012-06-01 00:00:00

  • A doorless entry system for high-energy radiation therapy rooms.

    abstract::A doorless entry system has been designed for use in high-energy radiation therapy rooms. The doorless entry improves patient access, safety and throughput, increases the physical safety for the radiation therapists, and avoids the significant cost of heavy shielding doors. The design meets concerns relating to radiat...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.598181

    authors: Dawson DJ,Wissing WW,Tonks RE

    更新日期:1998-02-01 00:00:00

  • Dual-film cassette technique for studying the effect of radiographic image quality on diagnostic accuracy.

    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

    authors: Higashida Y,Doi K,Lehr JL,MacMahon H

    更新日期:1984-09-01 00:00:00

  • Task-based assessment of breast tomosynthesis: effect of acquisition parameters and quantum noise.

    abstract:PURPOSE:Tomosynthesis is a promising modality for breast imaging. The appearance of the tomosynthesis reconstructed image is greatly affected by the choice of acquisition and reconstruction parameters. The purpose of this study was to investigate the limitations of tomosynthesis breast imaging due to scan parameters an...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3357288

    authors: Reiser I,Nishikawa RM

    更新日期:2010-04-01 00:00:00

  • SU-E-T-300: Monte Carlo Simulation of Single-Plane Magnetically Focused Narrow Proton Beams.

    abstract::Purpose To investigate narrow, elongated magnetically focused proton beams and compare their properties with passively collimated beams using Monte Carlo simulation. METHODS:We performed Geant4 Monte Carlo simulations involving a single quadrapole focusing magnet, thereby creating a flattened beam with an elongated e...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4735386

    authors: McAuley G,Barnes S,Wroe A,Slater J

    更新日期:2012-06-01 00:00:00

  • Radiation attenuation by lead and nonlead materials used in radiation shielding garments.

    abstract::The attenuating properties of several types of lead (Pb)-based and non-Pb radiation shielding materials were studied and a correlation was made of radiation attenuation, materials properties, calculated spectra and ambient dose equivalent. Utilizing the well-characterized x-ray and gamma ray beams at the National Rese...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2426404

    authors: McCaffrey JP,Shen H,Downton B,Mainegra-Hing E

    更新日期:2007-02-01 00:00:00

  • Temporal and spectral imaging with micro-CT.

    abstract:PURPOSE:Micro-CT is widely used for small animal imaging in preclinical studies of cardiopulmonary disease, but further development is needed to improve spatial resolution, temporal resolution, and material contrast. We present a technique for visualizing the changing distribution of iodine in the cardiac cycle with du...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4736809

    authors: Johnston SM,Johnson GA,Badea CT

    更新日期:2012-08-01 00:00:00

  • Characteristics of an OSLD in the diagnostic energy range.

    abstract:PURPOSE:Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3602456

    authors: Al-Senan RM,Hatab MR

    更新日期:2011-07-01 00:00:00

  • Dose distribution of a 125 keV mean energy microplanar x-ray beam for basic studies on microbeam radiotherapy.

    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

    authors: Ohno Y,Torikoshi M,Suzuki M,Umetani K,Imai Y,Uesugi K,Yagi N

    更新日期:2008-07-01 00:00:00

  • Photon-beam subsource sensitivity to the initial electron-beam parameters.

    abstract::One limitation to the widespread implementation of Monte Carlo (MC) patient dose-calculation algorithms for radiotherapy is the lack of a general and accurate source model of the accelerator radiation source. Our aim in this work is to investigate the sensitivity of the photon-beam subsource distributions in a MC sour...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.1884385

    authors: Fix MK,Keall PJ,Siebers JV

    更新日期:2005-04-01 00:00:00

  • Maximum likelihood estimation of proton irradiated field and deposited dose distribution.

    abstract::In proton therapy, it is important to evaluate the field irradiated with protons and the deposited dose distribution in a patient's body. Positron emitters generated through fragmentation reactions of target nuclei can be used for this purpose. By detecting the annihilation gamma rays from the positron emitters, the a...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2712572

    authors: Inaniwa T,Kohno T,Yamagata F,Tomitani T,Sato S,Kanazawa M,Kanai T,Urakabe E

    更新日期:2007-05-01 00:00:00

  • 4D DMLC leaf sequencing to minimize organ at risk dose in moving anatomy.

    abstract::The most favorable treatment for moving body anatomy should aim at utilizing organ motion to minimize the dose to sensitive structures without compromising the dose delivered to the target. The solution of the problem of appropriate intensity redistribution over different phases of body motion is achievable in dynamic...

    journal_title:Medical physics

    pub_type: 信件

    doi:10.1118/1.2804722

    authors: Papiez L,McMahon R,Timmerman R

    更新日期:2007-12-01 00:00:00

  • Dosimetric problems at low monitor unit settings for scanned and scattering foil electron beams.

    abstract::Electron beam dosimetry at low monitor unit (MU) settings is important for dosimetric applications. Dose linearity, beam flatness, and beam energies were studied at low MU settings with various dose rates for different types of linear accelerators. It is observed that for the scattering foil units, the dose/MU is a sm...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.597328

    authors: Das IJ,Harrington JC,Akber SF,Tomer AF,Murray JC,Cheng CW

    更新日期:1994-06-01 00:00:00

  • Novel methods of measuring single scan dose profiles and cumulative dose in CT.

    abstract::Computed tomography dose index (CTDI) is a conventional indicator of the patient dose in CT studies. It is measured as the integration of the longitudinal single scan dose profile (SSDP) by using a 100-mm-long pencil ionization chamber and a single axial scan. However, the assumption that most of the SSDP is contained...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.1835571

    authors: Nakonechny KD,Fallone BG,Rathee S

    更新日期:2005-01-01 00:00:00

  • The role of humidity and other correction factors in the AAPM TG-21 dosimetry protocol.

    abstract::A detailed derivation is presented of the formulas required to determine Ngas and Dmed in the AAPM TG-21 dosimetry protocol. This protocol specifies how to determine the absorbed dose in an electron or photon beam when using exposure or absorbed dose calibrated ion chambers. It is shown that the expression given in TG...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.596292

    authors: Rogers DW,Ross CK

    更新日期:1988-01-01 00:00:00

  • Dosimetric parameters for three low-energy brachytherapy sources using the Monte Carlo N-particle code.

    abstract::Monte Carlo calculations have been performed for the purpose of characterizing the dosimetric properties of three brachytherapy sources. The three sources are manufactured by Syncor Pharmaceuticals Inc. and consist of two 125I seeds (BT-125-1 and BT-125-2) and one 103Pd seed (BT-103-3). The BT-125-1 and BT-125-2 seed ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.1469627

    authors: DeMarco JJ,Hugo G,Solberg TD

    更新日期:2002-05-01 00:00:00

  • Technical note: An algorithm to calculate the tissue phantom ratio from depth dose in radiosurgery.

    abstract:PURPOSE:To propose a method to calculate the tissue phantom ratio (TPR) using the depth dose and to compare the proposed method with two other methods. METHODS:An analytical dose model from Bjärngard was used to describe the depth dose and the TPR. The parameters of the model were derived from depth dose measurements,...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3570575

    authors: Ramos Garcia LI,Almansa JF

    更新日期:2011-05-01 00:00:00

  • Broad line quantitative chemical shift spectroscopy.

    abstract::Proton NMR spectroscopy was applied to quantitate the measurement of total body water/fat distributions in vivo. A special MR protocol was developed to excite a thick slab of tissue and display the magnitude NMR spectrum of the collected response signal. Very short echo time TE (8 ms) and long repetition time TR (4000...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.596935

    authors: Sobol WT,Elster AD,Hinson WH,Chwals WJ

    更新日期:1992-01-01 00:00:00

  • A pencil beam algorithm for magnetic resonance image-guided proton therapy.

    abstract:PURPOSE:The feasibility of magnetic resonance image (MRI)-based proton therapy is based, among several other factors, on the implementation of appropriate extensions on current dose calculation methods. This work aims to develop a pencil beam algorithm (PBA) for dose calculation of proton beams within magnetic field re...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.12854

    authors: Padilla-Cabal F,Georg D,Fuchs H

    更新日期:2018-05-01 00:00:00

  • Optimized knot placement for B-splines in deformable image registration.

    abstract:PURPOSE:To develop an automatic knot placement algorithm to enable the use of NonUniform Rational B-Splines (NURBS) in deformable image registration. METHODS:The authors developed a two-step approach to fit a known displacement vector field (DVF). An initial fit was made with uniform knot spacing. The error generated ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3609416

    authors: Jacobson TJ,Murphy MJ

    更新日期:2011-08-01 00:00:00

  • Development and validation of a measurement-based source model for kilovoltage cone-beam CT Monte Carlo dosimetry simulations.

    abstract:PURPOSE:The purpose of this study is to adapt an equivalent source model originally developed for conventional CT Monte Carlo dose quantification to the radiation oncology context and validate its application for evaluating concomitant dose incurred by a kilovoltage (kV) cone-beam CT (CBCT) system integrated into a lin...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4823795

    authors: McMillan K,McNitt-Gray M,Ruan D

    更新日期:2013-11-01 00:00:00

  • Noise power spectra of images from digital mammography detectors.

    abstract::Noise characterization through estimation of the noise power spectrum (NPS) is a central component of the evaluation of digital x-ray systems. We begin with a brief review of the fundamentals of NPS theory and measurement, derive explicit expressions for calculation of the one- and two-dimensional (1D and 2D) NPS, and...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.598623

    authors: Williams MB,Mangiafico PA,Simoni PU

    更新日期:1999-07-01 00:00:00

  • Vision 20/20: Magnetic resonance imaging-guided attenuation correction in PET/MRI: Challenges, solutions, and opportunities.

    abstract::Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing nov...

    journal_title:Medical physics

    pub_type: 杂志文章,评审

    doi:10.1118/1.4941014

    authors: Mehranian A,Arabi H,Zaidi H

    更新日期:2016-03-01 00:00:00