Liquid ionization chambers for absorbed dose measurements in water at low dose rates and intermediate photon energies.

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 chambers have a sensitive liquid layer thickness of 1 mm and sensitive volumes of 7 mm3 (plane-parallel) and 20 mm3 (cylindrical). The liquids used as sensitive media in the chambers are either isooctane (C8H18), tetramethylsilane (Si(CH3)4) or mixtures of these two liquids in the approximate proportions 2 to 1. A chamber filled with such a liquid mixture and with a polarizing voltage of 300 V, provides a volume sensitivity of about 10(-9)C Gy(-1) mm(-3) for absorbed dose measurements in water in an x-ray radiation field with an effective photon energy of 120 keV. In the interval 30 to 140 keV, the relative change in sensitivity is less than +/- 2.5%. The leakage current of the chambers is low and stable, which implies that absorbed dose measurements can be done with good reproducibility at dose-rates as low as 50 microGy min-1 (sigma < 3%). The long-term calibration stability was tested for a set of five chambers over a period of more than 1 year. No systematic change in their sensitivity could be observed. The general recombination at a polarizing voltage of 300 V is less than 2% for dose-rates up to about 100 mGy min-1. The temperature dependence at room temperature is 0.5% per degree C. The response is almost independent of the direction of the radiation for the plane-parallel LIC.

journal_name

Med Phys

journal_title

Medical physics

authors

Wickman G,Johansson B,Bahar-Gogani J,Holmström T,Grindborg JE

doi

10.1118/1.598268

subject

Has Abstract

pub_date

1998-06-01 00:00:00

pages

900-7

issue

6

eissn

0094-2405

issn

2473-4209

journal_volume

25

pub_type

杂志文章
  • Assessment of the limiting spatial resolution of an MRI scanner by direct analysis of the edge spread function.

    abstract::Limiting spatial resolution is a key metric of the quality of magnetic resonance (MR) images, which can provide an indication of the smallest region that can effectively be imaged. In this paper a novel methodology for measuring the limiting spatial resolution of MR images is mathematically analyzed and successfully i...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.3097633

    authors: Delakis I,Xanthis C,Kitney RI

    更新日期:2009-05-01 00:00:00

  • First study of on-treatment volumetric imaging during respiratory gated VMAT.

    abstract:PURPOSE:To obtain on-treatment volumetric patient anatomy during respiratory gated volumetric modulated arc therapy (VMAT). METHODS:On-board imaging device integrated with Linacs offers a viable tool for obtaining patient anatomy during radiation treatment delivery. In this study, the authors acquired beam-level kV im...

    journal_title:Medical physics

    pub_type: 信件

    doi:10.1118/1.4794925

    authors: Choi K,Xing L,Koong A,Li R

    更新日期:2013-04-01 00:00:00

  • A data-mining framework for large scale analysis of dose-outcome relationships in a database of irradiated head and neck cancer patients.

    abstract:PURPOSE:To develop a hypothesis-generating framework for automatic extraction of dose-outcome relationships from an in-house, analytic oncology database. METHODS:Dose-volume histograms (DVH) and clinical outcomes have been routinely stored to the authors' database for 684 head and neck cancer patients treated from 200...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4922686

    authors: Robertson SP,Quon H,Kiess AP,Moore JA,Yang W,Cheng Z,Afonso S,Allen M,Richardson M,Choflet A,Sharabi A,McNutt TR

    更新日期:2015-07-01 00:00:00

  • Dose-averaged LET calculation for proton track segments using microdosimetric Monte Carlo simulations.

    abstract:PURPOSE:There is an increasing interest in calculating linear energy transfer (LET) distributions for proton therapy treatments in order to assess the influence of this quantity in biological terms. Microdosimetric Monte Carlo (MC) simulations are useful tools to calculate dose-averaged LET, as this has been broadly pr...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.13643

    authors: Bertolet A,Baratto-Roldán A,Barbieri S,Baiocco G,Carabe A,Cortés-Giraldo MA

    更新日期:2019-09-01 00:00:00

  • High correlation between radiation dose estimates for 256-slice CT obtained by highly parallelized hybrid Monte Carlo computation and solid-state metal-oxide semiconductor field-effect transistor measurements in physical anthropomorphic phantoms.

    abstract:PURPOSE:Accurate, patient-specific radiation dosimetry for CT scanning is critical to optimize radiation doses and balance dose against image quality. While Monte Carlo (MC) simulation is often used to estimate doses from CT, comparison of estimates to experimentally measured values is lacking for advanced CT scanners ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.13780

    authors: Prinsen P,Trattner S,Wiegert J,Gerland EL,Shefer E,Morton T,Thompson CM,Cheng B,Halliburton SS,Einstein AJ

    更新日期:2019-11-01 00:00:00

  • An investigation into the robustness of dynamically collimated proton therapy treatments.

    abstract:PURPOSE:To investigate the dosimetric robustness of dynamically collimated proton therapy (DCPT) treatment plans delivered using a dynamic collimation system (DCS) with respect to random uncertainties in beam spot and collimator position as well as systematic offsets in the DCS mounting alignment. This work also demons...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.14208

    authors: Smith BR,Hyer DE,Culberson WS

    更新日期:2020-08-01 00:00:00

  • Differences in the lesion formation process between focused ultrasound and microwave ablations.

    abstract::The objective is to understand the differences in the lesion formation processes between microwave and high-intensity focused ultrasound (HIFU) ablation. The lesions formed by microwaves and HIFU were real-time monitored and compared using transparent tissue-mimicking phantoms at 60 and 70 W of driving electrical powe...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2193689

    authors: Chen WS,Wu CC,Fang HY,Liu HL

    更新日期:2006-05-01 00:00:00

  • Static multileaf collimator for fast-neutron therapy.

    abstract::This paper describes a multileaf collimator, designed to obtain irregularly shaped neutron fields, that fits into an existing fixed field-size collimator system. The shape of the desired portal field is obtained by appropriately setting the position of each leaf of the collimator. The collimator consists of 40 polyeth...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.596084

    authors: Chu JC,Bloch P

    更新日期:1987-03-01 00:00:00

  • Evaluation of deformable registration of patient lung 4DCT with subanatomical region segmentations.

    abstract::Deformable registration is needed for a variety of tasks in establishing the voxel correspondence between respiratory phases. Most registration algorithms assume or imply that the deformation field is smooth and continuous everywhere. However, the lungs are contained within closed invaginated sacs called pleurae and a...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2828378

    authors: Wu Z,Rietzel E,Boldea V,Sarrut D,Sharp GC

    更新日期:2008-02-01 00:00:00

  • Unwanted radiation produced by leakage neutrons from medical electron accelerators.

    abstract::Monte Carlo calculations have been made to determine the energy delivered to a phantom by neutrons escaping from the head of a Varian Clinac 35 medical accelerator at an SSD of 1 m. The energy was sorted into two regions: inside and outside a volume defined by a circular beam of area 100 and 600 cm2. For the two beam ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.595067

    authors: Ing H,Shore RA

    更新日期:1982-01-01 00:00:00

  • MO-F-BRCD-01: Stereotactic Body Radiation Therapy: Updates on Clinical, Biological, and Physics/QA:SBRT (Part 1): Biological and Clinical Updates.

    abstract::Stereotactic Body Radiation Therapy (SBRT) is an important form of cancer therapy with increasingly broad application across a spectrum of tumor types in primary and metastatic settings. In this presentation the radiation biology, clinical experience from various trials, and cautionary updates on normal tissue toleran...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4735812

    authors: Read P

    更新日期:2012-06-01 00:00:00

  • Evaluation of a direct motion estimation/correction method in respiratory-gated PET/MRI with motion-adjusted attenuation.

    abstract:PURPOSE:Respiratory motion compensation in PET/CT and PET/MRI is essential as motion is a source of image degradation (motion blur, attenuation artifacts). In previous work, we developed a direct method for joint image reconstruction/motion estimation (JRM) for attenuation-corrected (AC) respiratory-gated PET, which us...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.12253

    authors: Bousse A,Manber R,Holman BF,Atkinson D,Arridge S,Ourselin S,Hutton BF,Thielemans K

    更新日期:2017-06-01 00:00:00

  • Use of capillary optics as a beam intensifier for a Compton x-ray source.

    abstract::The use of Kumakhov capillary optics will significantly enhance the performance of near-monochromatic, Compton backscattered x-ray programs. The Vanderbilt University Medical Free-Electron Laser Center is developing the capability to create these tunable x rays for medical imaging. The present transport has only refle...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.597218

    authors: Tompkins PA,Abreu CC,Carroll FE,Xiao QF,MacDonald CA

    更新日期:1994-11-01 00:00:00

  • Recognition of healthy and cancerous breast cells: Sensing the differences by dielectric spectroscopy.

    abstract:PURPOSE:The response of human cells to applied electrical signals depends on the cellular health status, because it is influenced by the composition and structure of the main cellular components. Therefore, electrical impedance-based techniques can be considered as sensitive tools to investigate healthy or disease stat...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.14425

    authors: Ambrico M,Lasalvia M,Ligonzo T,Ambrico PF,Perna G,Capozzi V

    更新日期:2020-10-01 00:00:00

  • Towards Data-Efficient Learning: A Benchmark for COVID-19 CT Lung and Infection Segmentation.

    abstract:PURPOSE:Accurate segmentation of lung and infection in COVID-19 computed tomography (CT) scans plays an important role in the quantitative management of patients. Most of the existing studies are based on large and private annotated datasets that are impractical to obtain from a single institution, especially when radi...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.14676

    authors: Ma J,Wang Y,An X,Ge C,Yu Z,Chen J,Zhu Q,Dong G,He J,He Z,Cao T,Zhu Y,Nie Z,Yang X

    更新日期:2020-12-23 00:00:00

  • Calibrated breast density methods for full field digital mammography: a system for serial quality control and inter-system generalization.

    abstract:PURPOSE:The authors are developing a system for calibrated breast density measurements using full field digital mammography (FFDM). Breast tissue equivalent (BTE) phantom images are used to establish baseline (BL) calibration curves at time zero. For a given FFDM unit, the full BL dataset is comprised of approximately ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4903299

    authors: Lu B,Smallwood AM,Sellers TA,Drukteinis JS,Heine JJ,Fowler EE

    更新日期:2015-02-01 00:00:00

  • Patch-based generation of a pseudo CT from conventional MRI sequences for MRI-only radiotherapy of the brain.

    abstract:PURPOSE:In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to e...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4914158

    authors: Andreasen D,Van Leemput K,Hansen RH,Andersen JA,Edmund JM

    更新日期:2015-04-01 00:00:00

  • Semiautomated registration of pre- and intraoperative CT for image-guided percutaneous liver tumor ablation interventions.

    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

    authors: Gunay G,Luu MH,Moelker A,van Walsum T,Klein S

    更新日期:2017-07-01 00:00:00

  • Impact of flat panel-imager veiling glare on scatter-estimation accuracy and image quality of a commercial on-board cone-beam CT imaging system.

    abstract:PURPOSE:The purposes of this study is to measure the low frequency drop (LFD) of the modulation transfer function (MTF), associated with the long tails of the detector point spread function (PSF) of an on-board flat panel imager and study its impact on cone-beam CT (CBCT) image quality and scatter measurement accuracy....

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4747260

    authors: Lazos D,Williamson JF

    更新日期:2012-09-01 00:00:00

  • Recent progress in x-ray stereoscopes.

    abstract::An improved reconstructed stereoscopic x-ray image display system, based on the principle of binocular parallax, is described. Pulse-synchronized operation of two triode x-ray tubes and one plumbicon TV camera is employed to separate the left and right images for presentation to the two eyes, respectively. The princip...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.595365

    authors: Zhang S,King PH,Pang XD

    更新日期:1983-09-01 00:00:00

  • An evaluation of the TSE MR sequence for time efficient data acquisition in polymer gel dosimetry of applications involving high doses and steep dose gradients.

    abstract::The use of magnetic resonance imaging as a readout method for polymer gel dosimetry commonly involves long imaging sessions, particularly when high spatial resolution is required in all three dimensions, for the investigation of dose distributions with steep dose gradients and stringent dose delivery specifications. I...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.2065367

    authors: Baras P,Seimenis I,Sandilos P,Vlahos L,Bieganski T,Georgiou E,Pantelis E,Papagiannis P,Sakelliou L

    更新日期:2005-11-01 00:00:00

  • On calculating kerma, collision kerma and radiative yields.

    abstract:PURPOSE:To study the relationships between dose (D), kerma (K), and collision kerma ( K col ) in photon beams and to investigate total radiative yields for electrons and positrons as a functio...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.13744

    authors: Rogers DWO,Townson RW

    更新日期:2019-11-01 00:00:00

  • Verification of radiotherapy treatments: computerized analysis of the size and shape of radiation fields.

    abstract::An automated technique has been developed for the verification of treatment field size and shape in external beam radiation therapy. Portal images from film or digital on-line imaging system are analyzed, and basic parameters are derived to describe the field size and shape from the contour points on the field boundar...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.597017

    authors: Leszczynski KW,Shalev S,Gluhchev G

    更新日期:1993-05-01 00:00:00

  • MO-F-BRA-02: Evaluation of 4D CT to 4D Cone-Beam CT Deformable Image Registration for Lung Cancer Adaptive Radiation Therapy.

    abstract:PURPOSE:To evaluate two deformable image registration (DIR) algorithms for the purpose of contour mapping to support image guided adaptive radiotherapy (IGART) with 4D cone beam CT (4DCBCT). METHODS:Eleven locally advanced non-small cell lung cancer (NSCLC) patients underwent one planning 4D fan- beam CT (4DFBCT) and ...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4735821

    authors: Balik S,Hugo G,Weiss E,Jan N,Roman N,Sleeman W,Fatyga M,Christensen G,Murphy M,Lu J,Keall P,Williamson J

    更新日期:2012-06-01 00:00:00

  • 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...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.4735656

    authors: Yang W,Sandler H,Fraass B

    更新日期:2012-06-01 00:00:00

  • SU-E-I-108: Simple Approach to Determine Patient's Entrance Skin Exposure for Radiographic.

    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

    authors: Maricle S,Jeutang L,Prasad G

    更新日期:2012-06-01 00:00:00

  • Use of simulated annealing for optimization of alignment parameters in limited MRI acquisition volumes of the brain.

    abstract::Studies suggest that clinical outcomes are improved in repeat trigeminal neuralgia (TN) Gamma Knife radiosurgery if a different part of the nerve from the previous radiosurgery is treated. The MR images taken in the first and repeat radiosurgery need to be coregistered to map the first radiosurgery volume onto the sec...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.1944287

    authors: Li X,Zhang P,Brisman R,Kutcher G

    更新日期:2005-07-01 00:00:00

  • Discriminating solitary cysts from soft tissue lesions in mammography using a pretrained deep convolutional neural network.

    abstract:PURPOSE:It is estimated that 7% of women in the western world will develop palpable breast cysts in their lifetime. Even though cysts have been correlated with risk of developing breast cancer, many of them are benign and do not require follow-up. We develop a method to discriminate benign solitary cysts from malignant...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.12110

    authors: Kooi T,van Ginneken B,Karssemeijer N,den Heeten A

    更新日期:2017-03-01 00:00:00

  • Comparison of planned dose on different CT image sets to four-dimensional Monte Carlo dose recalculation using the patient's actual breathing trace for lung stereotactic body radiation therapy.

    abstract:PURPOSE:The need for four-dimensional (4D) treatment planning becomes indispensable when it comes to radiation therapy for moving tumors in the thoracic and abdominal regions. The primary purpose of this study is to combine the actual breathing trace during each individual treatment fraction with the Linac's log file i...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1002/mp.13579

    authors: Freislederer P,von Münchow A,Kamp F,Heinz C,Gerum S,Corradini S,Söhn M,Reiner M,Roeder F,Floca R,Alber M,Belka C,Parodi K

    更新日期:2019-07-01 00:00:00

  • Modification of the University of Washington Neutron Radiotherapy Facility for optimization of neutron capture enhanced fast-neutron therapy.

    abstract::A modified neutron production target assembly has been developed to provide improved performance of the proton-cyclotron-based neutron radiotherapy facility at the University of Washington for applications involving neutron capture enhanced fast-neutron therapy. The new target produces a neutron beam that yields essen...

    journal_title:Medical physics

    pub_type: 杂志文章

    doi:10.1118/1.598839

    authors: Nigg DW,Wemple CA,Risler R,Hartwell JK,Harker YD,Laramore GE

    更新日期:2000-02-01 00:00:00