Abstract:
PURPOSE:To identify which physical properties of nanoparticles are correlated with the survival fraction of cells exposed in vitro to low-energy protons in combination with nanoparticles. METHODS:The Geant4 simulation toolkit (version 10.3) was used to model nanoparticles of different sizes (5-50 nm) and materials (Ti, Zr, Hf, Ta, Au, Pt), with or without an organic capping ensuring biocompatibility and to irradiate them with 1.3 or 4 MeV protons and 5.3 MeV alpha particles. The spectra of secondary electrons inside and at the nanoparticle surface were computed, as well as electron yields, Auger and organic capping contribution, trapping in metal bulk and linear energy transfer profiles as a function of distance from the nanoparticle center. In a next step, an in silico cell model was designed and loaded with gold nanoparticles, according to experimental uptake values. Dose to the cell was evaluated macroscopically and microscopically in 100 × 100 × 100 nm³ voxels for different radiation qualities. RESULTS:The cell geometry showed that radiation enhancement is negligible for the gold concentration used and for any radiation quality. However, when the single nanoparticle geometry is considered, we observed a local LET in its vicinity considerably higher than for the water equivalent case (up to 5 keV/μm at the titanium nanoparticle surface compared to 2.5 keV/μm in the water case). The yield of secondary electrons per primary interaction with 1.3 MeV protons was found to be most favorable for titanium (1.54), platinum (1.44), and gold (1.32), although results for higher Z metals are probably underestimated due to the incomplete simulation of de-excitation cascade in outer shells. It was also found that the organic capping contributed mostly to the production of low-energy electrons, adding a spike of dose near the nanoparticle surface. Indeed, the yield for the coated gold nanoparticle increased to 1.53 when exposed to 1.3 MeV protons. Although most electrons are retained inside larger nanoparticles (50 nm), it was shown that their yield is comparable to smaller sizes and that the linear energy transfer profile is better. From a combination of ballistic and nanoparticle size factors, it was concluded that 10-nm gold nanoparticles were better inducers of additional cell killing than 5-nm gold nanoparticles, matching our previous in vitro study. CONCLUSIONS:Although effects from a physical standpoint are limited, the high linear energy transfer profile at the nanoparticle surface generates detrimental events in the cell, in particular ROS-induced damage and local heating.
journal_name
Med Physjournal_title
Medical physicsauthors
Heuskin AC,Gallez B,Feron O,Martinive P,Michiels C,Lucas Sdoi
10.1002/mp.12362subject
Has Abstractpub_date
2017-08-01 00:00:00pages
4299-4312issue
8eissn
0094-2405issn
2473-4209journal_volume
44pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:The extensive use of computed tomography (CT) in diagnostic procedures is accompanied by a growing need for more accurate and patient-specific dosimetry techniques. Optically stimulated luminescent dosimeters (OSLDs) offer a potential solution for patient-specific CT point-based surface dosimetry by measuring a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4914398
更新日期:2015-04-01 00:00:00
abstract:PURPOSE:High resolution three-dimensional (3D) magnetic resonance (MR) images are well suited for automated cartilage segmentation in the human knee joint. However, volumetric scans such as 3D Double-Echo Steady-State (DESS) images are not routinely acquired in clinical practice which limits opportunities for reliable ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14421
更新日期:2020-10-01 00:00:00
abstract::A commercially available open MRI unit is under routine use for radiation therapy simulation. The effects of a gradient distortion correction (GDC) program used to post process the images were assessed by comparison with the known geometry of a phantom. The GDC reduced the magnitude of the distortions at the periphery...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1513991
更新日期:2002-11-01 00:00:00
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
更新日期:2020-08-01 00:00:00
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
更新日期:2007-05-01 00:00:00
abstract:PURPOSE:The purpose of this technical note is to introduce variance component analysis to the estimation of systematic and random components in setup error of radiotherapy. METHODS:Balanced data according to the one-factor random effect model were assumed. RESULTS:Analysis-of-variance (anova)-based computation was ap...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4961397
更新日期:2016-09-01 00:00:00
abstract::The purpose of this work is to demonstrate a proof of feasibility of the application of a commercial prototype deformable model algorithm to the problem of delineation of anatomic structures on four-dimensional (4D) computed tomography (CT) image data sets. We acquired a 4D CT image data set of a patient's thorax that...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1929207
更新日期:2005-07-01 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::The use of dedicated magnetic resonance simulation (MR-SIM) platforms in Radiation Oncology has expanded rapidly, introducing new equipment and functionality with the overall goal of improving the accuracy of radiation treatment planning. However, this emerging technology presents a new set of challenges that need to ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14695
更新日期:2021-01-01 00:00:00
abstract::A new type of radiographic film, EDR (extended dose range) film, has been recently become available for film dosimetry. It is particularly attractive for composite isodose verification of intensity modulated radiation therapy because of its low sensitivity relative to the more common Kodak XV film. For XV film, the re...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1568979
更新日期:2003-05-01 00:00:00
abstract::Stereotactic Body Radiation Therapy (SBRT) is being increasingly used in the radiation oncology community to treat tumors in extra-cranial sites such as spine, lung, liver, pancreas and prostate. There are well established RTOG protocols (e.g. RTOG 0631 for spine, RTOG 0813 and 0915 for lung and RTOG 0438 for liver) t...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4736142
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:The accuracy of a six degree of freedom (6DoF) couch was evaluated using a novel method. METHODS:Cone beam CT (CBCT) images of a 3D phantom (IsoCal) were acquired with different, known combinations of couch pitch and roll angles. Pitch and roll angles between the maximum allowable values of 357 and 3 degrees w...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12342
更新日期:2017-08-01 00:00:00
abstract::Assessment of clinic and site specific margins are essential for the effective use of three-dimensional and intensity modulated radiation therapy. An electronic portal imaging device (EPID) based methodology is introduced which allows individual and population based CTV-to-PTV margins to be determined and compared wit...
journal_title:Medical physics
pub_type: 临床试验,杂志文章
doi:10.1118/1.1800712
更新日期:2004-11-01 00:00:00
abstract:PURPOSE:The authors introduce a novel method for defining standardized uptake values (SUVs) in PET∕CT based on routinely collected CT data. The goal of the study is to reduce, if possible, the variability of SUV in a heterogeneous population. Two well established methods for defining SUV are based on body weight (BW) a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4816656
更新日期:2013-09-01 00:00:00
abstract::Reconstruction of electron spectra of medical accelerators from measured depth dose distributions is an attractive tool for commissioning of a Monte Carlo treatment planning system. However, the reconstruction method is an inverse radiation transport problem which is poorly conditioned, in the sense it may become unst...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1461840
更新日期:2002-04-01 00:00:00
abstract:PURPOSE:To investigate the acoustic radiation due to eddy current-cryostat interactions and perform a qualitative analysis on noise reduction methods. METHODS:In order to evaluate the sound pressure level (SPL) of the eddy current induced warm bore wall vibration, a Finite Element (FE) model was created to simulate th...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.12261
更新日期:2017-06-01 00:00:00
abstract::Intrafraction organ motion can limit the advantage of highly conformal dose techniques such as intensity modulated radiation therapy (IMRT) due to target position uncertainty. To ensure high accuracy in beam targeting, real-time knowledge of the target location is highly desired throughout the beam delivery process. T...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2905225
更新日期:2008-05-01 00:00:00
abstract::In conventional dose optimization algorithms, in brachytherapy, multiple objectives are expressed in terms of an aggregating function which combines individual objective values into a single utility value, making the problem single objective, prior to optimization. A multiobjective genetic algorithm (MOGA) was develop...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598697
更新日期:1999-09-01 00:00:00
abstract:PURPOSE:For cone-beam computed tomography (CBCT) systems, we propose a sphere phantom based method to estimate the full three-dimensional (3D) modulation transfer function (MTF). METHODS:The FDK reconstruction of CBCT system in a local region was modeled by a triple convolution operator. Afterward, we calculated the d...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14147
更新日期:2020-07-01 00:00:00
abstract:PURPOSE:New technology has been developed to treat age-related macular degeneration (AMD) using 100 kVp pencil-beams that enter the patient through the radio-resistant sclera with a depth of interest between 1.6 and 2.6 cm. Measurement of reference and relative dose in a kilovoltage x-ray beam with a 0.42 cm diameter f...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4863482
更新日期:2014-02-01 00:00:00
abstract::An important aspect of heavy charged particle radiotherapy is its ability to localize dose to the target volume. Current techniques generally employ beam delivery schemes which use range modulated beams in which the Bragg peak is spread out over a range of depths. The range modulation is constant over the entire beam ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.595419
更新日期:1983-11-01 00:00:00
abstract:PURPOSE:To measure patient-specific maximum skin dose (MSD) associated with CT fluoroscopy (CTF) lung biopsies and to compare measured MSD with the MSD estimated from phantom measurements, as well as with the CTDIvol of patient examinations. METHODS:Data from 50 patients with lung lesions who underwent a CT fluoroscop...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4884231
更新日期:2014-07-01 00:00:00
abstract::The BEAMnrc/EGSnrc Monte Carlo code system is employed to develop a model of the National Research Council of Canada primary standard of absorbed dose to tissue in a beta radiation field, comprising an extrapolation chamber and 90Sr/90Y beta source. We benchmark the model against the measured response of the chamber i...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1997347
更新日期:2005-10-01 00:00:00
abstract:PURPOSE:The aim of this study is to investigate the performance of Sentinel(™), a patient setup verification device based on a laser/camera system, when used on rigid-body phantoms. METHODS:The Sentinel system consists of a scanner unit, containing the laser and the camera, and surface-matching registration software. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3675973
更新日期:2012-02-01 00:00:00
abstract::The mixed-field dosimetry for 252Cf Applicator Tube (AT) type medical sources available from Oak Ridge National Laboratory (ORNL) has been characterized using ionization chambers, a GM counter, and Monte Carlo methods. Unlike the AAPM Task Group No. 43 (TG-43), specification of dose to muscle instead of water is recom...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598646
更新日期:1999-08-01 00:00:00
abstract::Electron spectral reconstruction of medical accelerators from measured depth doses is a practical method for providing the input initial phase space distribution at the patient surface that is required by Monte Carlo treatment planning systems. The posed inverse problem of spectral reconstruction is ill conditioned an...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2161404
更新日期:2006-02-01 00:00:00
abstract:PURPOSE:Air-communicating well ionization chambers are commonly used to assess air kerma strength of sources used in brachytherapy. The signal produced is supposed to be proportional to the air density within the chamber and, therefore, a density-independent air kerma strength is obtained when the measurement is correc...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4831757
更新日期:2013-12-01 00:00:00
abstract:PURPOSE:To determine the accuracy of VMAT treatment planning and delivery for patients undergoing radiotherapy in the head and neck. METHOD AND MATERIALS:A dosimetric study of a typical head and neck treatment plan has been carried out using Chamber, film and TLD's placed inside an anthropomorphic phantom. Lateral and...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735478
更新日期:2012-06-01 00:00:00
abstract::Three types of iterative algorithms, algebraic inverse treatment planning (AITP), simultaneous iterative inverse treatment planning (SIITP), and iterative least-square inverse treatment planning (ILSITP), differentiated according to their updating sequences, were generalized to three dimension with true beam geometry ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598374
更新日期:1998-10-01 00:00:00
abstract:PURPOSE:This study aims to investigate the feasibility of using the images of the treatment fields acquired by an electronic portal imaging device (EPID) for real-time target localization. METHODS:Forty one patients treated with IMRT and RapidArc were recruited in this study including 37 prostate patients and 4 lung p...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734975
更新日期:2012-06-01 00:00:00