Abstract:
:As known, in cancer therapy with ion beams the relative biological effectiveness (RBE) of ions changes in the course of their propagation in tissues. Such changes are caused not only by increasing the linear energy transfer (LET) of beam particles with the penetration depth towards the Bragg peak, but also by nuclear reactions induced by beam nuclei leading to the production of various secondary particles. Although the changes of RBE along the beam axis have been studied quite well, much less attention has been paid to the evolution of RBE in the transverse direction, perpendicular to the beam axis. In order to fill this gap, we simulated radiation fields of 1H, 4He, 12C and 16O nuclei of 20 mm in diameter by means of a Geant4-based Monte Carlo model for heavy-ion therapy connected with the modified microdosimetric kinetic model to describe the response of normal ([Formula: see text] Gy) and early-responding ([Formula: see text] Gy) tissues. Depth and radial distributions of saturation-corrected dose-mean lineal energy, RBE and RBE-weighted dose are investigated for passive beam shaping and active beam scanning. The field of 4He has a small lateral spread as compared with 1H field, and it is characterised by a modest lateral variation of RBE suggesting the use of fixed RBE values across the field transverse cross section at each depth. Reduced uncertainties of RBE on the boundary of a 4He treatment field can be advantageous in a specific case of an organ at risk located in lateral proximity to the target volume. It is found that the lateral distributions of RBE calculated for 12C and 16O fields demonstrate fast variations in the radial direction due to changes of dose and composition of secondary fragments in the field penumbra. Nevertheless, the radiation fields of all four projectiles at radii larger than 20 mm can be characterized by a common RBE value defined by tissue radiosensitivity. These findings can help, in particular, in accessing the transverse homogeneity of radiation fields of ions used in studies in vitro.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Dewey S,Burigo L,Pshenichnov I,Mishustin I,Bleicher Mdoi
10.1088/1361-6560/aa75b2subject
Has Abstractpub_date
2017-06-27 00:00:00pages
5884-5907issue
14eissn
0031-9155issn
1361-6560journal_volume
62pub_type
杂志文章abstract::This paper analyzes the radio frequencies (RF) exposure in the head tissues of children using a cellular handset or RF sources (a dipole and a generic handset) at 900, 1800, 2100 and 2400 MHz. Based on magnetic resonance imaging, child head models have been developed. The maximum specific absorption rate (SAR) over 10...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/13/019
更新日期:2008-07-07 00:00:00
abstract::In this paper, we present a segmentation and classification method for thyroid follicular neoplasms based on a combination of the prior-based level set method and deep convolutional neural network. The proposed method aims to discriminate thyroid follicular adenoma (TFA) and follicular thyroid carcinoma (FTC) in ultra...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/abc6f2
更新日期:2020-11-02 00:00:00
abstract::This work aims at developing a generic virtual source model (VSM) preserving all existing correlations between variables stored in a Monte Carlo pre-computed phase space (PS) file, for dose calculation and high-resolution portal image prediction. The reference PS file was calculated using the PENELOPE code, after the ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/14/5215
更新日期:2016-07-21 00:00:00
abstract::We review the application of fluorescence spectroscopy and elastic-scattering spectroscopy, over the ultraviolet-to-visible wavelength range, to minimally invasive medical diagnostics. The promises and hopes, as well as the difficulties, of these developing techniques are discussed. ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章,评审
doi:10.1088/0031-9155/42/5/005
更新日期:1997-05-01 00:00:00
abstract::Ultrasoft x-rays of 0.3-5 keV have provided a unique tool for the investigation of intracellular mechanisms of radiation action in biological organisms, including mammalian cells. However, their use presents unique practical problems in dosimetry and experimental design. Detailed interpretation of the biological resul...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/30/10/002
更新日期:1985-10-01 00:00:00
abstract::Sparse phased array ultrasound transducers with millimetre length scale elements have previously been proposed for generating hyperthermia but not for imaging. Numerical simulation with a pseudospectral solver was used to investigate: (a) how the position of the maximum pressure in the focal region changed with elemen...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aace07
更新日期:2018-07-16 00:00:00
abstract::The design, construction and use of a large-scale field-cycled proton-electron double-resonance imaging (FC-PEDRI) imager is described. The imager is based on a whole-body sized, vertical field, 59 mT permanent magnet. Field cycling is accomplished by the field compensation method, and uses a secondary, resistive magn...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/43/7/008
更新日期:1998-07-01 00:00:00
abstract::In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of H...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/7/013
更新日期:2005-04-07 00:00:00
abstract::A new hybrid imaging-treatment modality, the MRI-Linac, involves the irradiation of the patient in the presence of a strong magnetic field. This field acts on the charged particles, responsible for depositing dose, through the Lorentz force. These conditions require a dose calculation engine capable of taking into con...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/16/003
更新日期:2011-08-21 00:00:00
abstract::In recent years, the Monte Carlo method has been used in a large number of research studies in radiation therapy. For applications such as treatment planning, it is essential to validate the dosimetric accuracy of the Monte Carlo simulations in heterogeneous media. The AAPM Report no 105 addresses issues concerning cl...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/16/016
更新日期:2008-08-21 00:00:00
abstract::None of the existing protocols or codes of practice for high-energy electron dosimetry take any account of the accelerator-generated bremsstrahlung always present in electron beams. This results in a systematic error in the derivation of the absorbed dose. The purpose of this study is to draw attention to this omissio...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/39/7/004
更新日期:1994-07-01 00:00:00
abstract::K line x-ray fluorescence (KXRF) measurements of bone lead have emerged as a promising new biological marker of internal lead dose in epidemiological studies. Some disagreements exist, however, over the analysis of data at low levels of bone lead concentration. In this study, we performed 30 serial measurements on eac...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/40/9/007
更新日期:1995-09-01 00:00:00
abstract::The aim of the present work was to investigate how the native signal observed in the electron paramagnetic resonance (EPR) spectrum of tooth enamel and dentin is associated with the organic content of the two tissues. This was achieved by comparing the EPR native signal and the optical bands (Raman and infrared, IR) a...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/6/004
更新日期:2005-03-21 00:00:00
abstract::In a recent paper (Chamberland et al 2016 Phys. Med. Biol. 61 8214) develop a new Monte Carlo code called egs_brachy for brachytherapy treatments. It is based on EGSnrc, and written in the C++ programming language. In order to benchmark the egs_brachy code, the authors use it in various test case scenarios in which co...
journal_title:Physics in medicine and biology
pub_type: 评论,杂志文章,信件
doi:10.1088/1361-6560/aa9ea1
更新日期:2018-02-02 00:00:00
abstract::Photosensitizer fluorescence excited by photodynamic therapy (PDT) treatment light can be used to monitor the in vivo concentration of the photosensitizer and its photobleaching. The temporal integral of the product of in vivo photosensitizer concentration and light fluence is called PDT dose, which is an important do...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa9874
更新日期:2017-12-29 00:00:00
abstract::The most advanced delivery technique for proton radiotherapy is active spot scanning. So far, predominantly static targets have been treated with active spot scanning, since mobile targets in combination with dynamic treatment delivery can lead to interplay effects, causing inhomogeneous dose distributions. One way to...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/22/016
更新日期:2011-11-21 00:00:00
abstract::The layer-stacking method can provide three-dimensional conformal dose distributions to the target based on a passive scattering method using mini-spread-out Bragg peak (SOBP). The purpose of this work is to demonstrate the effectiveness of a new weight optimization algorithm that can enhance the robustness of dose di...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab9efd
更新日期:2020-09-28 00:00:00
abstract::Ultrasound shock wave therapy is increasingly used for non-invasive surgery. It requires the focusing of very high pressure amplitude in precisely controlled focal spots. In transcostal therapy of the heart or the liver, the high impedance mismatch between the bones and surrounding tissues gives rise to strong aberrat...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aad9b5
更新日期:2018-09-06 00:00:00
abstract::Average cross-sections for inactivation of dry ribonuclease by H, He and N projectiles with energies between 100 eV and 10 keV are presented. The trend of the damage cross-sections with particle energy is consistent with the trend of the molecular quasi-elastic scattering and ionization cross-sections. A tentative rad...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/20/6/005
更新日期:1975-11-01 00:00:00
abstract::In recent years, particle therapy has become a widely accepted form of cancer treatment and technological advances in beam delivery technology (i.e. pencil beam scanning (PBS)) have enabled the application of highly conformal dose distributions to static targets. Current research focuses on the possibilities for the t...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/22/7905
更新日期:2013-11-21 00:00:00
abstract::Ion beam therapy offers the possibility of a highly conformal tumor-dose distribution; however, this technique is extremely sensitive to inaccuracies in the treatment procedures. Ambiguities in the conversion of Hounsfield units of the treatment planning x-ray CT to relative stopping power (RSP) can cause uncertaintie...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa5602
更新日期:2017-02-07 00:00:00
abstract::In clinical computed tomography (CT) images, cortical bone features with sub-millimeter (sub-mm) thickness are substantially blurred, such that their thickness is overestimated and their intensity appears underestimated. Therefore, any inquiry of the geometry or the density of such bones based on these images is sever...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/23/8099
更新日期:2012-12-07 00:00:00
abstract::Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better or...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/9/2939
更新日期:2013-05-07 00:00:00
abstract::Quantification of nuclear medicine image data is a prerequisite for personalized absorbed dose calculations and quantitative biodistribution studies. The spatial response of a detector is a governing factor affecting the accuracy of image quantification, and the aim of this work was to model this impact. To simulate s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/6/013
更新日期:2010-03-21 00:00:00
abstract::Users of nuclear and atomic data for biomedical purposes often have difficulty in identifying the most up-to-date and appropriate sources of such data. The biomedical Subcommittee of the UK Nuclear Data Committee have prepared a list of recommended data sources available at the beginning of 1978 on radioactive decay s...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/24/1/001
更新日期:1979-01-01 00:00:00
abstract::We present a new image reconstruction algorithm for helical cone-beam computed tomography (CT). This algorithm is designed for data collected at or near maximum pitch, and provides a theoretically exact and stable reconstruction while beneficially using all measured data. The main operations involved are a differentia...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/54/15/001
更新日期:2009-08-07 00:00:00
abstract::Quantitative assessment of mammographic asymmetry has been investigated for breast cancer risk prediction. A new asymmetry feature extraction method was proposed in this study to enhance the risk prediction accuracy of near-term breast cancer. Breast areas in each pair of bilateral mammographic images were divided int...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aae452
更新日期:2018-10-17 00:00:00
abstract::A method for quantifying the tissue sodium concentration (TSC) in the rat brain from ²³Na-MR images was developed. TSC is known to change in a variety of common human diseases and holds considerable potential to contribute to their study; however, its accurate measurement in small laboratory animals has been hindered ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/55/24/019
更新日期:2010-12-21 00:00:00
abstract::In external beam radiation therapy, radioactive beams offer the best clinical solution to simultaneously treat and in vivo monitor the dose delivery and tumor response using PET or PET-CT imaging. However, difficulties mainly linked to the low production efficiency have so far limited their use. This study is devoted ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/56/6/005
更新日期:2011-03-21 00:00:00
abstract::The architecture of multi-layer imagers (MLIs) can be exploited to provide megavoltage spectral imaging (MVSPI) for specific imaging tasks. In the current work, we investigated bone suppression and gold fiducial contrast enhancement as two clinical tasks which could be improved with spectral imaging. A method based on...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aabe21
更新日期:2018-05-10 00:00:00