- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Optimal combined proton-photon therapy schemes based on the standard BED model
摘要： This paper investigates the potential of combined proton-photon therapy treatments in radiation oncology, with a special emphasis on fractionation. Several combined modality models, with and without fractionation, are discussed, and conditions under which combined modality treatments are of added value are demonstrated analytically and numerically. The combined modality optimal fractionation problem with multiple normal tissues is formulated based on the Biologically Effective Dose (BED) model and tested on real patient data. Results indicate that for several patients a combined modality treatment gives better results in terms of biological dose (up to 14.8% improvement) than single modality proton treatments. For several other patients, a combined modality treatment is found that offers an alternative to the optimal single modality proton treatment, being only marginally worse but using significantly fewer proton fractions, putting less pressure on the limited availability of proton slots. Overall, these results indicate that combined modality treatments can be a viable option, which is expected to become more important as proton therapy centers are spreading but the proton therapy price tag remains high.
关键词： biologically effective dose (BED),proton therapy,optimization,intensity-modulated radiation therapy (IMRT),multi-modality treatment
更新于2025-09-19 17:15:36
-
Occurrence and mechanism of visual phosphenes in external photon beam radiation therapy and how to influence them
摘要： Background and purpose: Two plausible mechanisms to explain the appearance of visual phosphenes are: direct activation of the photochemicals in the retina and the generation of Cherenkov radiation in the vitreous humour. In this clinical trial we investigated the occurrence of visual phosphenes in external photon beam radiation therapy. Material and methods: Logistic regression analysis is used to examine whether seeing light flashes and seeing steady light depended on the ambient light intensity and the dose. Results: In total, 465 treatments of 25 patients were analysed. The odds of seeing light flashes multiply by 0,926 as the ambient light intensity increases by 10 lux. Similarly, the odds multiply by 1,604 as the dose to the retina increases by 10 cGy. The odds of seeing steady light multiply by 1,540 as the dose to the vitreous humour increases by 10 cGy. Conclusions: We postulate that one should reduce the dose rate, instruct patients to keep the eyes open and increase the illuminance in the treatment room to reduce the probability of experiencing visual phosphenes. We hypothesize that melanopsin is involved in the visual phosphenes and that fatigue of patients might be correlated with the observation of visual phosphenes.
关键词： Light flashes,Visual phosphenes,Photoreceptor proteins,Cherenkov radiation,Photon beam radiation therapy
更新于2025-09-19 17:15:36
-
Calculation of Electron-Beam Dynamics in a C-Band Accelerator for a Radiotherapy Complex
摘要： The dynamics of the electron beam in a C-band linear accelerator, a bremsstrahlung source with a boundary energy switched between 2.5 MeV and 6 MeV, which is intended for stereotactic and three-dimensional conformal radiotherapy in static and rotational modes, was calculated.
关键词： bremsstrahlung target,linear electron accelerator,electron gun,beam dynamics,radiation therapy complex,accelerating structure
更新于2025-09-19 17:15:36
-
Hadron Therapy Based on Laser Acceleration in the Plasma Channel Using Oxygen Ionization
摘要： In a cancer radiation treatment, Hadron therapy plays an important role as a technique with a high accuracy providing treatment results better than conventional radiation therapy methods such as chemotherapy. The laser-based Hadron therapy techniques are attractive due to their compactness in producing miniaturized particle accelerators and supporting a more intense electric field compared to other methods. A good-quality laser beam focusing and guiding in a cold plasma channel leads to an accurate and precise laser spot after focus, which is an important necessity in medical aims and occurs in ????-wavelength (ultra-short pulse) laser types. A method used to level up this treatment approach has been emerged by using high-power lasers along with plasma channels as a source for high energy to more effectively perform the Hadron therapy. Additionally, cancer treatment by using ions as the particle transferor is preferred over other methods for Hadron therapy due to some physical properties such as maximum energy deposition to the cancerous targets providing a better dose delivery to the tumor. In this paper, multiple simulations around the dose delivery procedures were presented for efficient dosimetric evaluations. Moreover, the effects of the electric field on the particle energy enhancement were evaluated in the presence of the plasma channel. Finally, it was demonstrated that the use of Oxygen ion in the presence of plasma channel is the appropriate approach due to its minor energy dissipation through matter on the way to the tumor for a better dose delivery which was impressed with radially polarized laser accelerator simultaneously. The proposed research demonstrated that the Hadrons can reach the maximum accelerated energy and convey the maximum path through the body to the cancerous target and finally deliver the sufficient dose to the tumor by using Oxygen ion beam in a cold plasma channel, which is low in density, with appropriate laser power. Consequently, Hadron therapy by using Oxygen ionization in the laser-plasma based accelerator is an impressive and efficient method for precise cancer treatment. Lastly, Laser-Plasma accelerators have three important limitation factors of “Energy Spread”, “Dephasing Length”, and “Pump Depletion”, which can limit the energy increasing. In this paper, facing up to these limitations was a critical challenge in Hadron therapy for better Hadron acceleration and dose delivery.
关键词： Beam Focusing,Hadron Therapy,Oxygen Ionization,Plasma Channel,Laser Acceleration,Cancer Radiation Therapy,Pump Depletion,Dephasing Length,Energy Spread
更新于2025-09-16 10:30:52
-
Radioluminescence in biomedicine: physics, applications, and models
摘要： The electromagnetic spectrum contains different frequency bands useful for medical imaging and therapy. Short wavelengths (ionizing radiation) are commonly used for radiological and radionuclide imaging and for cancer radiation therapy. Intermediate wavelengths (optical radiation) are useful for more localized imaging and for photodynamic therapy. Finally, longer wavelengths are the basis for magnetic resonance imaging and for hyperthermia treatments. Recently, there has been a surge of interest for new biomedical methods that synergize optical and ionizing radiation by exploiting the ability of ionizing radiation to stimulate optical emissions. These physical phenomena, together known as radioluminescence, are being used for applications as diverse as radionuclide imaging, radiation therapy monitoring, phototherapy, and nanoparticle- based molecular imaging. This review provides a comprehensive treatment of the physics of radioluminescence and includes simple analytical models to estimate the luminescence yield of scintillators and nanoscintillators, Cherenkov radiation, air fluorescence, and biologically endogenous radioluminescence. Examples of methods that use radioluminescence for diagnostic or therapeutic applications are reviewed and analyzed in light of these quantitative physical models of radioluminescence.
关键词： Cherenkov luminescence,nanotechnology,Radioluminescence,biomedical imaging,scintillators,radiation therapy
更新于2025-09-11 14:15:04
-
Radiobiological Modeling Based on 18F-Fluorodeoxyglucose Positron Emission Tomography Data for Esophageal Cancer
摘要： Background: We investigated the relationship of standardized uptake values (SUVs) to radiobiological parameters, such a 25 s tumor control probability (TCP), to allow for quantitative prediction of tumor response based on SUVs from 18F fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) before and after treatment for esophageal cancer. Methods: We analyzed data from 20 esophageal cancer patients treated with chemoradiotherapy (CRT) followed by surgery. Tumor pathologic response to CRT was assessed in surgical specimens. Patients underwent 18F-FDG PET imaging before and after CRT. Rigid image registration was performed between both images. Because TCP in a heterogeneous tumor is a function of average cell survival, we modeled TCP as a function of <SUVR>, a possible surrogate for average cell survival (<SUVR>=<SUVafter/SUVbefore>). TCP was represented by a sigmoid function with two parameters: SUVR50, the <SUVR> at which TCP=0.5, and γ50, the slope of the curve at SUVR50. The two parameters and their confidence intervals (CIs) were estimated using the maximum-likelihood method. The correlation between SUV before CRT and SUV change <SUVbefore – SUVafter> was also studied. Results: A TCP model as a function of SUV before and after treatment was developed for esophageal cancer patients. The maximum-likelihood estimate of SUVR50 was 0.47 (90% CI, 0.30-0.61) and for γ50was 1.62 (90% CI, 0-4.2). High initial SUV and larger metabolic response (larger <SUVbefore –SUVafter>) were correlated, and this correlation was stronger among responders. Conclusions: Our TCP model indicates that <SUVafter/SUVbefore> is a possible surrogate for cell survival in esophageal cancer patients. Although CIs are large as a result of the small patient sample, parameters for a TCP curve can be derived and an individualized TCP can be calculated for future patients. Initial SUV does not predict response, whereas a correlation is found between surrogates for initial tumor burden and cell kill during therapy.
关键词： Quantitative imaging,Esophageal cancer,18F-FDG PET/CT,Tumor response,Radiation therapy
更新于2025-09-09 09:28:46
-
Imaging as a Personalized Biomarker for Prostate Cancer Risk Stratification
摘要： Biomarkers provide objective data to guide clinicians in disease management. Prostate-specific antigen serves as a biomarker for screening of prostate cancer but has come under scrutiny for detection of clinically indolent disease. Multiple imaging techniques demonstrate promising results for diagnosing, staging, and determining definitive management of prostate cancer. One such modality, multiparametric magnetic resonance imaging (mpMRI), detects more clinically significant disease while missing lower volume and clinically insignificant disease. It also provides valuable information regarding tumor characteristics such as location and extraprostatic extension to guide surgical planning. Information from mpMRI may also help patients avoid unnecessary biopsies in the future. It can also be incorporated into targeted biopsies as well as following patients on active surveillance. Other novel techniques have also been developed to detect metastatic disease with advantages over traditional computer tomography and magnetic resonance imaging, which primarily rely on defined size criteria. These new techniques take advantage of underlying biological changes in prostate cancer tissue to identify metastatic disease. The purpose of this review is to present literature on imaging as a personalized biomarker for prostate cancer risk stratification.
关键词： magnetic resonance imaging (MRI),cancer staging,active surveillance,radical prostatectomy,Gleason score,radiation therapy
更新于2025-09-09 09:28:46
-
Selecting noncoplanar beam directions in a patient coordinate system for radiotherapy planning
摘要： To introduce a beam angle selection method based on the patient coordinate system for treatment planning of noncoplanar intensity-modulated radiation therapy (IMRT). Traditionally, in radiotherapy planning, beam directions are selected in the machine coordinate system. A noncoplanar beam direction is established through a treatment table rotation followed by a gantry rotation. However, visualizing the beam direction relative to the patient is di?cult. The suggestion here is to describe the beam direction in the patient coordinate system. First, a coplanar beam direction is selected in the transverse plane of the patient coordinate system. The noncoplanar beam direction is then obtained by adjusting the coplanar beam toward the foot or head in the patient coordinate system. Finally, the noncoplanar beam direction is expressed in terms of gantry and table angles in the machine coordinate system via formulae developed in this study. A 3D computer-aided design model of the linear accelerator (linac) is established with Solidworks and used to validate the feasibility of the proposed method. A clinical case was chosen to demonstrate the effectiveness of this method. Treatment plans with the conventional coplanar and noncoplanar beam settings were made. Compared with the conventional coplanar IMRT plan, improved normal tissue sparing of the organs at risk using the noncoplanar IMRT plan is evident. The proposed method for noncoplanar treatment planning makes beam direction selection simpler and straightforward.
关键词： Noncoplanar intensity-modulated radiation therapy,Radiotherapy planning,Noncoplanar planning,Patient coordinate system,Noncoplanar beam direction
更新于2025-09-09 09:28:46
-
Raman spectroscopy monitoring of MCF10A cells irradiated by protons at clinical doses
摘要： Purpose: Protontherapy has been recently proposed as a radiotherapy form for breast cancer treatment in view of its potentially decreased normal-tissue toxicity compared with conventional photon-based radiotherapy. However, the risks for the healthy tissue cannot be completely eliminated. In the present study, the suitability of Raman spectroscopy to monitor the radiosensitivity of normal cells exposed to clinical proton beam was investigated. Materials and Methods: MCF10A normal human breast cells were irradiated at two different proton doses: 0.5 Gy and 4 Gy. They were fixed immediately after irradiation and measured by means of Raman spectroscopy technique. The obtained data were analyzed both by evaluating the intensity ratio of specific Raman spectral peaks and through Multivariate Distance Matrix Regression technique. Results: Certain Raman peaks associated with DNA showed a systematic suppression at both dose levels. In particular, the intensity of a Raman peak at 784 cm-1, related to a stretching mode inside the phosphate group of DNA, is very sensitive to the proton beam exposure, even at the lowest investigated dose. Therefore, it could be considered as a spectral marker of cytogenetic damage. Conclusions: The obtained results are encouraging for the future of Raman spectroscopy in radiobiology research, particularly for improving risk assessment in the field of proton radiotherapy. Specifically, these findings validate Raman spectroscopy to measure biological response in human breast cells exposed to standard proton therapy doses used in clinical setting.
关键词： Radiation therapy,Proton beam,Raman spectroscopy
更新于2025-09-09 09:28:46
-
[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Study of the photoneutron generation caused by a LinAc Beryllium window with a 6 MeV treatment beam
摘要： In most conventional radiation therapy treatments, special attention is payed for neutron contamination when working with energy beams above 8 MeV and generally it is only considered for shielding requirements, not for dose study in patients or employees. The present work is focused on studying the unwanted generated photoneutrons in a Medical Linear Accelerator (LinAc) Varian TrueBeam using a 6 MeV radiation treatment beam. To that, Monte Carlo (MC) simulation code MCNP6.1.1 was used. This version of the code allows the use of unstructured mesh geometries as a novelty, offering more reliable results and higher speed computation. The particularity of the studied LinAc is the presence of a beryllium filter at the treatment head. Since Beryllium causes photonuclear reactions (γ, n) at energies much lower than other LinAc composing materials, this work aims to analyze if this type of units, when using low energy treatment beams (6 MeV), produce neutron pollution and to ensure that this unwanted radiation can be considered negligible.
关键词： Monte Carlo simulation,Medical Linear Accelerator,radiation therapy,photoneutrons,Beryllium filter
更新于2025-09-09 09:28:46