Cerenkov Emission Research Articles

Terahertz acoustic phonon Cerenkov emission in bilayer graphene

We present a theoretical investigation on the generation of Cerenkov emission of terahertz acoustic phonons in bilayer graphene (BLG) in the presence of a driving dc electric field. We have numerically and analytically studied the Cerenkov phonon emission spectrum, Pspectrum(ωp,θ), and phonon intensity, Pintensity(θ), dependence on the phonon frequency ωp, drift velocity vd, electron temperature Te, concentration n, and phonon emission angle θ in BLG with and without considering the chirality of the charge carriers. We find that the magnitude of Pspectrum(ωp,θ) increases at larger drift velocities and applied electric fields with the peak of the spectrum shifting toward the higher frequency side. The spectrum magnitude in BLG is found to be much enhanced as compared to conventional 2D semiconductors and transition metal dichalcogenides, which makes it viable for SASER and other practical device applications. The chiral nature of carriers strongly influences the Pspectrum(ωp,θ) behavior and sharpens the spectrum peak but with a decrease in the magnitude. The chirality favors the negative emission spectrum caused by the absorption of acoustic phonons. Pspectrum(ωp,θ) and Pintensity(θ) are found to be strongly dependent on temperature but independent of carrier concentration in the equipartition regime. The study is significant from the point of application of BLG as an acousto/optoelectronic device and high-frequency phonon spectrometers.

Tunable terahertz acoustic-phonon emission from monolayer molybdenum disulfide

The acoustic-phonon emission from monolayer molybdenum disulfide (ML-MoS2) driven by a direct-current electric field is studied theoretically using the Boltzmann equation method. It is found that the Cerenkov emission of terahertz acoustic-phonons can be generated when a very weak electric field is applied to ML-MoS2. The physical mechanisms of acoustic-phonon emission are analyzed from the perspective of condensed matter physics. The acoustic-phonon emission from ML-MoS2 is also compared with those from graphene and GaAs. The results reveal that the frequencies of acoustic-phonons generated by ML-MoS2 are between the frequencies of those generated from GaAs and graphene. The results of this work suggest that the ML-MoS2 can make up for graphene and GaAs in respect of acoustic-phonon emission and be used in tunable hypersonic devices such as terahertz sound sources.

External beam irradiation angle measurement using a hybrid Cerenkov-scintillation detector

Objective. In this study, we propose a novel approach designed to take advantage of the Cerenkov light angular dependency to perform a direct measurement of an external beam irradiation angle. Approach. A Cerenkov probe composed of a 10 mm long filtered sensitive volume of clear PMMA optical fibre was built. Both filtered and raw Cerenkov signals from the transport fibre were collected through a single 1 mm diameter transport fibre. An independent plastic scintillation detector composed of 10 mm BCF12 scintillating fibre was also used for simultaneous dose measurements. A first series of measurements aimed at validating the ability to account for the Cerenkov electron energy spectrum dependency by simultaneously measuring the deposited dose, thus isolating signal variations resulting from the angular dependency. Angular calibration curve for fixed dose irradiations and incident angle measurements using electron and photon beams where also achieved. Main results. The beam nominal energy was found to have a significant impact on the shapes of the angular calibration curves. This can be linked to the electron energy spectrum dependency of the Cerenkov emission cone. Irradiation angle measurements exhibit an absolute mean error of 1.86° and 1.02° at 6 and 18 MV, respectively. Similar results were obtained with electron beams and the absolute mean error reaches 1.97°, 1.66°, 1.45° and 0.95° at 9, 12, 16 and 20 MeV, respectively. Reducing the numerical aperture of the Cerenkov probe leads to an increased angular dependency for the lowest energy while no major changes were observed at higher energy. This allowed irradiation angle measurements at 6 MeV with a mean absolute error of 4.82°. Significance. The detector offers promising perspectives as a potential tool for future quality assurance applications in radiotherapy, especially for stereotactic radiosurgery (SRS), magnetic resonance image-guided radiotherapy (MRgRT) and brachytherapy applications.

Optical Fiber-Based Monitoring of X-ray Pulse Series from a Linear Accelerator

We investigated in this work the radioluminescence properties of a Ce-doped multimode silica-based optical fiber (core diameter of 50 µm) manufactured by the sol–gel technique when exposed to the high-energy X-rays (~600 keV) of the ORIATRON facility of CEA. We demonstrated its potential to monitor in real-time the beam characteristics of this facility that can either operate in a pulsed regime (pulse duration of 4.8 µs, maximum repetition rate of 250 Hz) or in a quasi-continuous mode. The radiation-induced emission (radioluminescence and a minor Cerenkov contribution) linearly grew with the dose rate in the 15–130 mGy(SiO2)/s range, and the afterglow measured after each pulse was sufficiently limited to allow a clear measurement of pulse trains. A sensor with ~11 cm of sensitive Ce-doped fiber spliced to rad-hard fluorine-doped optical fiber, for the emitted light transport to the photomultiplier tube, exhibited interesting beam monitoring performance, even if the Cerenkov emission in the transport fiber was also considered (~5% of the signal). The beam monitoring potential of this class of optical fiber was demonstrated for such facilities and the possibilities of extending the dose rate range are discussed based on possible architecture choices such as fiber type, length or size.

Integration of polarization in the LUTDavis model for optical Monte Carlo simulation in radiation detectors

Objective: Cerenkov photons have distinctive features from scintillation photons. Among them is their polarization: their electric field is always perpendicular to the direction of propagation of light and parallel to the plane of incidence. Scintillation photons are instead considered unpolarized. Approach: This study aims at understanding and optimizing the reflectance of polarized Cerenkov photons for optical Monte Carlo simulation of scintillation detectors with Geant4/GATE. First, the Cerenkov emission spectrum and polarization were implemented in the previously developed look-up-table Davis model of crystal reflectance. Next, we modified Geant4/GATE source code to account for scintillation and Cerenkov photons LUTs simultaneously. Then, we performed optical Monte Carlo simulations in BGO using GATE to show the effect of Cerenkov features on the photons’ momentum at the photodetector face, using two surface finishes, with and without reflector. Main results: In this work, we describe the new features added to the algorithm and GATE. We showed that Cerenkov characteristics affect their probability to be reflected/refracted and thus their travel path within a material. Significance: We showed the importance of accounting for accurate Cerenkov photons reflectance while performing advanced optical Monte Carlo simulations.

Acoustoelectric current in graphene nanoribbon due to Landau damping

We perform self-consistent analysis of the Boltzmann transport equation for momentum and energy in the hypersound regime i.e., ql gg 1 (q is the acoustic wavenumber and l is the mean free path). We investigate the Landau damping of acoustic phonons (LDOAP) in graphene nanoribbons, which leads to acoustoelectric current generation. Under a non-quantized field with drift velocity, we observed an acoustic phonon energy quantization that depends on the energy gap, the width, and the sub-index of the material. An effect similar to Cerenkov emission was observed, where the electron absorbed the confined acoustic phonon energy, causing the generation of acoustoelectric current in the graphene nanoribbon. A qualitative analysis of the dependence of the absorption coefficient and the acoustoelectric current on the phonon frequency is in agreement with experimental reports. We observed a shift in the peaks when the energy gap and the drift velocity were varied. Most importantly, a transparency window appears when the absorption coefficient is zero, making graphene nanoribbons a potential candidate for use as an acoustic wave filter with applications in tunable gate-controlled quantum information devices and phonon spectrometers.

Measuring Tumor Microenvironment pH During Radiotherapy Using a Novel Cerenkov Emission Multispectral Optical Probe Based on Silicon Photomultipliers

Cerenkov Emission (CE) multispectral analysis with silicon photomultiplier (SiPM)-based optical probes is a promising tool for online tumor microenvironment interrogation and targeting during radiotherapy delivery. With the extreme sensitivity of SiPMs, deep tissue multispectral CE measurements can be realized in a clinical setting. In this work, we utilize our Cerenkov Emission Multi-spectral Imaging (CMSI) prototype probe to interrogate the spectral components of the CE signal generated during external beam radiotherapy. Our results demonstrated that CMSI enables effective probing of in vitro quantitative changes in the pH of cell media to monitor cancer cell proliferation after various treatment pathways and differentiate between varying treatment resistance cell lines. In addition, the feasibility of using the CMSI probe in vivo was also successfully demonstrated by measuring tumor pH during a pilot mouse study.

Radiation resistance of single-mode optical fibres with view to in-reactor applications

Single-mode optical fibres (SMFs) are required for ITER in-vessel applications as transport fibres to deliver the signal at wavelength λ = 1.55 µm from/to optical fibre sensors. The paper describes the first comparison study of radiation resistance of six pure-silica-core SMFs of different manufacturers performed in the process of fission-reactor irradiation in the conditions corresponding to the whole ITER lifetime (fast-neutron fluence, flux, γ-dose and dose rate of up to 1.8·1020n/cm2, 1.08·1014n/(cm2·s), 2.32 GGy and 1.39 kGy/s, respectively, temperature of 170–190 °C and vacuum pumping). Polyimide- and acrylate-coated SMFs failed mechanically during the irradiation; therefore, only metal-coated fibres can be considered for the in-vessel applications. Induced optical loss in all three metal-coated SMFs (copper- and aluminum-coated ones) at the fast-neutron fluence of 1·1020n/cm2 was found to lie in the range ~1.5–4 dB/m, the lower value of this range allowing the employment of at least 10-m-long transport fibre lengths in the in-vessel applications, assuming the dynamic range of 30 dB. The temperature-dependent microbending optical loss in metal-coated SMFs is discussed, of which the contribution to the total induced loss may be comparable in value to the radiation-induced absorption of light. Neither radiation-induced luminescence, nor Cerenkov emission was detected in the SMFs in the near-infrared range.

Monte Carlo modeling of the influence of strong magnetic fields on the stem-effect in plastic scintillation detectors used in radiotherapy dosimetry.

To investigate the impact of strong magnetic fields on the stem-effect in plastic scintillation detectors (PSDs) using Monte Carlo methods. Prior to building the light guide model, the properties of the Čerenkov process in GEANT4 were investigated by simulating depth-dose and depth-Čerenkov emission profiles in water as functions of Čerenkov process input parameters. In addition, profile simulations were performed for magnetic field strengths ranging from 0T to 1.5T. A PMMA light guide was constructed in GEANT4 using data from the manufacturer and literature. Simulations were performed with the model as functions of depth and fiber-beam angle where the simulated stem-effect spectrum and the Čerenkov light ratio (CLR) were scored and compared to measured data in the literature. The light guide optical properties were iteratively adjusted until agreement between the simulated and measured data was achieved. Simulations were performed with the validated model as functions of depth and magnetic field strength and the simulated data were compared to measured data in the literature. The model was also used to evaluate the sensitivity of the CLR to the various optical properties of the light guide in different irradiation conditions. No significant changes in the depth-dose or depth-Čerenkov emission profiles were observed with step-size restrictions imposed by the Čerenkov process input parameters, which was attributed to the condensed history algorithm and transport parameters used in this work. Similar changes in the depth-dose and depth-Čerenkov emission profiles were observed with increasing magnetic field strength, which indicates the Čerenkov process is not adversely impacted by the presence of the magnetic field. Following optimization of the light guide optical properties, agreement within two standard deviations was observed between the simulated and measured optical data for all validation geometries considered. Agreement within one standard deviation was observed between the simulated and measured data for all depths and field strengths ≥0T whereas discrepancies were observed for magnetic field strengths <-0.35T. These significant differences were attributed to insufficient measurement data for this irradiation configuration during model validation. Of the light guide optical properties investigated, the fluorescence signal had the greatest impact on the CLR sensitivity to the magnetic field. No significant change in the Čerenkov emission per dose in water was observed for magnetic field strengths up to 1.5T. The nominal fiber fluorescence signal was found to have a significant impact on the CLR sensitivity to varying irradiation conditions where changes up to 11.7% were observed whereas the mirror reflectivity and fiber attenuation had a modest impact with maximum CLR changes of 2.6% and 1.2% relative to 0T, respectively. The results of this work suggest light guides with low fiber fluorescence should be used with PSDs for dosimetry measurements in magnetic fields to minimize the impact of the magnetic field on the CLR correction.

Analysis of corrected Cerenkov emission during electron radiotherapy by Monte Carlo method

Cerenkov emission during electron radiotherapy had been emerging as a new dose assessment approach for clinical radiotherapy and could be imaged through a standard commercial camera. The purpose of this work aimed to study the accuracy of corrected Cerenkov emission method during electron radiotherapy by Monte Carlo (MC) method. GAMOS MC software was used to model the physics of electron therapy and calculated dose and Cerenkov photon distribution in water phantom. Compared to ionization chamber and diode measurement, MC simulated dose discrepancy was less than 1% in percentage depth dose (PDD) curves and less than.2% in crossline profile curves, which was acceptable for clinical criterion. Compared to ionization chamber dose measurement, MC simulated Cerenkov discrepancy was less than 2% in crossline profile distribution, which was acceptable for clinical criterion. However, the Cerenkov PDD curves tended to overestimate the dose at the build-up region and underestimate the dose at the remaining attenuation region. After increasing the Cerenkov distribution depth to 2–3 mm, the discrepancy became well within 1% at the remaining attenuation region, which was acceptable for clinical criterion. Therefore, corrected Cerenkov emission could be used to assess PDD accuracy and crossline profile accuracy during electron radiotherapy.

An advanced method for quick detection of heavy water leak in steam generators of pressurized heavy water reactors

A user friendly and rugged online system has been developed based on Cerenkov photon counting technique for heavy water leak detection in steam generators of pressurized heavy water reactor. The system has the capability to identify presence of fission and activation products in the secondary coolant of steam generator, an indication of leak from primary coolant, by detecting Cerenkov emission produced by hard beta emitting radionuclides in water. In this method the steam sample from steam generator is cooled during its transit through sampling line and the condensate is passed online through a polythene plastic flow cell placed between two matched bi-alkali photomultiplier tubes with coincident counting circuitry to observe the Cerenkov photon count rate. The minimum detectable leak rate for the newly developed system, when used in a steam generator of a 220 MWe reactor, was determined to be 3.6 kg h−1. Upon designing, construction and characterization, the system was successfully employed to detect and identify leak in steam generator of a reactor.

Emission of plasmons by drifting Dirac electrons: A hallmark of hydrodynamic transport

Direct current in clean semiconductors and metals was recently shown to obey the laws of hydrodynamics in a broad range of temperatures and sample dimensions. However, the determination of frequency window for hydrodynamic phenomena remains challenging. Here, we reveal a phenomenon being a hallmark of high-frequency hydrodynamic transport, the Cerenkov emission of plasmons by drifting Dirac electrons. The effect appears in hydrodynamic regime only due to reduction of plasmon velocity by electron-electron collisions below the velocity of carrier drift. To characterize the Cerenkov effect quantitatively, we analytically find the high-frequency non-local conductivity of drifting Dirac electrons across the hydrodynamic-to-ballistic crossover. We find the growth rates of hydrodynamic plasmon instabilities in two experimentally relevant setups: parallel graphene layers and graphene covered by subwavelength grating, further showing their absence in ballistic regime. We argue that the possibility of Cerenkov emission is linked to singular structure of non-local conductivity of Dirac materials and is independent on specific dielectric environment.

Dynamics of relaxation and dressing of a quenched Bose polaron

We study the non-equilibrium dynamics of relaxation and dressing of a mobile impurity suddenly immersed--or quenched-- into a zero temperature homogeneous Bose Einstein condensate (BEC) with velocity $v$. A many body generalization of Weisskopf-Wigner theory is implemented to obtain the impurity fidelity, reduced density matrix and entanglement entropy. The dynamics depend crucially on the Mach number $\beta =v/c$, with $c$ the speed of sound of superfluid phonons and features many different time scales. Quantum Zeno behavior at early time is followed by relaxational and dressing dynamics determined by Cerenkov emission of long-wavelength phonons for $\beta >1$ with a decay rate $\Gamma_p \propto (\beta-1)^3$. The polaron dressing dynamics \emph{slows-down} as $\beta \rightarrow 1$ and is characterized by power laws $t^{-\alpha}$ with different exponents for $\beta \lessgtr 1$. The asymptotic entanglement entropy features a sharp discontinuity and the residue features a cusp at $\beta =1$. These non-equilibrium features suggest \emph{universal} dynamical critical phenomena near $\beta \simeq 1$, and are a direct consequence of the linear dispersion relation of long wavelength superfluid phonons. We conjecture on the emergence of an asymptotic dynamical attractor with $\beta \leq 1$.

Silicon Photomultipliers for Deep Tissue Cerenkov Emission Detection During External Beam Radiotherapy.

Cerenkov Emission (CE) during external beam radiation therapy (EBRT) from a linear accelerator (Linac) has been demonstrated as a useful tool for radiotherapy quality assurance and potentially other applications for online tracking of tumors during treatment delivery. However, some of the current challenges that are impacting the potential of CE are related to the limited detection sensitivity and the lack of flexible tools to fit into an already complex treatment delivery environment. Silicon photomultiplier (SiPM) solid-state devices are new promising tools for low light detection due to their extreme sensitivity that mirrors photomultiplier tubes and yet have a form factor that is similar to silicon photodiodes, allowing for improved flexibility in device design that may help in the process of wider clinical applicability. In this work, we assess the feasibility of using SiPMs to detect CE during EBRT from a Linac and contrast their performance with commercially available silicon photodiodes (PDs). We demonstrate the feasibility of the SiPM based probes for standard dosimetry measurements. We also demonstrate that CE optical signals can be detected from tissue depths about five times greater than that for standard probes based on PDs, making our SiPM probe an enabling technology of CE measurements, particularly for deep tissue applications.

Causality in Plasma Electrodynamics

Causality in electrodynamics is reviewed in regard to the interrelations among the causal requirement, the analyticity of the dielectric permittivity, and the Kramers-Kronig relations. We show that the collisionless damping (Landau damping) of a plasma wave can be formally derived from the causal requirement imposed on the susceptibility of a Vlasov-Poisson plasma. Here, the causal requirement is that the susceptibility χ(t) be nil for t < 0, which means the future electric field has nothing to do with the response effected in the medium at the present time. We show that this single requirement provides the analyticity of χ(ω) in the upper half-ω plane, the Kramers- Kronig relations, and Landau damping. Cerenkov emission which is the inverse process of Landau damping is also discussed in the light of causality. We present an easy way to calculate the electric fluctuation in a magnetized plasma by regarding a plasma as an assembly of non-interacting cold beams. We investigate the case of a separable distribution function $$g(x,t,v) = \tilde g(v)f(x - {v_0}t)$$ , which corresponds to a special type of Benstein-Greene-Kruskal wave and a slight generalization of Van Kampen’s distribution function. We review Van Kampen’s theory of a Vlasov-Poisson system, which corresponds to the Sturm-Liouville theory of differential equations, and show that the Vlasov- Poisson equations in this separable case are trivially solved in terms of the separation constant. It is philosophically interesting that the collisionless damping of a plasma wave can be attributed to causality, which defines the direction of time and is operative in general electrodynamics.

Why Cerenkov Radiation May Not Occur, Even When It Is Allowed by Lorentz-Violating Kinematics

In a Lorentz-violating quantum field theory, the energy-momentum relations for the field quanta are typically modified. This affects the kinematics, and processes that are normally forbidden may become allowed. One reaction that clearly becomes kinematically possible when photons’ phase speeds are less than 1 is vacuum Cerenkov radiation. However, in spite of expectations, and in defiance of phase space estimates, a electromagnetic Chern–Simons theory with a timelike Lorentz violation coefficient does not feature any energy losses through Cerenkov emission. There is an unexpected cancelation, made possible by the existence of unstable long-wavelength modes of the field. The fact that the theory possesses a more limited form of gauge symmetry than conventional electrodynamics also plays a role.

+Cerenkov emission of terahertz acoustic phonons generated electrically from monolayers of transition metal dichalcogenides

We have studied theoretically the Cerenkov acoustic phonon emission from monolayers of transition metal dichalcogenides (TMDs) driven by an electric field. The features of emitted phonon spectrum P(ωq,θ) are investigated as a function of the phonon frequency ωq, electron concentration ns, electric field E, and phonon emission angle θ. Numerical evaluations are made for n-MoS2. Acoustic phonons in the terahertz (THz) frequency region are found to be generated when the Cerenkov emission condition is satisfied. Frequency dependence of P(ωq,θ) shows a maximum at a frequency ωqm, position which shifts to larger frequency for larger E and ns. We predict ωqm/ns1/2 and ωqm/E1/4 to be nearly constant. The angular dependence of P(ωq,θ) and the phonon intensity P(θ) show emission to be maximum along the direction of electric field, i.e., for θ = 0. Both P(ωq,θ) and P(θ) are found to be larger for larger E. In the Bloch-Gruneisen regime P(ωq,θ) and P(θ) ∼ ns−3/2 and P(θ) ∼ T4. The results are compared with those in the bulk and conventional two-dimensional semiconductors and graphene. It is suggested that monolayers of TMDs can find potential applications as a new source of electrical generation of acoustic phonons in the THz frequency region.

SU‐F‐J‐46: Feasibility of Cerenkov Emission for Absorption Spectroscopy

Purpose:Cerenkov emission (CE) is a promising tool for online tumor microenvironment interrogation and targeting during radiotherapy. In this work, we utilize CE generated during radiotherapy as a broadband excitation source for real‐time absorption spectroscopy. We demonstrate the feasibility of CE spectroscopy using a controlled experiment of materials with known emission/absorption properties.Methods:A water tank is irradiated with 20 MeV electron beam to induce Cerenkov emission. Food coloring dyes (Yellow #5, Red #40, and Blue #1), which have known emission/absorption properties were added to the water tank with increasing concentration (1 drop (0.05 mL), 2 drops, and 4 drops from a dispenser bottle). The signal is collected using a condensing lens which is coupled into a 20m optical fiber that is fed into a spectrometer that measures the emitted spectra. The resulting spectra from water/food coloring dye solutions were normalized by the reference spectrum, which is the Cerenkov spectrum of pure water, correcting for both the nonlinearity of the broadband Cerenkov emission spectrum as well as the non‐uniform spectral response of the spectrometer. The emitted spectra were then converted into absorbance and their characteristics were analyzed.Results:The food coloring dye had a drastic change on the Cerenkov emission, shifting its wavelength according to its visible color. The collected spectra showed various absorbance peaks which agrees with tabulated peak positions of the dyes added within 0.3% for yellow, 1.7% for red, and 0.16% for blue. The CE peak heights proportionally increased as the dye concentration is increased.Conclusion:This work shows the potential for real‐time functional spectroscopy using Cerenkov emission during radiotherapy. It was demonstrated that molecule identification as well as relative concentration can be extracted from the Cerenkov emission color shift.

SU‐F‐T‐507: Modeling Cerenkov Emissions From Medical Linear Accelerators: A Monte Carlo Study

Purpose:Cerenkov emissions are a natural byproduct of MV radiotherapy but are typically ignored as inconsequential. However, Cerenkov photons may be useful for activation of drugs such as psoralen. Here, we investigate Cerenkov radiation from common radiotherapy beams using Monte Carlo simulations.Methods:GAMOS, a GEANT4‐based framework for Monte Carlo simulations, was used to model 6 and 18MV photon beams from a Varian medical linac. Simulations were run to track Cerenkov production from these beams when irradiating a 50cm radius sphere of water. Electron contamination was neglected. 2 million primary photon histories were run for each energy, and values scored included integral dose and total track length of Cerenkov photons between 100 and 400 nm wavelength. By lowering process energy thresholds, simulations included low energy Bremsstrahlung photons to ensure comprehensive evaluation of UV production in the medium.Results:For the same number of primary photons, UV Cerenkov production for 18MV was greater than 6MV by a factor of 3.72 as determined by total track length. The total integral dose was a factor of 2.31 greater for the 18MV beam. Bremsstrahlung photons were a negligibly small component of photons in the wavelength range of interest, comprising 0.02% of such photons.Conclusion:Cerenkov emissions in water are 1.6x greater for 18MV than 6MV for the same integral dose. Future work will expand the analysis to include optical properties of tissues, and to investigate strategies to maximize Cerenkov emission per unit dose for MV radiotherapy.

WE-FG-BRA-12: Research Work of the Radio-Dynamic Treatment Mechanism

Purpose: The finite penetration depth of Laser light has limited clinical applications for PDT. This present work investigates the activation of photosensitizers using Cerenkov light emission from 45MV photon beams produced in an LA45 cancer therapy accelerator. We have named this new treatment technique Radio-Dynamic Therapy (RDT). Methods: Monte Carlo simulations were made on various Cerenkov emission energies and their spectroscopy in excited target areas in order to estimate their photosensitizer inner activation efficiency. The Cerenkov light excitation efficiency used in RDT has been theoretically compared with the exotic excitation efficiency of external Laser light used in PDT. In addition, laboratory tests showed the differences of the excitation efficiencies between a patented catalyst coenzyme added as a substrate, and then without the coenzyme. A specific probe of DMA (Singlet Oxygen fluorescent probe-9, 10-dimethylanthracene) was also used to detect singlet oxygen. Finally, we also compared our results with similar previous experimental work reported in the scientific literature. Results: Our Monte Carlo results showed that the Cerenkov light intensity induced with 45MV beams from an LA45 is 8 – 10 times the Cerenkov light intensity induced with 6MV beams from conventional accelerators. Furthermore, the patented catalyst coenzyme enhanced the excitation efficiency of photosensitizers by 3–6 times under different conditions. In clinical situations, the new RDT technique also showed favorable outcomes for early and late stages of specific cancers and it is also good at metastatic cancer treatment. Conclusion: Our results indicated that the process of using the Cerenkov light emission to excite photosensitizers from 45MV photons has a similar process and efficiency as the conventional laser in PDT. Comparing the advantages of RDT with a conventional PDT, the RDT may be developed into a potential treatment modality for a wider range of cancers stages as well as for other diseases.