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Articles 1 - 30 of 43
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Intraoperative Solid-State Based Urethral Dosimetry In Low Dose Rate Prostate Brachytherapy, Dean Cutajar, G. Takacs, M. Lerch, T. Braddock, J. Bucci, J. Brady, L. Duggan, K. Enari, M. Zaider, M. Zelefsky, Anatoly Rosenfeld
Intraoperative Solid-State Based Urethral Dosimetry In Low Dose Rate Prostate Brachytherapy, Dean Cutajar, G. Takacs, M. Lerch, T. Braddock, J. Bucci, J. Brady, L. Duggan, K. Enari, M. Zaider, M. Zelefsky, Anatoly Rosenfeld
Michael L.F. Lerch
This paper presents in phantom testing of a recently developed intraoperative minidosimetry system, designed to measure the dose along the urethra during low dose rate prostate brachytherapy. This system is based on a silicon minidetector and uses spectroscopy to calculate the localized dose from the treatment radiation. The minidosimetry system was demonstrated to be operational at body temperature, with a near isotropic response to radiation at all angles. Phantom measurements have shown the minidosimetry system to measure the dose from multiple seeds to within 5% of planning system calculated doses. This system is an ideal complement to ultrasound guided seed …
The Feasibility Study And Characterziation Of A Two-Dimensional Diode Array In “Magic Phantom” For High Dose Rate Brachytherapy Quality Assurance, A Espinoza, B Beeksma, M Petasecca, I Fuduli, C Porumb, D L. Cutajar, S Corde, M A. Jackson, M Lf Lerch, Anatoly B. Rosenfeld
The Feasibility Study And Characterziation Of A Two-Dimensional Diode Array In “Magic Phantom” For High Dose Rate Brachytherapy Quality Assurance, A Espinoza, B Beeksma, M Petasecca, I Fuduli, C Porumb, D L. Cutajar, S Corde, M A. Jackson, M Lf Lerch, Anatoly B. Rosenfeld
Michael L.F. Lerch
High dose rate (HDR) brachytherapy is a radiation treatment technique capable of delivering large dose rates to the tumor. Radiation is delivered using remote afterloaders to drive highly active sources (commonly 192Ir with an air KERMA strength range between 20 000 and 40 000 U, where 1 U = 1 uGy m2/h in air) through applicators directly into the patient's prescribed region of treatment. Due to the obvious ramifications of incorrect treatment while using such an active source, it is essential that there are methods for quality assurance (QA) that can directly and accurately verify the treatment plan and the …
Neutron Dosimetry With Planar Silicon P-I-N Diodes, Anatoly B. Rosenfeld, M. Yudelev, M. L. Lerch, I. Cornelius, P. Griffin, V. L. Perevertailo, I. E. Anokhin, O. S. Zinets, V. I. Khivrich, M. Pinkovskaya, D. Alexiev, M. Reinhard
Neutron Dosimetry With Planar Silicon P-I-N Diodes, Anatoly B. Rosenfeld, M. Yudelev, M. L. Lerch, I. Cornelius, P. Griffin, V. L. Perevertailo, I. E. Anokhin, O. S. Zinets, V. I. Khivrich, M. Pinkovskaya, D. Alexiev, M. Reinhard
Michael L.F. Lerch
New nonionizing energy losses (NIEL) sensors based on silicon planar p-i-n diodes of different geometry have been investigated and their response to fast neutron field compared with bulk diodes. The possibility of obtaining a wide range of sensitivities in these NIEL sensors simultaneously with measurements of IEL has been demonstrated.
Optical And Electrical Studies Of Resonant Tunneling Heterostructures, Michael L.F. Lerch
Optical And Electrical Studies Of Resonant Tunneling Heterostructures, Michael L.F. Lerch
Michael L.F. Lerch
In this thesis, a new measurement technique is used to study the electronic properties of resonant tunneling heterostructures. The measurement technique incorporates an active operational amplifier circuit to simulate negative resistance and capacitance, and is used to probe regions of intrinsic bistability. Intrinsic bistability is observed in the experimental current-voltage characteristics of some resonant tunneling heterostructures when measured using conventional techniques. The tunneling resonance characteristic of an asymmetric, double barrier resonant tunneling heterostructure which displays intrinsic bistability is shown to be smooth, continuous and multistable when measured using the new technique. It is the multistable region which is the main …
In Vivo Real-Time Rectal Wall Dosimetry For Prostate Radiotherapy, Nicholas Hardcastle, Dean L. Cutajar, Peter E. Metcalfe, Michael L F Lerch, Vladimir L. Perevertaylo, Wolfgang A. Tome, Anatoly B. Rosenfeld
In Vivo Real-Time Rectal Wall Dosimetry For Prostate Radiotherapy, Nicholas Hardcastle, Dean L. Cutajar, Peter E. Metcalfe, Michael L F Lerch, Vladimir L. Perevertaylo, Wolfgang A. Tome, Anatoly B. Rosenfeld
Michael L.F. Lerch
Rectal balloons are used in external beam prostate radiotherapy to provide reproducible anatomy and rectal dose reductions. This is an investigation into the combination of a MOSFET radiation detector with a rectal balloon for realtime in vivo rectal wall dosimetry. The MOSFET used in the study is a radiation detector that provides a water equivalent depth of measurement of 70 μm. Two MOSFETs were combined in a face-to-face orientation. The reproducibility, sensitivity and angular dependence were measured for the dual MOSFET in a 6 MV photon beam. The dual MOSFET was combined with a rectal balloon and irradiated with hypothetical …
Comparison Of The New Moskin Detector And Fiber Optic Dosimetry System For Radiotherapy, Ian Kwan, Bong Soo Lee, Wook Jae Yoo, Donghyun Cho, Kyoungwon Jang, Sanghun Shin, Martin Carolan, Michael Lerch, V Perevertaylo, Anatoly Rosenfeld
Comparison Of The New Moskin Detector And Fiber Optic Dosimetry System For Radiotherapy, Ian Kwan, Bong Soo Lee, Wook Jae Yoo, Donghyun Cho, Kyoungwon Jang, Sanghun Shin, Martin Carolan, Michael Lerch, V Perevertaylo, Anatoly Rosenfeld
Michael L.F. Lerch
In radiotherapy, interest in real-time dosimetry stems from the desire to monitor the dose delivered to the target volume and the surrounding normal tissue to enable clinicians to track the progress of the treatment, and prevent surrounding tissue from receiving too much radiation dose. In this study, the dosimetric performance of the new MOSkin dosimeter and a Bicron BCF-20 scintillating fiber was compared to depth dose measurements taken with a Farmer-type ionization chamber. The performance of the MOSkin and BCF-20 detectors in the build-up region of the depth dose curve, where the dose gradient is steep, is also compared to …
Potential High Resolution Dosimeters For Mrt, E. Brauer-Krisch, Anatoly B. Rosenfeld, Michael L. Lerch, Marco Petasecca, M. Akselrod, J. Sykora, J. Bartz, M. Ptaszkiewicz, P. Olko, A. Berg, M. Wieland, S. Doran, T. Brochard, A. Kamlowski, G. Cellere, A. Paccagnella, Erik A. Siegbahn, Y. Prezado, I. Martinez-Rovira, A. Bravin, Laurent Dusseau, P. Berkvens
Potential High Resolution Dosimeters For Mrt, E. Brauer-Krisch, Anatoly B. Rosenfeld, Michael L. Lerch, Marco Petasecca, M. Akselrod, J. Sykora, J. Bartz, M. Ptaszkiewicz, P. Olko, A. Berg, M. Wieland, S. Doran, T. Brochard, A. Kamlowski, G. Cellere, A. Paccagnella, Erik A. Siegbahn, Y. Prezado, I. Martinez-Rovira, A. Bravin, Laurent Dusseau, P. Berkvens
Michael L.F. Lerch
Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2nd and 3rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than …
Studies Of The Characteristics Of A Silicon Neutron Sensor, Igor E. Anokhin, Oleg S. Zinets, Anatoly B. Rosenfeld, Michael L. Lerch, M. Yudelev, V. L. Perevertaylo, Mark I. Reinhard, Marco Petasecca
Studies Of The Characteristics Of A Silicon Neutron Sensor, Igor E. Anokhin, Oleg S. Zinets, Anatoly B. Rosenfeld, Michael L. Lerch, M. Yudelev, V. L. Perevertaylo, Mark I. Reinhard, Marco Petasecca
Michael L.F. Lerch
Electrical characteristics and neutron dosimetry properties of silicon based p-i-n diodes are presented in support of the applications in the sensors for beam monitoring and medical physics. Both the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of silicon planar p-i-n diode sensors with cylindrical geometry have been theoretically modeled and experimentally measured. The shifts of the forward and reverse diode characteristics of the sensors versus the neutron dose have been obtained. It is shown that the neutron irradiation caused shift of the forward voltage of the p-i-n diodes is proportional to the current at which it is measured in the case …
Evaluation Of A Thin Microstrip Detector For High Spatial Resolution Dosimetry, J Kalliopuska, Ashley Cullen, Michael Lerch, Marco Petasecca, M Santala, Anatoly Rosenfeld
Evaluation Of A Thin Microstrip Detector For High Spatial Resolution Dosimetry, J Kalliopuska, Ashley Cullen, Michael Lerch, Marco Petasecca, M Santala, Anatoly Rosenfeld
Michael L.F. Lerch
VTT and Aalto University have supplied thin microstrip detector prototypes to CMRP for evaluation for the high spatial resolution dosimetry. The evaluation for dosimetry in microbeam radiation therapy (MRT) was done in a synchrotron microbeam at ESRF, France. Measurements studied a response of a single strip on the synchrotron microbeam in face-on and edge-on modes using CMRP designed and developed readout electronics for a parallel readout of single strips. Measurements were done in a passive mode without bias voltage and the detector was scanned through an array of intensive planar microbeams with the nominal width of 50 μm. The face-on …
In Vivo Dosimetry And Seed Localization In Prostate Brachytherapy With Permanent Implants, Anatoly B. Rosenfeld, Dean Cutajar, M. L. Lerch, G. J. Takacs, T. Braddock, V. L. Perevertailo, J. Bucci, J. Kearsley, M. Zaider, M. Zelefsky
In Vivo Dosimetry And Seed Localization In Prostate Brachytherapy With Permanent Implants, Anatoly B. Rosenfeld, Dean Cutajar, M. L. Lerch, G. J. Takacs, T. Braddock, V. L. Perevertailo, J. Bucci, J. Kearsley, M. Zaider, M. Zelefsky
Michael L.F. Lerch
This paper reports on the development of an interactive, intraoperative dose planning system for seed implant brachytherapy in cancer treatment. This system involves in vivo dosimetry and the ability to determine implanted seed positions. The first stage of this project is the development of a urethral alarm probe to measure the dose along the urethra during a prostate brachytherapy treatment procedure. Ultimately, the system will be used to advise the physicians upon reaching a preset dose rate or dose after total seed decay in the urethra during the seed placement. The second stage is the development of a method and …
Characterisation Of Delta E-E Particle Telescope Using The Ansto Heavy Ion Microprobe, Andrew Wroe, Dale Prokopovich, Michael Lerch, Anatoly Rosenfeld, David Cohen, Mihail Ionescu, Iwan Cornelius, Rainer Siegele, A Fazzi, S Agosteo, A Pola, Mark Reinhard
Characterisation Of Delta E-E Particle Telescope Using The Ansto Heavy Ion Microprobe, Andrew Wroe, Dale Prokopovich, Michael Lerch, Anatoly Rosenfeld, David Cohen, Mihail Ionescu, Iwan Cornelius, Rainer Siegele, A Fazzi, S Agosteo, A Pola, Mark Reinhard
Michael L.F. Lerch
No abstract provided.
Edge-On Face-To-Face Mosfet For Synchrotron Microbeam Dosimetry: Mc Modeling, Anatoly B. Rosenfeld, E. A. Siegbahn, E. Brauer-Krisch, A. Holmes-Siedle, M. L. Lerch, A. Bravin, I. Cornelius, G. J. Takacs, N. Painuly, H. Nettleback, T. Kron
Edge-On Face-To-Face Mosfet For Synchrotron Microbeam Dosimetry: Mc Modeling, Anatoly B. Rosenfeld, E. A. Siegbahn, E. Brauer-Krisch, A. Holmes-Siedle, M. L. Lerch, A. Bravin, I. Cornelius, G. J. Takacs, N. Painuly, H. Nettleback, T. Kron
Michael L.F. Lerch
The dosimetry of X-ray microbeams using MOSFETs results in an asymmetrical beam profile due to a lack of lateral charged particle equilibrium. Monte Carlo simulations were carried out using PENELOPE and GEANT4 codes to study this effect and a MOSFET on a micropositioner was scanned in the microbeam. Based on the simulations a new method of microbeam dosimetry is proposed. The proposed edge-on face-to-face (EOFF) MOSFET detector, a die arrangement proposed here for the first time, should alleviate the asymmetry. Further improvement is possible by thinning the silicon body of the MOSFET.
Urethral Spectroscopic Alarm (Usa) Probe For Prostate Implants, Anatoly Rosenfeld, Dean Cutajar, Michael Lerch, George Takacs, J Bucci, L Duggan, M Zaider, M Zelefsky, Gil'ad Cohen
Urethral Spectroscopic Alarm (Usa) Probe For Prostate Implants, Anatoly Rosenfeld, Dean Cutajar, Michael Lerch, George Takacs, J Bucci, L Duggan, M Zaider, M Zelefsky, Gil'ad Cohen
Michael L.F. Lerch
Urethral Spectroscopic Alarm (USA) Probe for Prostate Implants 1A.B. Rosenfeld, 1D.L. Cutajar, 1M.L.F. Lerch, 1G.J. Takacs, 2J.A. Bucci, 2L.J. Duggan, 3M. Zaider, 4M. Zelefsky and 3G.N. Cohen 1Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia, 2Institute for Prostate Cancer, St. George Cancer Care Centre, Kogarah, Australia, 3Department of Medical Physics and 4Department of Radiation Oncology, MSKCC, New York, NY Purpose: Prostate implants are associated with excellent biochemical outcome; however, their benefit in terms of overall survival remains unknown. For many patients with early, localized prostate cancer the decision to undergo a treatment of questionable benefit yet because of …
Modelling The Readout Performance Of A New Silicon Photodetector For Use In Pet, Michael Lerch, Philip Simmonds, Robert Ward, Tony Young, George Takacs, Anatoly Rosenfeld, V L Perevertaylo, Steven Meikle
Modelling The Readout Performance Of A New Silicon Photodetector For Use In Pet, Michael Lerch, Philip Simmonds, Robert Ward, Tony Young, George Takacs, Anatoly Rosenfeld, V L Perevertaylo, Steven Meikle
Michael L.F. Lerch
No abstract provided.
Feasibility Study Of Online High-Spatial-Resolution Mosfet Dosimetry In Static And Pulsed X-Ray Radiation Fields, Anatoly B. Rosenfeld, M. L. Lerch, T. Kron, E. Brauer-Krisch, A. Bravin, A. Holmes-Siedle, B. J. Allen
Feasibility Study Of Online High-Spatial-Resolution Mosfet Dosimetry In Static And Pulsed X-Ray Radiation Fields, Anatoly B. Rosenfeld, M. L. Lerch, T. Kron, E. Brauer-Krisch, A. Bravin, A. Holmes-Siedle, B. J. Allen
Michael L.F. Lerch
Improvements have been made in the measurement of dose profiles in several types of X-ray beams. These include 120-kVp X-ray beams from an orthovoltage X-ray machine, 6-MV Bremsstrahlung from a medical LINAC in conformal mode and the 50-200 keV energy spectrum of microbeams produced at the medical beamline station of the European Synchrotron Radiation Facility. Using a quadruple metal-oxide-semiconductor field-effect transistor (MOSFET) sensor chip in "edge on" mode together with a newly developed sensor readout system, the feasibility of online scanning of the profiles of quasi-static and pulsed radiation beams was demonstrated. Measurements of synchrotron pulsed microbeams showed that a …
Evaluation Of Pixellated, Back-Sided Planar Photodetectors For High-Resolution Imaging Instrumentation, Mark Safavi-Naeini, Michael Lerch, Marco Petasecca, Giorgio Pignatel, Mark Reinhard, Anatoly Rosenfeld
Evaluation Of Pixellated, Back-Sided Planar Photodetectors For High-Resolution Imaging Instrumentation, Mark Safavi-Naeini, Michael Lerch, Marco Petasecca, Giorgio Pignatel, Mark Reinhard, Anatoly Rosenfeld
Michael L.F. Lerch
Future generations of solid-state high-energy gamma imaging cameras require pixellated semiconductor photodetectors with the greatest possible detection efficiency. In this paper, a new type of planar silicon PIN photodiode is presented, in which both p+ and n+ electrodes are located on the same side of the device. The design offers highly efficient optical coupling between the backside and scintillator, providing a fill factor of close to 100%. The performance of this detector is modelled using the ISE-TCAD simulator and its electrical and spectroscopic characteristics are experimentally investigated for the case of direct interaction of ionising radiation and also with an …
Spectral Characterization Of A Blue-Enhanced Silicon Photodetector, M. L. Lerch, Anatoly B. Rosenfeld, Philip E. Simmonds, G. N. Taylor, S. R. Meikle, V. L. Perevertailo
Spectral Characterization Of A Blue-Enhanced Silicon Photodetector, M. L. Lerch, Anatoly B. Rosenfeld, Philip E. Simmonds, G. N. Taylor, S. R. Meikle, V. L. Perevertailo
Michael L.F. Lerch
In this paper, we report on spectral response data and gamma ray spectroscopy measurements using two newly developed silicon photodetectors that are designed to have enhanced sensitivity in the blue spectral region. The enhanced sensitivity is a result of our newly developed ion implantation profile used to create the active area of the photodetector. The quantum efficiency of the new photodetectors (without any optimized antireflective coating) has been measured to be ~40% at a wavelength of 420 nm. Gamma ray spectroscopy experiments have been performed using a thallium doped cesium iodide, [CsI(Tl)], and a cerium doped lutetium oxy-orthosilicate, (LSO) crystal …
Design And Simulation Of Continuous Scintillator With Pixellated Photodetector, G. J. Takacs, Anatoly B. Rosenfeld, M. L. Lerch
Design And Simulation Of Continuous Scintillator With Pixellated Photodetector, G. J. Takacs, Anatoly B. Rosenfeld, M. L. Lerch
Michael L.F. Lerch
Presents results of simulations performed as part of the development of a gamma-ray detector module comprising a nonpixellated scintillator and pixellated photodiode detector. The simulations have been carried out to determine the effect of surface treatment and dimensions of the scintillator on the ability to determine the two-dimensional position of interaction. A set of 32 different combinations of surface treatments have been considered for each crystal size. Scintillator dimensions considered have been 25×25×(3-6 mm3). For scintillator thicknesses at the low end of this range, an average accuracy of 0.5-0.6 mm is achievable for many different surface treatments. At the higher …
Performance Evaluation Of A Multipinhole Small Animal Spect System, S. R. Meikle, P. Kench, R. Wojcik, M. F. Smith, A. G. Weisenberger, S. Majewski, M. L. Lerch, Anatoly B. Rosenfeld
Performance Evaluation Of A Multipinhole Small Animal Spect System, S. R. Meikle, P. Kench, R. Wojcik, M. F. Smith, A. G. Weisenberger, S. Majewski, M. L. Lerch, Anatoly B. Rosenfeld
Michael L.F. Lerch
We have designed and constructed a small animal SPECT system based on compact, high resolution detectors and multipinhole apertures. The scanner is currently configured with two detectors mounted on a rotating gantry. Each detector comprises a NaI(Tl) crystal array (1/spl times/1/spl times/5 mm elements), a 12 cm diameter position-sensitive photomultiplier tube (Hamamatsu R3292) and a tungsten aperture with 1 or more pinholes. In this study, we performed phantom experiments to characterise the planar and tomographic performance of the scanner. Intrinsic resolution measured with a highly collimated /sup 99m/Tc point source stepped across the detector face was 1.0 /spl plusmn/ 0;.1 …
Magneto-Radiotherapy: Effect Of Magnetic Field On Dose Distribution And Rbe, Heidi Nettelbeck, Anatoly Rosenfeld, George Takacs, Michael Lerch
Magneto-Radiotherapy: Effect Of Magnetic Field On Dose Distribution And Rbe, Heidi Nettelbeck, Anatoly Rosenfeld, George Takacs, Michael Lerch
Michael L.F. Lerch
Magneto-radiotherapy is the application of magnetic fields during radiotherapy procedures. It aims to improve the quality of cancer treatment by altering the dose deposition of charged particles in the tissue volume being targeted. Our research has focused on applying the concept of magneto-radiotherapy to conventional linac treatment and MRT (Microbeam Radiation Therapy) oncology modalities.
Solid State Diode - Ionization Chamber Method For Measuring Out-Of-Field Neutron Dose In Proton Therapy, Amy Ziebell, B Clasie, Andrew Wroe, Reinhard Schulte, Mark Reinhard, Stephen Dowdell, Michael Lerch, Marco Petasecca, V Perevertaylo, Oleg Zinets, Igor Anokhin, Anatoly Rosenfeld
Solid State Diode - Ionization Chamber Method For Measuring Out-Of-Field Neutron Dose In Proton Therapy, Amy Ziebell, B Clasie, Andrew Wroe, Reinhard Schulte, Mark Reinhard, Stephen Dowdell, Michael Lerch, Marco Petasecca, V Perevertaylo, Oleg Zinets, Igor Anokhin, Anatoly Rosenfeld
Michael L.F. Lerch
In proton therapy neutrons are introduced to out-of-field regions inside the patient. Clinicians would like to know the absorbed dose being deposited by neutrons separately to that from protons, so as to be able to directly apply their own dose equivalent weighting factors based on their opinion of the biological risk posed by neutrons in this region. The purpose of this study is to investigate a novel approach to experimentally separating the proton and neutron contributions to the absorbed dose in out-of-field regions. The method pairs specially designed silicon PIN diodes with a standard clinical ionization chamber. The sensitivity of …
Mosfet Dosimetry For Microbeam Radiation Therapy At The European Synchrotron Radiation Facility, E. Brauer-Krisch, A. Bravin, M. L. Lerch, Anatoly B. Rosenfeld, J. Stepanek, M. Di Michiel, J. A. Laissue
Mosfet Dosimetry For Microbeam Radiation Therapy At The European Synchrotron Radiation Facility, E. Brauer-Krisch, A. Bravin, M. L. Lerch, Anatoly B. Rosenfeld, J. Stepanek, M. Di Michiel, J. A. Laissue
Michael L.F. Lerch
Preclinical experiments are carried out with ~20–30 μm wide, ~10 mm high parallel microbeams of hard, broad-‘‘white’’-spectrum x rays (~50–600 keV) to investigate microbeam radiation therapy (MRT) of brain tumors in infants for whom other kinds of radiotherapy are inadequate and/or unsafe. Novel physical microdosimetry (implemented with MOSFET chips in the ‘‘edge-on’’ mode) and Monte Carlo computer-simulated dosimetry are described here for selected points in the peak and valley regions of a microbeam-irradiated tissue-equivalent phantom. Such microbeam irradiation causes minimal damage to normal tissues, possible because of rapid repair of their microscopic lesions. Radiation damage from an array of parallel …
A Real-Time In Vivo Dosimetric Verification Method For High-Dose Rate Intracavitary Brachytherapy Of Nasopharyngeal Carcinoma, Zhen-Yu Qi, Xiao-Wu Deng, X Cao, Shao-Min Huang, Michael Lerch, Anatoly Rosenfeld
A Real-Time In Vivo Dosimetric Verification Method For High-Dose Rate Intracavitary Brachytherapy Of Nasopharyngeal Carcinoma, Zhen-Yu Qi, Xiao-Wu Deng, X Cao, Shao-Min Huang, Michael Lerch, Anatoly Rosenfeld
Michael L.F. Lerch
Purpose: A real-time in vivo dosimetric verification method using metal-oxide-semiconductor field effect transistor (MOSFET) dosimeters has been developed for patient dosimetry in high-dose rate (HDR) intracavitary brachytherapy of nasopharyngeal carcinoma (NPC). Methods: The necessary calibration and correction factors for MOSFET measurements in 192Iridium source were determined in a water phantom. With the detector placed inside a custom-made nasopharyngeal applicator, the actual dose delivered to the tumor was measured in vivo and compared to the calculated values using a commercial brachytherapy planning system. Results: Five MOSFETs were independently calibrated with the HDR source, yielding calibration factors of 0.48 ± 0.007 cGymV. …
Radiation Monitoring In Mixed Environments At Cern: From The Irrad6 Facility To The Lhc Experiments, F Ravotti, M Glaser, Anatoly B. Rosenfeld, Michael L. Lerch, A Holmes-Siedle, G Sarrrabayrouse
Radiation Monitoring In Mixed Environments At Cern: From The Irrad6 Facility To The Lhc Experiments, F Ravotti, M Glaser, Anatoly B. Rosenfeld, Michael L. Lerch, A Holmes-Siedle, G Sarrrabayrouse
Michael L.F. Lerch
RadFET and p-i-n diode semiconductor dosimeters from different manufacturers will be used for radiation monitoring at the Experiments of the CERN LHC accelerator. In this work these sensors were exposed over three months in the CERN-IRRAD6 facility that provides mixed high-energy particles at low rates. The aim was to validate the operation of such sensors in a radiation field where the conditions are close to the ones expected inside full working LHC particle detectors. The results of this long-term irradiation campaign are presented, discussed and compared with measurements by other dosimetric means as well as Monte Carlo simulations. Finally, the …
Evaluation Of Silicon Detectors With Integrated Jfet For Biomedical Applications, Mitra Safavi-Naeini, D. Franklin, Michael L. Lerch, Marco Petasecca, Giorgio U. Pignatel, Mark I. Reinhard, G. F. Dalla Betta, N. Zorzi, Anatoly B. Rosenfeld
Evaluation Of Silicon Detectors With Integrated Jfet For Biomedical Applications, Mitra Safavi-Naeini, D. Franklin, Michael L. Lerch, Marco Petasecca, Giorgio U. Pignatel, Mark I. Reinhard, G. F. Dalla Betta, N. Zorzi, Anatoly B. Rosenfeld
Michael L.F. Lerch
This paper presents initial results from electrical, spectroscopic and ion beam induced charge (IBIC) characterisation of a novel silicon PIN detector, featuring an on-chip n -channel JFET and matched feedback capacitor integrated on its p-side (frontside). This structure reduces electronic noise by minimising stray capacitance and enables highly efficient optical coupling between the detector back-side and scintillator, providing a fill factor of close to 100%. The detector is specifically designed for use in high resolution gamma cameras, where a pixellated scintillator crystal is directly coupled to an array of silicon photodetectors. The on-chip JFET is matched with the photodiode capacitance …
Readout Of Lyso Using A New Silicon Photodetector For Positron Emission Tomography, M. L. Lerch, R. Ward, Philip E. Simmonds, V. L. Perevertailo, S. R. Meikle, G. N. Taylor, Anatoly B. Rosenfeld
Readout Of Lyso Using A New Silicon Photodetector For Positron Emission Tomography, M. L. Lerch, R. Ward, Philip E. Simmonds, V. L. Perevertailo, S. R. Meikle, G. N. Taylor, Anatoly B. Rosenfeld
Michael L.F. Lerch
This article focuses on the characterisation of three versions of a custom designed silicon photodetector using nuclear spectroscopy techniques. Room temperature gamma ray spectroscopy experiments have been performed using an LYSO excited by /sup 137/Cs and /sup 22/Na sources and read out by the new photodiodes. We have measured an energy resolution of 13.1% FWHM for the 511 keV gamma rays from a /sup 22/Na source and 11.2% FWHM for the 662 keV gamma rays from a /sup 137/Cs source. This is one of the best ever-reported energy resolutions for a lutetium based scintillator crystal read out by a silicon …
A Dual Scintillator - Dual Silicon Photodiode Detector Module For Intraoperative Gamma\Beta Probe And Portable Anti-Compton Spectrometer, Anatoly Rosenfeld, Michael Lerch, M. Chan, Dean Inwood, George Takacs, Bong Soo Lee, A Gektin, V L Perevertaylo
A Dual Scintillator - Dual Silicon Photodiode Detector Module For Intraoperative Gamma\Beta Probe And Portable Anti-Compton Spectrometer, Anatoly Rosenfeld, Michael Lerch, M. Chan, Dean Inwood, George Takacs, Bong Soo Lee, A Gektin, V L Perevertaylo
Michael L.F. Lerch
A new approach has been investigated for the miniaturization and simplification of intraoperative gamma and beta probes that have recently found application in radioguided surgery and sentinel lymph node biopsy. The probe design that is based on dual annular scintillators coupled to specially designed silicon concentric dual photodiode (CDPD). This approach allows us to avoid fiber optics coupling and PMTs. Two channels readout front-end electronics including shaper amplifier attached directly to the back of the detector module has been proposed. Two geometries of Si dual photodiodes coupled to CsI(Tl) annular scintillators with light masking between them were fabricated and investigated. …
Neutron Dosimeter Development Based On Medipix2, Mohd Amir R. Othman, Marco Petasecca, Susanna Guatelli, J. Uher, Damion Marinaro, Dale A. Prokopovich, Mark I. Reinhard, Michael L. F. Lerch, J. Jakubek, S. Pospisil, Anatoly B. Rosenfeld
Neutron Dosimeter Development Based On Medipix2, Mohd Amir R. Othman, Marco Petasecca, Susanna Guatelli, J. Uher, Damion Marinaro, Dale A. Prokopovich, Mark I. Reinhard, Michael L. F. Lerch, J. Jakubek, S. Pospisil, Anatoly B. Rosenfeld
Michael L.F. Lerch
A novel neutron dosimetry system for avionics and space applications is described. The new dosimetric system is based on Medipix2, a high density silicon based pixilated detector with integrated readout and digital interface circuitry. Real time dose equivalent response to fast neutron fields with flattened energy response is achieved through the coupling of a structured variable thickness polyethylene (PE) over layer with the high density pixilated detector. Experimental results obtained to 14 MeV D-T and Am-Be neutron fields are described along with a comparison to results obtained with GEANT4 simulations.
Spectral Characterisation Of A Blue-Enhanced Silicon Photodetector, M. Lerch, Anatoly Rosenfeld, Philip Simmonds, G. Taylor, S. Meikle, V. Perevertailo
Spectral Characterisation Of A Blue-Enhanced Silicon Photodetector, M. Lerch, Anatoly Rosenfeld, Philip Simmonds, G. Taylor, S. Meikle, V. Perevertailo
Michael L.F. Lerch
In this work we report on spectral response data and gamma ray spectroscopy measurements using two newly developed silicon photodetectors that are designed to have enhanced sensitivity in the blue spectral region. The enhanced sensitivity is a result of our newly developed ion implantation profile used to create the active area of the photodetector. The quantum efficiency of the new photodetectors (without any optimised antireflective coating) has been measured to be ~40% at a wavelength of 420 nm. Gamma ray spectroscopy experiments have been performed using a CsI(Tl) and a LSO crystal excited by a 137Cs or 22Na source and …
Urethral Alarm Probe For Permanent Prostate Implants, Dean Cutajar, Michael Lerch, George Takacs, Bong Soo Lee, Y Chin, J Bucci, M Zaider, M Zelefsky, J. Yamada, Gil'ad Cohen, V L Perevertaylo, Anatoly Rosenfeld
Urethral Alarm Probe For Permanent Prostate Implants, Dean Cutajar, Michael Lerch, George Takacs, Bong Soo Lee, Y Chin, J Bucci, M Zaider, M Zelefsky, J. Yamada, Gil'ad Cohen, V L Perevertaylo, Anatoly Rosenfeld
Michael L.F. Lerch
We have developed a urethral dosimetry system for real time dose verification along the urethra during permanent implant prostate brachytherapy. The urethral alarm probe uses “spectroscopic dosimetry” to calculate the dose rate along the urethra in real time. The application of spectroscopic dosimetry for the urethral alarm probe was verified using Monte Carlo calculations. In phantom depth dose measurements as well as isotropy measurements were performed to verify the usefulness of the urethra alarm probe as an in vivo real time dosimeter.