The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Richard L. Maughan - One of the best experts on this subject based on the ideXlab platform.
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Characterization of a Modified Fast Neutron Beam for Boron Neutron Capture Enhancement of Fast Neutron Therapy
Frontiers in Neutron Capture Therapy, 2001Co-Authors: Jay Burmeister, Chandrasekhar Kota, Mark Yudelev, Richard L. MaughanAbstract:The use of the boron Neutron capture reaction to provide a localized tumor boost in fast Neutron Therapy was originally proposed by Waterman et al.1 This treatment modality may be referred to as boron Neutron capture enhanced fast Neutron Therapy (BNCEFNT).2 Many fast Neutron facilities are currently investigating the possibility of treating with BNCEFNT Investigations are underway at the Harper Hospital cyclotron produced d(48.5)+Be fast Neutron Therapy facility in an attempt to produce a suitable modified beam for BNCEFNT3,4,5 Characterization of this modified beam is in progress using both proportional counter and ionization chamber techniques with results presented.
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HOSPITAL BASED SUPERCONDUCTING CYCLOTRON FOR Neutron Therapy: MEDICAL PHYSICS PERSPECTIVE
AIP Conference Proceedings, 2001Co-Authors: Mark Yudelev, Jay Burmeister, Richard L. Maughan, E. Blosser, Chandrasekhar KotaAbstract:The Neutron Therapy facility at the Gershenson Radiation Oncology Center, Harper University Hospital in Detroit has been operational since September 1991. The d(48.5)+Be beam is produced in a gantry mounted superconducting cyclotron designed and built at the National Superconducting Cyclotron Laboratory (NSCL). Measurements were performed in order to obtain the physical characteristics of the Neutron beam and to collect the data necessary for treatment planning. This included profiles of the dose distribution in a water phantom, relative output factors and the design of various beam modifiers, i.e. wedges and tissue compensators. The beam was calibrated in accordance with international protocol for fast Neutron dosimetry. Dosimetry and radiobiology intercomparisons with three Neutron Therapy facilities were performed prior to clinical use. The radiation safety program was established in order to monitor and reduce the exposure levels of the personnel. The activation products were identified and the exposure in the treatment room was mapped. A comprehensive quality assurance (QA) program was developed to sustain safe and reliable operation of the unit at treatment standards comparable to those for conventional photon radiation. The program can be divided into three major parts: maintenance of the cyclotron and related hardware; QA of the Neutron beam dosimetry and treatment delivery; safety and radiation protection. In addition the Neutron beam is used in various non-clinical applications. Among these are the microdosimetric characterization of the beam, the effects of tissue heterogeneity on dose distribution, the development of boron Neutron capture enhanced fast Neutron Therapy and variety of radiobiology experiments.
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Calculated Fluence Spectra at Neutron Therapy Facilities
Radiation Protection Dosimetry, 1997Co-Authors: M.a. Ross, Arlene Lennox, Paul M. Deluca, D. T. L. Jones, Richard L. MaughanAbstract:The Monte Carlo transport codes LAHET and MCNP were used to calculate energy fluence spectra at three Neutron Therapy facilities. The results compare very favourably with measured data. Kerma spectra and the ratio of ICRU muscle tissue kerma to A-150 kerma, along with the carbon to oxygen kerma ratio, were determined. Absorbed dose rate calculations are in reasonable agreement with measured values. Use of these codes to study modifications to existing Therapy beams is briefly discussed.
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The application of a multirod collimator in fast Neutron Therapy
Bulletin du Cancer Radiothérapie, 1996Co-Authors: Mark Yudelev, Richard L. Maughan, Renu Sharma, Jeffrey D. FormanAbstract:The application of a novel multirod collimator in fast Neutron Therapy to produce irregularly shaped fields with partial transmission and fully blocked areas is discussed. The transmission through the tungsten rods is measured in free space in broad beam geometry. A model based on scatter analysis is applied in calculating the thickness of the rods required to produce partially blocked areas. The effect of a full beam block is also measured. Measurements have been made in a water phantom to confirm the computational model. The good agreement between the measured and calculated values demonstrates that the scatter model can be safely applied to fast Neutron beam dose computations.
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Physical characteristics of a clinical d(48.5)+Be Neutron Therapy beam produced by a superconducting cyclotron.
Medical physics, 1995Co-Authors: Richard L. Maughan, Mark YudelevAbstract:The Harper Hospital and Wayne State University fast Neutron Therapy facility is the only one in the world to use a compact superconducting cyclotron and multirod collimator. Neutrons are produced by the interaction of the 48.5-MeV deuteron beam with a thick internal beryllium target and the compact accelerator is gantry mounted to allow full 360 degrees rotation of the Neutron beam about the Therapy couch. The deuteron beam strikes the beryllium target at a glancing angle. A flattening filter is used to flatten the asymmetric Neutron beam which results from this geometry. Details of the flattening filter design and construction are discussed. The physical characteristics of the resulting Neutron Therapy beam were measured. The central axis depth-dose values are approximately equivalent to those of a 4-MV photon beam. The dose buildup curve reaches its maximum value at a depth of 9 mm in a water phantom and the surface dose is approximately 42%. The beam penumbra produced by the multirod collimator has been measured in terms of the distance between the 20% and 80% isodose lines. The penumbra width for a 10 x 10-cm2 field at a depth of 10 cm in a water phantom is 1.65 +/- 0.1 cm, and is comparable to that achieved with other high-energy Neutron beams. The long-term stability of the dose monitoring system has been measured and found to be satisfactory. The physical characteristics of the Neutron beam are comparable with those of other modern fast Neutron Therapy facilities.
George E. Laramore - One of the best experts on this subject based on the ideXlab platform.
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Dosimetric characteristics of the University of Washington Clinical Neutron Therapy System
Physics in medicine and biology, 2018Co-Authors: Gregory B Moffitt, Robert D. Stewart, George A. Sandison, John T. Goorley, David C. Argento, Tatjana Jevremovic, Robert Emery, L. Wootton, Upendra Parvathaneni, George E. LaramoreAbstract:The University of Washington (UW) Clinical Neutron Therapy System (CNTS), which generates high linear energy transfer fast Neutrons through interactions of 50.5 MeV protons incident on a Be target, has depth-dose characteristics similar to 6 MV x-rays. In contrast to the fixed beam angles and primitive blocking used in early clinical trials of Neutron Therapy, the CNTS has a gantry with a full 360° of rotation, internal wedges, and a multi-leaf collimator (MLC). Since October of 1984, over 3178 patients have received conformal Neutron Therapy treatments using the UW CNTS. In this work, the physical and dosimetric characteristics of the CNTS are documented through comparisons of measurements and Monte Carlo simulations. A high resolution computed tomography scan of the model 17 ionization chamber (IC-17) has also been used to improve the accuracy of simulations of the absolute calibration geometry. The response of the IC-17 approximates well the kinetic energy released per unit mass (KERMA) in water for Neutrons and photons for energies from a few tens of keV up to about 20 MeV. Above 20 MeV, the simulated model 17 ion chamber response is 20%-30% higher than the Neutron KERMA in water. For CNTS Neutrons, simulated on- and off-axis output factors in water match measured values within ~2% ± 2% for rectangular and irregularly shaped field with equivalent square areas ranging in a side dimension from 2.8 cm to 30.7 cm. Wedge factors vary by less than 1.9% of the measured dose in water for clinically relevant field sizes. Simulated tissue maximum ratios in water match measured values within 3.3% at depths up to 20 cm. Although the absorbed dose for water and adipose tissue are within 2% at a depth of 1.7 cm, the absorbed dose in muscle and bone can be as much as 12 to 40% lower than the absorbed dose in water. The reported studies are significant from a historical perspective and as additional validation of a new tool for patient quality assurance and as an aid in ongoing efforts to clinically implement advanced treatment techniques, such as intensity modulated Neutron Therapy, at the UW.
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Experimental Transport Benchmarks for Physical Dosimetry to Support Development of Fast-Neutron Therapy with Neutron Capture Augmentation
Transactions of the American Nuclear Society, 2006Co-Authors: David W. Nigg, R. Risler, J. K. Hartwell, J.r. Venhuizen, C.a. Wemple, George E. Laramore, W. Sauerwein, G. Hudepohl, Arlene LennoxAbstract:The Idaho National Laboratory (INL), the University of Washington (UW) Neutron Therapy Center, the University of Essen (Germany) Neutron Therapy Clinic, and the Northern Illinois University(NIU) Institute for Neutron Therapy at Fermilab have been collaborating in the development of fast-Neutron Therapy (FNT) with concurrent Neutron capture (NCT) augmentation [1,2]. As part of this effort, we have conducted measurements to produce suitable benchmark data as an aid in validation of advanced three-dimensional treatment planning methodologies required for successful administration of FNT/NCT. Free-beam spectral measurements as well as phantom measurements with Lucite{trademark} cylinders using thermal, resonance, and threshold activation foil techniques have now been completed at all three clinical accelerator facilities. The same protocol was used for all measurements to facilitate intercomparison of data. The results will be useful for further detailed characterization of the Neutron beams of interest as well as for validation of various charged particle and Neutron transport codes and methodologies for FNT/NCT computational dosimetry, such as MCNP [3], LAHET [4], and MINERVA [5].
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modification of the university of washington Neutron radioTherapy facility for optimization of Neutron capture enhanced fast Neutron Therapy
Medical Physics, 2000Co-Authors: David W. Nigg, R. Risler, J. K. Hartwell, C.a. Wemple, Y D Harker, George E. LaramoreAbstract:The Fast-Neutron Therapy (FNT) facility at the University of Washington (UW) is the focus for an ongoing collaborative investigation of BNCT-enhanced fast-Neutron Therapy for certain lung tumors and possibly for other malignancies. This paper describes the design and testing of a modified Neutron production target assembly that has been developed to provide improved performance of the UW system for applications involving BNCT-enhanced FNT.
Mark Yudelev - One of the best experts on this subject based on the ideXlab platform.
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Characterization of a Modified Fast Neutron Beam for Boron Neutron Capture Enhancement of Fast Neutron Therapy
Frontiers in Neutron Capture Therapy, 2001Co-Authors: Jay Burmeister, Chandrasekhar Kota, Mark Yudelev, Richard L. MaughanAbstract:The use of the boron Neutron capture reaction to provide a localized tumor boost in fast Neutron Therapy was originally proposed by Waterman et al.1 This treatment modality may be referred to as boron Neutron capture enhanced fast Neutron Therapy (BNCEFNT).2 Many fast Neutron facilities are currently investigating the possibility of treating with BNCEFNT Investigations are underway at the Harper Hospital cyclotron produced d(48.5)+Be fast Neutron Therapy facility in an attempt to produce a suitable modified beam for BNCEFNT3,4,5 Characterization of this modified beam is in progress using both proportional counter and ionization chamber techniques with results presented.
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HOSPITAL BASED SUPERCONDUCTING CYCLOTRON FOR Neutron Therapy: MEDICAL PHYSICS PERSPECTIVE
AIP Conference Proceedings, 2001Co-Authors: Mark Yudelev, Jay Burmeister, Richard L. Maughan, E. Blosser, Chandrasekhar KotaAbstract:The Neutron Therapy facility at the Gershenson Radiation Oncology Center, Harper University Hospital in Detroit has been operational since September 1991. The d(48.5)+Be beam is produced in a gantry mounted superconducting cyclotron designed and built at the National Superconducting Cyclotron Laboratory (NSCL). Measurements were performed in order to obtain the physical characteristics of the Neutron beam and to collect the data necessary for treatment planning. This included profiles of the dose distribution in a water phantom, relative output factors and the design of various beam modifiers, i.e. wedges and tissue compensators. The beam was calibrated in accordance with international protocol for fast Neutron dosimetry. Dosimetry and radiobiology intercomparisons with three Neutron Therapy facilities were performed prior to clinical use. The radiation safety program was established in order to monitor and reduce the exposure levels of the personnel. The activation products were identified and the exposure in the treatment room was mapped. A comprehensive quality assurance (QA) program was developed to sustain safe and reliable operation of the unit at treatment standards comparable to those for conventional photon radiation. The program can be divided into three major parts: maintenance of the cyclotron and related hardware; QA of the Neutron beam dosimetry and treatment delivery; safety and radiation protection. In addition the Neutron beam is used in various non-clinical applications. Among these are the microdosimetric characterization of the beam, the effects of tissue heterogeneity on dose distribution, the development of boron Neutron capture enhanced fast Neutron Therapy and variety of radiobiology experiments.
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The application of a multirod collimator in fast Neutron Therapy
Bulletin du Cancer Radiothérapie, 1996Co-Authors: Mark Yudelev, Richard L. Maughan, Renu Sharma, Jeffrey D. FormanAbstract:The application of a novel multirod collimator in fast Neutron Therapy to produce irregularly shaped fields with partial transmission and fully blocked areas is discussed. The transmission through the tungsten rods is measured in free space in broad beam geometry. A model based on scatter analysis is applied in calculating the thickness of the rods required to produce partially blocked areas. The effect of a full beam block is also measured. Measurements have been made in a water phantom to confirm the computational model. The good agreement between the measured and calculated values demonstrates that the scatter model can be safely applied to fast Neutron beam dose computations.
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Physical characteristics of a clinical d(48.5)+Be Neutron Therapy beam produced by a superconducting cyclotron.
Medical physics, 1995Co-Authors: Richard L. Maughan, Mark YudelevAbstract:The Harper Hospital and Wayne State University fast Neutron Therapy facility is the only one in the world to use a compact superconducting cyclotron and multirod collimator. Neutrons are produced by the interaction of the 48.5-MeV deuteron beam with a thick internal beryllium target and the compact accelerator is gantry mounted to allow full 360 degrees rotation of the Neutron beam about the Therapy couch. The deuteron beam strikes the beryllium target at a glancing angle. A flattening filter is used to flatten the asymmetric Neutron beam which results from this geometry. Details of the flattening filter design and construction are discussed. The physical characteristics of the resulting Neutron Therapy beam were measured. The central axis depth-dose values are approximately equivalent to those of a 4-MV photon beam. The dose buildup curve reaches its maximum value at a depth of 9 mm in a water phantom and the surface dose is approximately 42%. The beam penumbra produced by the multirod collimator has been measured in terms of the distance between the 20% and 80% isodose lines. The penumbra width for a 10 x 10-cm2 field at a depth of 10 cm in a water phantom is 1.65 +/- 0.1 cm, and is comparable to that achieved with other high-energy Neutron beams. The long-term stability of the dose monitoring system has been measured and found to be satisfactory. The physical characteristics of the Neutron beam are comparable with those of other modern fast Neutron Therapy facilities.
R. Risler - One of the best experts on this subject based on the ideXlab platform.
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Experimental Transport Benchmarks for Physical Dosimetry to Support Development of Fast-Neutron Therapy with Neutron Capture Augmentation
Transactions of the American Nuclear Society, 2006Co-Authors: David W. Nigg, R. Risler, J. K. Hartwell, J.r. Venhuizen, C.a. Wemple, George E. Laramore, W. Sauerwein, G. Hudepohl, Arlene LennoxAbstract:The Idaho National Laboratory (INL), the University of Washington (UW) Neutron Therapy Center, the University of Essen (Germany) Neutron Therapy Clinic, and the Northern Illinois University(NIU) Institute for Neutron Therapy at Fermilab have been collaborating in the development of fast-Neutron Therapy (FNT) with concurrent Neutron capture (NCT) augmentation [1,2]. As part of this effort, we have conducted measurements to produce suitable benchmark data as an aid in validation of advanced three-dimensional treatment planning methodologies required for successful administration of FNT/NCT. Free-beam spectral measurements as well as phantom measurements with Lucite{trademark} cylinders using thermal, resonance, and threshold activation foil techniques have now been completed at all three clinical accelerator facilities. The same protocol was used for all measurements to facilitate intercomparison of data. The results will be useful for further detailed characterization of the Neutron beams of interest as well as for validation of various charged particle and Neutron transport codes and methodologies for FNT/NCT computational dosimetry, such as MCNP [3], LAHET [4], and MINERVA [5].
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20 YEARS OF CLINICAL OPERATION WITH THE FAST Neutron Therapy SYSTEM IN SEATTLE
2003Co-Authors: R. Risler, J. Jacky, David M. ReidAbstract:The Clinical Neutron Therapy System at the University of Washington Medical Center in Seattle has now treated patients with fast Neutrons for 20 years. During the past three years roughly 75 % of the treatments were for salivary gland tumors, where Neutron Therapy is the treatment of choice. After the installation of a small dedicated cyclotron in the Nuclear Medicine department for PET isotope production this service is no longer required from the Scanditronix MC50 cyclotron. Instead, a new beam line has been added for the production of 211-At using an alpha beam. The clinical operation remains very reliable with an 18 month time period where not a single patient session had to be cancelled for machine reasons. During the same time period all major system components were secured seismically, which required considerable construction activity during weekends with normal Therapy operation continuing during the week. Besides the continuing upgrade and replacement of system parts a program is under way to migrate the accelerator / beam line controls to an EPICS based control system.
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Clinical Neutron Therapy System Therapist's Guide
2002Co-Authors: Jonathan Jacky, R. RislerAbstract:This is the therapist’s guide for the control of the isocentric treatment unit at the Clinical Neutron Therapy System (CNTS) at the University of Washington Medical Center. This guide provides instructions for performing typical treatment procedures. A separate reference manual provides detailed descriptions of each key, display, message, etc. This guide only describes the features of CNTS that are needed to perform treatments and which are the therapist’s responsibility. Other manuals describe the features that support troubleshooting and recovering from problems, calibration, physics, and engineering.
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modification of the university of washington Neutron radioTherapy facility for optimization of Neutron capture enhanced fast Neutron Therapy
Medical Physics, 2000Co-Authors: David W. Nigg, R. Risler, J. K. Hartwell, C.a. Wemple, Y D Harker, George E. LaramoreAbstract:The Fast-Neutron Therapy (FNT) facility at the University of Washington (UW) is the focus for an ongoing collaborative investigation of BNCT-enhanced fast-Neutron Therapy for certain lung tumors and possibly for other malignancies. This paper describes the design and testing of a modified Neutron production target assembly that has been developed to provide improved performance of the UW system for applications involving BNCT-enhanced FNT.
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Routine operation of the University of Washington fast Neutron Therapy facility and plans for improvements
AIP Conference Proceedings, 1999Co-Authors: R. Risler, Robert Emery, G. E. LaramoreAbstract:The fast Neutron Therapy facility in Seattle is based on a cyclotron, which produces a 50.5 MeV proton beam. Neutrons are produced in a beryllium target installed in an isocentric gantry equipped with a multi-leaf collimator. The system has been in routine operation for 14 years and over 1800 patients have been treated. Downtime has been minimal, over the past 10 years less than 1.5% of the scheduled daily treatment sessions could not be delivered for equipment related reasons. Fast Neutron Therapy has been shown to be highly effective for the treatment of salivary gland tumors, sarcomas of bone and soft tissues and for certain prostate cancers. In addition there are situations such as non-small cell lung cancer, where results are promising, but success is limited by normal tissue complications. A relatively small selective increase in the tumor dose might lead to a significant clinical improvement in these situations. The use of a boron Neutron capture (BNC) boost, utilizing the moderated slow Neutrons n...
Alina Popescu - One of the best experts on this subject based on the ideXlab platform.
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Dosimetry measurements at the fast Neutron Therapy facility in Seattle
Radiation Measurements, 2010Co-Authors: Ruedi Risler, Alina PopescuAbstract:Abstract The fast Neutron Therapy facility at the University of Washington has been in routine clinical use for 25 years. 50.5 MeV protons produce Neutrons in a beryllium target mounted on an isocentric gantry. Beam shaping is accomplished with a 40-leaf collimator. Dosimetry measurements for treatment planning and calibration are performed with tissue equivalent ion chambers. A layered phantom of alternating Solid Water ® and Plastic Water ® slabs has been developed for rapid dose verification measurements. The Neutron field in the room has been used for radiation testing of electronic components.
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Changes in prescribed doses for the Seattle Neutron Therapy system
Physics in medicine and biology, 2008Co-Authors: Alina PopescuAbstract:From the beginning of the Neutron Therapy program at the University of Washington Medical Center, the Neutron dose distribution in tissue has been calculated using an in-house treatment planning system called PRISM. In order to increase the accuracy of the absorbed dose calculations, two main improvements were made to the PRISM treatment planning system: (a) the algorithm was changed by the addition of an analytical expression of the central axis wedge factor dependence with field size and depth developed at UWMC. Older versions of the treatment-planning algorithm used a constant central axis wedge factor; (b) a complete newly commissioned set of measured data was introduced in the latest version of PRISM. The new version of the PRISM algorithm allowed for the use of the wedge profiles measured at different depths instead of one wedge profile measured at one depth. The comparison of the absorbed dose calculations using the old and the improved algorithm showed discrepancies mainly due to the missing central axis wedge factor dependence with field size and depth and due to the absence of the wedge profiles at depths different from 10 cm. This study concludes that the previously reported prescribed doses for Neutron Therapy should be changed.