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John Broadhurst

TATEH 201-25 (office), 624-2502
broad010 @ umn.edu • http://www.biophysics.umn.edu/~johnb

BroadhurstLarge.jpg

Collaborations

A collaboration with the Veterans Administration Hospital in Minneapolis to study the magnetic response of the human brain to selected sound stimuli. CEO of small company (Sysmed Inc.) involved in a former SBIR contract for the development of high gradient small electrostatic accelerators with novel charging and insulating systems.. CFO of small company (Spectrameasure Inc.) involved in medical instrumentation for pulmonary function analysis.

Summary of Interests
The process of human hearing, using locally induced nuclear reactions to enhance the treatment of cancers by high energy (Mev) photons or thermal neutrons. The role of heavy cations in controlling contracting muscle cells.. [Research Web Page]

About My Work

My work on the process of human hearing has now expanded to include a study of the time resolution of sounds presented to the human ear Previously one of my students, Steven Gardeen, graduated from the physics department, his thesis establishing that the human hearing (auditory cortex) is capable of discriminating small frequency shifts in equal loudness anharmonic partials (Fourier components). Also resulting from this research was the discovery that ‘mismatch’ sounds, i.e. a sound differing from the sound immediately preceding it, is processed at a different brain location in male and female subjects. Also determined was that the processing of this sound mismatch processor contains filters to determine whether the brain should be involved at the conscious level. It appears that a similar process is present for sounds with small (millisecond) time deviations.

Frank’s work was to determine if one could quantitatively measure permanent radiation damage to biological tissue due to ionizing radiation. (This is important in radiation cancer treatment, increasing the dose by 60% will change the cure rate from 5% to 95%). Currently dose is measured by mechanical equipment such as air filled ion chambers. Frank’s work was to measure permanent changes in the complex impedance of tissue (bovine muscle) as a function of radiation ‘dose’. He found that although the conductivity was relatively unchanged, the permittivity decreased as complex molecules were dissociated into smaller molecules. (With smaller dipole moments). Two papers have been written on Frank’s work, currently they are being released after being held from publication by the U patent office, which was assessing the patent prospects.

I am working on two projects associated with the selective local enhancement of cancer treatment dose by high -energy photon induced nuclear processes. My medical physics graduate student Pamela Soorian is studying selectively enhancing radiation dose in bones using the giant dipole resonance (at 16 Mev photon energy) of the bone calcium nuclei. The experimental verification is expected to be complete by the end of 2016. My physics student, Siddarth Karuka is assisting with research on local enhancement of radiation dose by the injection of high Z (gold) nanoparticles and irradiation by high-energy photons, while student Yao Meng is working on the possibility of using accelerator produce epithermal neutrons to interact with10boron. The enhancement in treatment dose by high-energy photons is caused by induced pair production producing additional beta particle recoils, whereas the boron neutron enhancement is due to nuclear dissociation after neutron capture by the 10boron. This photon work has already been proven in principle by my previous study using tissue equivalent plastic films, and has now reached the first animal tests. The neutron work extends the treatment of brain cancers (glioblastomas) already practiced in Japan using neutrons produced by a nuclear reactor to other cancerous growths.

Part of this work is currently funded by a University grant. We are currently discussing the possibility of government funding with the National Cancer Institute of the NIH for a more extended study .Their opinion was that an introductory animal study would greatly enhance the possibility of funding, and therefore we are at present carrying out small-scale work on rabbits.

Selected Publications

Yasayuki Nogi, John H. Broadhurst, Yoshiki Takano, Eisui Uematsu , Textbook:“Butsurigaku Jikken” (Advanced Experimentation for Students), Shokabo Press Tokyo (1996)

Ahmed Alkhatib, Yoichi Watanabe, And John H.Broadhurst, The local enhancement of radiation dose from photon of MeV energies obtained by introducing materials of high atomic number into the treatment region., Journal of Medical Physics 36 Aug 2009

Knuth K.H. Broadhurst J.H. and Schwartz B. J., The auditory evoked gamma band response evoked by multiple clicks, Journal of Electroenceph Clin. Neurophysiol.Oct 1997

J.H. Broadhurst, J.J. Moore, “Detailed macrosegregation studies using a tandem van de accelerator facility N.A. Shah ,, Microstructural Science (1983)

P. Thieberger, H. E. Wegner, M. McKeown, R. Lindgren, N. Burn, J.H. Broadhurst, T.S. Lund, T.EMiller, K. Sato, C.E.L. Gingell, T.A. Barker, P.D. Parker and D.A. Bromley, The North American MP Tandem Accelerators, Nuclear Inst. and Methods (1981)

J.H. Broadhurst, “Some Problems Associated with the Use of Small Scale Measurements in Determining the Dielectric Strength Of Insulating Gases,”, Proceedings of the Third International Conference on Electrostatic Accelerator Technology (1981)

J.H.Broadhurst, M. Bacaner, M. Fuhr, J.S. Lilley and M. Macres, J. , “The Determination of Absolute Concentrations of Elements in thin(0.1micron) Sections of Biological Tissue by X-ray Microanalysis in the Scanning Electron Microscope and Calibration with Monenergetic Alpha Particle Scattering Techniques, (1980)

Education

B.S. magna laude major Physics, University of Birmingham (UK), 1956.
Ph.D. Mining, University of Birmingham (UK), 1959.
Post-doctoral fellow Physics University of Birmingham (UK), 1959-1961.