Semiconductor radiation dosimeter in the form of a slender probe is easily inserted into body tissue. The probe has a signal-to-noise ratio that is acceptable to recording equipment and provides realistic measurements of the spatial and energy distributions of radiant electrons and protons

Burns, F. P.

Friedericks, J. E.

English

NASA Technical Reports Server

Coaxial 
Cable
Central Aluminum 
CI.
stal 
June 1966	 Brief 66-10252 
NASA TECH BRIEF	
Cf, 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Semiconductor Forms Biomedical Radiation Probe 
Braided	 Silver	 Nickel	 ouiuer	 . . 
Shield	 Casing	 Lead	 Coating 
The problem: 
To produce a reliable miniaturized radiation do-
simeter for biomedical application in vivo. External 
dosimeters do not accurately indicate dose level within 
the irradiated cells because the greater radiation dam-
age is caused by photoelectrons and knock-on pro-
tons. Proposed chemical dosimeters for in vivo appli-
cations are only partially satisfactory since they will 
not indicate rate of absorption or number of particles 
absorbed. 
The solution: 
A semiconductor radiation detector in the form of 
a slender probe that is easily inserted into body tissue. 
The probe has a signal-to-noise ratio that is accepta-
ble to recording equipment and it provides realistic 
measurements of the spatial and energy distributions 
of radiant electrons and protons. 
How it's done: 
The probe detecting element is a semiconductor 
diode of the junction type fabricated from a high 
resistivity silicon crystal doped with P-type impurities.
The probe has the general shape of a clinical ther-
mometer with the detector in the form of the mercury 
reservoir. The P-N type junction at the crystal is 
formed by the diffusion of phosphorus over the crystal 
surface. A silver casing holds the phosphorus coated 
crystal and connects with the ground lead (braided 
shield) of a miniature coaxial cable whose central 
conductor contacts a nickel lead from an aluminum 
slug in the body of the crystal. The silver casing is 
tin soldered to the phosphorus coated crystal by 
means of a nickel plate on the phosphorus and the 
other end is hermetically sealed to the coaxial cable 
external insulation that is impervious to body fluids. 
In operation, reverse bias is applied to the P-N junc-
tion, and radiation penetrating the junction is con-
verted to voltage pulses that are conducted to record-
ing equipment via the coaxial cable. 
Notes: 
I. This device would be useful in evaluating blood 
flow problems by insertion into veins and arteries 
to measure the spatial and energy distributions of 
radioactive tracers.
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000251 2020-03-11T17:31:58+00:00Z
2. Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Manned Spacecraft Center 
Houston, Texas 77058 
Reference: B66-10252
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Royalty-free, nonexclusive 
licenses for its commercial use will be granted by 
NASA. Inquiries concerning license rights should be 
made to NASA, Code GP, Washington, D.C. 20546. 
Source: Fred P. Burns and Josef E. Friedericks 
of Solid State Radiation Incorporated 
under contract to 
Manned Spacecraft Center 
(MSC-320) 
Brief 66-10252	 Category 04


Semiconductor forms biomedical radiation probe

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