Personal dosimeter having a volume of gas atop an integrated circuit

• US 4,769,547 A
• Filed: 01/27/1987
• Issued: 09/06/1988
• Est. Priority Date: 01/27/1987
• Status: Expired due to Term

• Current Assignee: Ongard Systems, Inc.
• Original Assignee: Medrad Incorporated (Bayer AG)
• Inventors: Uber, Arthur E. III
• Primary Examiner(s): Howell, Janice A.
• Assistant Examiner(s): Hannaher, Constantine
• Application Number:
  US07/007,196
• Time in Patent Office: 588 Days
• Field of Search: 250/374, 250/386, 250/388, 250/389, 250/370 F, 250/370 R, 357/29
• US Class Current: 250/374
• CPC Class Codes: G01T 1/185 with ionisation chamber arrangements
• CPC Class Codes: G01T 7/125 Alarm- or controlling circuits using ionisation chambers, proportional counters or Geiger-Mueller tubes, also functioning as UV detectors measuring radiation intensity with counting tubes G01T1/18; measuring radiation intensity with ionisation chambers G01T1/185; flame monitoring in combustion devices F23Q7/00, F23N; fire alarms actuated by presence of radiation of particles, e.g. of infrared radiation, of ions G08B17/11; discharge tubes per se H01J47/00
• CPC Class Codes: H01J 47/02 Ionisation chambers

Abstract

A dosimeter that includes tissue equivalent bubbles of plastic defining volumes of gas to be ionized by radiation. One or more integrated circuits (ICs) are disposed below the volumes of gas and a collecting electrode on the IC is in direct contact with the gas. Circuitry for generating an electric field within the volume of gas moves the ions therein to the collecting electrode. The collecting electrode is part of an amplifying circuit disposed within the IC. The output from the amplifier is representative of the collected ions and therefore representative of the radiation. The signal from the amplifier is sent to an interface which conditions, buffers and stores the signal. The radiation dose and dose rate are computed in the interface. A communications section transfers that data from the dosimeter upon receipt of an externally generated data transfer command. A separate calibration and display unit calibrates the dosimeter by controlling the conditioning of the signal.

Claims

1. A dosimeter for monitoring radiation and providing radiation data upon receipt of a transfer command comprising:

at least one radiation detection subassembly including;

means for defining a volume of gas, said gas adapted to be ionized by said radiation;

an integrated circuit element;

a surface segment of said integrated circuit element in direct contact with said gas as part of said means for defining said volume of gas and having a collecting electrode thereon;

means for generating an electric field within said volume of gas and for collecting ions present therein that includes said collecting electrode;

an amplifying means incorporating said collecting electrode and disposed within said integrated circuit element for generating a signal representative of the collected ions;

said radiation detection subassembly coupled to;

an interface means for buffering and storing said signal from said amplifying means;

means for transferring said signal as said radiation data upon receipt of said transfer command; and

means for supplying power to at least said amplifying means in said radiation detection subassembly and to said interface means.

2. A dosimeter as claimed in claim 1 wherein said interface means includes means for converting said signal into storable radiation data and for accumulating said storable data, the radiation accumulated data being said radiation data.

3. A dosimeter as claimed in claim 2 wherein said collecting electrode is electrically biased by said means for generating said electric field and the bias changes due to said collected ions;

the radiation detection subassembly includes means for restoring said collecting electrode to said bias.

4. A dosimeter as claimed in claim 3 wherein said means for restoring is controlled by a detector control means that is part of said interface means, said detector control means for controlling said bias dependent upon said signal.

5. A dosimeter as claimed in claim 3 including a biasing segment a part of both said means for defining said volume of gas and said means for generating said electric field, the flux lines of said electric field intersecting said collecting electrode and said biasing segment, and said detector control means setting a corresponding bias on said biasing segment.

6. A dosimeter as claimed in claim 5 wherein said detector control means sets said bias and said corresponding bias at a plurality of discrete voltage levels, higher voltage levels being set for higher detected levels of radiation as represented by said signal.

7. A dosimeter as claimed in claim 5 wherein said detector control means includes means for determining when said signal exceeds a first threshold in one instance and falls below a second threshold in another instance, and said detector control means sets said bias at a high predetermined level and a low predetermined level and sets said corresponding bias at the inverse of said high and low levels dependent upon said means for determining.

8. A dosimeter as claimed in claim 4 wherein said collecting electrode is a sense electrode exposed to said volume of gas and is a control gate for an amplifying transistor, said amplifying transistor being part of said amplifying means.

9. A dosimeter as claimed in claim 8 wherein said means for restoring includes a transistor switch interposed between said control gate and a clearing voltage supply providing said bias, said detector control means generating a clearing control signal that controls said transistor switch and the application of said bias.

10. A dosimeter as claimed in claim 9 including means for compensating for the leakage current from said transistor switch to said control gate.

11. A dosimeter as claimed in claim 4 wherein said transfer signal is one of a dose transfer command and a dose rate transfer command, said interface means includes a radiation dose rate monitor means for receiving said signal and for computing and storing radiation dose rate data, a human interface means coupled thereto, means for transferring said accumulated radiation data and said dose rate data, respectively, upon receipt of said dose and dose rate transfer command.

12. A dosimeter as claimed in claim 4 including first and second radiation detection subassemblies, both being part of a radiation detection assembly, wherein:

a first volume of gas is larger than a second volume of gas of respective first and second subassemblies;

first and second representative signals from respective first and second subassemblies are applied via a first and a second coupling means to said interface means;

wherein said interface means is coupled to said radiation detection assembly via said first and second coupling means and includes;

a radiation dose monitor means for receiving and converting said first and second representative signals to a uniform unit of radiation measurement.

13. A dosimeter as claimed in claim 12 wherein said dose monitor means includes means for selecting one of the converted signals dependent upon at least one of said first and second signals, and the interface means includes a storage means for storing the selected converted signal.

14. A dosimeter as claimed in claim 13 wherein said means for converting and accumulating is part of said dose monitor means and includes means for calculating the dose of radiation and the dose rate;

said interface means includes means for producing an alarm signal when said dose or said dose rate exceeds a programmable alarm threshold.

15. A dosimeter as claimed in claim 14 wherein said interface means includes alarm means for receiving said alarm signal and for generating at least one type of alarm selected from the group of visual, audio, electrical, tactile and olefactory alarms.

16. A dosimeter as claimed in claim 15 wherein said means for producing produces a plurality of alarm signals of different intensity and duty cycle dependent upon the level of one of said dose and dose rate.

17. A dosimeter as claimed in claim 4 wherein said gas is a tissue equivalent gas.

18. A dosimeter as claimed in claim 4 wherein said means for defining said volume of gas is made of a tissue equivalent material.

19. A dosimeter for monitoring radiation and providing radiation data upon receipt of a transfer command comprising:

at least one radiation detection subassembly including;

means for defining a volume of gas, said gas adapted to be ionized by said radiation;

an integrated circuit having a plurality of conductive but electrically isolated surface segments in direct contact with said gas;

means for generating an electric field with controllable flux lines that intersect at least two of said conductive surface segments, one of which is a designated collecting electrode, said flux lines extend through said volume of gas such that the ions move in accordance with said electric field;

an amplifying means for each conductive surface segment and disposed within said integrated circuit element for generating a respective signal, said conductive surface segments being part of said amplifying means;

said radiation detection subassembly coupled to;

an interface means for buffering said respective signals from said amplifying means;

means for transferring at least one of said respective signals as said radiation data upon receipt of said transfer command; and

,

means for supplying power to said amplifying means in said radiation detection subassembly and to said interface means.

20. A dosimeter as claimed in claim 19 wherein said interface means includes means for selecting said designated collecting electrode from said plurality of conductive surface segments and selecting one of said respective signals dependent upon said respective signals, said interface means including means for storing the selected respective signal as said radiation data.

21. A dosimeter as claimed in claim 20 wherein the remaining plurality of conductive surface segments are biasing segments and are part of said means for generating said electric field, said flux lines intersect said designated collecting electrode and said biasing segments, and said collecting electrode is electrically biased by said means for generating said electric field and said bias changes due to said collected ions.

22. A dosimeter as claimed in claim 21 wherein said means for generating said electric field electrically biases said biasing segments to a plurality of discrete predetermined levels.

23. A dosimeter for monitoring radiation and providing radiation data upon receipt of a transfer command comprising:

at least on radiation detection subassembly that includes;

means for defining at least two substantially discrete volumes of gas, said gas adapted to be ionized by said radiation;

an integrated circuit element;

a conductive surface segment on said integrated circuit element in direct contact with one of said discrete volumes of gas for collecting ions therein;

a conductive volume segment as part of the means for defining the other discrete volume of gas in direct contact therewith for collecting ions therein;

two amplifying means within said integrated circuit element, said surface segment incorporated within one amplifying means and said volume segment being in close proximity to said integrated circuit and being electrically coupled to the other amplifying means, both amplifying means generating respective representative signals of the collected ions from respective discrete volumes of gas;

means for generating an electric field within each said discrete volume of gas such that said ions move in accordance with said electric field, said surface and volume segments being part of said means for generating;

said radiation detection subassembly coupled to;

an interface means for buffering and selecting one of said respective signals from said amplifying means dependent upon said respective signals;

means for storing the selected respective signal as radiation data;

means for transferring said selected respective signals as said radiation data upon receipt of said transfer command; and

,

means for supplying power to at least said amplifying means and to said interface means.

24. A dosimeter for monitoring and displaying radiation data upon receipt of dose and dose rate transfer commands comprising:

a radiation detecting unit;

a controllable display unit separably mated with said radiation detecting unit;

said radiation detecting unit including;

at least one radiation detection subassembly including;

means for defining a volume of gas, said gas adapted to be ionized by said radiation;

an integrated circuit element;

a conductive surface segment on said integrated circuit element in direct contact with said gas for collecting ions therein;

means for generating an electric field with flux lines that intersect said surface segment and extend through said volume of gas such that said ions move in accordance with said electric field;

an amplifying means incorporating said surface segment and disposed within said integrated circuit element for generating a signal representative of the collected ions;

said radiation detection subassembly coupled to;

a controllable interface means for conditioning and storing said signal from said amplifying means, said interface means including;

means for measuring the dose and dose rate of radiation based upon said signal and for storing said dose and dose rate as radiation data;

means for transferring the dose and dose rate data from said means for measuring respectively upon receipt of said dose and dose rate transfer commands;

both said radiation detecting subassembly and said interface means coupled to;

means for supplying power to said means for generating, said amplifying means and said means for measuring;

said display unit including;

a power supply;

means for coupling said power supply to said means for supplying power;

means for controllably generating said dose and dose rate transfer commands and sending said transfer commands to said means for transferring; and

,

display means for displaying said dose and dose rate data.

25. A dosimeter and a calibration and display device for monitoring and displaying radiation data upon receipt of dose and dose rate transfer commands comprising:

a radiation detecting unit;

a calibration and display unit separably mated with said radiation detecting unit;

said radiation detecting unit including;

at least one radiation detection subassembly including;

means for defining a volume of gas, said gas adapted to be ionized by said radiation;

an integrated circuit element;

a conductive surface segment on said integrated circuit element in direct contact with said gas for collecting ions therein;

means for generating an electric field with flux lines that intersect said surface segment and extend through said volume of gas such that said ions move in accordance with said electric field;

an amplifying means incorporating said surface segment and disposed within said integrated circuit element for generating a signal representative of the collected ions;

said radiation detection subassembly coupled to;

a controllable interface means for conditioning and buffering said signal from said amplifying means, said interface means including;

means for measuring the dose and dose rate of radiation based upon said signal and for storing said dose and dose rate as radiation data;

means for transferring the dose and dose rate data from said means for measuring respectively upon receipt of said dose and dose rate transfer commands;

both said radiation detection subassembly and said interface means coupled to;

means for supplying power to said means for generating, said amplifying means and said means for measuring;

said calibration and display unit including;

a power supply;

means for coupling said power supply to said means for supplying power;

means for controllably generating said dose and dose rate transfer commands and sending said transfer command to said means for transferring;

display means for displaying said dose and dose rate data transferred by said means for transferring; and

,

means for controlling said interface means by changing the conditioning of said signal.

26. A dosimeter and calibration device as claimed in claim 25 wherein said means for measuring calculates and stores total radiation dose data and dose rate data as said radiation data;

and said calibration and display unit including;

a radiation source having a predetermined level of radiation; and

means for comparing said total radiation dose data and said dose rate data from said radiation detecting unit with predetermined values and for providing an indication of the difference therebetween.

27. A dosimeter and calibration device as claimed in claim 26 wherein said calibration and display unit includes a clock and calendar means and a memory both coupled to a controller, and said radiation detecting unit including a data storage component in the interface means, said controller reading and recording a time, a date and said radiation data in said memory upon command and recording the time and date of calibration into said data storage component.

28. A wide area network for monitoring radiation comprising:

a central monitoring station;

a plurality of radiation detecting units dispersed throughout said wide area;

each radiation detecting unit including;

at least one radiation detection subassembly including;

means for defining a volume of gas, said gas adapted to be ionized by said radiation;

an integrated circuit element;

a conductive surface segment on said integrated circuit element in direct contact with said gas for collecting ions in said gas;

means for generating an electric field with flux lines that intersect said surface segment and extend through said volume of gas such that said ions move in accordance with said electric field;

an amplifying means incorporating said surface segment and disposed within said integrated circuit element for generating a signal representative of the collected ions;

said radiation detection subassembly coupled to;

an interface means for buffering, measuring and storing said signal as a radiation data;

means for transmitting said radiation data from said interface means dependent upon said radiation data; and

means for supplying power to said means for generating, said amplifying means and said interface means;

the central monitoring station including;

a memory unit;

a central monitor means for receiving the transmitted radiation data and storing the radiation data into said memory unit; and

,

a power source supplying power to said central monitoring station.

means for supplying power to at least said amplifying means and to said interface means.

29. A controllable display unit for use with a dosimeter that monitors radiation and sends radiation data upon receipt of dose and dose rate transfer commands to the display unit, said dosimeter being separably mated with the display unit, said dosimeter including:

at least one radiation detection subassembly including;

means for defining a volume of gas, said gas adapted to be ionized by said radiation;

an integrated circuit element;

a conductive surface segment on said integrated circuit element in direct contact with said gas for collecting ions therein;

means for generating an electric field with flux lines that intersect said surface segment and extend through said volume of gas such that said ions move in accordance with said electric field;

an amplifying means incorporating said surface segment and disposed within said integrated circuit element for generating a signal representative of the collected ions;

said radiation detection subassembly coupled to;

a controllable interface means for conditioning and storing said signal from said amplifying means, said interface means including;

means for measuring the dose and dose rate of radiation based upon said signal and for storing said dose and dose rate as radiation data;

means for transferring the dose and dose rate data from said means for measuring respectively upon receipt of said dose and dose rate transfer commands;

both said radiation detecting subassembly and said interface means coupled to;

means for supplying power to said means for generating, said amplifying means and said means for measuring;

the display unit comprising;

a power supply;

means for coupling said power supply to said means for supplying power;

means for controllably generating said dose and dose rate transfer commands and sending said transfer commands to said means for transferring; and

,

display means for displaying said dose and dose rate data.