Echoencephalograph

Claim 2

An echoencephalograph apparatus for determining the position of a particular structure within a patient''s head comprising: transducer means adapted to be positioned on the surface of a patient''s head to transmit an ultrasonic energy pulse therein and receive a group of echo pulses from structures within the head, said transducer means further adapted to convert said echo pulses to electrical echo signals; amplifier means coupled to said transducer means to amplify said echo signals, said amplifier having controllable gain means; first control means coupled to said controllable gain means and adapted to variably control the amplifier gain to compensate for ultrasonic pulse energy attenuation within the patient''s head; gating means coupled to the output of said amplifier means, said gating means adapted to be open for a predetermined gating period to pass amplified echo signals which correspond to echoes from the region of said particular structure; sensing means coupled to the gating means and adapted to provide an output signal in response to a gated echo signal above a predetermined amplitude; and counter and display means controlled by said sensing means output signal and adapted to determine the travel time through the patient''s head of the echo pulse represented by said gated echo signal above a predetermined amplitude and to display said travel time in terms of distance travelled.

Claim 3

An apparatus as claimed in claim 1 wherein said first control means includes first generator means to generate a ramp function output signal during said predetermined gated period to linearly increase the amplifier gain.

Claim 4

An apparatus as claimed in claim 2 which further includes: pulser means adapted to pulse said transducer means; first clock means to provide output pulse signals at a first frequency, said clock means adapted to provide frequency control pulses to control said pulser means and said first generator means.

Claim 5

An apparatus as claimed in claim 3 which further includes: second generator means to generate a ramp function output signal having a frequency lower than said first frequency, said second generator means output coupled to said controllable gain means to further linearly increase the amplifier gain, for a number of groups of echo signals, and said second generator means further coupled to said sensing means and adapted to be disabled by said sensing means output signal.

Claim 6

An apparatus as claimed in claim 4 wherein said first clock means is connected to said sensing means output and adapted to be disabled by said sensing means output signal.

Claim 7

An apparatus as claimed in claim 1 wherein said gating means includes means to vary said predetermined gating period.

Claim 8

An apparatus as claimed in claim 3 which further includes variable delay circuit means adapted to receive said frequency control pulses to synchronously enable said first Generator means and said gating means after a predetermined time delay.

Claim 9

An apparatus as claimed in claim 7 which further includes: means connected to said variable delay circuit means to generate a set gate pulse; and switch means adapted to connect said set gate pulse means to said sensing means and disconnect said gating means from said sensing means.

Claim 10

An echoencephalograph apparatus for determining the position of a particular structure within a patient''s head, comprising: first clock means to generate pulses at a low frequency; second clock means to generate pulses at a high frequency; synchronizer means adapted to receive first and second clock pulses and provide output pulses at said low frequency, phase synchronized with the second clock pulses; transducer means adapted to apply ultrasonic energy pulses to the surface of said head, to receive echo pulses from within said head, and to generate electrical pulses corresponding to said echo pulses; means connected between said transducer means and said synchronizer means output and adapted to pulse said transducer means at said low frequency; amplifier means coupled to said transducer means and adapted to amplify said electrical transducer pulses, said amplifier having controllable gain means; gating means coupled to said amplifier means and adapted to pass amplified pulses in response to a gate width pulse; sensor means adapted to generate an output pulse in response to an input pulse above a predetermined amplitude; switch means having a first and second position, said switch means adapted to couple said gated pulses to said sensor means input when in the first position; counter means having a first input connected to said second clock, a second input connected to said synchronizer means and a third input connected to said sensor means, said counter means adapted to start count of said high frequency pulses on the first counter input in response to a pulse on said second counter input and stop count in response to a pulse on said third counter input; display means adapted to display the count on said counter means; adjustable delay means coupled to said synchronizer means and adapted to provide delayed pulses at said low frequency; gate generator means connected to said delay means and adapted to generate said gate width pulses at said low frequency on a first output and mid-gate pulses on a second output, said switch means adapted to connect said second output of said gate generator to said sensor means when in the second position; and first ramp generator means coupled between said first output of said gate generator means and said amplifier gain control means, said ramp generator adapted to generate a ramp function signal in response to each of said gate width pulses.

Claim 11

An echoencephalograph apparatus for determining the position of a particular structure within a patient''s head, comprising: first clock means to generate pulses at a low frequency; second clock means to generate pulses at a high frequency; synchronizer means adapted to receive first and second clock pulses and provide output pulses at said low frequency, phase synchronized with the second clock pulses; transducer means adapted to apply ultrasonic energy pulses to the surface of said head, to receive echo pulses from within said head, and to generate electrical pulses corresponding to said echo pulses; means connected between said transducer means and said synchronizer means output and adapted to pulse said transducer means at said low frequency; amplifier means coupled to said transducer means and adapted to amplify said electrical transducer pulses, said amplifier having controllable gain means; gating means coupled to said amplifier means and adapted to pass amplified pulses in response to a gate width pulse; sensor means adapted to generate an output pulse in response to an input pulse above a predetermined amplitude; switch means having a first and second position, said switch means adapted to couple said gated pulses to said sensor means input when in the first position; counter means having a first input connected to said second clock, a second input connected to said synchronizer means and a third input connected to said sensor means, said counter means adapted to start count of said high frequency pulses on the first counter input in response to a pulse on said second counter input and stop count in response to a pulse on said third counter input; display means adapted to display the count on said counter means; adjustable delay means coupled to said synchronizer means and adapted to provide delayed pulses at said low frequency; gate generator means connected to said delay means and adapted to generate said gate width pulses at said low frequency on a first output and mid-gate pulses on a second output, said switch means adapted to connect said second output of said gate generator to said sensor means when in the second position; and first ramp generator means coupled between said first output of said gate generator means and said amplifier gain control means, said ramp generator adapted to generate a ramp function signal in response to each of said gate width pulses.

Claim 12

An apparatus as claimed in claim 9 which further includes: a second ramp generator means to generate a cyclic ramp function signal having a frequency lower than said low frequency said second ramp generator coupled to said amplifier gain control means to cyclically increase the amplifier gain.

Claim 13

An apparatus as claimed in claim 10 which further includes means for applying said second ramp signal to said first ramp generator to control the amplitude of said first ramp signal.

Claim 14

An apparatus as claimed in claim 11 which further includes means adapted to disable said second ramp generator and said first clock for a predetermined duration in response to said sensor means output.

Claim 15

Method of determining the distance from the surface of a patient''s head to a particular structure within the head comprising: periodically applying an ultrasonic energy pulse to the patient''s head; sensing the resulting groups of echo pulses reflected from structure interfaces within said head; converting the groups of echo pulses into groups of electrical echo signals; variably amplifying the echo signals within each of said groups sO as to compensate for ultrasonic energy attenuation within the patient''s head; gating a portion of each group of echo signals which corresponds to echoes from the region of said particular structure; detecting the first echo signal above a predetermined amplitude from among the gated echo signals; determining the travel time of the echo pulse represented by said detected signal; and converting said travel time into distance travelled through said head.

Claim 16

Method of determining the distance from the surface of a patient''s head to a particular structure within the head comprising: periodically applying an ultrasonic energy pulse to the patient''s head; sensing the resulting groups of echo pulses reflected from structure interfaces within said head; converting the groups of echo pulses into groups of electrical echo signals; variably amplifying the echo signals within each of said groups sO as to compensate for ultrasonic energy attenuation within the patient''s head; gating a portion of each group of echo signals which corresponds to echoes from the region of said particular structure; detecting the first echo signal above a predetermined amplitude from among the gated echo signals; determining the travel time of the echo pulse represented by said detected signal; and converting said travel time into distance travelled through said head.

Claim 17

A method as claimed in claim 13 which further includes: successively increasing the amplification of each successive group of echo signals until said echo signal of predetermined amplitude is detected.