Bone mineral analyzer

Claim 2

A bone mineral analyzer for determination of the mineral content of a bone surrounded by a tissue cover, said analyzer comprising scanning means including a beam detection means and a beam producing means establishing a penetrating beam means directed to said detection means, said beam means including a scanning beam with a selected essentially monoenergetic energy portion selectively absorbed at one absorption level per unit thickness by said bone in accordance with the mineral content of the bone and at another different absorption level per unit thickness by the tissue cover, said scanning means establishing an output proportional to absorption of said selected monoenergetic portion of the scanning beam, support means including an absorbent tissue equivalent material located to cover said tissue-covered bone and defining an artificial profile for a non-bone tissue reference specimen and a bone-tissue specimen, drive means to establish relative movement between said beam means and support means and thereby effect scanning of a selected portion of said specimen including the non-bone and bone specimens, bone edge sensing means connected to said detection means for sensing the interception of said beam means by said bone, signal receiving means connected to said detection means, said signal receiving means including automatic referencing means responsive to predetermined alignment of said scanning beam and the tissue reference specimen to establish a tissue reference signal and including control means responsive to said bone edge sensing means and connected to said drive means for determining bone scan movement of said beam during which said beam is intercepted by said bone, to establish a bone-tissue signal related to beam absorption by the bone-tissue specimen throughout said bone scan movement, and readout means for comparing said tissue and bone-tissue signals to establish a bone-related output functionally related to the absorption of said beam by the bone of said tissue-covered bone.

Claim 3

A bone mineral analyzer for determination of the mineral content of a bone surrounded by a tissue cover, said analyzer comprising scanning means including a beam detection means and a beam producing means establishing a penetrating beam means directed to said detection means, said beam means including a scanning beam with a selected essentially monoenergetic energy portion selectively absorbed at one absorption level per unit thickness by said bone in accordance with the mineral content of the bone and at another different absorption level per unit thickness by the tissue cover, said scanning means establishing an output proportional to absorption of said selected monoenergetic portion of the scanning beam, support means including an absorbent tissue equivalent material located to cover said tissue-covered bone and defining an artificial profile for a non-bone tissue reference specimen and a bone-tissue specimen, drive means to establish relative movement between said beam means and support means and thereby effect scanning of a selected portion of said specimen including the non-bone and bone specimens, bone edge sensing means connected to said detection means for sensing the interception of said beam means by said bone, signal receiving means connected to said detection means, said signal receiving means including automatic referencing means responsive to predetermined alignment of said scanning beam and the tissue reference specimen to establish a tissue reference signal and including control means responsive to said bone edge sensing means and connected to said drive means for determining bone scan movement of said beam during which said beam is intercepted by said bone, to establish a bone-tissue signal related to beam absorption by the bone-tissue specimen throughout said bone scan movement, and readout means for comparing said tissue and bone-tissue signals to establish a bone-related output functionally related to the absorption of said beam by the bone of said tissue-covered bone.

Claim 4

A bone mineral analyzer for determination of the mineral content of a bone surrounded by a tissue cover, said analyzer comprising scanning means including a beam detection means and a beam producing means establishing a penetrating beam means directed to said detection means, said beam means including a scanning beam with a selected essentially monoenergetic energy portion selectively absorbed at one absorption level per unit thickness by said bone in accordance with the mineral content of the bone and at another different absorption level per unit thickness by the tissue cover, said scanning means establishing an output proportional to absorption of said selected monoenergetic portion of the scanning beam, support means including an absorbent tissue equivalent material located to cover said tissue-covered bone and defining an artificial profile for a non-bone tissue reference specimen and a bone-tissue specimen, drive means to establish relative movement between said beam means and support means and thereby effect scanning of a selected portion of said specimen including the non-bone and bone specimens, bone edge sensing means connected to said detection means for sensing the interception of said beam means by said bone, signal receiving means connected to said detection means, said signal receiving means including automatic referencing means responsive to predetermined alignment of said scanning beam and the tissue reference specimen to establish a tissue reference signal and including control means responsive to said bone edge sensing means and connected to said drive means for determining bone scan movement of said beam during which said beam is intercepted by said bone, to establish a bone-tissue signal related to beam absorption by the bone-tissue specimen throughout said bone scan movement, and readout means for comparing said tissue and bone-tissue signals to establish a bone-related output functionally related to the absorption of said beam by the bone of said tissue-covered bone.

Claim 5

The bone mineral analyzer of claim 1, wherein said beam is an essentially monochromatic energy beam of emitted radiant energy and said detection means comprises a collimated detector associated with said receiving means to establish output energy pulses in accordance with the relative level of the emitted radiant energy, discriminating means to transmit energy pulses within a selected range, and means to establish a pulse signal output related to the average of the pulses per unit of time.

Claim 6

The bone mineral analyzer of claim 1, including means associated with said control means and said bone edge sensing means and responsive to alignment of said beam means and the leading edge of the bone to align said scanning beam with said reference specimen in preselected spaced relation to the bone, logarithmic converting means connected to receive said signals, storage means to store said tissue reference signal, and integrating means having input means connected to said logarithmic converting means and to said storage means and establishing an output equal to the difference between the integrals of said signals, and said readout means being connected to said integrating means.

Claim 7

The bone mineral analyzer of claim 1 including logarithmic conversion means to convert the signal output of the detection means to the logarithm thereof, storage means to store the signal during said alignment of the scanning beam with said reference specimen to establish said tissue reference signal, and integrating means to effectively integrate said signals over the width of the bone and establish the difference between said integrations to produce said bone-related output.

Claim 8

The bone mineral analyzer of claim 4 wherein said storage means is a capacitive meAns and a resistive means connects said capacitive means to the conversion means, and switch means responsive to the predetermined alignment of said scanning beam with the tissue reference portion to increase the time constant of the capacitive and resistive means to charge the capacitive means to an approximate value at a short time constant compared to fluctuation in the scanning beam and to a final value at a relatively long time constant.

Claim 9

The bone mineral analyzer of claim 4 including a summating means having a first input means connected to said storage means and a second input means connected to said detection means to establish an integrating input signal equal to the difference of said tissue reference signal and said bone-tissue signal.

Claim 10

The bone mineral analyzer of claim 6 wherein said summating means is connected to the output of said conversion means.

Claim 11

The bone mineral analyzer of claim 1 wherein said beam producing means includes a radionuclide means establishing a random intensity supply, said receiving means having a logarithmic convertor means to establish a logarithmic signal in accordance with a selected average pulse rate of said beam, said referencing means including an automatic zero circuit means selectively connected to said convertor and having a capacitive storage means connected to the output of the zero circuit means in series with a variable resistance means to charge said storage means in accordance with said logarithmic signal, resistance control means responsive to said alignment of the scanning beam with the tissue reference portion and adapted to actuate said resistance means to increase the resistance level and thereby increase the time constant whereby said storage means is charged to an approximate value at a short time constant compared to the statistical fluctuations in the signal arising from said source fluctuation and to the final value with a relatively long time constant.

Claim 12

The bone mineral analyzer of claim 8 wherein said zero circuit means includes an operational amplifier having a first input means connected to said convertor and a second input means selectively connected to said capacitive storage means and an output means selectively connected to the capacitive storage means in series with said resistance means, switch means connected to the opposite sides of the capacitive means to connect said capacitive means to said operational amplifier, said switch means having a first input responsive to the starting of said beam means to connect the capacitive means to the operational amplifier in series with a minimum resistance and having a second input means to increase said resistance and thereby the time constant and a third input means to connect said capacitive means to said operational amplifier, and a sequential timing means connected to said input means and responsive to alignment of said beam means with said bone to sequentially energize said input means.

Claim 13

The bone mineral analyzer of claim 8 wherein said drive means includes a variable speed drive motor means connected to said beam means to move said beam means across said specimen, start means to actuate said drive motor means at a rapid feed speed to move said beam means to rapidly effect interception of the beam means by said bone portion, and means responsive to predetermined interception of said beam means by said bone to establish a slow forward scan speed to slowly scan said bone-tissue specimen.

Claim 14

The bone mineral analyzer of claim 10 wherein said bone edge sensing means includes a coarse edge detection means and a fine edge detection means, said coarse edge detection means being connected to control the drive means and the receiving means during said rapid forward movement and said fine edge detection means being connected to control the drive means and the receiving means during said scan movement.

Claim 15

The bone mineral analyzer of claim 8 wherein said automatic referencing means includes means establishing said alignment of the scanning beam and the tissue reference specimen for a predetermined minimum period in response to selected interception of said beam means by said bone and switching means connected to said resistance means to increase said resistance level within said minimum period.

Claim 16

The bone mineral analyzer of claim 12 wherein said automatic referencing means stops said scanning beam in alignment with an area of said tissue reference portion, and said switching means is responsive to establishment of that alignment of the scanning beam and the tissue reference specimen to increase said resistance level.

Claim 17

The bone mineral analyzer of claim 1 including means connected to said automatic referencing means and directly establishing said predetermined alignment of the scanning beam and the tissue reference specimen in response to selected detection of said bone.

Claim 18

The bone mineral analyzer of claim 1 wherein said control means includes means responsive to said bone edge sensing means to align said scanning beam with said tissue reference specimen slightly spaced from an edge of the bone.

Claim 19

The bone mineral analyzer of claim 1 wherein said drive means includes timing means holding said scanning beam in stationary alignment with said tissue reference portion for a selected period to average the intensity of the scanning beam and store reference voltage and for moving said scanning beam forwardly to traverse said bone-tissue specimen at a selected scanning rate after said selected period.

Claim 20

The bone mineral analyzer of claim 1 wherein said drive means includes a variable speed drive motor means connected to said beam producing means to move said beam means across said specimen, start means to actuate said drive motor means at a rapid feed speed to move said beam producing means to rapidly effect interception of said bone portion by said beam means, and means responsive to selected interception of said bone by said beam means to establish a slow forward scan speed to slowly scan said bone-tissue specimen.

Claim 21

The bone mineral analyzer of claim 17 wherein said drive motor means is reversible and is operated in the reverse direction at said rapid feed speed response to the interception of an edge of said bone by said beam means and is thereupon operatively disabled to align said beam means with said tissue reference portion for a holding period and then is operated at said slow forward scan speed.

Claim 22

The bone mineral analyzer of claim 17 wherein said drive motor means includes a plurality of different slow scan speeds, and said analyzer includes means to select different ones of those speeds in accordance with the power level of the beam producing means and to effect corresponding adjustment of the bone related output.

Claim 23

A bone mineral analyzer of claim 17 wherein a said bone edge sensing means including a coarse edge detection means and a fine edge detection means, said coarse edge detection means being connected to control the drive means and the receiving means during rapid forward movement and said fine edge detection means being connected to control the drive means and the receiving means during a bone scan movement.

Claim 24

The bone mineral analyzer of claim 20 wherein said coarse edge detection means includes a level detector, an electronic capacitive coupling circuit connecting said level detector to the output of a logarithmic convertor and having means to vary the time constant of the coupling circuit, means responsive to starting of said drive means to increase the time constant after a selected time period, level detection means associated with said fine edge detection means and connected to the logarithmic convertor, and interlock means connecting said fine edge detection means to the output of the coarse edge detector to inhibit said fine edge detection means until said tissue reference signal is established.

Claim 25

The bone mineral analyzer of claim 20 wherein said fine eDge detection means is connected to respond to the signal established by engagement of the beam with the bone, said analyzer includes an inhibit means which holds said fine edge detection means off and which is responsive to establishing of said tissue reference signal to release said fine edge detection means, and said readout means including an integrating means connected to said fine edge detection means and responsive to the interception of said beam means by the leading edge of said bone to initiate integration and to the interception of said beam means by the trailing edge of said bone to terminate integration.

Claim 26

The bone mineral analyzer of claim 22 wherein said fine edge detection means includes a level detector, and said analyzer includes logic circuit means having a first input connected to said level detector and a second input connected to said inhibit means.

Claim 27

The bone mineral analyzer of claim 1 for analyzing a tissue covered bone including a first bone and a second bone spaced from the first bone within a common tissue cover, said analyzer including a presettable selection means included in said drive means to control said drive means to respond selectively to interception of said beam means by the edge of a preselected one of said first and second bones and to actuate said receiving means to establish said bone-tissue signal.

Claim 28

The bone mineral analyzer of claim 24 having a detector establishing a first pulse in response to interception of said beam means by a bone and a second pulse of an opposite polarity in response to termination of interception of said beam means by a bone, a first bone logic means connected to said detector and having a first output means connected to actuate said drive means, a second bone logic means connected to said detector and connected to actuate said drive means, a second bone control means connected to the detector and responsive to said second pulse to condition said second bone logic means for operation, and said selection control means selectively enabling one of said logic means, whereby interception of said beam means by the leading edge of a preselected one of said first and second bones actuates said drive means.

Claim 29

The bone mineral analyzer of claim 25 wherein said detector includes a time-delay means operatively disconnecting said detection means for a selected period after starting of a scan cycle.

Claim 30

The bone mineral analyzer of claim 25 wherein said level detector includes a timing pulse means actuated by a search start signal, a coupling capacitor connected to the detection means, a triggered impedance switch means connected to said capacitor and to said timing pulse means to control the time constant of said coupling capacitor in response to the operation of the timing pulse means, a high input impedance electronic switch connected to said capacitor, a level responsive trigger circuit connected to the electronic switch, and a differentiating means connected to the level responsive trigger switch to differentiate the output and establish said output pulses.

Claim 31

The bone mineral analyzer of claim 1 wherein said beam source is a radionuclide source establishing a monochromatic collimated gamma ray in the range of 20 to 80 kev, said signal receiving means including a gamma ray detection means connected to a signal averaging means to establish an output signal proportional to the average gamma ray photons received per unit of time, log conversion means to establish a logarithmic signal proportional to said output signal, and an integrating means having input means connected to said conversion means to integrate the logarithmic signal, said integrating means having means to integrate said tissue reference signal and said bone-tissue signal and establish the difference therebetween to produce said bone mineral output signal.

Claim 32

The bone mineral analyzer of claim 1 wherein said support means includes a means defining a selected specimen support area, said drive means having a plurality of output speeds including at least one rapid search speed and one constant rate scan speed, means defining a first home position of said scanning means at which said beam is spaced from said bone support area, start means actuating said drive means to move said beam means forward of the specimen support area at a rapid search speed, said bone edge sensing means being responsive to interception of said beam by a bone of said tissue-covered bone to terminate said forward movement of the beam apparatus, and to retract and stop said scanning means to align the beam with said tissue equivalent cover, said receiving means having a signal storage means and establishing said reference signal in said storage means during the period said beam is stationary, scan initiating means to initiate movement of said scanning means forwardly at said scan speed, means responsive to the second interception of said beam by the bone of the tissue-covered bone to actuate said receiving means to establish said bone-tissue signal, said receiving means including a summating means having a first input connected to said storage means for said tissue reference signal and having a second input connected to receive said bone-tissue signal to establish an output related to said absorption characteristic of said bone, and an integrating means connected to said summating means and to said readout means to establish a direct reading of said characteristic of said bone.

Claim 33

The bone mineral analyzer of claim 1 wherein said support means includes means defining a selected specimen support area, and in which said beam producing means includes a radioactive source emitting a gamma ray scanning beam as said scanning beam, said drive means for said beam means including a plurality of output speeds including at least one rapid search speed and one constant rate scan speed, said beam means having a first home position spaced from said support area, start means actuating said drive means to move said beam means toward the specimen support area at a rapid search speed to locate the bone of said tissue-covered bone and to move said scanning beam over said bone at a substantially slower scan speed, said detection means including a gamma ray beam amplifying detector to establish a train of pulses, a count rate meter connected to said beam detection means and having a rapid response to establish a signal proportional to the intensity of the gamma ray pulses, a logarithmic convertor, and coupling means connecting the count rate meter to the logarithmic convertor and having a first resistance capacitance circuit with means to vary the time constant between a small time constant selected to establish accurate detection of the bone edge during the rapid search and a large time constant selected to compensate for logarithmic errors associated with the statistical fluctuation in the radioactive source during the scan speed.

Claim 34

The bone mineral analyzer of claim 30 wherein said resistance-capacitance circuit includes a coupling resistor connected to the output of the count rate meter, a first capacitor connected in series with the resistor to a reference potential, a second capacitor, a switch means connected in series with said second capacitor and in parallel with said first capacitor, and means responsive to establishment of said scan speed to establish a measurement mode signal and to actuate and close said switch means and connect said second capacitor in circuit.

Claim 35

The bone mineral analyzer of claim 31 wherein said switch means includes a field effect transistor connected in series with said second capacitor, a resistor in parallel with said field effect transistor, and a switching transistor connected to hold said field effect transistor off and responsive to establishment of said measurement mode signal to turn said transistors on. 33. The bone mineral analyzer of claim 30 having a differential discriminator means coupled to the beam detection means and to the rate meter to transmit pulses within a selected range.

Claim 36

The bone mineral analyzer of claim 1 having convertor means to establish an analog logarithmic signal proportional to the detected intensity of the scanning beam, said referencing means including a difference amplifier having a first input connected to said conversion means and having a second input, a signal storage means to hold said tissue reference signal, switching means selectively connecting said storage means to the output of the difference amplifier and to the second input of the difference amplifier, said bone edge sensing means including a coarse edge detector connected to the output of the difference amplifier, and including a fine edge detector connected to the output of the difference amplifier, a mineral content integrator connected to the output of the difference amplifier and having a start means connected to the output of the fine edge detector, a second integrator having a preselected constant signal input means and a start means connected to the output of the fine edge detector, a reversible drive motor means coupled to said beam producing means and having a first rapid drive feed connection and a second slow drive scan connection, start means to establish the first rapid drive feed connection to rapidly move the beam means in a search mode, a motor logic control means connected to said coarse edge detector circuit and operable to reverse the direction of the drive to retract the beam at said rapid drive feed connection a selected distance, timing means to hold the scanning beam slightly spaced from the bone edge for a selected time period and to then establish said scan connection of said motor means, said fine edge detector actuating said integrators to integrate over the period said beam scans the bone, and reset means responsive to termination of interception of the scanning beam by the bone to reverse said motor with said feed connection to rapidly return said beam means to the home position.

Claim 37

The bone mineral analyzer of claim 34 wherein said signal storage means is a capacitor connected in a feedback path of an operational amplifier, said operational amplifier having an inverting input connected to the junction of said capacitor and a pair of parallel charging resistors, and said switching means selectively connecting said resistors to the output of the difference amplifier to charge said capacitor with different time constants.

Claim 38

The bone mineral analyzer of claim 34 wherein said coarse edge detector includes a level detector, an electronic-capacitive coupling circuit connecting said level detector to the output of a logarithmic convertor and having means to vary the time constant of the coupling circuit, means responsive to starting of said drive means to increase the time constant after a selected time period, said fine edge detector includes a level detection means connected to the logarithmic convertor, and interlock means connected to said fine edge detector to inhibit said fine edge detector until said tissue reference signal is established.

Claim 39

The bone mineral analyzer of claim 36 wherein said beam producing means establishes a random energy scanning beam, said analyzer including a differential discriminator connected to said detection means to transmit a signal proportional to the detected energy of the scanning beam within a selected range, a count rate meter, first and second timing capacitors connecting said count rate meter to said convertor, and means operably disconnecting one of said capacitors from the meter and responsive to said establishment of the scan speed for moving the beam over the bone-tissue specimen to connect the disconnected capacitor and thereby increase the time constant.

Claim 40

The bone mineral analyzer of claim 1 wHerein said beam source includes a radionuclide element selected from Iodine 125 and Americium 241 and establishing a monochromatic collimated photon energy beam, said detection means including a collimated crystal detector mounted in alignment with said beam and having a means to convert the photon energy absorbed by the crystal detector into a corresponding electrical signal, said support means including a support having planar parallel surfaced clamp members to clamp the specimen to said support and thereby establish a corresponding constant total thickness of said clamp members, said tissue equivalent cover and said tissue-covered bone and having means to locate the specimen perpendicular to the clamp members, said drive means having a holder to mount said beam producing means to move over said clamp members, conversion means to detect the photons of said beam and establish an analog logarithmic signal proportional to the intensity of the detected scanning beam, said referencing means including an automatic zero referencing difference amplifier having a first input connected to said conversion means and having a second input, a signal storage means to hold said tissue reference signal, switching means selectively connecting said storage means to the output of the difference amplifier and to the second input of the difference amplifier, said bone edge sensing means including a coarse edge detector connected to the output of the difference amplifier and including a fine edge detector connected to the output of the difference amplifier, a mineral content integrator connected to the output of the difference amplifier and having a start means connected to the output of the fine edge detector, a second integrator having a preselected constant signal input means and a start means connected to the output of the fine edge detector, a drive motor means coupled to said holder and having a first rapid drive feed connection and a second slow drive scan connection, a motor logic control means connected to said coarse edge detector circuit and operable to reverse the direction of the drive to retract the holder a selected distance and hold the scanning beam spaced from the bone edge for a selected time period and to then establish said scan connection of said motor means, and said fine edge detector actuating said integrator to integrate over the period said beam scans the bone.

Claim 41

The bone mineral analyzer of claim 38 wherein said drive means includes a U-shaped holder having a pair of parallel spaced arms, said beam producing means being mounted in the outer end of one of said arms with the beam means directed toward said second arm, said detection means includes a collimated scintillation crystal detector mounted in said second arm in alignment with said beam means and having a photomultiplier to amplify scintillations due to the photons of said beam, said support means including parallel surfaced clamp members including a housing wall and an overlying arm, means to mount said holder to said housing with the first arm slidably mounted in said housing and the second arm spaced outwardly of said clamp members in alignment with said first arm, said conversion means including a differential discriminator coupled to the photomultiplier to transmit the photon energy of a selected range, a count rate meter connected to said differential discriminator to establish an analog signal proportional to the intensity of the photon beam, and a logarithmic convertor connected to the count rate meter and to said automatic zero referencing difference amplifier.

Claim 42

The bone mineral analyzer of claim 38 wherein said difference amplifier includes an operational amplifier, said switching means being connected to the opposite sides of the capacitive means to connect said capacitive means to said operational amplifier, said switching means having a first input responsive to the starting of saiD beam means to connect the capacitive means to the output of the operational amplifier in series with a minimum resistance and having a second input means to increase said resistance and thereby the time constant and a third input means to connect said capacitive means to the input of said operational amplifier, and a sequential timing means connected to said input means and responsive to alignment of said beam means with said bone to sequentially energize said input means.

Claim 43

The bone mineral analyzer of claim 1 having a visual display means connected to said readout means, said display means including a signal storage means to store said output signal and a coupling means connected to establish a corresponding display, and a calibration control means to vary the display of said display means for a given stored signal, said calibration control means being connected to the output of said signal storage means to permit calibration without varying of the signal in said signal storage means and thereby permit calibration with a single pass operation.

Claim 44

The bone mineral analyzer of claim 41 wherein said display means includes an integration circuit means including a capacitor means forming said storage means, said calibration control means including an adjustable voltage dividing means connecting said integration circuit means to said display means to adjust the proportion of the signal in said capacitor applied to the display means and thereby, the display for a given stored signal.

Claim 45

The bone mineral analyzer of claim 1 having a digital readout means including a calibration reset means to adjust the readout magnitude per unit input and to simultaneously and correspondingly vary the output reading of an input established in said readout means.

Claim 46

The bone mineral analyzer of claim 1 including a housing having a planar support wall defining said support means, a generally movable bracket having a first arm slidably mounted within said housing and an interconnected second arm overlying said first arm in spaced relation to said planar wall, said beam producing means being mounted in one of said arms and establishing a scanning beam directed toward the opposite arm, and said drive means being connected to position said bracket and including switch means for selectively establishing an extended start scan position for scanning operation and a retracted carry position.

Claim 47

The bone mineral analyzer of claim 1 having means to store said bone-related output, means to recycle said drive means to establish a series of said bone-related outputs, and means to summate and average the bone-related outputs and display the average of said several scans. said beam means and support means and thereby scanning a selected portion of said non-bone and bone portions, and automatic referencing means connected to said detection means with said scanning beam aligned with the tissue reference specimen to establish a tissue reference signal related to the beam absorption and including a signal storage means responsive to the level of the output of said detection means to directly establish a signal in said storage means directly proportional to the level of the output of said detection means, means to establish a bone-tissue signal related to beam absorption by the tissue-covered bone specimen, and readout means to compare said signals over the total length of the bone scan and establishing a bone-related output related to the absorption of said beam by the bone mineral of said bone.

Claim 48

The bone mineral analyzer for in vivo determination of the mineral content of a bone surrounded by body tissue, said analyzer comprising beam producing means to provide a penetrating beam that is absorbed by transmission through a unit thickness of bone at a bone absorption level determined by the bone mineral content and that is absorbed by transmission through a unit thickness of body tissue at a tissue absorption level distinctly diFferent from the range within which said bone absorption level varies according to bone mineral content, drive means for causing relative lateral movement of said penetrating beam along a predetermined scanning path, support means for supporting a tissue covered bone along said scanning path for transverse scanning by said penetrating beam, said support means including a tissue equivalent material having substantially the same beam absorption characteristics as body tissue, said material being located to provide said tissue covered bone with an artificial profile of a generally uniform depth to provide a tissue specimen comprising body tissue and tissue equivalent material but no bone and a bone specimen comprising said bone together with said body tissue and said tissue equivalent material, beam receiving means for sensing the intensity of said beam after penetration of said beam through the specimen aligned therewith, reference establishing means responsive to said beam receiving means for measuring the absorption of said beam during penetration of said beam through said tissue specimen, bone detecting means operable while said beam scans along said scanning path for detecting the onset and termination of the penetration of said bone by said beam as a function of the corresponding changes in beam absorption sensed by said beam receiving means, integrating means for measuring the integrated absorption of said beam sensed by said beam receiving means while said beam scans said bone specimen, computer means for automatically calculating the mineral content of a predetermined unit volume of said bone as a function of the measurements performed by said reference establishing means and said integrating means, and timing means for automatically providing predetermined timed coordination between the operations of said drive means, said reference establishing means, said bone detecting means, said integrating means and said computer means.

Claim 49

The bone mineral analyzer for in vivo determination of the mineral content of a bone surrounded by body tissue, said analyzer comprising beam producing means to provide a penetrating beam that is absorbed by transmission through a unit thickness of bone at a bone absorption level determined by the bone mineral content and that is absorbed by transmission through a unit thickness of body tissue at a tissue absorption level distinctly diFferent from the range within which said bone absorption level varies according to bone mineral content, drive means for causing relative lateral movement of said penetrating beam along a predetermined scanning path, support means for supporting a tissue covered bone along said scanning path for transverse scanning by said penetrating beam, said support means including a tissue equivalent material having substantially the same beam absorption characteristics as body tissue, said material being located to provide said tissue covered bone with an artificial profile of a generally uniform depth to provide a tissue specimen comprising body tissue and tissue equivalent material but no bone and a bone specimen comprising said bone together with said body tissue and said tissue equivalent material, beam receiving means for sensing the intensity of said beam after penetration of said beam through the specimen aligned therewith, reference establishing means responsive to said beam receiving means for measuring the absorption of said beam during penetration of said beam through said tissue specimen, bone detecting means operable while said beam scans along said scanning path for detecting the onset and termination of the penetration of said bone by said beam as a function of the corresponding changes in beam absorption sensed by said beam receiving means, integrating means for measuring the integrated absorption of said beam sensed by said beam receiving means while said beam scans said bone specimen, computer means for automatically calculating the mineral content of a predetermined unit volume of said bone as a function of the measurements performed by said reference establishing means and said integrating means, and timing means for automatically providing predetermined timed coordination between the operations of said drive means, said reference establishing means, said bone detecting means, said integrating means and said computer means.

Claim 50

The bone material analyzer of claim 46 including bone size determining means for measuring the scanned width of said bone reference specimen as a function of the distance by which said scanning means moves between the onset and termination of bone penetration detected by said bone detecting means, and said timing means automatically and selectively interconnects said bone size determining means to said computer means.

Claim 51

A bone mineral analyzer for determination of the mineral content of a bone, comprising scanning means including a beam detection means and a beam producing means establishing a penetrating beam means directed to said detection means, said beam means including a scanning beam with a selected essentially monoenergetic energy portion selectively absorbed at one absorption level per unit thickness by said bone in accordance with the mineral content of the bone and at another different absorption level per unit thickness by the tissue cover, said scanning means establishing an output proportional to absorption of said selected monoenergetic portion of the scanning beam, support means including an absorbent tissue equivalent material located to cover said tissue-covered bone and defining an artificial profile having a non-bone tissue reference specimen and a bone-tissue specimen, a variable speed drive means having start means to establish rapid relative forward search movement between said beam means and said support means, first motor control means responsive to selected interception of the beam means by said bone to actuate said drive means to terminate said forward movement for alignment of said beam with said tissue reference specimen for a selected period, reference means responsive to the output of the detection means during said selected period to establish a tissue reference signal, second motor control means connected to said variable speed drive means to actuate said drive means to establish a relatively low forward scan speed, and meaNs to establish a bone-tissue signal related to beam absorption by the bone-tissue specimen.

Claim 52

A bone mineral analyzer for determination of the mineral content of a bone, comprising scanning means including a beam detection means and a beam producing means establishing a penetrating beam means directed to said detection means, said beam means including a scanning beam with a selected essentially monoenergetic energy portion selectively absorbed at one absorption level per unit thickness by said bone in accordance with the mineral content of the bone and at another different absorption level per unit thickness by the tissue cover, said scanning means establishing an output proportional to absorption of said selected monoenergetic portion of the scanning beam, support means including an absorbent tissue equivalent material located to cover said tissue-covered bone and defining an artificial profile having a non-bone tissue reference specimen and a bone-tissue specimen, a variable speed drive means having start means to establish rapid relative forward search movement between said beam means and said support means, first motor control means responsive to selected interception of the beam means by said bone to actuate said drive means to terminate said forward movement for alignment of said beam with said tissue reference specimen for a selected period, reference means responsive to the output of the detection means during said selected period to establish a tissue reference signal, second motor control means connected to said variable speed drive means to actuate said drive means to establish a relatively low forward scan speed, and meaNs to establish a bone-tissue signal related to beam absorption by the bone-tissue specimen.

Claim 53

The bone mineral analyzer of claim 48 wherein said first motor control means aligns and holds said beam in fixed relation with said tissue reference specimen and with said beam spaced from the edge of the bone in the order of 3 millimeters.

Claim 54

The bone mineral analyzer of claim 48 wherein said reference means is actuated by said first motor control means, and said second motor control means is actuated by said reference means.

Claim 55

A bone mineral analyzer of claim 48 wherein said beam producing means includes a radioactive source and in which said scanning beam is a random intensity beam, said analyzer including a count rate meter connected to said detection means and having a rapid response to establish a signal proportional to the intensity of the beam, a logarithmic convertor, coupling means connecting the count rate meter to the logarithmic convertor and having a resistance-capacitance circuit with means to vary the time constant between a small time constant selected to establish accurate detection of a bone edge during the rapid search and a large time constant selected to compensate for logarithmic errors associated with the statistical fluctuation in the radioactive source during the scan speed.

Claim 56

The bone mineral analyzer of claim 51 wherein said resistance-capacitance circuit includes a coupling resistor connected to the output of the count rate meter, a first capacitor connected in series with the resistor to a reference potential, a second capacitor, switch means connected in series with said second capacitor in parallel with said first capacitor, and means responsive to initiation of low forward scan movement of said drive means to actuate and close said switch means and connect said second capacitor in circuit.

Claim 57

The bone mineral analyzer of claim 48 wherein said beam producing beam establishes a random intensity scanning beam, said analyzer including a first time constant means connected to said detection means for establishing a short time constant during said search movement and a long time constant for transmission of the signal to compensate for logarithmic errors associated with the statistical fluctuation in the radioactive source during the scan speed, and a second time constant means connecting said reference means to said detection means for establishing a short time constant during the initial search movement and a long time constant during said selected period the tissue reference signal is established.

Claim 58

The bone mineral analyzer of claim 48 having a bone selection means for selectively actuating said beam means to select one of two bones spaced along the scan path in said tissue cover, said bone selection means including signal forming means responsive to interception of said beam by the first bone to establish a first signal responsive to such interception, a second signal responsive to termination of such interception of said beam by said first bone, and a third signal in response to interception of said beam by the second bone, a first bone logic circuit means connected to said signal forming means, a second bone logic circuit means connected to said signal forming means, input means to operably condition one of said logic circuit means to operate in response to the corresponding one of said first and third signals, said first bone logic circuit means being connected to said second bone logic circuit means to transmit said second signal to said second logic circuit means to signal said second bone logic circuit means for operation, and selectively actuated means connecting said first and second motor control means with said bone logic circuit means and to rapidly search for the selected bone and condition said second motor control means for operation in response to location of said selected bone.

Claim 59

A bone mineral analyzer for determination oF the mineral content of one of two spaced bones surrounded by a common tissue cover, comprising scanning means including a beam detection means and a beam producing means establishing a penetrating beam means directed to said detection means, said beam means including a scanning beam with a selected essentially monoenergetic energy portion selectively absorbed at one absorption level per unit thickness by said bone in accordance with the mineral content of the bone and at another different absorption level per unit thickness by the tissue cover, said scanning means establishing an output proportional to said selected monoenergetic portion of the scanning beam, support means including an absorbent tissue equivalent material located to cover said tissue-covered bones and defining an artificial profile for a non-bone tissue reference specimen and a plurality of bone-tissue specimens, signal receiving means connected to said detection means, said signal receiving means including referencing means connected to said detection means to establish a tissue reference signal related to the beam absorption of the non-bone tissue of the specimen and scan initiating means responsive to selected interception of said beam means by a bone to initiate scanning of said bone and to establish a bone-tissue signal related to beam absorption by the tissue-covered bone specimen, and control means including a presettable selection means to control said receiving means to respond to interception of beam means by a preselected one of the edges of the first bone and the second bone to establish a bone-tissue signal related to the corresponding bone of said two spaced bones.

Claim 60

A bone mineral analyzer for determination oF the mineral content of one of two spaced bones surrounded by a common tissue cover, comprising scanning means including a beam detection means and a beam producing means establishing a penetrating beam means directed to said detection means, said beam means including a scanning beam with a selected essentially monoenergetic energy portion selectively absorbed at one absorption level per unit thickness by said bone in accordance with the mineral content of the bone and at another different absorption level per unit thickness by the tissue cover, said scanning means establishing an output proportional to said selected monoenergetic portion of the scanning beam, support means including an absorbent tissue equivalent material located to cover said tissue-covered bones and defining an artificial profile for a non-bone tissue reference specimen and a plurality of bone-tissue specimens, signal receiving means connected to said detection means, said signal receiving means including referencing means connected to said detection means to establish a tissue reference signal related to the beam absorption of the non-bone tissue of the specimen and scan initiating means responsive to selected interception of said beam means by a bone to initiate scanning of said bone and to establish a bone-tissue signal related to beam absorption by the tissue-covered bone specimen, and control means including a presettable selection means to control said receiving means to respond to interception of beam means by a preselected one of the edges of the first bone and the second bone to establish a bone-tissue signal related to the corresponding bone of said two spaced bones.

Claim 61

The bone mineral analyzer of claim 55 having a detector establishing a first pulse in response to interception of said beam by a bone and a second pulse in response to termination of such interception of said beam by a bone, a first bone logic means connected to said detector and having a first output means connected to actuate said drive means, a second bone logic means connected to said detector and connected to said detector to actuate said drive means, a second bone control means connected to the detector and responsive to said second pulse to condition said second bone logic means for operation, and said selection means selectively enabling one of said logic means, whereby interception of said beam means by preselected leading edge of one of said first or second bones actuates said control means.