Ultrasonic apparatus and for precisely locating cavitations within jawbones and the like

A method and apparatus detects cavitation in the jawbone of human. The apparatus generates an ultrasonic pulse and passes the pulse through the jawbone of a human. The pulse is detected by an ultrasonic receiving unit. Attenuations in the amplitude of the pulse are detected and displayed on a color monitor. The color monitor allows the detection of cavitations by interpreting color codes in a 4.times.4 matrix displayed on the monitor.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to an apparatus and a method for locating 
cavitations and the like in the jawbone of a living being. More 
particularly, the present invention relates to an apparatus which 
comprises an ultrasonic transmitter and an ultrasonic receiver oppositely 
arranged around the jawbone of a patient to implement a method which 
introduces ultrasonic sound waves and determines the attenuation thereof. 
Thereby, a precise location and size of cavitations can be determined. 
Ultrasound has long been used for a variety of applications including use 
in the medical field. Its predominant use has been to obtain 
two-dimensional soft tissue images, e.g. in a developing fetus or in a 
kidney. U.S. Pat. No. 5,402,781 describes a technique for measuring bone 
density and diagnosing osteoporosis using a frequency generator and a 
power amplifier to drive a transducer for inducing continuous vibration in 
hard tissue. Other bone and tissue analyzers are described in U.S. Pat. 
Nos. 4,610,255; 5,006,984; 5,518,0008; and 5,651,363. 
In contrast to other techniques, ultrasound does not subject a patient to 
radiation. Also, it is less costly and the equipment is typically smaller 
in size and easier to use than X-ray equipment and the like. 
More recently, ultrasound has been used to characterize the physical 
properties of cancellous bones using velocity of sound and broadband 
ultrasonic attenuation parameters which relate to elasticity, density and 
structure of bones. The attenuation of ultrasound in bone is derived by 
comparing signal amplitudes transmitted through cancellous bone with that 
of the same signal transmitted through water. In this connection, see Role 
of Ultrasound in Assessment of Osteoporosis 
(http.//www.mccueplc.com/ultrasnd.htm). 
Some recent medical studies suggest that there are significant health risks 
associated with jawbone infections resulting from cavities in the jawbone 
(hereinafter, cavitations). There is an emerging view of a relationship 
between chronic medical diseases and jawbone infections, e.g., emaciation, 
rheumatic diseases, heart and other circulatory problems. See, for 
example, Levy and Huggins, Routine Dental Extractions Routinely Produce 
Cavitations, Journal of Advancement in Medicine, pp. 235-249 (Vol. 9, No. 
4, Winter 1996), George E. Meining D.D.D., F.A.C.D., Root Canal Cover-Up, 
1996. 
We have recognized that a considerable advantage to patient wellbeing can 
be gained by the ability to accurately detect the location of such 
cavitations within the jawbone of a human patient and that ultrasound 
technology is the most effective way to provide this ability. 
The use of ultrasound technology in the dental field is known and has 
generally been limited to root canal treatment. During a root canal 
procedure, removing infected nerve endings and filling with an inert 
substance are required. Before the tooth under treatment is filled with a 
sterile substance, the canals of the teeth containing the infected nerve 
endings require cleaning to ensure that the entire nerve ending is removed 
and thus to prevent later reinfection. During this nerve removal and 
cleaning, the depths of the canals are increased. To aid in this 
procedure, prior art techniques disclose the use of ultrasound to either 
detect the depth of root canals, or to diagnose the health of teeth tissue 
(i.e., teeth pulp). 
Another use for ultrasound technology in the dental field has been in the 
diagnosis of periodontal pockets. Periodontists can use metal probes to 
determine the depths of periodontal pockets during inspections for gum 
disease. The prior art teaches the use of ultrasound to determine the 
depths of periodontal pockets, with deeper pockets indicating the 
likelihood of gum disease. Thus, the need for the invasive probing 
associated with the prior art methods of measuring dental pockets would be 
eliminated. 
One known method and apparatus for performing ultrasound measurements is 
described in U.S. Pat. No. 5,100,318. The presence of diseased gum tissue 
by measuring the depth of the periodontal pocket along an outer surface of 
a tooth. In particular, a first ultrasonic pulse travel path having a 
fixed, reflected delay time and a second ultrasound pulse travel path 
having a variable, reflected delay time are established. The difference 
between the fixed, reflected time delay time of the first ultrasonic pulse 
echo pulse reflected at the gum line and the variable, reflected delay 
time of a second ultrasonic echo pulse reflected from the bone surface at 
the bottom of the periodontal pocket is measured. The difference between 
these reflected delay times is displayed and indicates the depth 
measurement for the periodontal pocket. 
U.S. Pat. No. 5,115,813 describes an ultrasound based measurement method 
and apparatus for examining dental tissue, in particular teeth. The method 
involves the use of ultrasound to determine the health of teeth by 
subjecting them to a low frequency vibration and determining the intensity 
and delay of returning echo signals in relation to the pulse transmitted 
to the teeth under examination. The intensity and delay of the echo 
signals is used to form a picture which dentists can use to determine the 
overall health of dental tissue (i.e., teeth pulp, root paths, etc.). 
Dental root canal diagnosis and treatment are the subjects of U.S. Pat. No. 
5,295,833. During a root canal procedure, a dentist uses a probing tool to 
clean the roots of an infected tooth. Usually the root is enlarged to 
ensure the complete removal of the nerve from the canal path. This 
procedure is generally performed based on the experience of the dentist 
and is, more or less, completed using trial and error. Dental diagnosing 
and treating equipment is proposed in this patent document to enable a 
dentist to determine the exact depth of root canals during such root canal 
procedures. Ultrasound is used in this known approach to detect the depth 
of the canal, thus improving the less precise conventional root canal 
cleaning procedure. 
U.S. Pat. No. 4,485,823 also proposes a dental diagnostic apparatus using 
ultrasound. That is, the apparatus is intended to measure environmental 
tissue of the teeth and numerically identify the degree of health. To 
effect this measurement, the apparatus is provided with an oscillation 
converter for converting electrical oscillation into mechanical 
oscillation. A probe is connected to the converter and is brought into 
contact with a patient's tooth for applying the mechanical oscillation 
thereto. The patient has a means for actuation when he or she detects the 
sense threshold of the oscillation applied through the probe. This 
approach is intended to allow the dentist to more specifically diagnose 
the health of the tissue without visual examination. 
Similarly, U.S. Pat. No. 3,883,954 discloses the use of acoustic vibrations 
produced by dental occlusions for providing a viewable display. U.S. Pat. 
No. 3,094,115 proposes to provide a tooth mobility measuring instrument 
using a piezoelectric transducer in a small probe intended for ready 
insertion into an oral cavity. A percussion instrument is described in 
U.S. Pat. No. 4,499,906 whereby the degree of looseness of teeth is 
determined. Finally, U.S. Pat. No. 4,673,352 shows a device which uses 
transmit times of an ultrasonic pulse to measure relative jaw positions 
and movements. 
Whereas the use of ultrasound has in the past been limited to soft tissue 
imaging, bone analysis and treatment of disorders of the teeth (i.e., root 
canals and gum disease), it is an object of the present invention to 
provide an apparatus and novel method using ultrasound for detecting with 
great accuracy cavitations within a person's jawbone, not the teeth 
themselves, thereby permitting medical personnel to undertake corrective 
action and prevent further complications or harmful side effects. 
The foregoing object has been achieved in accordance with the present 
invention by generating an output pulse with an ultrasonic pulser/receiver 
and by configuring a multiplexer in order to output a single output to a 
common output from a plurality of sequentially selected input channels. An 
ultrasonic sound wave passed through the jawbone of a patient is 
subsequently received by a multiple-element (e.g., 16 elements) ultrasonic 
receiver array coupled to the multiplexer and converted into an electrical 
signal. An ultrasonic sound wave is generated using a single element 
ultrasonic transmitter or the like coupled to the ultrasonic 
pulser/receiver based on the digital output pulse generated by the 
ultrasonic pulser/receiver. A digital output trigger is produced and the 
electrical signal is converted into a digital value using a digitizer. 
Cavitations within the jawbone of a patient are therefore located quickly, 
easily and precisely by displaying on the monitor the digital value 
produced from the signals of each of the array elements representing the 
attenuation of a sound wave generated by the ultrasonic transmitter 
element that is passed through the jawbone. Thus, the medical profession 
now has the ability to more easily treat cavitations which increasingly 
are believed to cause health problems.

DETAILED DESCRIPTION OF THE DRAWING 
The sole FIGURE shows a portion of the jawbone 5 of a patient in which the 
presence and the location of cavitation represented by the solid dark 
circle is detected by emitting an ultrasonic sound wave via a one-element 
ultrasonic pulse transmitted by an ultrasonic pulser/receiver 1. The 
ultrasonic pulser/receiver 1 of the type used to implement the invention 
is well know in the art and can be, for example, a commercially available 
one such as a SONIX PRC-35 manufactured by Sonix, Inc. of Springfield, Va. 
The location or inclusion of a cavitation within the jawbone 5 has the 
effect of attenuating the amplitude of the sound wave (shown by the 
parallel lines above the jawbone 5) as it passes though the jawbone 5. 
A sixteen channel multiplexer (in practice, a unit comprising two 8-channel 
multiplexers, such as a Sonix model MUX 4800), is connected with the 
ultrasonic pulser/receiver 1 and a digitizer 3 such as a commercially 
available SONIX STR8 100D, 8-bit, 100 MX digitizer also produced by Sonix, 
Inc. Multiple channels of the multiplexer 2 are sequentially selected. The 
one-element ultrasonic transmitter element 4 is excited by the 
pulser/receiver 1 when the latter is triggered by the digitizer 3 to 
produce an ultrasonic sound wave having a frequency of, for example, about 
2.5 MHz. The ultrasonic sound wave is passed through the patient's jawbone 
5 to detect and precisely locate the presence of one or more cavitations 
within the jawbone 5 by virtue of the attenuation of the strength of the 
wave amplitude. 
In order to precisely determine and depict the exact location of the 
cavitations, a 16-element ultrasonic receiver array 6 is connected to the 
bus of the multiplexer 2 to detect the sound wave whose amplitude is 
proportional to the attenuation through the jawbone 5. The ultrasonic 
receiver array 6 is positioned on the side of the patient's jawbone 5 
opposite to the transmitter 4 and comprises an array of multiple 
transducer elements corresponding to the channels of the multiplexer 2, 
e.g. sixteen in the illustrated embodiment. It will, of course, be 
understood that the number of channels and array elements can be varied 
without departing from the scope of the present invention. 
The sound wave is converted into an electrical signal by the ultrasonic 
pulser/receiver array 6 and sent to the multiplexer 2. The multiplexer 2 
sequentially routes one of a plurality of inputs to a "COMMON" output. 
This common output is fed to the digitizer 3, where the electrical signal 
is converted into an 8-bit digital value that represents 256 levels. A 
processor, e.g. a "Pentium".RTM. 200, located within a computer 10 
processes the 8-bit digital data and displays, on a color monitor 7, a 4 
.times.4 color coded image representing the attenuation of the sound wave 
through the patient's jawbone 5. This attenuation represents the presence 
and precise location of a cavitation within the jawbone 5. Of course, the 
results can also be printed out, remotely displayed at another location 
and/or stored for subsequent retrieval. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.