US 3683706 A
Drive mechanism for a rectilinear scanner for organ imaging in which a detector and its focusing collimator is reciprocated at a constant speed across and back over the patient's organ being examined and simultaneously being gradually and continuously moved in a direction at substantially right angles to the reciprocal movement to thereby uniformly scan the entire organ.
Claims available in
Description (OCR text may contain errors)
United States Patent ONeill  DRIVE FOR A RECTILINEAR SCANNER FOR ORGAN IMAGING  Inventor: William J. ONeill, 459 N. Winston Dr., Palatine, 111. 60067  Filed: Nov. 30, 1970  Appl. No.2 93,607
 US. Cl ..74/27, 128/2 A, 74/57  Int. Cl ..Fl6h 21/02  Field of Search...74/27, 57, 50, 89.15; 112/118, 112/12l.l2, 121.14; 128/2 A, 2 V, 2 H, 2 R
 References Cited UNITED STATES PATENTS 3,001,489 9/1961 Bond et a1. ..112/118 3,233,450 2/1966 Fry ..l28/2.1 R 3,247,709 4/1966 Gordon ..128/2 V 3,374,354 3/1968 Hood ..128/2 A 3,418,471 12/1968 Gydesen ..128/2 A 3,312,184 f /1967 Cash ..1l2/l21.12
[ Aug. 15, 1972 3,442,234 5/1969 Cash ..112/1 18 2,608,697 9/ l 952 Condemi ..74/27 2,840,037 6/1958 Verba ..74/27 3,334,829 8/ 1967 Fisher et a1. ..74/57 2,872,825 2/1959 Van Doren ..74/57 2,747,417 5/1956 Brown ..74/57 2,552,717 5/1951 l-loughton ..74/27 Primary Examinerwilliam E. O'Dea Assistant Examiner--Wesley S. Ratliff, Jr. Attorney-Snow and Benno  ABSTRACT Drive mechanism for a rectilinear scanner for organ imaging in which a detector and its focusing collimator is reciprocated at a constant speed across and back over the patients organ being examined and simultaneously being gradually and continuously moved in a direction at substantially right angles to the reciprocal movement to thereby uniformly scan the entire organ.
5 Claims, 7 Drawing Figures Patented Aug. 15, 1972 3 Sheets-Sheet 2 kflrfu e/ez' View Patented Aug. 15, 1972 3,683,706
3 Sheets-Sheet 5 DRIVE FOR A RECTILINEAR SCANNER FOR ORGAN IMAGING BACKGROUND OF THE INVENTION 1. Field of the Invention The subject scanner is in the field of instrumentation in nuclear medicine. The device is for the purpose of detecting and locating abnormalities, such as tumors, in various human organs. More particularly, the invention is directed to the means for driving the detector in a predetermined pattern over and across the organ to be tested.
2. Description of the Prior Art Scanners for detecting such organ abnormalities are described in the book entitled, Instrumentation in Nuclear Medicine, Edited by Gerald J. Him and Published by Academic Press in 1967. Particular attention is directed to Chapter 16 of this book, entitled, Radioisotope Scanning as written by Gordon L. Brownell, Saul Aronow and Gerald J. I-Iine. Pages 381 to 387 appear pertinent to a background knowledge of rectilinear scanners.
To obtain good readings or scans" of organs which will enable diagnostic doctors to identify and pinpoint malignancies it is an absolute essential that the detectors move over the organ with a uniform constant velocity. Scanners of the past have not always been too reliable in this regard and the result has been scans with incorrect and faulty data thereon. Also, in past scanners the path of the scanner has been a horizontal movement of the detector, then a short vertical movement, then a return horizontal movement, and continuing in this alternating horizontal and vertical movement until the whole of a rectangularly shaped outline has been scanned.
In the present invention the detector is moved with an absolute constant linear velocity. Also, the vertical movement of the detector is continuous throughout the entire reciprocation of the detector so that the resultant movement of the detector is a zig-zag path which more completely and more uniformly scans an organ with reliable abnormality detection.
SUMMARY OF THE INVENTION A principal object of the present invention is to provide a novel drive means for a rectilinear scanner for organ imaging in which the scanner is moved at a more uniform speed and at the same time more completely scans the entire area of the organ being examined.
An important object of this invention is the provision of a novel drive means for a radioisotope scanner in which the path of travel of the scanner is zig-zag rather than a right angle jogging.
Another important object of this invention is to provide novel drive means for a detector in a scanning device in which the detector is continuously moved by a screw drive along the y coordinate of the single plane scan area.
Still another important object of this invention is a device as set forth in the preceding object and further including a novel cam drive for effecting reciprocation of the detector along the x coordinate of the single plane scan area whereupon the detector moves in a uniform, constant velocity zig-zag path.
Other and further important objects and advantages will become apparent from the following specification and the accompanying drawings.
In the drawings:
FIG. 1 is a perspective view of the rectilinear scanner for organ imaging of this invention. a
FIG. 2 is a diagram of movement of a detector in existing scanners before the subject invention.
FIG. 3 is a diagram of the zig-zag movement of the detector in the scanner of this invention.
FIG. 4 is an illustration of a scan record as taken by the scanner of the present invention.
FIG. 5 is a sectional view of the scanner as taken on the line 5-5 of FIG. 1.
FIG. 6 is a sectional view of the scanner as taken on the line 66 FIG. 1.
FIG. 7 is a view of the detector supporting table and its drive mechanism as taken on the line 7 -7 of FIG. 6.
As shown in the drawings The reference numeral 10 indicates generally a hospital bed or table for supporting a patient during examination by the organ imaging scanner of the present invention. The scanner 1 l is provided with a supporting structure including a box-like housing 12 containing the scanner operating mechanisms. The supporting structure further includes spaced apart U-shaped supports for the purpose of carrying the box 12 and positioning the box at a height where it will be disposed above the bed and a patient lying on the bed. THe U- frame 13 is equipped with a generally horizontal top 15 and spaced apart, generally vertically disposed legs 16 and 17. The U-frame 14 is similarly provided with a horizontal top member 18 and spaced apart, generally vertically disposed legs 19 and 20.. Each of the legs 16, 17, 19 and 20 is provided with a caster at its lower end for floor engagement. The scanner and its supporting structure is thus permitted free rolling movement in hospitals or other areas where the device of this invention would be used. Also, the leg spacing is such that the device straddles the normal size hospital bed to eliminate the necessity for a patient to get out of bed for movement to some table such as used for X-rays. The scanner also includes a control console 22 which permits an operator to have easy access to the scanner and to his patient.
As best shown in FIG. 2 the diagram 23 depicts scan patterns as made by existing scanners. The detector is moved in what might be termed a jogging path of horizontal and vertical movements. This jogging path of past scanners has a first horizontal path 24 across the top of the diagram 23 in the direction of the arrow 25. From this point the detector moves vertically downwardly along the short path 26. This is in effect jogging to the next scan line. Here the detector is moved back over the scan area along the second horizontal path 27 in the direction of the arrow 28. At its end of travel along the path 27 the detector then turns at right angles and moves downwardly along the short vertical path 29 and thus jogs to the position of the third horizontal path 30. The detector is then moved horizontally along the path 30 in the direction of the arrow 31. This reciprocating horizontal movement with alternate intermediate: vertical jogs is continued until all of the scan area has been covered by the detector.
Applicants drive mechanisms eliminate the jogging of prior art scanning. As best shown in FIG. 3 the scan diagram 32 produced by applicants device is a zig-zag path for the detector. There is no jogging but rather a continuous vertical movement of the detector while it is horizontally reciprocated. The differential in speeds of the two directions creates the desired zig-zag pattern which more thoroughly covers the scan area and gives examining physicians an opportunity for better diagnosis. Horizontally the detector is moved relatively fast while vertically the detector moves relatively slow. However, in both movements the speeds are constant and uniform. This absolutely constant speed of travel of the detector over the scan area prevents faulty information from being recorded on the scan diagram.
In FIG. 3 the detector of applicants scanner moves in a first angular path 33 across the diagram 32 with primarily horizontal movement and just slight downward or vertical movement. The arrow 34 indicates the direction of movement of the detector along the path 33. Now the detector is reversed and moves along a second angular path 35 in its return across the scan area as shown by the arrow 36. Again the movement of the detector is primarily horizontal with only slight vertical movement. When the detector reaches the end of the path 35 it is again reversed and now moves back across the scan area on a third angular path 37 in the direction of the arrow 38. This zig-zag movement of the detector continues until the entire area to be scanned has been traversed. The resultant scan is one in which there is less space between scan lines than in scans made by prior scanners with the resultant that diagnosticians need interpolate less with applicants device.
Further in FIG. 3 there is included on the diagram vertically disposed, horizontally spaced apart lines 39 and 40 which define the lateral extent of the organ of the patient being examined on the diagram. Thus the center portion of the scan is used for material readings by the scanner. The overtravel at each end of the reversing detector is utilized to overcome slight velocity variations in the detector at the end of each pass across the scanarea that would be caused by the reversal of movement. In each reversal the velocity must be reduced to zero and then the device accelerated to resume its constant uniform speed of travel.
In FIG. 4 an attempt has been made to reproduce an actual scan made be applicants device. However, rather than scanning a human organ the field to be scanned was provided with two separate sources of radiation. One was considerably larger than the other and they were spaced apart. The photograph made by this artificial radiation field is reproduced in part in FIG. 4 as indicated by the numeral 41. In this illustration the zig-zag lines are seen as well as the larger and more intense radiation source shown at 43 and the lesser radiation source shown at 44. These sources of radiation were recorded by the detector in its zig-zag path of travel over the scan area. The illustration also shows the relatively uniform field produced by the detector in its movement over the scan field. This of course means that truer readings can be made by applicants scanner in its use on human patients with less chance of error.
FIGS. and 6 show the interior of the housing 12 which includes all of the operating mechanisms of the scanner of this invention. The housing 12 is provided with a top 45, a bottom 46 and spaced apart end walls 47 and 48. The box housing preferably includes reinforcing frame members and a covering skin of lightweight sheet metal. The end wall members 47 and 48 are carried by the supporting legs 16, 17, 19 and 20.
Within the housing 12 there are spaced apart brackets 49 and 50 which are fixedly attached to and depend from the top 45. As best shown in FIG. 6 a third bracket 51 is attached to and depends from the top 45 at a position in axial alignment with the bracket 49. The aligned brackets 49 and 51 fixedly support a cylindrical rod 52. A spaced apart and parallel rod 53 is fixedly suspended beneath the bracket 50 and another bracket (not shown) in axial alignment therewith which is similar to the bracket 51.
A bracket 54 is mounted to and on the underside of the top 45 at a position generally between the spaced brackets 49 and 50 as shown in FIG. 6. The bracket 54 carries a motor 55 for the driving of the detector in its vertical direction in a manner to be subsequently described. The motor 55 is provided with a drive shaft 56, the axis of which lies parallel to the top 45 of the housing 12. The drive shaft is provided with a coupling 57 which joins the drive shaft with a threaded screw shaft 58. The drive shaft 56 and the screw shaft 58 are in axial alignment. The screw shaft is journaled for rotation within the housing 12 by spaced apart hanger bearings 59 and 60 depending from the underside of the top 45. As best shown in FIG. 6 an internally threaded nut-bracket 61 is shown engaging the threaded shaft 58. Bolt fastening means 62 are used to join the nut-bracket 61 to a movable frame 63 which is joumally supported on the spaced rod members 52 and 53 for movement therealong. This is accomplished by a plurality of sleeve-like bearings 64. It is preferable that these bearings 64 be ball bushings to drastically minimize friction in the movement of the frame 63 along the spaced rods 52 and 53.
A second motor 65 is provided in applicants device to provide the source of power for driving the detector in its reciprocal horizontal movement. The second motor 65 is carried on and moves with the frame 63. The drive shaft 66 of the motor 65 is disposed on a generally vertical axis as shown in FIG. 6. As best shown in FIG. 5 spaced apart brackets 67 and 68 are affixed to the movable frame 63 and are arranged in axial alignment to receive and carry a rod 69. Similar spaced apart brackets 70 are arranged to fixedly carry a rod 71 which is spaced from the rod 69 but parallel thereto. THe rods 69 and 71 are disposed at right angles to the guide rods 52 and 53. The frame 63 with its motor 65 moves as a unit along the supporting guide rods 52 and 53 and itself has supporting guide rods to permit the detector to be moved in a direction at right angles to the direction of movement of the frame 63.
A detector supporting table 72 is disposed beneath the movalbe frame 63 and by means of sleeve bearings 73 the table is slidably carried on the guide rods 69 and 71. The sleeve hearings in this instance also are preferably in the form of ball bushings in order to minimize friction and to insure accuracy and uniformity of travel of the detector in its scanning of an organ.
The lower end of the motor drive shaft 66 is provided with a drive arm 74 which extends radially outwardly from the shaft. The attachment of the drive arm 74 to the shaft is such that rotation of the shaft causes rotation of the arm. This is more clearly shown in FIG. 7. A cam follower in the form of a roller 75 is journally mounted on the end of the drive arm spaced from its attachment to the motor drive shaft 66. The table 72 is provided with a diagonally positioned cam block 76. The block is bolted or otherwise fastened to the table so that it forms an integral part therewith. The block is equipped with an elongated groove or cam track 77 which is disposed generally diagonally of the table. The width of the cam groove 77 is commensurate with the size of the cam roller 75. The roller 75 engages the groove and the drive arm 74 is rotated in a single direction in its circular path 78 in the direction of the arrows 79 the table 72 is caused to have reciprocal movement along the guide rods 69 and 71. The reciprocal linear movement of the table 72 is indicated by the double ended arrows 80 in FIGS. 5 and 7. The cam drive thus converts rotary motion to a reciprocal linear motion. The shape of the cam 77 is designed with a long sweeping curve throughout the major portion of its length and with relatively short curve endings. It is this particular cam shape that permits the cam to slide easily therethrough and drive the table 72 in a continuous reciprocating movement although the direction of rotation of the motor 65 is constant in one direction.
The actual detecting portions of applicants scanner are carried on the table 72. A radiation detector 81 is mounted on the underside of the table 72. A multiplier photo tube 82 forms a part of the detector. Similarly the detector includes a crystal 83, such as sodium iodide, to detect radiation and impart energy impulses to a circuit (not shown) which includes an oscilloscope (also not shown). The readings of the oscilloscope may be recorded by a camera or the like (not shown).
The detector still further includes a collimator 84. The drawings show a large rectangular opening 85 in the bottom 46 of the housing 12 to permit the small aperture or apertures 86 of the collimator to be directed downwardly on a patient 87.
In the use of the device of this invention the patient 87 is placed on the bed 10 and the scanner placed above him in the area of the organ to be tested. The usual procedure is to preliminarily feed or inject some radioactive pharmaceutical to the patient. The particular radioactive pharmaceutical used would be one which the medical profession has discovered will lodge in the particular organ to be tested. Not only will the radiation substance be attracted to a particular organ but nuclear medicine personnel have found that such radiation substances will accumulate in greater or lesser amounts in diseased area of the organ. This is especially true of tumors having cellular structure quite abnormal compared to the normal cell structure of the organ. The patient so prepared is then subjected to this scanning test and the detector in effect takes a picture of the organ. Aggregations or lack thereof of the radioactive drugs in one or more areas of the organ indicate to the medical profession that the organ is diseased. The detector of this invention moves at a constant uniform speed in two directions in a single plane in the zigzag path previously described and enables the scanner to record meaningful data.
Radiation beams 88 are received through the collimator 84 and concentrated on the crystal 83. The scanner thus encompasses the entire organ to be examined by the linear movements of the detector in two directions at right angles to one another and producing a zig-zag path by reason of the particular drive employed. The horizontal scanning is accomplished by the cam drive in the direction of the arrow and the vertical scanning is accomplished by the screw drive in the direction of the arrow 89. The arrow 89 has been made two ended to show not that the detector reciprocates vertically during one scan, but that the detector can be moved back to start over or may be reversed to start a scan from the other end. The vertical movement of the detector during a scan runs continuously from one end of the drive screw to the other.
What is claimed is:
1. A drive mechanism for a rectilinear scanner for organ imaging comprising a supporting structure, means carrying a detector on said supporting structure for movement relative thereto in a single plane, means on said supporting structure for imparting linear movement of a constant velocity to the detector in the single plane, said means including a motor having a rotatable shaft, a drive arm affixed to said shaft, said drive arm having a cam follower at a position spaced from its attachment to said shaft, a cam affixed to said detector, said cam follower engaging said cam, the cam having a shape to cause the detector to be linearly reciprocated at a constant velocity across and back through the said single plane by rotation of said motor shaft in a single direction at a constant speed, means for continuously moving said detector at a considerably lesser but constant velocity in a direction at substantially right angles to the linearly reciprocating movement obtained by the cooperating cam and cam follower, whereby the detector is moved in a zig-zag manner throughout the single plane to thereby completely and uniformly scan a generally rectangular area.
2. A drive mechanism for a rectilinear scanner for organ imaging comprising a supporting structure, means carrying a detector on said supporting structure for movement of the detector relative to the supporting structure in a single scan plane, drive means arranged and constructed to cause the detector to continuously move at a constant slow velocity from top to bottom of the scan plane and further to cause the detector to reciprocate at a constant relatively fast velocity from side-to-side of the scan plane to thereby impart a zigzag movement of the detector in the single plane whereby the detector may scan the whole of a patients organ.
3. A device as set forth in claim 2 in which that part of the said drive means causing the detector to continuously move at a constant slow velocity from top to bottom of the scan plane comprises a motordriven screw.
4. A device as set forth in claim 3 in which that part of the said drive means causing the detector to reciprocate at a constant relatively fast velocity from side-to-side of the scan plane comprises a motor driven rotating arm having a cam follower on its outer end and a cooperative cam associated with said detector.
5. A drive mechanism for a rectilinear scanner for organ imaging comprising a supporting structure, a frame, means carrying said frame on said supporting structure for movement relative thereto, said means carrying said frame including spaced apart parallel guide rods on the supporting structure and sleeve bearing members on said frame for slidably receiving said guide rods, means on said supporting structure for imparting movement to the frame in the direction of said guide rods, said means on the supporting structure comprising a motor driven screw to impart movement of the frame at a constant slow velocity in one direction, a table, a detector for scanning organs mounted on said table, means carrying said table on said frame for movement relative thereto, means on said frame for imparting movement to the table, said means carrying said table including spaced apart parallel guide rods on the frame disposed at right'angles to the guide rods carrying the frame on the supporting structure whereby movement of the table is in the direction of the guide rods carrying the table, said means on said frame for imparting movement to the table including a motor having} rotatable shaft, a drive arm affixed to said shaft, said drive arm having a cam follower at a position spaced from its attachment to said shaft, a cam affixed to said table, said cam follower engaging said cam, the cam extending generally diagonally of the table and arranged in general parallelism with the axes of the guide rods, whereby the rota tion of the motor shaft in one direction at a constant speed will produce a reciprocating action of the table at a constant speed linear velocity and considerably faster than the simultaneous movement of the frame by the motor driven screw whereby the resultant movement of the detector is a zig-zag path over the entire organ being scanned.