US2484366A - Radiograph calculator - Google Patents

Description

' Oct. ll, A1949. J. w. wlLKsoN RADIOGRAPH CALCULA'I.0R Filed June`14, 1947 v l 5 Sheets-Sheet 1 REENS ma PRESCNBE PAR A H/ ATTORNEY Oct. 1l, 1949.

J. w. wgLsoN RADIOGRAPH CALCULATOR 3 Sheets-Sheet 2 Filed June l4, 1947 INVENTOR.

JOHN W W/LSO/V H15 Arm/wry 0t.1-1,1949. ...wwlLsoN f y 2,484,366

RADIOGRAPH CALCULATOR Filed June 14, 1947 v 5 sneaks-sheet s INVENTOR.

JQH/v w. w/Lso/v W5 ATTORNEY.

Patented Oct. 11, 1949 UNITED STATES ATENT OFFICE 8 Claims.

This invention relates to rotary calculators of the type having concentrically mounted discs or equivalent pivotally connected elements, wherein the discs carry markings or legends adapted to be juxtaposed cr brought into predetermined relation to one another, certain of the discs being provided with slots or apertures throughwhich preselected characters, indicative of a predetermined result, may be read. Such result may be based upon a mathematical formula or upon empirical data.

More particularly, the present invention relates to calculators of the above-described type wherein the indicated characters are determined by a plurality of arguments or variables. In a specific embodiment, the calculator yields several simultaneous indications, some being dependent only upon one argument, and others being dependent upon two or three arguments.

In the specific embodiment described in detail in this specification as illustrative of the invention, the calculator is adapted for use as a radiograph calculator, i. e., as a device for indicating to an operator of an X-ray or radiograph machine certain information useful or necessary for the proper taking of a radiograph, including such data asthe proper position lof the body to .be radiographed, the correct adjustment of the machine, the length of the exposure and the selection of appropriate accessories, such as intensifying screens. This information is dependent upon the following arguments: (1) The type of radiological examination to be made and the part of the body to lbe radiographed; (2) the thickness of the part of the body to be radiographed; (3) the correction to be applied because of deviations from normal of the output of the particular radiographic machine used, and because of individual preferences of radiologists for lighter or denser radiographs.

The device according to this invention affords a rapid and reliable means flor obtaining the inn formation required for making a radiograph, without recourse to charts or tables, and without the use of slide rules involving careful setting of mathematically determined constants and graduations. An embodiment of the invention adapted to this -purpose is illustrated in the drawing forming a part of this specification, wherein:

Fig. 1 is a lplan view of a complete calculator according to the invention, with the discs set to yield a reading;

Fig. 2 is a sectional view, taken on line 2-2 of Fig. 1; and

Figs. 3 and 4 are plan views of the intermediate disc and of the lowest disc, respectively.

The calculator comprises three discs 5, 6 and 1, held' together by a central pin 8 which functions as a pivot and permits relative turning of the discs. The lowest orr base disc 1 may serve as a supporting base or may be mounted on a heavier frame, not shown. An adjustable index 9 is clamped to the lowest disc 1, and may be constructed of resilient material, such as metal or transparent plastic. It has a slot 9a, the purpose of which will -be explained below.

The upper or face disc 5 is provided with different sight apertures l0 and Il. The first aperture I!! is, for structural reasons, provided with webs subdividing it into seven windows through which the information for the taking of a radiograph may be read. These windows are herein collectively referred to as an aperture. The seven items of information, indicated by legends above or below the windows, are as follows:

1. Position. This indicates the position of the part of the body to fbe radiographed, sometimes known as viewf When all positions are suitable, this indication is All. Other positions are indicated as Lat for lateral, AP for anteriorposterior, PA for posterior-anterior, and Obl" for oblique.

2. Distance. This indicates the correct distance, in inches, that the X-ray tube or projector is to be placed from the lm.

3. MAS, This indicates the milliampere seconds to .be used for the radiograph.

4. MA. This indicates the current intensity in milliamperes.

5. Time. This indicates the exposure time in seconds.

6, Bucky. This window indicates, by the words Yes or Nd whether or not a Bucky diaphragm is to be used. This has reference to the Potter Bucky diaphragm, which is a lamination of very narrow lead and Wood strips of equal thickness. The laminated portion moves transversely to the strips, between the part to be radiographed and the film below such part.

7. Screen. This window indicates the proper type of intensifying screen or film holder to be used for the other data displayed; Par indicates a par screen, and F '7 a dental nlm number or indicating code.

The second aperture Il is, likewise, subdivided into several, viz., four windows, the windows being herein collectively referred to as an aperture. The calculator is so constructed that, at any particular setting (except for dentals), an

3 indication will appear in only one of these windows. This indication shows the voltage to be applied to the machine, expressed in kilovolts. For dentals, four indications, pertaining to different types of examinations, appear.

The face disc is, further, provided on its upper, central portion with instructions for special situations, as will be explained hereafter. A circular scale I2, at the periphery of the disc, is subdivided to indicate the thickness of the part of the body to be radiographed, thickness being indicated in centimeters, measured at the central ray point. The scale I2 is equicrescent, i. e., its subdivisions subtend equal angular intervals at the pivot point. An index I3, formed integrally with the face disc, protrucles slightly beyond the otherwise circular margin.

The intermediate disc 5, shown in Fig. 3, is generally of circular outline with a diameter equal to that of the facing disc. It is provided with a protruding marginal tab I4, which extends radially beyond the margin of the facing disc and is, therefore, visible when the discs are assembled. It extends circumferentially slightly less than a semi-circle and may be made thinner than the main body of the disc, so as to be spaced slightly from the base disc 'I (see the top of Fig. 2). The tab is thereby adapted to enter and move freely through the slot 9a in the adjustable index 9. The tab I4 is subdivided into a plurality of sectors subtending equal angles at the pivot point, corresponding to the angular differences between the graduations of the scale I2 on the facing disc. These sectors bear characters or legends showing the part of the body to be radiographed and the type of examination to be made. In certain instances shorter exposures are made for children, because of the difficulty of insuring immobility of the patient; hence different legends are in some instances provided for children and for adults. In the embodiment shown, these legends, reading counter-clockwise, are as follows: Extremitiea adult, Extremities, children, Cervical spine, shoulder, Cervical spine, lateral, Humerus, lateral, through lateral chest, Thoracic spine AP, lumbar spine AP, Pelvis and Hip AP, Thoracic spine, lateral, Thoraco-lumber, lateral, Lumbar spine, lateral, lumbo-sacral, lateral, colon, lateral, Hip, lateral, non-bucky, Abdomen, gallbladder, K. U. B., rib-beloW-diaphragm, Esophagus, Stomachj Colon, for lateral see lateral lumbar, Rib-above-diaphragm, sternum-oblique, Chest PA, adult, Chest-lateral, sternum-lateral, esophagus-lateral, adult, Adultr skull, sinus, mastoid, maxilla, mandible-PA only, Mandible, lateral, Nasal bones, Childz skull, sinus, mastoid, maxilla, mandible PA only, Abdomen, children, Chest, children, Fetus, Pelvimetry, coccyx, lateral, and Dentals Certain of these legends are abbreviated in the drawings. On the inner portion of disc 6, within each sector corresponding to the sectors on the tab I 4, is a radial column `of information indications pertaining to the legend in the corresponding sector, and located so as to be viewed through the aperture ID in the facing disc. These data or information columns, indicated generally by the reference number I5, occupy slightly less than half of the inner portion of the disc.

The remaining portion of the disc E5 contains data indications to be read through the aperture I I and slots or apertures adapted to be registered with the aperture II, but of lesser radial extent. These indications and slots are diametrically opposite the sectors on the marginal tab I4 corresponding thereto. For dentals, four indications are provided: U '7-8 62, Upper 54, L 7-8 58, and Lower 54. These indications are identified in the drawing by the reference character I6. In each other sector one aperture I1 is provided. It will be noted that the apertures I'I are radially offset, i. e., they are at different radial distances from the pivot point; because of this arrangement only one of the four annular series of numbers on the lowest disc is selected for display through the apertures II and II. Four radial spacings, corresponding to the four windows of the aperture II, are used in positioning the apertures I'I. Certain sectors may be provided with an indication instead of an aperture; thus, in the sector corresponding to the legend Nasal bones the number 38 is written, and no indication from the lowest disc will be visible when the calculator is set to this legend. The number 38 is, therefore, a number dependent upon a single argument, viz., the part of the body to be radiographed, as distinguished from other voltage indications read through apertures II and I'I, which depend upon three variables or arguments.

The lowest disc 1, shown in Fig. 4, is generally circular and has a diameter equal to that of the facing disc. It has a protruding marginal tab I8, extending beyond the margins of the facing disc and the intermediate disc and is, therefore, visible when the discs are assembled. The tab extends circumferentially slightly less than a right angle, and bears a density scale I9. This scale is subdivided into equally spaced subdivisions subtending angles at the pivot point corresponding to the angular differences between graduations on the scale I2, i. e., it subdivides the tab I8 into sectors. The graduations are numbered from 1 through 10 and represent density factors. The adjustable index 9 is clamped to the tab I 8, as shown in Figs. 1 and 2. Since, with any given machine, and when making radiographs repeatedly for the same radiologist, the same correction factor is used in successive radiographs, it is convenient to set the index 9 to the empirically determined density factor and to use the index thereafter when setting the upper discs in relation to the lowest disc. Using a smaller number on the density scale I9 results in a denser or darker radiograph.

On the inner portion of the lowest disc 1 is a plurality of radial columns 20 containing voltage indications. These radial columns are angularly spaced to correspond to the angular differences between graduations on the scale I2, occupying different sectors on the face of the disc; the indications within each column or sector are radially spaced to correspond to the distances from the pivot point of the four windows of the aperture II on the face disc. It will be noted that the indications form four concentric arcs of circles ,of indications or numbers, increasing in magnitude generally in a counter-clockwise direction, but at different increments. These arcs extend over more than a semi-circle, so that the .graduations or legends on the tab I8 correspond only to some of the sectors containing radial columns 20.

In using the calculator, the operator rotates the face disc 5 and the intermediate disc 6 with respect to the lowest disc 1 until the index I3 points to the proper legend on the tab I4, and the correct density factor on the scale I9 is opposite the graduation on the scale I2 which indicates the thickness of the part of the body to be radiographed. It is advantageous to set the index 9 to the selected density factor preliminarily; it then remains iixed on the tab i8 and it is only necessary to bring the selected graduation on the scale I2 opposite to the point of the index. For thicknesses which. may be opposite the tabA I4, this tab enters the notch @a in the index, it being noted that the notch 9a is above the part of the index 9 which engages the upper face of the tab l8` and below the uppermost face of the index, and that the tab I!! is thin enough to enter the notch, as shown in Fig. 2. This arrangement permits smooth operation of the device at any relative positions discs.

EcmzpZe.-To take a radiograph of the skull of a child having a thickness of 17 cm., and applying a density factor of '7, the index 9 is first set over "I on the scale Iii. The face disc is turned until the index i3 points to the proper legend on the tab lli; then, maintaining the face disc and intermediate disc relatively fixed, they are rotated until the number 17 on the scale l2 is opposite the index S. The resulting setting is shown in Fig. 1. The operator then reads the data appearing through the apertures; as illustrated, they show that such a radiograph should be taken as follows: All positions are suitable; the target or film should be 36 inches from the X- ray tube; the exposure should be for 2O milliampere seconds, taken at a current intensity of 200 milliamperes, for one tenth of a second, with a Bucky diaphragm and with par-speed nlm screen; the correct voltage is 30 kilovolts.

The exposure time indicated on the calculator is based upon par-speed intensifying screens, as explained above. For ease in transposing parspeed technique to the other possible speed holders, the screen ratio is given in the upper portion of the face disc.

The legend Dry cast refers to the plaster dressing that is often placed on an injured part of the body to immobilize it until it heals. The cast thus adds material through which the X-rays must pass to expose the hlm, so that the time factor must be changed This is explained on the front of the calculator, which indicates that twice the time shown in the aperture l must be used, all other adjustments being unchanged (it being understood that the milliampere second value will thereby be doubled). When a freshly applied cast which is still wet is to be radiographed the opacity is greater; therefore, a longer exposure time is required. The exposure time is, in such a case, three to four times that shown in the aperture Il).

The ratio of exposure time with a Potter Bucky diaphragm to an exposure without such diaphragm is given as 5 to l, so that the operator can readily alter his time factor if the Potter Bucky diaphragm is not in use or if, for any reason, a much shorter exposure time is required.

It will be understood that changes can be made in the arrangement of parts of the calculator without departing from the spirit and scope of the invention. Thus, the relations between the legends on the tab i4 and the index may be reversed, using an index on the intermediate disc; similarly, the density factor scale I9 and the anatomical thickness scale l2 may, in certain in stances, be interchanged; finally, instead of using tabs, the legends may be viewed through circular apertures in the discs. The embodiment shown is, however, particularly advantageous in a device of the type shown, wherein the anatom- 6. ical thickness scale and the voltage indications extend for more than a semi-circle, andthe legends on the tab I4 occupy almost a semi-circle, because it permits the most eflicient utilization of space.

he scales shown on the drawings are for a machine capable of using a maximum current of 500 milliamperes. For other machines the face disc and lowest disc would be the same; a different intermediate disc, bearing appropriate indications, would be substituted.

I claim as my invention:

1. In a calculator of the type described, a base disc having a pivot point and bearing a first series of characters arranged in different sectors about said pivot point and at different radial distances therefrom; an intermediate disc mounted over said base disc for rotation and arranged to cover said iirst series of characters, having a plurality of slots positioned at different radial distances to register with selected characters of said first series, and bearing a second series of characters arranged in different sectors thereof; a facing disc mounted over said intermediate disc for rotation having two apertures, the lfirst aperture being positioned to register with any of the characters of the second series to permit selective reading of the characters of the second series, the second aperture being positioned to register with any of the apertures in the intermediate disc to permit selective reading of the characters of the rst series; a rst index and an annular series of characterss, one on the face disc and the other on the intermediate disc, adapted to loe brought into coincidence; and an annular scale bearing graduations and a second index. one on the face disc and the other on the base disc, adapted to be brought into coincidence.

2. The calculator according to claim 1 wherein the base disc is provided with a marginal tab extending beyond the margin of the intermediate and face discs, said tab being provided with a graduated scale and an adjustable index thereon forming said second index, and the said annular scale bearing graduations is on the margin of the face disc.

3. The calculator according to claim 1 wherein the intermediate disc is provided with a marginal tab extending beyond the margin of the face disc, said annular series of characters being on the marginal tab on the intermediate disc and said rst index being on the margin of the face disc.

4. The calculator according to claim 1 wherein the intermediate disc carries a third series of characters positioned for registry with the second aperture oi the face disc, whereby characters of either the first series or the third series may be selectively read through said second aperture.

5. A radiograph calculator comprising a, plurality of concentric, pivotally connected discs, the lowest disc having on its face radial voltage columns, each column containing a series of voltage indications, and having an annular series of density designations circumferentially spaced corresponding to the angular spacing of said radial voltage columns; an intermediate disc having, on one sector thereof, radial data columns, each containing indications of data for the making of a radiograph, and, in another series of substantially diametrically opposite sectors, a series of Voltage-indicating slots positioned at successively different radial distances from the pivot for registry with the Voltage indications on the lowest disc; a facing disc having on its face an annular series of anatomical thickness indications alignable with said density designations and two radial apertures, the first of said apertures being positioned to register' with the data indications on the intermediate disc, whereby each radial data column may be viewed singly, and the second of said apertures being positioned to register with the Voltage indications and with the Voltage-indicating slots, whereby a portion of each of said radial voltage columns may be viewed singly; and an index and an annular series of anatomical designations circumferentially spaced corresponding to the angular spacing of said radial voltage columns, one on the intermediate disc and the other on the face disc, said index and annular series of anatomical designations being alignable with each other, whereby, when the selected anatomical designations are aligned with the index and selected density designations are aligned with selected anatomical thickness indications, radiograph exposure data are brought to View through the rst aperture in the facing disc and a voltage indication will be brought to View in the second aperture in the facing disc.

6. The radiograph calculator according to claim 5 wherein the lowest disc and the intermediate disc are each provided with marginal tabs extending beyond the margin of the facing disc, the density designations are on the marginal tab of the lowest disc, the annular series of anatomical designations is on the marginal tab of the intermediate disc, and the index is on the facing disc.

7. In combination with the calculator according to claim 6, an adjustable index clamped to the marginal tab of the lowest disc and alignable with the anatomical thickness indications on the face disc.

8. The calculator according to claim 7 wherein the adjustable index has a slot adapted to receive the tab on the intermediate disc.

JOHN W. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,207,448 Venable Dec. 5, 1916 1,453,100 Fulgora Apr. 24, 1923 1,966,971 Rochlus July 17, 1934

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