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X-Ray filter for chest X-rays
| Details |
Inventors: Ferlic, Daniel J.;
Assignee: Minnesota Mining and Manufacturing Company (St. Paul, MN)
Primary Examiner: Smith; Alfred E.
Assistant Examiner: Grigsby; T. N.
Attorney, Agent or Firm: Sell; Donald M., Smith; James A., Weinstein; David L.
Filter for use in medical x-ray apparatus to permit higher intensity x-ray exposure in the heart and mediastinum area while maintaining a normal level of x-ray exposure in other areas of the body, particularly in the lung area. The filter comprises a sheet of radiation absorbing material having an opening therein, said opening corresponding to the spine and central portion of the heart. Accordingly, the upper portion of the filter exhibits a relatively narrow opening which becomes gradually wider toward the lower portion of the filter. |
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DETAILED DESCRIPTION A conventional radiographic apparatus comprises (1) an object plane for an object, or patient, to be radiographed, (2) a source for a beam of penetrative radiation, i.
e.
x-rays, directed towards the object plane, (3) a radiation absorbing filter device positioned in the path of the radiation beam between the radiation source and the object plane.
The x-rays traversing the object plane expose an x-ray film (directly or by means of an intensifying screen) which is then developed, yielding a permanent record of the x-ray image.
The filter device of the present invention comprises a material capable of absorbing x-ray radiation having areas of differential radiation absorption capability formed in a predetermined pattern or configuration.
The filter can be formed of a single radiation absorbing sheet having the desired pattern cut into it.
The required pattern in the sheet allows a higher level of x-ray exposure in the heart and mediastinum (spinal) areas of the body of a patient than in other areas of the body of the patient.
It is preferable, however, to provide means for adjusting the filter for the purpose of adapting the filter for use on a variety of subjects or on a variety of radiographic apparatus.
A preferred filter construction comprises (a) a base plate forming a frame and an open area therein, (b) a plurality of movable members fastened to said base plate, said movable members forming a defined opening, said defined opening increasing in width from a relatively narrow area from the top to a wider area at the bottom of the base plate open area to provide a shaped pattern of greater exposure around the area of projected penetrating radiation corresponding to the human heart and around the area corresponding to the human spine and lesser exposure in the other areas of the body, and particularly in the area of the lungs.
The pattern formed by the movable members is particularly desirable because a relatively high level of x-ray exposure (e.
g.
, 250% of normal exposure levels) is required in the area of the spine and in the area of the central portion of the heart, both of which areas have high tissue density
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