US3484604A - Axial transverse tomography wherein the angle of spread of radiation is controlled - Google Patents

Axial transverse tomography wherein the angle of spread of radiation is controlled Download PDF

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Publication number
US3484604A
US3484604A US675972A US3484604DA US3484604A US 3484604 A US3484604 A US 3484604A US 675972 A US675972 A US 675972A US 3484604D A US3484604D A US 3484604DA US 3484604 A US3484604 A US 3484604A
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Prior art keywords
angle
radiation
film
rays
controlled
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Expired - Lifetime
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US675972A
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English (en)
Inventor
Tadayoshi Matsuda
Shigeo Endo
Sumio Makino
Katsumi Nagai
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]
    • A61B6/032—Transmission computed tomography [CT]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/06—Diaphragms
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/58—Testing, adjusting or calibrating thereof
    • A61B6/582—Calibration
    • A61B6/583—Calibration using calibration phantoms

Definitions

  • This invention relates to tomography and more particularly to rotatography wherein tomographs are taken with respect to a cross-section intersecting with the axis of the patients body at right angles.
  • An image corresponding to the tumour part of a patients body obtained by a rotatography on a film and an image corresponding to contour of the body are required to be clear in order to ascertain their relative positions.
  • the mean degree of X-ray absorption or the mean degree of attenuation from the beginning of r0- tating motion to the end thereof is lower near the periphery of the body than in the inner portions of the body so that the degree of blackening of the developed film is higher at portions corresponding to the periphery of the body than at portions corresponding to the inside of the body.
  • the intensity of X-rays is adjusted to clearly indicate on the film the image of the tumour part in the body the concentration of the image of the periphery of the body will approach or exceed the saturation of the film density thus rendering the image non-clear.
  • the direct cause for the above deficiency is the degree of absorption of X-rays that penetrate through the patients body.
  • Factors that determine the degree of absorbing X-rays by the patients body are the distance through the body and the tissue thereof.
  • the tissue does not unevenly affect the film density because it is photographed by rotating motion. It was confirmed by experience and experiment that uneven concentration of the image on the film is caused by the difference in the distance through the patients body. We have actually measured the effect of the difference in the distance of X-rays through the body upon the density formed on the film by utilising a waist phantom.
  • the angle 0 as well as the distance between an X-ray source and a focal point on the film would vary except the case wherein X-rays pass through the center of rotation, but the amount of such variation is negligibly small.
  • the angle of rotating motion from the starting point to the final point of rotating motion is nearly equal to 200, but in measuring the phantom this angle was set to be equal to 180.
  • Curve I corresponding to the point of inspection I has smaller ordinates than curves II through V corresponding to points of inspections II through V, respectively, at angles smaller than 50 and larger than which means that distances of travel of X-rays are short. Whereas in a range of angle 4) represented by 50 140, curve I substantially overlaps upon curves II through V so that the integral of the curve I from the starting point to the final point of the rotating motion is smaller than those of curves II through V. This means that the density of the image on the developed film is higher than those images at points of inspection II through V.
  • the ordinate of curve IV corresponding to the point of inspection VI is smaller than those of curves II through V at angles larger than 30 and smaller than Thus in this range of angles the distances of travel of X-rays are greatly reduced.
  • the curve VI substantially overlaps upon curves II through V. This means that the integral of curve VI in a range of angle of 30 150 the integral of the path of travel of X-rays is smaller than those of curves II through V thus increasing the concentration of the image on the film.
  • This invention contemplates the coincidence of density of the images on the developed film corresponding to the periphery of the patients body and to the tumour in the body obtained by the rotatography whereby to clearly indicate the relative position of a tumour with reference to the peripheral portion of the body.
  • a method of tomography wherein when effecting rotating motion of a source of radiation and a cassette opposing thereto about a centre of rotation included in a cross-section of the patients body, the angle of spreading of the radiation flux arriving at the film through the patients body is controlled to follow a predetermined program. Said control of the angle of spreading is effected by means of a diaphragm located between the source of radiation and the body to be examined. The diaphragm may be substituted by a filter which attenuates the X-ray passing therethroughv
  • FIG. 1 represents relative positions of a source of radiation and a photographic film with reference to a Waist phantom wherein a cross-section along a line Y-Y' shows a section of a body to be examined;
  • FIG. 2 shows a schematic cross-section of the Waist phantom representing positions of various points of inspection I through VI included in said cross-section;
  • FIG. 3 shows a group of characteristic curves showing distances of travel of X-rays at each of said points of inspection I through VI wherein the abscissa represents the angle of rotating motion es of the radiation source and the ordinate the distance I of transmission through the patients body including the table;
  • FIG. 4 is a diagrammatic representation of a conventional X-ray tomographic apparatus
  • FIG. 5 is a diagram to explain diaphragm control of X-rays
  • FIG. 6 is a graph to show the relation between the opening of the diaphragm and the angle of rotating motion.
  • FIG. 7 is a graph similar to FIG. 3 but diaphragm control is employed.
  • the radiation photographic apparatus shown in FIG. 4 is designed to be especially suitable for tomography.
  • a source of radiations for example an X-ray tube 12 and a cassette holder 13 (the imaging means) are supported by a supporting beam 15 on the opposite sides of a table 11 supporting a human body 20, said beam being rotatably journalled on a horizontal shaft 14 fixed to a frame 16.
  • a suitable diaphragm mechanism At the projection window of the X-ray tube 12 there is provided a suitable diaphragm mechanism, not shown, to control the angle of spread of radiations emanated from the X-ray tube 12.
  • the opening of the diaphragm is controlled by means of a control device (not shown) to follow a predetermined program (which shows the degree of throttling generally predetermined with respect to a particular cross-section) with reference to the angle of rotation of the horizontal shaft 14 or the angle of rotating motion of the X-ray tube 12.
  • a control device not shown to follow a predetermined program (which shows the degree of throttling generally predetermined with respect to a particular cross-section) with reference to the angle of rotation of the horizontal shaft 14 or the angle of rotating motion of the X-ray tube 12.
  • Points 12a, 12b, 12c and 12d represent respective particular positions of the X-ray tube during rotating motion.
  • the membranes of the diaphragm mechanism 17 at these positions are schematically represented by 17:1 17a 17b 1717 171: 17c and 172 17e and angles of spreading of X-rays defined by centre lines extending between the centre of radiation of the X-ray tube 12 at each of said positions and the centre of the body (a point included in a section to be photographed) and the edges of said membranes are represented by :1 ,8 a ⁇ 3 a 5 respectively.
  • the angles of spreading or and [3 of the diaphragm 17 are controlled with the increase of rotating motion angle 95, as shown in FIG. 6, as the X-ray tube 12 is rotated. It is to be understood that the curve illustrated in FIG. 6 is to explain the principle of the invention and that the configuration of the actual curve is more complicated.
  • Characteristic curves shown in FIG. 3 are corrected in the following manner.
  • the angle of opening at is gradually increased as shown in FIG. 5 but gradually decreased in a range greater than 140 as shown by a portion ,8.
  • the concentration of the image on the photographic film of each of said points of inspection I through VI would be proportional to the integral of the distance of travel of X-rays through the body throughout the angle of rotation or rotating motion of the X-ray tube, whereby the density of respective points of inspection would become substantially equal. For this reason when the position of the tumour is clearly developed the peripheral portion of the body will also be clearly photographed, thus enabling accurate and easy determination of the relative positions thereof.
  • the diaphragm mechanism has been shown to completely intercept X-rays it may be constructed of a material that suitably attenuates X-rays whereby to act as a filter.
  • a method of cross-section tomography comprising the steps of:

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Medical Informatics (AREA)
  • Optics & Photonics (AREA)
  • Biomedical Technology (AREA)
  • Biophysics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Veterinary Medicine (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Public Health (AREA)
  • Pathology (AREA)
  • Radiology & Medical Imaging (AREA)
  • Physics & Mathematics (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Pulmonology (AREA)
  • Theoretical Computer Science (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
US675972A 1967-10-17 1967-10-17 Axial transverse tomography wherein the angle of spread of radiation is controlled Expired - Lifetime US3484604A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US67597267A 1967-10-17 1967-10-17
GB48751/67A GB1164859A (en) 1967-10-17 1967-10-26 Tomography
NL6714606A NL134725C (enExample) 1967-10-17 1967-10-27
FR127793 1967-11-10

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US3484604A true US3484604A (en) 1969-12-16

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US675972A Expired - Lifetime US3484604A (en) 1967-10-17 1967-10-17 Axial transverse tomography wherein the angle of spread of radiation is controlled

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US (1) US3484604A (enExample)
FR (1) FR1550456A (enExample)
GB (1) GB1164859A (enExample)
NL (1) NL134725C (enExample)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973128A (en) * 1973-08-18 1976-08-03 Emi Limited Tomography
US5449913A (en) * 1993-11-03 1995-09-12 Chang; Wei Apparatus for producing attenuation scan

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2609925C2 (de) * 1976-03-10 1982-06-09 Philips Patentverwaltung Gmbh, 2000 Hamburg Anordnung zur Ermittlung der Verteilung der Absorption eines Körpers

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1535359A (en) * 1920-12-28 1925-04-28 Tousey Sinclair X-ray filter or screen
DE1081186B (de) * 1958-11-03 1960-05-05 Mueller C H F Ag Vorrichtung fuer Schichtbild-Aufnahmegeraete
US3248547A (en) * 1963-10-21 1966-04-26 Picker X Ray Corp Device for accurately positioning X-ray filters in the beam path

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1535359A (en) * 1920-12-28 1925-04-28 Tousey Sinclair X-ray filter or screen
DE1081186B (de) * 1958-11-03 1960-05-05 Mueller C H F Ag Vorrichtung fuer Schichtbild-Aufnahmegeraete
US3248547A (en) * 1963-10-21 1966-04-26 Picker X Ray Corp Device for accurately positioning X-ray filters in the beam path

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973128A (en) * 1973-08-18 1976-08-03 Emi Limited Tomography
US5449913A (en) * 1993-11-03 1995-09-12 Chang; Wei Apparatus for producing attenuation scan

Also Published As

Publication number Publication date
GB1164859A (en) 1969-09-24
NL6714606A (enExample) 1969-04-29
FR1550456A (enExample) 1968-12-20
NL134725C (enExample) 1972-03-15

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