Masked scanning X-ray apparatus

Claim 2

An X-ray system for radiological examination of a subject comprising: an X-ray beam source of finite size radiating through the position of a radiological subject to an imaging area; an X-ray receptor at the imaging area emitting secondary radiation on receipt of X-rays; moving X-ray mask means between the source and receptor including an X-ray window transmitting a shaped X-ray beam of width scanning across and through the subject position to the receptor to produce a secondary radiation image at the imaging area; electro-optical means viewing the imaging area for utilization of the secondary image; and moving light mask means between the receptor and electro-optical viewing means including a light window transmitting the secondary image; wherein the X-ray and light mask means include means for adjusting the width of the mask windows, thereby to minimize the fraction of scattered radiation reaching the X-ray receptor while operating the X-ray tube within its power capacity and to adjust the intensity of the light image transmitted to the electro-optical light viewing means.

Claim 3

A system according to claim 1 wherein the distance from the source to the receptor is between 60 and 200 centimeters.

Claim 4

A system according to claim 1 wherein the size of the X-ray source is between 0.03 and 0.2 centimeters.

Claim 5

A system according to claim 1 wherein the utilization means includes electro-optical means viewing the image area for converting the secondary image to electrical signals corresponding to the subject under examination.

Claim 6

A system according to claim 1 wherein the utilization means includes a flying spot scanner with lens means projecting the secondary image on the scanner through the adjustable window of the light mask.

Claim 7

A system according to claim 5 wherein the light mask means is between at least a part of the lens means and the scanner, before the image plane of the lens means.

Claim 8

A system according to claim 1 wherein the second mask means is closely adjacent the scanner.

Claim 9

A system according to claim 1 including control means to synchronize movement of the first said and second mask means for substantially simultaneous transmission of X-rays and secondary radiation through respective windows of the masks.

Claim 10

A system according to claim 8 wherein the control means includes means limiting energization of the X-ray source substantially only to times when the first said mask means windows are transmissive to the receptor.

Claim 11

A system according to claim 1 wherein the receptor includes means for storing the secondary radiation image.

Claim 12

A system according to claim 1 including an X-ray transmissive support wherein the subject position is between the X-ray source and the support.

Claim 13

A system according to claim 11 wherein the radiation receptor is located between the support and the utilization means.

Claim 14

A system according to claim 1 wherein the viewing means is a flying spot scanner coordinated with the movement at the X-ray mask means.

Claim 15

A system according to claim 1 wherein the mask means moves continuously on an orbital path so that the window repeatedly scans the subject position to produce a series of secondary images, and wherein the electro-optical means includes means for converting the secondary images into corresponding series of video signals.

Claim 18

The method according to claim 15 wherein E is varied between 0.25 and 100 milliroentgens.

Claim 19

The method according to claim 15 wherein V is varied between 50 and 150 peak kilovolts.

Claim 20

The method according to claim 15 wherein T is varied between 5 and 1500 milliseconds.

Claim 21

The method according to claim 15 wherein the distance L is varied between 60 and 200 centimeters.

Claim 22

The method according to claim 15 wherein the size X* of the X-ray source is between 0.03 and 0.2 centimeters.

Claim 25

An X-ray system for radiological examination of a subject comprising: an X-ray beam source of finite size radiating through the position of a radiological subject of an imaging area; an X-ray receptor at the imaging area emitting the secondary radiation on receipt of X-rays; moving X-ray mask means between the source and receptor including an X-ray window transmitting a shaped X-ray beam of narrow width scanning across and through the subject position to the receptor to produce a secondary radiation image at the imaging area; and means viewing the imaging area for utilizing the secondary image; wherein the mask window has a minimum width W Min in the direction of mask movement defined by the expression: 5/10,000(E/(12VT-VT 1n T))(A.sup.2 DW/LX*); wherein E is the desired X-ray dosage in milliroentgens, V is the X-radiation source peak voltage, T is the time the X-radiation is transmitted to a subject in each scan, A is the distance from the source through the subject, D is the distance from the X-radiation source to the mask means, W is the width of the receptor, L is the distance from the source to the receptor, and X* is the size of the radiation source.

Claim 26

An X-ray system for radiological examination of a subject comprising: an X-ray beam source of finite size radiating through the position of a radiological subject of an imaging area; an X-ray receptor at the imaging area emitting the secondary radiation on receipt of X-rays; moving X-ray mask means between the source and receptor including an X-ray window transmitting a shaped X-ray beam of narrow width scanning across and through the subject position to the receptor to produce a secondary radiation image at the imaging area; and means viewing the imaging area for utilizing the secondary image; wherein the mask window has a minimum width W Min in the direction of mask movement defined by the expression: 5/10,000(E/(12VT-VT 1n T))(A.sup.2 DW/LX*); wherein E is the desired X-ray dosage in milliroentgens, V is the X-radiation source peak voltage, T is the time the X-radiation is transmitted to a subject in each scan, A is the distance from the source through the subject, D is the distance from the X-radiation source to the mask means, W is the width of the receptor, L is the distance from the source to the receptor, and X* is the size of the radiation source.

Claim 27

An X-ray system for radiological examination of a subject comprising: an X-ray beam source of finite size radiating through the position of a radiological subject to an imaging area; an X-ray receptor at the imaging area emitting secondary radiation on receipt of X-rays; moving X-ray mask means between the source and receptor including an X-ray window transmitting a shaped X-ray beam of narrow width scanning across and through the subject position to the receptor to produce a secondary radiation image at the imaging area; and means viewing the imaging area for utilizing the secondary image; wherein the mask window has a maximum width M Max in the direction of mask movement defined by the expression: F(DW/L); wherein F is the selected fraction of X-radiation scattered to the detector, D is the distance from the source to the mask means, W is the width of the receptor and L is the distance from the source to the receptor.

Claim 28

An X-ray system for radiological examination of a subject comprising: an X-ray beam source of finite size radiating through the position of a radiological subject to an imaging area; an X-ray receptor at the imaging area emitting secondary radiation on receipt of X-rays; moving X-ray mask means between the source and receptor including an X-ray window transmitting a shaped X-ray beam of narrow width scanning across and through the subject position to the receptor to produce a secondary radiation image at the imaging area; and means viewing the imaging area for utilizing the secondary image; wherein the mask window has a maximum width M Max in the direction of mask movement defined by the expression: F(DW/L); wherein F is the selected fraction of X-radiation scattered to the detector, D is the distance from the source to the mask means, W is the width of the receptor and L is the distance from the source to the receptor.

Claim 29

An X-ray system for radiological examination of a subject comprising: an X-ray beam source of finite size radiating through the position of a radiological subject to an imaging area; an X-ray receptor at the imaging area emitting secondary radiation on receipt of X-rays; moving X-ray mask means between the source and receptor including an X-ray window transmitting a shaped X-ray beam of narrow width scanning across and through the subject position to the receptor to produce a secondary radiation image at the imaging area; and means viewing the imaging area for utilizing the secondary image; wherein the mask window has a width in the direction of mask movement in the range between a minimum W Min and maximum W Max respectively defined by the expressions: W.sub.Min =5/10000(E/(12VT-VT 1n T))(A.sup.2 DW/LX*); and W.sub.Max =F(DW/L); wherein E is the desired X-ray dosage in milliroentgens, V is the X-radiation source peak voltage, T is the time the X-radiation is transmitted to a subject in each scan, A is the distance from the source through the subject, D is the distance from the X-radiation source to the mask means, W is the width of the receptor, L is the distance from the source to the receptor, and F is the selected fraction of X-radiation scattered to the detector.

Claim 30

An X-ray system for radiological examination of a subject comprising: an X-ray beam source of finite size radiating through the position of a radiological subject to an imaging area; an X-ray receptor at the imaging area emitting secondary radiation on receipt of X-rays; moving X-ray mask means between the source and receptor including an X-ray window transmitting a shaped X-ray beam of narrow width scanning across and through the subject position to the receptor to produce a secondary radiation image at the imaging area; and means viewing the imaging area for utilizing the secondary image; wherein the mask window has a width in the direction of mask movement in the range between a minimum W Min and maximum W Max respectively defined by the expressions: W.sub.Min =5/10000(E/(12VT-VT 1n T))(A.sup.2 DW/LX*); and W.sub.Max =F(DW/L); wherein E is the desired X-ray dosage in milliroentgens, V is the X-radiation source peak voltage, T is the time the X-radiation is transmitted to a subject in each scan, A is the distance from the source through the subject, D is the distance from the X-radiation source to the mask means, W is the width of the receptor, L is the distance from the source to the receptor, and F is the selected fraction of X-radiation scattered to the detector.