Four-dimensional computed tomography quality assurance device
View Patent ↗Quality assurance device for calibrating and testing the accuracy of movement-correlated computed tomography (“4D CT”) target-locating systems has a test unit sub-assembly adapted to be combined with a dynamic phantom system. The test unit sub-assembly has an axially and rotationally moveable test rod slideably disposed inside of a substantially hollow fixed housing. A matrix of markers, or “fiducials”, are located in the wall of the housing. A single fiducial is located near the distal end of the moveable test rod. The distal end portion of the moveable test rod is adapted to be connected to a motion actuator, which is programmed to oscillate the test rod in a predetermined pattern. When the test unit sub-assembly is inserted into a tissue equivalent phantom member, the combined sub-assembly and phantom member can then be subjected to four-dimensional imaging to generate a visual image. A visual comparison actual relative positions of the fiducials to the know positions of the fiducials in time indicates the accuracy of the 4D CT system.
1. A medical imaging quality assurance device, comprising:
a housing, said housing having a housing wall encircling a hollow interior chamber,
said interior chamber having a chamber longitudinal axis, and said chamber having a chamber cross-sectional geometry and area measurable perpendicular to said chamber longitudinal axis, and said chamber cross-sectional geometry and area being constant between two longitudinally spaced apart points;
a rod member having a proximal end portion and a distal end portion,
said distal end portion of said rod member being slideably disposed inside of said interior chamber between said two longitudinally spaced apart points;
a first marker, said first marker being disposed in said distal end portion of said rod member, wherein said first marker comprises a discontinuity in said distal end portion of said rod member;
a plurality of second markers disposed in said wall of said housing,
wherein each of said plurality of second markers comprises a discontinuity in said housing;
and means for attaching said proximal end portion of said rod member to a motion actuator.
2. The device according to claim 1 ,
wherein said plurality of second markers comprises at least two markers spaced apart and in a line parallel to said chamber axis.
3. The device according to claim 2 ,
wherein said first marker has a different mass density than a mass density of a material of construction of said distal end portion of said rod member;
and wherein each of said plurality of second markers has a different mass density than a mass density of a material of construction of said material of construction of said housing.
4. The device according to claim 3 ,
wherein said first marker further comprises an elongate member disposed in said distal end portion of said rod member;
and wherein each of said plurality of second markers further comprises an elongate member disposed in said housing wall.
5. The device according to claim 4 ,
wherein said rod member further comprises a shaft portion extending between said proximal end portion and said distal end portion;
and wherein said proximal end portion of said rod member is slideably disposed inside of said interior chamber.
6. The device according to claim 5 , wherein
said housing has a cylindrical outer surface.
7. The device according to claim 6 , further comprising:
motion actuator means,
wherein said motion actuator means comprise a motor and a motor output shaft,
and wherein said motor output shaft is connected to said proximal end portion of said rod member.
8. The device according to claim 7 , further comprising:
a tissue equivalent phantom member,
said phantom member having a first phantom opening extending through said phantom member;
and wherein said housing member is disposed within said first phantom opening.
9. The device according to claim 8 , wherein said chamber cross-sectional geometry perpendicular to said chamber axis is circular.
10. The device according to claim 2 ,
wherein said first marker has a different mass density, radiopacity or magnetic resonance imaging signature than a respective mass density, radiopacity or magnetic resonance imaging signature of said material of construction of said distal end portion of said rod member;
and wherein each of said plurality of second markers has mass density, radiopacity or magnetic resonance imaging signature than a respective mass density, radiopacity or magnetic resonance imaging signature of said material of construction of said material of construction of said housing.