JPH11276469A - Detector for x-ray ct system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector for an X-ray CT system capable of obtaining a good quality image having no cross talk and scattered ray by arranging even channel directional and slice directional shielding plates so as to turn in the specific focal direction. SOLUTION: Respective shapes of channel directional shielding plates A, B, C, D of a collimator are formed so that its one sides become parallel to the incident direction of X-rays, a slice directional shielding plate (a) is sandwiched between these shielding plates A, B, a slice directional shielding plate (b) is sandwiched between the shielding plates B, C and a slice directional shielding plate (c) is sandwiched between the shielding plates C, D to form the collimator part. A scintillator 6 and a PDA board 7 are arranged so as to coincide with the X-ray opening part of the collimator parts constituted in a plurality of rows.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a multi-slice detector used in an X-ray CT apparatus.

[0002]

2. Description of the Related Art In an X-ray CT apparatus, for example, as shown in FIG. 5, X-rays emitted from an X-ray tube 31 pass through a subject 32, and unnecessary scattered X-rays are removed by a collimator unit 33. Thereafter, the image is detected and imaged by the detector array unit 34 arranged in an arc shape.

When it is desired to simultaneously obtain a plurality of tomographic images of the subject 32 in one scan, the collimator 3
3 and the detector array unit 34 are arranged in parallel in a plurality of columns in a direction orthogonal to the channel direction (a direction perpendicular to the paper surface), and multi-slice data can be obtained by this configuration.

For example, in the case of two rows, a configuration as shown in FIG. 6 is conventionally known.

FIG. 6 shows a view seen in a cross section orthogonal to the channel direction. In the collimator unit 33, shielding plates 43A and 43B for preventing X-ray crosstalk in the channel direction are inserted and fixed between the support plates 41 and 44 via the slice direction shielding plate 42, The shielding plates 43A and 43B are stacked and arranged in the channel direction.

The detector array section 34 has a structure in which two rows of scintillators 46 are arranged on a PDA (photodiode array) substrate 47. To prevent crosstalk between slice directions between the two rows of scintillators,
A light reflection film is formed.

[0007]

However, in the conventional structure, although the shield plates 43A and 43B in the normal channel direction are stacked and arranged in the focal direction of the X-ray tube,
The shielding plate in the slice direction is oriented vertically,
Since the opening of the collimator is oriented in the vertical direction, extra scattered radiation is incident, crosstalk occurs, and a high-quality slice image cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In addition to the channel direction, the shielding plate in the slice direction is arranged so as to face a specific focal direction.
An object of the present invention is to provide a detector for an X-ray CT apparatus capable of obtaining a high-quality image free of crosstalk and scattered radiation.

[0009]

In order to achieve the above object, a detector for an X-ray CT apparatus according to the present invention has a plurality of collimator rows for obtaining a plurality of slice images. In a detector having an X-ray detection element arranged in a line opening, a slice direction shield plate is arranged between collimator rows so as to face a specific focal direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG.

FIG. 1 is a cross-sectional view in the slice direction of an embodiment of a detector for an X-ray CT apparatus according to the present invention. FIGS. 2 to 4 show a method of manufacturing a detector for an X-ray CT apparatus according to the present invention. Show.

1 is an arc-shaped support plate made of aluminum, stainless steel, etc., a to c are formed in an arc shape, and a slice-direction shielding plate for preventing cross-talk in the slice direction, and 2 is a light source of an adjacent scintillator. A light reflecting film for preventing crosstalk, 3 is a jig having a hollow inside, 4 is an arc-shaped support plate made of aluminum or stainless steel, 5 is a groove formed in the jig 3, 6 is an X-ray. Is a PDA board on which a photodiode array for converting light from the scintillator 6 into an electric signal is mounted, and the scintillator 6 and the PDA board 7 constitute an X-ray detecting element 8.

The shielding plates A, B, C and D are made of a material having a large atomic number such as tungsten or tantalum,
It is a shielding plate for shielding radiation in the channel direction.

These shielding plates have a trapezoidal shape, and their heights are both h. However, the upper and lower sides of the shielding plates of A and D are W1 and W2, respectively, and the shielding plates of B and C are respectively. The upper and lower sides of the plate are W3 and W4, respectively, and W1 + W3 = W2 + W4
= W. That is, one side of each of the shielding plates A, B, C, and D is angled so as to be parallel to the X-ray incident direction so as to expose a specific focal direction (for example, the focal point of the X-ray tube) P. I have. Support plate 1
Is larger than the height h of the shielding plates A and B so that the scintillator 6 and the PDA substrate 7 can be attached. The support plate 4 has a thickness of 0.5 mm.
A very thin plate made of aluminum, SUS, etc. is used, and it is formed in a bow shape so as to form a part of an arc centered on the point P so that it can fit in the hollowed part of the jig 3. ,
Further, it is configured to be slightly smaller than the area of the hollowed portion. By doing so, when a detector for an X-ray CT apparatus is manufactured, not only the channel direction shielding plates but also the slice direction shielding plates a to c can be all directed to the focal point of the X-ray tube. The inclination can be configured to be parallel to the X-ray incident direction.

Therefore, when X-rays are emitted from the X-ray tube, the X-rays can be removed only by the channel-direction shielding plate and the slice-direction shielding plate before reaching the scintillator 6. High quality images of slices can be obtained.

Next, a method of manufacturing a collimator will be described.

First, the jig 3 is arranged at a predetermined position on the support plate 1 so that the position is not shifted by a fixing pin or the like. The hollow portion of the jig 3 is formed by wire electric discharge machining or the like so as to have a certain width in an arc shape forming a part of an arc around the point P along the entire outer shape of the collimator portion. Grooves 5 are formed in the inner portion of the rear arc-shaped portion so as to face left and right.

The groove 5 is formed in accordance with the side width of the shielding plates A to D so that the shielding plates A, B, C and D can be inserted from above, respectively. Are formed at a predetermined pitch.

Next, an adhesive is applied to a surface that comes into contact with the support plate 1 when the shielding plate A cut in advance to a predetermined size is inserted into the groove 5, that is, a lower surface of the plate A, and the shielding plate A is removed. It is inserted into the groove 5 and slid down to adhere to the support plate 1. This operation is repeated by the number of the grooves 5.

After inserting the shielding plates A into all the grooves and adhering them to the support plate 1, the slicing direction shielding plates a are inserted from above into the cut-out openings of the jig 3, and each upper surface of the shielding plates A is inserted. And bonding with an adhesive.

Next, an adhesive is applied to the lower surface of the shielding plate B from above, and the shielding plate B is inserted into the groove 5 and slid down to adhere to the slice direction shielding plate a. This operation is repeated by the number of the grooves 5.

After the two collimator rows are formed by the shielding plates A and B in this manner, the slice direction shielding plate b is inserted into the cutout opening of the jig 3 from above, and the upper surface of the shielding plate B is Glue with an adhesive.

Next, an adhesive is applied to the lower surface of the shielding plate C, and the shielding plate C is inserted into the groove 5 and slid down to adhere to the slice direction shielding plate b. After this operation is repeated by the number of the grooves 5, the slice direction shielding plate c is inserted into the jig 3, and the upper surface of the shielding plate C is bonded with an adhesive.

Further, an adhesive is applied to the lower surface of the shielding plate D, and the shielding plate D is inserted into the groove 5 and slid down to adhere to the slice direction shielding plate c.
The fourth collimator row is completed by the shielding plate D.

Finally, the support plate 4 is placed over the cut-out opening of the jig 3, and the upper surface of the shielding plate D already inserted is bonded with an adhesive.

FIG. 3 is a sectional view showing a state in which all the fixings have been completed. Here, the collimator portion is completed by pulling out the jig 3 upward, and FIG. 4 shows an overview of the collimator portion after the jig 3 is pulled out.

Next, as shown in FIG. 4, an X-ray detecting element comprising a scintillator 6 and a PDA substrate 7 which are two-dimensionally arranged so as to coincide with the X-ray openings of the collimator portion composed of four rows. By arranging and fixing with screws etc.,
A multi-slice detector as shown in FIG. 1 is completed.

In the above-described embodiment, the number of collimator rows in the slice direction is four. However, the jig 3 is made to have a larger depth, and is further processed so as to face a slice direction shield plate and a specific focal direction. If the shielding plate is additionally inserted and bonded, and these steps are repeated, a plurality of collimator rows can be formed, and a collimator portion corresponding to a plurality of slices such as 6 slices, 8 slices,. Can be. By arranging two-dimensionally arranged scintillators and X-ray detecting elements consisting of a PDA substrate so as to coincide with these X-ray openings, it is possible to produce a detector for an X-ray CT apparatus for a multilayer slice. Can be.

As described above, since the jig is integrally formed, the accuracy of the arrangement pitch of the shielding plates can be improved. If this jig is used repeatedly, the grooves can be cut in the support plate. Since there is no need to assemble, a large number of collimator sections can be easily manufactured, and the cost can be reduced.

Further, only the slice direction shield plate is interposed between adjacent slices, and the thickness of the slice direction shield plate can be reduced as much as possible. Therefore, the size of the entire detector can be reduced. In addition, the dead area in the slice direction can be made very small.

Further, since the same jig is used, the size and the position of the X-ray opening are not different between slices, so that an artifact due to a displacement can be prevented.

[0032]

As described above, according to the present invention,
Since the shielding plate is configured so that not only the channel direction but also the slice direction is directed to a specific focal direction, adverse effects such as scattered radiation and crosstalk can be eliminated, and a high-quality image can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional configuration of a detector for an X-ray CT apparatus of the present invention.

FIG. 2 is a diagram illustrating a method of manufacturing a collimator portion.

FIG. 3 is a diagram showing a cross section when a collimator portion is completed by a jig.

FIG. 4 is a diagram showing a completed collimator portion and mounting of an X-ray detection element.

FIG. 5 is a diagram showing a schematic configuration of a general X-ray CT apparatus.

FIG. 6 is a diagram showing a configuration of a conventional detector for an X-ray CT apparatus.

Claims (1)

[Claims] 1. A detector having a plurality of collimator rows for obtaining a plurality of slice images, and an X-ray detecting element arranged in an X-ray opening of the collimator section, wherein a specific portion is provided between the respective collimator rows. A detector for an X-ray CT apparatus, wherein a slice direction shielding plate facing a focal direction is arranged.