JPH0543425Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a shield collimator that is used in a positron camera, etc., and is used to prevent background noise from entering from outside the measurement field of view.

[Conventional technology]

2. Description of the Related Art Conventionally, a positron camera is known as a device for measuring the state of a predetermined portion of an object to be measured, which distributes radioisotopes within the object and detects gamma rays emitted from the predetermined portion of the object.

FIG. 5 and FIG. 6 are a perspective view and a schematic configuration diagram of the above-mentioned positron camera, respectively. The positron camera 50 includes a shield collimator 51, each detector group 52a to 52n in which a plurality of detectors for detecting gamma rays are arranged in an annular shape, and each detector group 52.
It includes slice collimators 53a to 53n arranged between a to 52n. The shield collimator 51 is an annular member with an opening 54 in the center, and is installed to prevent background noise from outside the measurement field of view from being detected by the detectors in each of the detector groups 52a to 52n. . As the shield collimator 51, lead (Pb) with a thickness of 5 to 10 cm is usually used to provide a shielding effect.

When a human being is used as the object to be measured and its head 61 is to be measured, the neck 6 is measured as shown in FIG.
0 is positioned in the opening 54 of the shield collimator 51 so that the head 61 is surrounded by each of the detector groups 52a to 52n. With this arrangement, gamma rays emitted from the radioactive isotopes distributed in the parts 61a and 61b of the human head 61 are respectively detected by the detectors of the detector groups 52a and 52b. Conditions can be measured and observed. On the other hand, gamma rays emitted from radioactive isotopes distributed in an arbitrary region 64 of the body section 63 are blocked by the shield collimator 51 and prevented from entering each detector group 52a to 52n. Background noise from the body portion 63 can be prevented from being mixed into the measurement data.

[Problem that the invention attempts to solve]

In the conventional shield collimator 51 described above,
The part to be measured (i.e., the head 61) and the part outside the measurement field (i.e., the torso part 6) are shown in the opening 54.
3), and if the connecting portion (i.e., neck portion 60) has a length of approximately 5 to 10 cm, the entire head 61 is positioned within the field of view of each detector group 52a to 52n. can be put in.

However, when the neck portion 60 is short, a portion of the head 61, for example, the portion 61a, is positioned in the opening 54 of the shield collimator 51, so that the entire head 61 is within the field of view of each detection group 52a to 52n. There was a problem that I couldn't put it in. In particular, when studying the brain, animals with short necks, such as monkeys and baboons, which are similar to humans, are generally used, so the conventional shield collimator 51 is not suitable for measuring the state of the entire brain. In addition, the conventional shield collimator 51 does not have a structure that firmly holds the shoulder portion 62, so during measurement,
There was a problem in that it was difficult to obtain accurate and stable measurement results because the head 61 moved.

This invention makes it possible to place the entire part to be measured within the field of view of the detector group even if the length of the connection between the part to be measured and the part outside the measurement field of view is short, and is accurate and stable. The purpose of this project is to present a shield collimator that can obtain accurate measurement results.

[Means for solving problems]

The present invention includes a main body part and a contact part formed between the main body parts and cooperating with the main body part to form an opening,
The contact part is formed of a material with a higher radiation shielding effect than the main body part, and a groove is formed on the side where the part outside the measurement field enters so that the thickness is thinner than the main body part. The above-mentioned problems of the prior art are improved by the characteristic shield collimator.

[Effect]

In the shield collimator of the present invention, a contact portion is formed between the main body portions, and the main body portion and the contact portion are formed into, for example, an annular shape and an opening is formed in the center. Further, the abutment part is made of a material with a higher radiation shielding effect than the main body part, and a groove is formed in a part outside the measurement field of view, for example, on the side where the shoulder part enters, so that the contact part is thinner than the main body part. When using such a shield collimator in a positron camera to measure the brain condition of an animal with a short neck such as a monkey, the neck is positioned in the opening and the shoulders are placed in the groove. Even when the neck is short, the contact part is thin, so the entire head falls within the field of view of the positron camera, making it possible to measure the entire brain. At this time, radiation from outside the measurement field of view, for example from the body part, is blocked by the thick main body part and the contact part, which is thin but has a high shielding effect, and is prevented from entering the positron camera.
Further, with the above configuration, it is possible to firmly hold the shoulder portion within the groove, so that movement of the head is prevented and stable and accurate measurement results can be obtained at all times during measurement.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a perspective view of an embodiment of a shield collimator according to the present invention, and FIG. 2 is a schematic diagram of a positron camera using the shield collimator shown in FIG. 1.

Referring to FIG. 1, the shield collimator 1
is an annular member having an opening 2, and includes main body parts 3 and 4, and an abutment part 5 formed between the main bodies 3 and 4;
It consists of 6. Main body parts 3 and 4 are made of lead (Pb)
The contact parts 5 and 6 are made of tungsten (W), which has excellent radiation absorption properties and has a higher shielding effect than lead (Pb).
Or tungsten alloy (tungsten (W): 90%, nickel (Ni): 7%, copper (Cu):
3%), etc., and the thickness d' is thinner than the thickness d of the main body parts 3 and 4. That is, the thickness d' of the abutting portions 5 and 6 can be reduced by an amount corresponding to the enhanced shielding effect. As a result, grooves 7 and 8 are formed in the contact portions 5 and 6 in cooperation with the main body portions 3 and 4 in a portion outside the measurement field of view, for example, on the side where the shoulder portion 10 is inserted.

The shield collimator 1 having such a configuration is used as a second shield collimator 1.
As shown in the figure, when trying to measure the brain condition of an animal with a short neck, such as a monkey, using a positron camera, the shoulder 10 of the object to be measured is brought into contact with the shield collimator 1 at 5 and 6. Put it in. As a result, even if the neck portion 11 is as short as the thickness d' of the contact portions 5 and 6, the entire head 12 can be placed within the field of view of each of the detector groups 52a to 52n. At this time, the gamma rays emitted from the radioactive isotope distributed in the arbitrary region 14 of the body part 13 of the object to be measured are absorbed by the thick body parts 3 and 4 and the thin material made of a material with a high shielding effect. contact part 5,
6 and each detector group 52a to 52
n is blocked.

On the other hand, in the case of an object to be measured (for example, a human) whose neck 11 has a length of approximately 5 to 10 cm, the entire neck 11 and head 12 can be placed within the field of view of each of the detector groups 52a to 52n. .

In this manner, whether the neck portion 11 is long or short, the entire head 12 can be seen within the field of view. Furthermore, since the structure allows the shoulder portion 10 to abut against the contact portions 5 and 6, if the shoulder portion 10 is firmly held within the grooves 7 and 8, the head 12 will not move during measurement. This allows you to obtain more accurate measurement results in a stable state at all times.

In addition, the shield collimator has a structure that maintains the shape of the shield collimator 51 shown in FIG. 5, but is made entirely of a heavy metal such as tungsten (W) or tungsten alloy, and its thickness is reduced overall. was also proposed, but
If heavy metal is used throughout, it will be very expensive, and if the thickness is uniform throughout, there is a disadvantage in that it is structurally impossible to securely hold the shoulder portion 10 as described above. In addition, the outer diameter and opening diameter of the shield collimator are increased,
It has also been proposed that up to the shoulder 10 can be inserted into the opening, but in this case, each detector group 52
There are disadvantages in that the number of detectors constituting a to 52n increases and the cost becomes high, and the structure cannot firmly hold the shoulder portion 10.

When used for animal experiments, it is necessary to make the positron camera small and inexpensive, and for this purpose heavy metal is only used in some parts, and the outside diameter of the shield collimator and the diameter of the aperture are A shield collimator 1 having a structure as shown in FIG. 1, which does not require a large size, is suitable.

In the shield collimator 1 shown in FIGS. 1 and 2, contact portions 5 and 6 are formed at positions opposite to the center on a straight line passing through the center. 6 is only required to be formed so that when the neck 11 of the object to be measured is passed through the opening 2, the shoulder 10 can be comfortably inserted therein, and it does not need to be formed on a straight line passing through the center.

In addition, the shield collimator 1 of the present invention has a head 1
It is also applied to positron cameras that measure objects other than 2, and depending on the shape of the connection between the part to be measured and the part outside the measurement field, only one of the contact parts 5 and 6 is required. In some cases, more contact parts may be required. Furthermore, although the shield collimator 1 has an annular overall shape in the above embodiment, it does not necessarily have to be annular, and may have various shapes depending on the type and shape of the object to be measured. be able to.

In addition, the shield collimator 1 in Figures 1 and 2
Attach a sponge or the like to the part outside the measurement field of view, for example, the surface of the contact parts 5 and 6 on the side where the shoulder part 10 enters,
The shoulder 10 may be protected or held more securely.

Furthermore, the shield collimator of the present invention has a first
The shield collimator 1 is not limited to the structure shown in FIGS. 3 and 2, but may be shield collimators 20 and 30 having the structure shown in FIGS. 3 and 4. In the shield collimator 20 shown in FIG.
Grooves 23 and 24 are formed in the shield collimator 30 shown in FIG. Even with such a configuration, effects similar to those of the shield collimator 1 can be obtained.

[Effect of idea]

As explained above, according to the present invention, the contact part is formed of a material with a higher radiation shielding effect than the material of the main body part, and its thickness is made thinner, so that a groove is formed on the side where the part outside the measurement field enters. Since it forms a It can be placed within the field of view of a group of detectors such as a camera, and furthermore, it is possible to prevent movement of the object to be measured during measurement and obtain accurate and stable measurement results.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the shield collimator according to the present invention, Fig. 2 is a schematic configuration diagram of a positron camera using the shield collimator shown in Fig. 1, and Figs. 3 and 4 are each according to the present invention. 5 and 6 are respectively a perspective view and a schematic configuration diagram of a positron camera using a conventional shield collimator. 1, 20, 30...shield collimator, 2...
...Opening, 3, 4...Main body, 5, 6, 21, 2
2, 31, 32... Contact portion, 7, 8, 23, 2
4, 33, 34...groove, d...thickness of main body,
d′...Thickness of the contact part.

Claims (1)

[Scope of utility model registration request] comprising a main body part and a contact part formed between the main body parts and cooperating with the main body part to form an opening, the contact part being formed of a material with a higher radiation shielding effect than the main body part, A shield collimator characterized in that a groove is formed on the side where a portion outside the measurement field enters so that the thickness is thinner than the main body portion.