JPH07318655A - Scintillation camera - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a scintillation camera capable of solving the problem of crosstalk that occurs when multiple types of RIs are simultaneously administered. [Structure] The scintillation camera according to the present invention is the first
And the camera body 1 for detecting γ-rays from the second photoelectric peak TI-201 and the third photoelectric peak I-123 close to the second photoelectric peak, the energy calculation unit 6, and the position calculation unit 7
And a counter for counting, for each incident position, a first incident number in the first window including the first photoelectric peak and a second incident number of energy in the second window including the second photoelectric peak and the third photoelectric peak. 12, 15 and the decay rate multiplication unit 20 for obtaining the third incident number of energy emitted from TI-201 in the second window based on the first incident number, and based on the first incident number and the third incident number TI-201 image creation unit 21 that creates a TI-201 image based on the number of second and third incidents
And an I-123 image creating unit 22 for creating an I-123 image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scintillation camera for imaging the spatial distribution of radioisotope (RI) administered in a subject.

[0002]

2. Description of the Related Art Nuclear medicine diagnostic methods utilize the property that a radioactive isotope or its labeled compound is selectively taken up by a specific tissue or organ, and the emission from the radioactive isotope.
It is a diagnostic method in which the γ-rays generated are measured from the outside of the body and the spatial distribution (scintigram) of the radioisotope is imaged to make a diagnosis. A scintillation camera is a device that realizes this diagnostic method.

The energy distribution of γ-rays emitted from a radioisotope is broadened around a photopeak unique to the radioisotope. The scintillation camera is equipped with a window circuit in order to count only γ-rays from the radioisotope having an energy within a window (energy band) of a predetermined width centered on the photopeak.

In such a nuclear medicine diagnostic method, it has recently been suggested that it is effective to simultaneously administer a plurality of types of radioisotopes to a subject and compare the scintigrams of the radioisotopes. However, this has the following crosstalk problems.

Consider the case where two radioisotopes, T1-201 and I-123, are simultaneously administered. I-123 is characteristic of a photopeak of 160 keV. The window of I-123 is set around 160keV. T1-201 has two unique photopeaks of 71 keV and 167 keV. 71 keV for T1-201
Two windows are set, a window centered at 167 keV and a window centered at 167 keV. The window of I-123 and the window of T1-201 centered around 167 keV overlap. Therefore,
The γ-ray from I-123 and the γ-ray from T1-201 cannot be distinguished. This is called crosstalk.

The conventional solution to this problem is as follows. First, I-123 window and T1-201 167
A wide window including the window for keV is set, and γ rays in this wide window are counted. The gamma ray counts in this wide window are calculated according to the ratio of the counts of I-123 and T1 -201 in the wide window, which are individually measured in advance by using a phantom, and I-123 and T1- By distributing to 201, I-123
And T1-201 each count number is estimated. However, this conventional solution was inaccurate because the ratio was different between the phantom and the actual subject.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a scintillation camera capable of solving the problem of crosstalk that occurs when a plurality of types of radioisotopes are simultaneously administered.

[0008]

The invention according to claim 1 is
A first radioisotope having a first photoelectric peak and a second photoelectric peak, and a second radioisotope having a third photoelectric peak close to the second photoelectric peak, which were co-administered to a subject. A camera body that detects gamma rays from elements and
Energy calculating means for calculating the energy of γ-rays based on the output from the camera body, position calculating means for calculating the incident position of γ-rays based on the output from the camera body, and the energy calculating means It is connected to the output of the position calculating means, and counts, for each incident position, a first incident number of γ rays having energy in a first window including the first photoelectric peak, Counting means for counting, for each incident position, a second number of incidences of γ-rays having energy in a second window including the third photoelectric peak, and the first number of incidences based on the first number of incidences. Means for determining a third number of incidences of γ-rays emitted from the radioisotope and having the energy in the second window; and the first number of incidences. Serial third incident number and the first based on the radioactive and the first image forming means for forming a first image associated isotope, the second incident number and the third
And a second image creating means for creating a second image relating to the second radioisotope based on the number of incidents.

According to a third aspect of the present invention, a first radioisotope having a first photoelectric peak and a second photoelectric peak, which is co-administered to a subject, and a second radioisotope which is close to the second photoelectric peak are provided. A camera body for detecting γ-rays from the second radioisotope having a photoelectric peak of 3 from a plurality of directions around the subject, and energy for calculating γ-ray energy based on the output from the camera body. Calculation means, position calculation means for calculating the incident position of γ-rays based on the output from the camera body, and connection to the output of the energy calculation means and the position calculation means, including the first photoelectric peak The first number of incident γ-rays having energy in the first window is counted for each incident position and direction, and the energy in the second window including the second photoelectric peak and the third photoelectric peak is counted. Counting means for counting a second number of incident of γ-rays having a ghee to incidence positions and different directions,
Based on the first number of incidences, a third number of incidences of γ-rays emitted from the first radioisotope and having energy in the second window is set to an incident position and A γ-ray emitted from the first radioisotope based on the means for obtaining each direction and the first number of incidences and the third number of incidences, and the first window or the Means for obtaining a fourth incidence number of γ-rays having energy in a second window for each incidence position and direction, and the second incidence number based on the second incidence number and the third incidence number. Means for determining a fifth incidence number of γ rays emitted from the radioisotope and having energy in the second window for each incidence position and direction, and for the fourth incidence number. On the basis of said first radioisotope Reconfigure the layer images, a SPECT apparatus characterized by comprising a reconstructing means for reconstructing a second tomographic image regarding the second radioisotope based on the incident speed of the fifth.

According to a fifth aspect of the present invention, a first radioisotope having a first photoelectric peak and a second photoelectric peak, which is co-administered to a subject, and a second radioisotope which is close to the second photoelectric peak are provided. A camera body for detecting γ-rays from the second radioisotope having a photoelectric peak of 3 from a plurality of directions around the subject, and energy for calculating γ-ray energy based on the output from the camera body. Calculation means, position calculation means for calculating the incident position of γ-rays based on the output from the camera body, and connection to the output of the energy calculation means and the position calculation means, including the first photoelectric peak Counting the first number of incidences for γ rays having energy in the first window for each incidence position and direction;
Counting means for counting, for each incident position and direction, a second number of incidents of γ-rays having energy within a second window including the second photoelectric peak and the third photoelectric peak; Reconstructing means for reconstructing a first tomographic image based on the number of incidents and reconstructing a second tomographic image based on the second number of incidents, and the first tomographic image based on the first tomographic image. Means for producing a third tomographic image of the γ-rays emitted from the first radioisotope and having the energy in the second window, the first tomographic image and the third tomographic image. Means for creating a tomographic image of the first radioisotope based on the tomographic image of No. 2 and a tomographic image of the second radioisotope based on the second tomographic image and the third tomographic image. And means for creating an image. A SPECT device that.

[0011]

In the invention according to claim 1, a first radioisotope having a first photoelectric peak and a second photoelectric peak, and a second radioisotope having a third photoelectric peak close to the second photoelectric peak. Of the first radioisotope by solving the problem of crosstalk occurring near the second photoelectric peak and the third photoelectric peak even when the radioisotope of The first image and the second image relating to the second radioisotope can be created separately. The first number of incidents is the number of incidents of energy in the vicinity of the first photoelectric peak among the γ rays emitted from the first radioisotope. The second number of incidences is the number of γ-rays (third incidence number) of γ-rays of energy near the second photoelectric peak among the γ-rays emitted from the first radioisotope,
It is emitted from the second radioisotope and is given as the total number of the energies near the third photopeak and the incident number of γ-rays, where crosstalk occurs. To solve this crosstalk problem, the number of incidences of both radioisotopes must be separated from the second number of incidences. In the invention according to claim 1, the third incident number near the second photoelectric peak relating to the same first radioisotope is obtained based on the first incident number. The incident number of all γ rays emitted from the first radioisotope is given based on the first incident number and the third incident number. Further, the number of all γ-rays emitted from the second radioisotope can be calculated based on the third number of incidences and the second number of incidences. Using the total number of incident γ rays emitted from each radioisotope separately,
Images of each radioisotope can be obtained. This solves the problem of crosstalk.

In the invention according to claim 3, the number of incidents of all γ rays from each radioisotope is obtained for each incident position and direction by the same principle as the invention according to claim 1, and a tomographic image of each radioisotope is obtained. Can be reconfigured.

In the invention according to claim 5, different from the invention according to claim 3, two tomographic images are reconstructed based on each of the number of incidences of each window, and based on the two tomographic images. A tomographic image of each radioisotope can be obtained by the same principle as that of the invention according to.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a scintillation camera according to the present invention will be described below with reference to the drawings. Here, it is assumed that T1-201 and I-123, which are typical radioisotopes, are simultaneously administered. As shown in FIG.
Of T1-201 as a radioisotope of is 71keV and 167keV
Are unique to the two photopeaks of As shown in FIG. 5, I-123 as the second radioisotope is unique to the 160 keV photopeak. The window centered around 167 keV of T1-201 overlaps the window centered around 160 keV of I-123.

FIG. 1 is a block diagram of a preferred embodiment of a scintillation camera according to the present invention. Camera body 1
Has a scintillator 2 using, for example, sodium iodide (NaI) as a fluorescent substance. In front of the scintillator 2, a collimator 3 having a lead plate with a large number of parallel holes is provided. Behind the scintillator 2, a plurality of photomultiplier tubes (PMT) 5 are arranged in a matrix via a light guide 4. When the γ-ray emitted from the radioisotope in the subject in a specific direction enters the scintillator 2, fluorescence is generated at that position. This light passes through the light guide 4 and all P
It is incident on MT5. The PMT 5 produces a pulse whose amplitude is proportional to this incident light.

The pulses from all PMTs 5 are individually
It is taken into the energy calculation unit 6 and the position calculation unit 7.
The energy calculation unit 6 calculates the Z signal proportional to the energy of the incident γ-ray by adding the outputs of all PMTs 5. The position calculator 7 determines the incident position (X, Y) of the γ-ray based on the spatial change in pulse amplitude. That is, in this position calculation, if light is emitted directly below a certain PMT5, the amplitude of the pulse from that PMT5 becomes the maximum among all PMT5, and if light is emitted in the middle of a certain three PMT5, the three PMT5 are calculated. The general principle is that the amplitudes of the pulses are equal.

The Z signal and the position signal (X, Y) are taken into the scattered radiation correction unit 8. The scattered ray correction unit 8 is
By subtracting the scattered ray number PW12scatl for each position (X, Y) from the count number (incident number) PW12all of γ rays having the energy in the window W12 centered at 71 keV, from T1-201 in the body The number PW12prim of only the γ rays having the energy in the window W12, which is directly incident on the camera body 1, is obtained for each position (X, Y).

PW12all = PW12prim + PW12scatl (1) Further, the scattered radiation correction unit 8 has a T1-201 of 167 keV and I-123.
Wide window W22 set based on 160keV of
Count number (incident number) of γ-rays with internal energy PW2
By subtracting the scattered radiation number PW22scatl for each position (X, Y) from 2all, a wide window W22 directly incident on the camera body 1 from T1-201 or I-123 inside the body
Find the number PW22prim of only γ-rays with the energy inside.

PW22all = PW22prim + PW22scatl (2) The separated image creating unit 9 calculates PW1 obtained by the scattered radiation correcting unit 8.
T1-201 based on 2prim (X, Y) and PW22prim (X, Y)
Image (scintigram) PT1-201 (X, Y) and I-123
Image PI-123 (X, Y) is created. The PT1-201 (X, Y) and the image PI-123 (X, Y) are displayed on the image display unit 10 and are also stored in the storage unit 11 such as a magnetic disk device.

FIG. 2 is a block diagram of the scattered radiation correction unit 8. Various methods have been put into practical use as a method for correcting scattered rays, and any of them may be adopted. Here, TE
Description will be made assuming that a correction method called the W method is adopted. In the window parts 12 to 17, the Z signals from the energy calculation part 6 are displayed in windows W11, W12, W13 and W, respectively.
When included in 21, W22 and W23, it outputs a pulse. As shown in FIG. 6, the window W12 is 71-keV of T1-201.
Centered on, for example, the range of high and low 10%. The window W22 is relatively wide from the lowest value to the highest value in the range of high and low 10% centered around 167 keV of T1-201 and the range of high and low 10% centered around 160 keV of I-123, for example. Set to range. Windows W11, W13, W21,
W23 is a window peculiar to the TEW method, and is adjacent to both sides of the windows W12 and W22, for example, 5 keV, respectively.
Is set to the width of. Windows W11, W12, W13, W2
Since 1, W22 and W23 do not overlap, one pulse is output from one of the window units 12 to 17 for one Z signal.

The counter 18 counts the number of pulses from the window unit 12 for each position (X, Y) to obtain a count number (incident number) PW11all (X, Y) of γ rays having energy in the window W11. Ask for. Further, the counter 18 counts the number of pulses from the window unit 13 for each position (X, Y), and thereby the window W
Count number (incident number) of γ rays with energy within 12 P
Find W12all (X, Y). Further, the counter 18 counts the number of pulses from the window unit 14 for each position (X, Y) to obtain the count number (incident number) PW13all (X, Y) of γ rays having energy in the window W13. Ask. Further, the counter 18 counts the number of pulses from the window unit 15 for each position (X, Y),
The count number (incident number) PW21all (X, Y) of γ rays having energy in the window W21 is obtained. Also, counter 1
8 indicates the number of pulses from the window unit 16 at the position (X,
By counting every Y), the count number (incident number) of γ rays having energy in the window W22 PW22all
Find (X, Y). Further, the counter 18 counts the number of pulses from the window unit 17 for each position (X, Y) to obtain the count number (incident number) PW23all (X, Y) of γ rays having energy in the window W23. Ask.

The scattered component removing unit 19 uses the count number PW11all (X, Y) in the window W11 and the count number PW13all (X, Y) in the window W13 to determine the window W12.
Estimate the number of scattered rays in PW12scatl (X, Y). The number of scattered rays PW12scatl (X, Y) can be obtained by approximating the trapezoidal area surrounded by the energy axis, the window W12, and the line connecting the two intersections of the energy spectrum and the window W12 in FIG. Is obtained by This trapezoid has a height of W12, the lower side is PW11all (X, Y) / W11, and the upper side is PW13a.
Since it is defined by ll (X, Y) / W13, its area, that is, P
W12scatl (X, Y) is given by equation (3).

PW12scatl (X, Y) = {(PW11all (X, Y) / W11 + PW13all (X, Y) / W13) × W12} / 2 (3) Similarly, the scattered component removing unit 19 is in the window W21. The number of scattered rays PW22scatl (X, Y) in the window W22 is estimated by the equation (4) based on the count number PW21all (X, Y) in the window W23 and the count number PW23all (X, Y) in the window W23. .

PW22scatl (X, Y) = {(PW21all (X, Y) / W21 + PW23all (X, Y) / W23) × W22} / 2 (4) Further, the scattered component removing unit 19 calculates the equation (1). By subtracting the scattered radiation number PW12scatl (X, Y) from PW12all (X, Y) according to
The number PW12prim (X, Y) of only γ-rays that are directly incident on and have energy in the window W12 is obtained. In addition, the scattered component removing unit 19 uses P according to the equation (2).
By subtracting the scattered radiation number PW22scatl (X, Y) from W22all (X, Y), the energy from the T1-201 or I-123 inside the body is directly incident on the camera body 1 and the energy in the wide window W22 is reduced. Find the number PW22prim (X, Y) of only γ-rays.

FIG. 3 is a block diagram of the separated image creating section 9. FIG. 7 shows an energy spectrum for a certain position after the scattered radiation correction. In FIG. 7, T1-201
The energy spectrum near the photoelectric peak of 167 keV is shown by the one-dot chain line, and the energy spectrum near the photoelectric peak of I-123 of 160 keV is shown by the two-dot chain line.

Here, T1-201 counted at a certain position
The number of counts in the vicinity of 71 keV is represented by P71prim (X, Y), and the number of counts in the vicinity of 167 keV of T1-201 counted at a certain position is represented by P167prim (X, Y). Note that P71
prim (X, Y) has the energy in the window W12 γ
Since the number of lines is equal to PW12prim (X, Y), the equation (5) is obtained.

P71prim (X, Y) = PW12prim (X, Y) (5) The image PT1-201 (X, Y) of only T1-201 is the sum of the count numbers in the vicinity of two photoelectric peaks. It is defined by the equation (6).

PT1-201 (X, Y) = P71prim (X, Y) + P167prim (X, Y) (6) The equation (6) is transformed from the equation (5) into the following equation (7). PT1-201 (X, Y) = PW12prim (X, Y) + P167prim (X, Y) (7) Also, the count number near 160keV of only I-123 is P160p.
It shall be represented as rim (X, Y). The count number PW22prim (X, Y) in the wide window W22 is γ from T1-201 in the body.
Since it is the sum of the number of rays and the number of γ rays from I-123,
It is defined by the equation (8).

PW22prim (X, Y) = P167prim (X, Y) + P160prim (X, Y) (8) The image PI-123 (X, Y) of only I-123 is a γ-ray near the only photoelectric peak. Is defined by equation (9).

PI-123 (X, Y) = P160prim (X, Y) (9) Equation (9) is transformed from Equation (8) into the following Equation (10): PI-123 (X, Y) Y) = PW22prim (X, Y) -P167prim (X, Y) (10) Thus, the image PT1-201 (X, Y) of only T1-201 is expressed by the equation (7) and I-123. Image PI-123 (X, Y) is obtained from the equation (10). That is, since the count number PW12prim (X, Y) in the window W12 and the count number PW22prim (X, Y) in the window W22 are known as the output of the scattered radiation correction unit 8, only T1-201 near 167 keV. It is understood that if the count number P167prim (X, Y) of is obtained, the image PT1-201 (X, Y) of only T1-201 and the image PI-123 (X, Y) of only I-123 can be separated. Will be done.

The count number P167prim (X, Y) near 167 keV of only T1-201 can be obtained by the decay rate multiplication unit 20. As is well known, the decay ratio of T1-201 between 71 keV and 167 keV is 96:11. Therefore, 71 of T1-201
The decay rate k of 167 keV with respect to keV is given by 11/96. This decay rate k is a value unique to T1-201.
Therefore, P167prim (X, Y) is given by the following equation (11).

P167prim (X, Y) = k × P71prim (X, Y) = k × PW12prim (X, Y) (11) The P167prim (X, Y) obtained by the decay rate multiplication unit 20 is T1-
201 The image is sent to the image creating unit 21 and the I-123 image creating unit 22. The T1-201 image creating unit 21 takes the image PT1-201 (X, Y) of T1-201 according to the above formula (7), and the I-123 image creating unit 22 takes the image of I-123 according to the above formula (10). PI-
Create 123 (X, Y) respectively.

As described above, according to the present embodiment, even when a plurality of radioisotopes whose photopeaks are close to each other are simultaneously administered, the count numbers are separated for each radioisotope,
Images of each radioisotope can be obtained.

Although the embodiment in which the present invention is applied to the scintillation camera has been described above, it goes without saying that it can also be applied to a SPECT apparatus. What is SPECT? Single
Abbreviation for Photon Emission Computed Tomography. For example, the camera body 1 intermittently rotates around the subject at every predetermined angle. At each of these angles, the γ-ray emitted from the subject is detected by the camera body 1 for a certain period of time. Each time one γ-ray enters the camera body 1, the incident position (X, Y) on the incident surface (detection surface) of the camera body 1 is calculated, and the number of incidents for each incident position (X, Y). Is counted. The counting of the number of incidents P (X, Y) is repeated for each rotation angle (θ) of the camera body 1. This allows
Each incident number is identified by an incident position and an angle (X, Y, θ). Each incident number is treated equivalently to projection data in the X-ray CT scanner device, and is subjected to reconstruction processing in the same manner as the X-ray CT scanner device, so that the γ-ray distribution (tomographic image) of the cross section is obtained. ) Can be obtained. The present invention is SPEC
When applied to the T-apparatus, a tomographic image of T1-201 and a tomographic image of I-123 are obtained for a certain cross section. In the above-described embodiment, the number of incidents is identified by the position (X, Y), but in the SPECT device, the incident position and the rotation angle (projection direction) are identified by (X, Y, θ). .
If the SPECT device is a rotation system in which the camera body 1 rotates around the subject, θ is obtained by an angle detector such as a rotary encoder that detects this rotation angle. A special SPECT device in which the line counters are arranged in a ring around the subject can be obtained as a channel of the γ-ray counter. The scattered ray correction unit 8 obtains PW12prim (X, Y, θ) and PW22prim (X, Y, θ) by correcting scattered rays for each (X, Y, θ). Then, the separated image creating unit 9 uses PW12prim (X, Y,
θ), PW22prim (X, Y, θ), and count (T1-201) PT1-201 (X, Y, θ) for each (X, Y, θ), and I-123
The count number PI-123 (X, Y, θ) of is calculated. A reconstruction processing unit will be provided at the output of the separated image creating unit 9. The reconstruction processor may be 360 ° or 180 for a cross section.
Based on PT1-201 (X, Y, θ) for one minute, a tomographic image of only T1-201 relating to the cross section is reconstructed. Further, the reconstruction processing unit, based on PI-123 (X, Y, θ) for 360 ° or 180 ° for a certain cross section, I
Reconstruct a tomographic image of -123 only. These tomographic images are displayed on the image display unit 10 and are also stored in the storage unit 11 such as a magnetic disk device.

When the present invention is applied to the SPECT apparatus, it is conceivable to correct the crosstalk after the reconstruction processing as well as correct the crosstalk before the reconstruction processing as described above. In this case, the reconstruction processing unit will be provided at the output of the scattered radiation correction unit 8. The reconstruction processing unit
PW12pri for 360 ° or 180 ° for a given cross section
Based on m (X, Y, θ), the first tomographic image regarding the count number near the photoelectric peak 71 keV of T1-201 is reconstructed. Further, the reconstruction processing unit uses T1-201 based on PW22prim (X, Y, θ) for 360 ° or 180 ° for a certain cross section.
Alternatively, the second tomographic image regarding the number of counts passing through the wide window W22 from I-123 is reconstructed. The separated image creating unit 9 multiplies each pixel of the first tomographic image by the decay rate as shown in Expression (11) to obtain the photoelectric peak of T1-201.
A third tomographic image regarding the count number near keV is obtained.
The image creating unit 21 of the separated image creating unit 9 adds the first tomographic image and the third tomographic image between the frames as in the expression (7), so that only T1-201 relating to the cross section is obtained. Create a tomographic image. Further, the image creating unit 22 of the separated image creating unit 9 subtracts only the I-123 related to the cross section by subtracting the second tomographic image from the third tomographic image between frames as shown in Expression (10). Create a tomographic image of. The present invention is not limited to the above embodiment,
Various modifications are possible.

[0036]

In the invention according to claim 1, the first radioisotope having the first photoelectric peak and the second photoelectric peak, and the third photoelectric peak close to the second photoelectric peak are provided. Even when the second radioisotope is co-administered to the subject, the problem of crosstalk occurring near the second photoelectric peak and the third photoelectric peak is solved, and the first radioisotope is resolved. The first image regarding the element and the second image regarding the second radioisotope can be created separately. The first number of incidents is the number of incidents of energy in the vicinity of the first photoelectric peak among the γ rays emitted from the first radioisotope. The second number of incidences is the number of γ-rays of energy near the second photopeak (third number of incidences) of the γ-rays emitted from the first radioisotope and the second radioisotope. It is emitted from the element and is given as the total number of the energies near the third photoelectric peak and the incident number of γ-rays, where crosstalk occurs. To solve this crosstalk problem, the number of incidences of both radioisotopes must be separated from the second number of incidences. In the invention according to claim 1, the third incident number near the second photoelectric peak relating to the same first radioisotope is obtained based on the first incident number. The incident number of all γ rays emitted from the first radioisotope is given based on the first incident number and the third incident number. Further, the number of all γ-rays emitted from the second radioisotope can be calculated based on the third number of incidences and the second number of incidences.
Images of each radioisotope can be obtained by separately using the total number of incident γ rays emitted from each radioisotope. This solves the problem of crosstalk.

In the invention according to claim 3, the number of incidents of all γ rays from each radioisotope is obtained for each incident position and direction by the same principle as the invention according to claim 1, and a tomographic image of each radioisotope is obtained. Can be reconfigured.

The invention according to claim 5 differs from the invention according to claim 3 in that two tomographic images are reconstructed based on the respective numbers of incidences in each window, and the two tomographic images are based on the two tomographic images. A tomographic image of each radioisotope can be obtained by the same principle as that of the invention according to.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a scintillation camera according to the present invention.

FIG. 2 is a block diagram of a scattered radiation correction unit in FIG.

FIG. 3 is a block diagram of a separated image creating unit in FIG.

FIG. 4 is a diagram showing an energy spectrum regarding a certain position when only T1-201 is administered.

FIG. 5 shows an energy spectrum for a position when only I-123 is administered.

FIG. 6 is a diagram showing an energy spectrum regarding a certain position when T1-201 and I-123 are simultaneously administered.

7 is a diagram showing an energy spectrum after scattered radiation correction corresponding to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Camera main body, 2 ... Scintillator, 3 ... Collimator, 4 ... Light guide, 5 ... Photomultiplier tube, 6 ... Energy calculation part, 7 ... Position calculation part, 8 ... Scattered ray correction part, 9 ... Separation image creation part , 10 ... Image display unit, 11 ... Storage unit.

Claims (6)

[Claims] 1. A first radioisotope having a first photoelectric peak and a second photoelectric peak, which is co-administered to a subject, and a third photoelectric peak close to the second photoelectric peak. A camera body that detects γ-rays from the second radioisotope, energy calculation means that calculates the energy of γ-rays based on the output from the camera body, and based on the output from the camera body, a position calculating means for calculating the incident position of the γ-ray, a first γ-ray connected to the energy calculating means and an output of the position calculating means, and having an energy within a first window including the first photoelectric peak; The number of incidents of γ rays having energy in a second window including the second photoelectric peak and the third photoelectric peak is counted for each incident position A counting means for counting, and a third γ-ray emitted from the first radioisotope based on the first number of incidents, the γ-ray having energy in the second window. A first image creating means for creating a first image of the first radioisotope based on the first and third incident numbers; A scintillation camera, comprising: a second image creating means for creating a second image relating to the second radioisotope based on the number of two incidents and the third number of incidents. 2. The scintillation camera according to claim 1, further comprising means for performing scattered ray correction for each of the first incident number and the second incident number. 3. A first radioisotope having a first photoelectric peak and a second photoelectric peak, which is co-administered to a subject, and a third photoelectric peak close to the second photoelectric peak. A camera body that detects γ-rays from the second radioisotope from a plurality of directions around the subject; energy calculation means that calculates γ-ray energy based on the output from the camera body; Based on the output from the main body, position calculating means for calculating the incident position of γ-rays, the energy calculating means and the output of the position calculating means, connected to the output, the first window in the first window including the first photoelectric peak The first number of incident γ-rays having energy is counted for each incident position and direction, and the γ-rays having energy in the second window including the second photoelectric peak and the third photoelectric peak are counted. Counting means for counting the number of two incidents for each incident position and direction; γ-rays emitted from the first radioactive isotope based on the first number of incidents; and the second window Means for determining a third incidence number of γ-rays having energy in each of the incident positions and directions, and based on the first incidence number and the third incidence number, from the first radioisotope Emitted gamma rays,
And means for obtaining a fourth incidence number of γ-rays having energy in the first window or the second window for each incidence position and direction, the second incidence number and the third incidence number The γ-rays emitted from the second radioisotope based on
And means for determining a fifth incidence number of γ-rays having energy in the second window for each incidence position and direction; and a first radioisotope-related first element based on the fourth incidence number. And a reconstructing means for reconstructing a second tomographic image of the second radioisotope based on the fifth number of incidences. 4. The SPECT apparatus according to claim 3, further comprising means for performing scattered ray correction for each of the first incident number and the second incident number. 5. A first radioisotope having a first photoelectric peak and a second photoelectric peak, which is co-administered to a subject, and a third photoelectric peak close to the second photoelectric peak. A camera body that detects γ-rays from the second radioisotope from a plurality of directions around the subject; energy calculation means that calculates γ-ray energy based on the output from the camera body; Based on the output from the main body, position calculating means for calculating the incident position of γ-rays, the energy calculating means and the output of the position calculating means, connected to the output, the first window in the first window including the first photoelectric peak The first number of incidents of γ-rays having energy is counted for each incident position and direction, and the energy is within a second window including the second photoelectric peak and the third photoelectric peak. Reconstituted counting means for counting a second number of incident regarding line for each incident position and direction, the first tomographic image based on the first number of incident,
Reconstructing means for reconstructing a second tomographic image based on the second number of incidents, and γ-rays emitted from the first radioisotope based on the first tomographic image, And means for creating a third tomographic image of γ-rays having energy in the second window, and the first radioisotope based on the first tomographic image and the third tomographic image. SPECT comprising: means for creating a tomographic image; and means for creating a tomographic image concerning the second radioisotope based on the second tomographic image and the third tomographic image. apparatus. 6. The SPECT apparatus according to claim 5, further comprising means for performing scattered ray correction for each of the first number of incidences and the second number of incidences.