ENERGY CALIBRATION METHOD AND RADIATION DETECTING AND RADIOLOGICAL IMAGING APPARATUS

Abstract

It is an object of the invention to provide a stable and linear energy reference against a variation in an amount of electronic noise or the like. The present invention is an energy calibration method detecting irradiation of radiation with predetermined energy from a calibration radiation source using a plurality of radiation detectors having a peak value distribution whose mode and mean value are different and performing calibration so that mean values become identical within the peak value distributions of the respective radiation detectors obtained through irradiation of radiation with predetermined energy from the calibration radiation source.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram showing the configuration of a SPECT apparatus as a radiological imaging apparatus according to the present invention;

FIG. 2 shows a trapping loss peak value distribution of a semiconductor detection element;

FIG. 3 shows a peak value distribution variation (transfer of mode) according to an amount of superimposing noise of the semiconductor detection element;

FIG. 4 shows nonlinearity of a mode position in an energy spectrum of the semiconductor detection element; and

FIG. 5 shows a relationship between a noise variation and an ROI.

Claims

1. An energy calibration method comprising the steps of: detecting irradiation of radiation with predetermined energy from a calibration radiation source using a plurality of radiation detectors having a peak value distribution whose mode and mean value are different; andperforming calibration so that mean values become identical within the peak value distributions of the respective radiation detectors obtained through irradiation of radiation with predetermined energy from the calibration radiation source.

2. A setting method of region of interest for energy (hereinafter referred to as “ROI”) using the calibration method according to claim 1, whereby a mean value in the peak value distribution through irradiation of the radiation with predetermined energy is used as a reference for the ROI.

3. A radiation detecting device comprising: a plurality of detectors which detect radiation;a plurality of signal amplifiers provided in correspondence with the respective detectors for amplifying outputs of the detectors; anda data processing circuit calibrated so that mean values become identical within the peak value distributions of the respective radiation detectors obtained through irradiation of radiation with predetermined energy from the calibration radiation source which irradiates radiation.

4. A radiological imaging apparatus comprising: the radiation detecting device according to claim 3; anda data collector/analyzer which receives data from the data processing circuit and performs the calibration on the data processing circuit.

5. The radiation detecting device according to claim 3, wherein the data processing circuit sets a region of interest for energy (hereinafter referred to as “ROI”) relative to a mean value in the peak value distribution through irradiation of the radiation with predetermined energy.

6. A radiological imaging apparatus comprising: the radiation detecting device according to claim 5; anda data collector/analyzer which receives data from the data processing circuit and sets the ROI in the data processing circuit.

7. The energy calibration method according to claim 1, wherein when performing the calibration, a calibration coefficient is calculated by dividing an index value independently set by each detector for each energy value by the mean value and calibration is performed using the calibration coefficient.

8. The radiation detecting device according to claim 3, wherein the data processing circuit performs calibration using a calibration coefficient calculated by dividing an index value independently set by each detector for each energy value by the mean value.

9. The radiological imaging apparatus according to claim 4, wherein the data collector/analyzer calculates a calibration coefficient by dividing an index value independently set by each detector for each energy value by the mean value and performs calibration on the data processing circuit using the calibration coefficient.

10. The ROI setting method according to claim 2, wherein a region in which a predetermined amount of count relative to a mean value is included is created with respect to peak value distributions of all the radiation detectors and the region corresponding to the detector having a largest region is set as an ROI.

11. The radiation detecting device according to claim 5, wherein the data processing circuit sets a region corresponding to the detector having a largest region as an ROI out of the region created in which a predetermined amount of count relative to a mean value is included with respect to peak value distributions of all the radiation detectors.

12. The radiological imaging apparatus according to claim 6, wherein when setting an ROI in the data processing circuit, the data collector/analyzer creates a region in which a predetermined amount of count relative to a mean value is included with respect to peak value distributions of all the radiation detectors and sets the region corresponding to the detector having a largest region as the ROI.