Method and apparatus for estimating photomultiplier sensitivity change

1. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

obtaining exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet;

calculating an estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit; and

obtaining the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier.

2. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

calculating an estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit; and

obtaining the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier.

3. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

obtaining exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet;

calculating an estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit;

obtaining the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier; and

alarming when the cumulative value has amounted to or exceeded a predetermined threshold value.

4. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

calculating an estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit;

obtaining the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier; and

alarming when the cumulative value has amounted to or exceeded a predetermined threshold value.

5. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

obtaining exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet;

calculating an estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit;

obtaining the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier; and

correcting the sensitivity of the photomultiplier based on the cumulative value.

6. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

calculating an estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit;

obtaining the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier; and

correcting the sensitivity of the photomultiplier based on the cumulative value.

7. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet though the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

obtaining exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet;

calculating a first estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained;

cumulatively adding the first estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the first cumulative value of the estimated amounts;

calculating a second estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the second cumulative value of the estimated amounts; and

obtaining the difference between the first and second cumulative values as the information that indicates the sensitivity change in the photomultiplier.

8. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

obtaining exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet;

calculating a first estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained;

cumulatively adding the first estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the first cumulative value of the estimated amounts;

calculating a second estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the second cumulative value of the estimated amounts;

obtaining the difference between the first and second cumulative values as the information that indicates the sensitivity change in the photomultiplier; and

alarming when the difference between the first and second cumulative values has amounted to or exceeded a predetermined threshold value.

9. A method for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, wherein information that indicates the sensitivity change in the photomultiplier is obtained by the steps of:

obtaining exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet;

calculating a first estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained;

cumulatively adding the first estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the first cumulative value of the estimated amounts;

calculating a second estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier;

cumulatively adding the estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the second cumulative value of the estimated amounts;

obtaining the difference between the first and second cumulative values as the information that indicates the sensitivity change in the photomultiplier; and

correcting the sensitivity of the photomultiplier based on the difference between the first and second cumulative values.

10. An apparatus for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, the apparatus comprising:

an exposure condition obtaining means constructed to obtain exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet; and

a sensitivity change information obtaining means constructed to calculate an estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained by the exposure condition obtaining means, to cumulatively add the estimated amount of radiation for each radiation image read out by the radiation image reading unit, and to obtain the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier.

11. The apparatus according to claim 10 , further comprising an alarming means for alarming when the cumulative value has amounted to or exceeded a predetermined threshold value.

12. The apparatus according to claim 10 , further comprising a sensitivity correcting means constructed to correct the sensitivity of the photomultiplier based on the cumulative value.

13. The apparatus according to claim 10 , wherein the exposure conditions are imaging menu items.

14. An apparatus for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier,

the apparatus comprising a sensitivity change information obtaining means constructed to calculate an estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier, to cumulatively add the estimated amount of radiation for each radiation image read out by the radiation image reading unit, and to obtain the cumulative value of the estimated amounts as the information that indicates the sensitivity change in the photomultiplier.

15. The apparatus according to claim 14 , further comprising an alarming means for alarming when the cumulative value has amounted to or exceeded a predetermined threshold value.

16. The apparatus according to claim 14 , further comprising a sensitivity correcting means constructed to correct the sensitivity of the photomultiplier based on the cumulative value.

17. An apparatus for estimating sensitivity change in a photomultiplier used in a radiation image reading unit in which a radiation image recorded on a storage phosphor sheet through the exposure of the radiation carrying the image is read out by irradiating excitation light on the storage phosphor sheet to produce stimulated luminescence light, and obtaining image signals that correspond to the radiation image through photoelectrical detection of the stimulated luminescence light emitted from the storage phosphor sheet using the photomultiplier, the apparatus comprising:

an exposure condition obtaining means constructed to obtain exposure conditions which were set when the radiation image was recorded on the storage phosphor sheet;

a sensitivity change information obtaining means constructed to calculate a first estimated amount of radiation irradiated on the storage phosphor sheet based on the exposure conditions obtained by the exposure condition obtaining means, to cumulatively add the first estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the first cumulative value of the estimated amounts, to calculate a second estimated amount of radiation irradiated on the storage phosphor sheet based on the image signals detected by the photomultiplier, to cumulatively add the second estimated amount of radiation for each radiation image read out by the radiation image reading unit to obtain the second cumulative value of the estimated amounts, and to obtain the difference between the first and second cumulative values as the information that indicates the sensitivity change in the photomultiplier.

18. The apparatus according to claim 17 , further comprising an alarming means for alarming when the difference between the first and second cumulative values has amounted to or exceeded a predetermined threshold value.

19. The apparatus according to claim 17 , further comprising a sensitivity correcting means constructed to correct the sensitivity of the photomultiplier based on the difference between the first and second cumulative values.