Improved temperature stability for a digital positron emission tomography (pet) detector

Abstract

A detector ( 16 ) maintains thermal stability between two different operating modes. The detector ( 16 ) includes at least one controller ( 36, 38 ) which sets the detection sensitivity of the detector ( 16 ) to a level disabling the detection of gamma photons. The controller ( 36, 38 ) further controls a heat generator ( 36, 38, 86 ) to maintain the temperature of the detector ( 16 ) at a predetermined temperature. The predetermined temperature is the steady state temperature of the detector ( 16 ) when the detection sensitivity of the detector ( 16 ) is set to a level enabling the detection of gamma photons. A method ( 100 ) for maintaining thermal stability of a detector ( 16 ) between two different operating modes is also provided.

1 . A gamma detector with thermal stability, said gamma detector comprising:
 at least one controller which:
 sets the detection sensitivity of the detectors to a level disabling the detection of gamma photons; and 
 controls a heat generator to maintain the temperature of the detector at a predetermined temperature, the predetermined temperature being the steady state temperature of the detector when the detection sensitivity of the detector is set to a level enabling the detection of gamma photons. 
   
     
     
         2 . The detector according to  claim 1 , wherein the controller further determines whether the detection sensitivity of the detector is set to a level disabling the detection of gamma photons by:
 monitoring a signal indicating whether the gamma detector is in a quiet mode or a data collection mode, the quiet mode corresponding to the detection sensitivity level disabling the detection of gamma photons, and the data collection mode corresponding to the detection sensitivity level enabling the detection of gamma photons.   
     
     
         3 . The detector according to  claim 1 , further including:
 a temperature sensor measuring the current temperature of the detector, wherein the at least one controller:
 receives measurements of the current temperature of the detector; and 
 controls the heat generator to maintain the received measurements of the current temperature of the detector at the predetermined temperature. 
   
     
     
         4 . The detector according to  claim 1 , wherein the at least one controller controls the detector to generate false events to maintain the current temperature of the detector at the predetermined temperature. 
     
     
         5 . The detector according to  claim 1 , further including:
 a plurality of die controllers;   a tile controller which receives event data describing the generated false events from the die controllers;   scintillators; and   arrays of silicon photomultipliers (SiPMs) corresponding to the plurality of die controllers and optically coupled to the scintillators;   wherein the at least one controller generates the false events at the steady state rate with which the SiPMs detect light pulses generated by the scintillators at the detection sensitivity level enabling the detection of gamma photons.   
     
     
         6 . The detector according to  claim 5 , wherein the tile controller generates the false events. 
     
     
         7 . The detector according to  claim 1 , wherein the heat generator includes:
 a resistive heater.   
     
     
         8 . The detector according to  claim 1 , wherein the heat generator includes:
 a controller generating heat through operation.   
     
     
         9 . A medical imaging system comprising:
 a first, nuclear scanner including a plurality of detectors arranged around a bore of the first scanner, each of the detectors according to  claim 1 , wherein the first scanner:   receives a request to transition the detector, from a data collection mode to a quiet mode; and   in response to the request, sets the detection sensitivity of the detectors to the level disabling the detection of gamma photons.   
     
     
         10 . The medical imaging system, according to  claim 9 , further including:
 a second, x-ray scanner positioned proximate to the first scanner; and   a control system which:
 coordinates imaging using the first and second scanners; and 
 in response to imaging using the second scanner, provides the request to the first scanner. 
   
     
     
         11 . A method for maintaining thermal stability of a gamma detector, said method comprising:
 determining whether the detection sensitivity of the detector is set to a level disabling the detection of gamma photons; and   in response to determining that the detection sensitivity of the detector is set to a level disabling the detection of gamma photons, generating heat to maintain the current temperature of the detector at a predetermined temperature, the predetermined temperature being the steady state temperature of the detector when the detection sensitivity of the detector is set to a level enabling the detection of gamma photons.   
     
     
         12 . The method according to  claim 11 , wherein the determining includes:
 receiving a signal indicating whether the gamma detector is in a quiet mode or a data collection mode, the quiet mode corresponding to the detection sensitivity level disabling the detection of gamma photons, and the data collection mode corresponding to the detection sensitivity level enabling the detection of gamma photons.   
     
     
         13 . The method according to  claim 11 , further including:
 measuring the current temperature of the detector;   generating to maintain the measured temperature at the predetermined temperature.   
     
     
         14 . The method according to  claim 11 , wherein the detector includes a plurality of die controllers and a tile controller, and wherein the generating of heat includes:
 generating false events to maintain the current temperature of the detector at the predetermined temperature; and   by the tile controller:
 receiving event data describing the generated false events from the die controllers; and 
 discarding the received event data. 
   
     
     
         15 . The method according to  claim 14 , wherein the detector includes arrays of silicon photomultipliers (SiPMs) corresponding to the plurality of die controllers and optically coupled to scintillators, and wherein the generating of heat further includes:
 generating the false events at the steady state rate with which the SiPMs detect light pulses generated by the scintillators at the detection sensitivity level enabling the detection of gamma photons.   
     
     
         16 . The method according to  claim 14 , wherein the generating of heat further includes:
 generating the false events by the tile controller.   
     
     
         17 . The method according to  claim 11 , further including:
 generating heat to maintain the current temperature of the detector at the predetermined temperature by enabling a resistive heater.   
     
     
         18 . The method according to  claim 11 , further including:
 generating heat to maintain the current temperature of the detector at the predetermined temperature through operation of a controller of the detector.   
     
     
         19 . The method according to  claim 11 , further including:
 performing a computed tomography (CT) scan of a subject while the detection sensitivity of the detector is set to the level disabling the detection of gamma photons; and   performing a positron emission tomography (PET) or single-photon emission computed tomography (SPECT) scan of the subject while the detection sensitivity of the detector is set to the level enabling the detection of gamma photons.   
     
     
         20 . A nuclear imaging system comprising:
 a detector including a quiet mode and a data collection mode, the detector including at least one controller which:   determines whether the detector is in quiet mode or data collection mode; and   in response to determining that the detector is in quiet mode, generating heat to maintain the current temperature of the detector at the steady state temperature of the detector in the data collection mode.