Energy correction for one-to-one coupled radiation detectors having non-linear sensors
View Patent ↗Systems and methods for correcting output signals from non-linear photosensors, specifically silicon photomultipliers (SiPMs). SiPMs are used in a PET detector to readout light emissions from LSO scintillator crystals. The non-linear output of the SiPM can distort and compress the energy spectrum which is crucial in PET imaging. The non-linearity effect for inter-crystal scattered events can place an energy event outside of the PET detector energy window, resulting in a rejected event. Systems and methods to correct the SiPM non-linearity for inter-crystal scattered events, so as to be able to obtain the proper energy event and produce an accurate medical image, are disclosed.
1. A system for correcting energy readings from a solid state photosensor having a plurality of microcells coupled to a single output electrode, comprising:
at least one scintillator configured to receive at least one incident radiation particle and to convert energy from said particle into photoelectrons;
at least one solid state photosensor in communication with the at least one scintillator and configured to convert energy of said photoelectrons into an electrical signal;
an analog-to-digital converter (ADC) coupled to the output electrode at least one solid state photosensor and configured to convert an output from said output electrode into digital data;
a data analyzer in communication with the ADC and configured to receive said digital data; and
a linearization system configured to receive output from the data analyzer and configured to determine at least one corrected datum corresponding to a least one raw datum output from the data analyzer in accordance with predetermined characteristics of said solid state photosensor,
wherein the linearization system determines the value of corrected data as a function of the raw data by solving the equation:
corrected_data
=
-
A
*
ln
(
-
Raw_data
A
+
1
)
wherein A is an experimentally determined constant corresponding to a SiPM nonlinearity relationship and Raw Data is the value of the at least one data output from the data analyzer.
2. The system of claim 1 , wherein the data analyzer is a field programmable gate array (FPGA) configured to enable the system to operate in real-time.
3. The system of claim 2 , wherein the linearization system is configured to receive raw data from the data analyzer and output corrected data to the data analyzer.
4. The system of claim 1 , wherein the linearization system comprises:
executable program code for determining the values of corrected data; and
a controller configured to execute the executable program code that determines the values of corrected data.
5. The system of claim 1 , further comprising a summation unit in communication with the data analyzer and configured to sum corrected data output from the data analyzer.
6. The system of claim 1 , wherein the linearization system determines the value of corrected data as a function of the raw data by consulting a look-up table.
7. The system of claim 1 , further comprising a display in communication with the linearization system and configured to display data output from the linearization system.
8. The system of claim 1 , wherein the at least one solid state photosensor is a silicon photomultiplier (SiPM).
9. The system of claim 8 , wherein for each at least one scintillator there is exactly one SiPM.
10. The system of claim 1 , wherein the scintillator is a Lutetium Oxyorthosilicate (LSO) crystal.
11. A method of correcting output signals of a solid state photosensor having a plurality of microcells coupled to a single output electrode for non-linearities, comprising:
receiving at least one incident nuclear radiation particle on at least one a scintillator;
receiving at least one photoelectron associated with the at least one incident particle in at least one solid state photosensor from said at least one scintillator;
transmitting an electrical signal corresponding to an energy of said at least one photoelectron from said at least one solid state photosensor to an analog-to-digital converter (ADC) for conversion to digital data;
transmitting digital data received from the ADC to a data analyzer; and
transmitting the data received at the data analyzer to a linearization system configured to correct a non-linearity associated with said solid state photosensor corresponding to a least one raw datum output from the data analyzer,
wherein the linearization system determines the value of corrected data as a function of the raw data by solving the equation:
corrected_data
=
-
A
*
ln
(
-
Raw_data
A
+
1
)
wherein A is an experimentally determined constant corresponding to a SiPM nonlinearity relationship and Raw Data is the value of the at least one data output from the data analyzer.
12. The method of claim 11 , wherein the linearization system determines the value of corrected data as a function of the raw data by consulting a look-up table.
13. The method of claim 11 , wherein the data analyzer is a field programmable gate array (FPGA) configured to enable the system to operate in real-time.
14. The system of claim 11 , wherein the at least one photomultiplier is a silicon photomultiplier.
15. A system comprising a computer recordable storage medium tangibly embodying computer executable program code, which when executed by a controller, causes the system to receive data from a data analyzer and calculate corrected data corresponding to raw data output from the data analyzer as a function of the raw data by solving the equation:
corrected_data
=
-
A
*
ln
(
-
Raw_data
A
+
1
)
wherein A is an experimentally determined constant corresponding to a SiPM nonlinearity relationship and Raw Data is the value of the at least one data output from the data analyzer.