Summing circuit for positron emission tomography diagnostic apparatus

Patent metadata

Field	Value
Publication number	US-11835668-B2
Application number	US-202117345823-A
Country	US
Kind code	B2
Filing date	Jun 11, 2021
Priority date	Jun 11, 2021
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

A circuit for receiving signals from a photodetector array arranged to detect signals generated by a crystal includes a plurality of summing circuits having weighting circuits, the summing circuits being configured to produce outputs corresponding to a total energy of the signals, a position of the signals in a first dimension of the photodetector array, a position of the signals in a second dimension of the photodetector array, and a radius of a charge distribution of the signals.

First claim

The invention claimed is:

1. A positron emission apparatus, comprising:
a crystal configured to convert gamma rays into photons;
a photodetector array arranged to detect the photons and to output signals based on the detected photons; and
a circuit connected to the photodetector array comprising a plurality of summing circuits having weighting circuits, each of the summing circuits being configured to weight and sum the signals output by the array with weights determined individually for each position in a first dimension and a second dimension of the photodetector array, and the summing circuits thereby producing a first signal weighted with a constant weight as an output corresponding to a total energy of the signals, producing a second signal weighted with a weight proportion to the position in the first dimension as an output corresponding to a position of the signals in the first dimension of the photodetector array, producing a third signal weighted with a weight proportion to the position in the second dimension as an output corresponding to a position of the signals in the second dimension of the photodetector array, and producing a fourth signal weighted with a weight varying nonlinearly to the position in the first or second dimension as an output corresponding to a radius of a charge distribution of the signals, wherein:
a first one of the summing circuits includes weighting circuits each having the same weight to produce the output corresponding to the total energy of the signals;
a second one of the summing circuits includes weighting circuits having weights corresponding to positions in the first dimension in the photodetector array;
a third one of the summing circuits includes weighting circuits having weights corresponding to positions in the second dimension in the photodetector array;
a fourth one of the summing circuits includes weighting circuits having weights corresponding to a variance of the positions in the first and second dimensions of the photodetector array,
the photodetector array comprises a matrix of photodetector elements in two dimensions, x and y, corresponding to the first and second dimensions, respectively;
the weighting circuits in the first one of the summing circuits produces a signal E as the output corresponding to the total energy of the signals, using
E=ΣE xy ;

the weighting circuits in the second one of the summing circuits produces a signal X corresponding to the x dimension using
X=ΣxE xy ;

the weighting circuits in the third one of the summing circuits produces a signal Y corresponding to the y dimension using
Y=ΣyE xy ; and

the weighting circuits in the fourth one of the summing circuits produces a signal R corresponding to the charge distribution using
R =Σ( x 2 +y 2 ) E xy ,

where E xy is a value of a signal from a buffer corresponding to a photodetector element at position (x,y).

2. The positron emission apparatus as recited in claim 1 , comprising a processor configured to determine a summed variance of the charge distribution using

σ
2

=

R
E

-

X
2

+

Y
2

E
2

.

3. The positron emission apparatus as recited in claim 1 , comprising a fifth summing circuit configured to produce a signal S using
S =Σ( x 3 +y 3 ) E xy .

4. The positron emission apparatus as recited in claim 1 , wherein at least the weights of the weighting circuits in the fourth one of the summing circuits are non-linear with respect to a dimension of the photodetector array.

5. The positron emission apparatus as recited in claim 1 , wherein the summing circuit comprises:
a plurality of buffer circuits each configured to receive an output of one element of the photodetector array;
a plurality of sets of weighting circuits, each weighting circuit being connected to respectively receive an output of one of the buffer circuits; and
a plurality of summing amplifiers each of which are connected to receive an output from one set of the weighting circuits.

6. The positron emission apparatus as recited in claim 5 , wherein each one of the summing amplifiers is configured to be integral with the corresponding set of weighting circuits.

7. The positron emission apparatus as recited in claim 1 , wherein the summing circuit comprises:
a plurality of buffer circuits each configured to receive an output of one element of the photodetector array;
a plurality of sets of first weighting circuits, each set of first weighting circuits being connected to respectively receive outputs from respective groups of the buffer circuits;
a plurality of sets of first summing amplifiers, each set of first summing amplifiers being connected to outputs from one set of the plurality of sets of first weighting circuits;
a plurality of sets of second weighting circuits each connected to receive selected ones of outputs of the sets of first summing amplifiers; and
a plurality of second summing amplifiers each connected to receive outputs from one set of the second weighting circuits.

8. A circuit for receiving signals from a photodetector array arranged to detect photons converted from gamma rays by a crystal and to output signals based on the detected photons, the photodetector array comprising a matrix of photodetector elements in two dimensions, x and y, corresponding to first and second dimensions, respectively, comprising:
a plurality of summing circuits having weighting circuits, the summing circuits each being configured to weight and sum the signals from the array with weights determined individually for each position in the first dimension and the second dimension of the photodetector array, the summing circuits thereby producing a first signal weighted with a constant weight as an output corresponding to a total energy of the signals, producing a second signal weighted with a weight proportion to the position in the first dimension as an output corresponding to a position of the signals in the first dimension of the photodetector array, producing a third signal weighted with a weight proportion to the position in the second dimension as an output corresponding to a position of the signals in the second dimension of the photodetector array, and producing a fourth signal weighted with a weight varying nonlinearly to the position in the first or second dimension as an output corresponding to a radius of a charge distribution of the signals, wherein:
a first one of the summing circuits includes weighting circuits each having the same weight to produce the output corresponding to the total energy of the signals;
a second one of the summing circuits includes weighting circuits having weights corresponding to positions in a first dimension in the photodetector array;
a third one of the summing circuits includes weighting circuits having weights corresponding to positions in a second dimension in the photodetector array;
a fourth one of the summing circuits includes weighting circuits having weights corresponding to a variance of the positions in the first and

Assignees

• Canon Medical Systems Corp

Inventors

• Qiang Yi
• Burr Kent C
• Peng Peng
• Li Xiaoli

Classifications

• G01T1/2985 Primary

  In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); (using external radiation sources A61B6/02) · CPC title

• A61B6/037

  Emission tomography · CPC title

• A61B6/5258

  involving detection or reduction of artifacts or noise · CPC title