Granted Patent B2

US 12,654,035 · App. 18/731,698 · Granted Jun 16, 2026

Inventors: Peter Demetri Olcott (Los Gatos, CA); Matthew Francis Bieniosek (Danville, CA)

Assignee: RefleXion Medical, Inc.

A61N5/1075A61N5/1049A61N5/1064A61N5/1081A61N2005/1052A61N2005/1095

Abstract

Claims (33)

1 . A method for monitoring time of flight (TOF) PET detector function during a radiotherapy treatment session, the method comprising:

acquiring positron emission path data using one or more TOF PET detectors;

determining positron emission path data that originated from a PET calibration source by applying a spatial filter to the acquired positron emission path data;

generating calibration data from the positron emission path data that originated from the PET calibration source; and

determining whether one or more TOF PET detectors are faulty based on the generated calibration data.

2 . The method of claim 1 , further comprising generating a fault signal if one or more TOF PET detectors are faulty.

3 . The method of claim 1 , wherein the spatial filter comprises a volume that includes the PET calibration source.

4 . The method of claim 3 , wherein the spatial filter further comprises a margin around the PET calibration source volume.

5 . The method of claim 4 , wherein the margin is from about 1 cm to about 10 cm.

6 . The method of claim 4 , wherein the margin is predetermined.

7 . The method of claim 4 , wherein the margin is adjustable.

8 . The method of claim 1 , wherein the spatial filter comprises a volume located at an expected location of the PET calibration source.

9 . The method of claim 8 , wherein the volume is adjustable.

10 . The method of claim 9 , wherein a geometry of the volume is adjustable according to a treatment plan.

11 . The method of claim 1 , wherein the generated calibration data comprises a set of positron annihilation event locations, and wherein determining whether one or more TOF PET detectors are faulty comprises comparing the set of positron annihilation event locations with a reference location, and determining that one or more TOF PET detectors are faulty if the positron annihilation event locations do not correspond with the reference location.

12 . The method of claim 1 , wherein calibration data comprises a set of positron annihilation event locations and wherein determining whether one or more TOF PET detectors are faulty comprises comparing the set of positron annihilation event locations with a location range of the PET calibration source, and determining that one or more TOF PET detectors are faulty if the positron annihilation event locations do not correspond with the location range of the PET calibration source.

13 . The method of claim 1 , wherein determining positron emission path data that originated from the PET calibration source comprises calculating locations of positron annihilation events using reception time differences between pairs of photons detected by the TOF PET detectors, and wherein calibration data comprises an amount of time that the calculated locations of the positron annihilation events are outside a location range of the PET calibration source, and determining that one or more TOF PET detectors are faulty if the amount of time exceeds a variability threshold parameter.

14 . The method of claim 13 , wherein the variability threshold is a percentage of time that the calculated locations of the positron annihilation events are outside a location range of the PET calibration source.

15 . The method of claim 1 , wherein the calibration data comprises a mean reception time window, and wherein determining that the one or more TOF PET detectors are faulty if the mean reception time offset exceeds a time offset threshold parameter.

16 . The method of claim 1 , wherein determining positron emission path data that originated from the PET calibration source comprises calculating locations of positron annihilation events using reception time differences between pairs of photons detected by the TOF PET detectors, and wherein determining whether one or more TOF PET detectors are faulty comprises determining whether the calculated locations of the positron annihilation events are within a location deviation threshold of a location of the PET calibration source.

17 . The method of claim 1 , wherein determining positron emission path data that originated from the PET calibration source further comprises comparing reception time differences between pairs of photons detected by the TOF PET detectors with a time threshold range that corresponds to the PET calibration source.

18 . The method of claim 1 , wherein determining positron emission path data that originated from the PET calibration source further comprises comparing reception time differences between pairs of photons detected by the TOF PET detectors with a reference time offset.

19 . The method of claim 1 , wherein a positron emission path is defined by a pair of photons emitted by a positron annihilation event, and positron emission path data comprises differences between reception times of pairs of photons by the TOF PET detectors for a plurality of positron annihilation events, and wherein determining positron emission path data that originated from the PET calibration source comprises calculating locations of the positron annihilation events using the differences in reception times.

20 . A method for calibrating time of flight (TOF) PET detectors during a radiotherapy treatment session, the method comprising:

acquiring positron emission path data using one or more TOF PET detectors, wherein the positron emission path data originates from a PET calibration source on a radiotherapy system;

generating calibration data from the acquired positron emission path data; and

calibrating one or more TOF PET detectors using the generated calibration data.

21 . The method of claim 20 , wherein calibration data comprises one or more of spatial resolution data, temporal resolution data, energy sensitivity data, energy precision data, and a number of positron emission paths that intersect with a location of the PET calibration source.

22 . The method of claim 20 , wherein positron emission path data comprises coincident photon data, and wherein generating calibration data comprises determining a number of coincident photon events involving photons with an energy level that deviate from 511 keV.

23 . The method of claim 22 , wherein generating calibration data further comprises determining a number of coincident photon events involving photons with an energy level at around 511 keV.

24 . The method of claim 20 , wherein calibrating one or more TOF PET detectors comprises adjusting a time calibration of the TOF PET detectors.

25 . The method of claim 24 , wherein adjusting the time calibration of the TOF PET detectors comprises compensating for a time offset error in the calibration data.

26 . The method of claim 20 , wherein calibrating one or more TOF PET detectors comprises adjusting one or more of energy calibration, energy resolution, detector count-rate uniformity, and dead-time corrections of the TOF PET detectors.

Assignments (1)

Continuity (6)

References Cited (400)