The picosecond club
Download
1 / 31

A group from Chicago, Argonne and Fermilab are interested in the development - PowerPoint PPT Presentation


  • 69 Views
  • Uploaded on

The picosecond club. A group from Chicago, Argonne and Fermilab are interested in the development of large-area systems to measure the time-of-arrival of relativistic particles with (ultimately) 1 pico-second resolution, and for signals typical of Positron-Emission

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' A group from Chicago, Argonne and Fermilab are interested in the development ' - zeus-albert


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

The picosecond club

A group from Chicago, Argonne and Fermilab are interested in the development

of large-area systems to measure the time-of-arrival of relativistic particles with

(ultimately) 1 pico-second resolution, and for signals typical of Positron-Emission

Tomography (PET), a resolution of 30 pico-seconds (sigma on one channel).

These are respectively a factor of 100 and 20 better than the present state-of-the-art.

This would involve development in a number of intellectually challenging areas:

three-dimensional modeling of photo-optical devices, the design and construction

of ultra-fast (200 GHz) electronics, the `end-to-end' (i.e. complete) simulation of

large systems, real-time image processing and reconstruction, and the optimization

of large detector and analysis systems for medical imaging. In each of these areas

there is immense room for creative and innovative thinking, as the underlying

technologies have moved faster than the applications. We collectively are an

interdisciplinary (High Energy Physics, Radiology, and Electrical Engineering)

group working on these problems, and it's interesting and rewarding to cross

the knowledge bases of different intellectual disciplines.

http://psec.uchicago.edu/


- 2”x2” Burle/Photonis 85011

1024-anodes 10-micron pore tubes

(skew timing over a 2”x2” tube ~100 ps)

- Hamamatsu PLP-10 picosec laser


TESTING A SILICON PHOTOMULTIPLIER TIME-OF FLIGHT(TOF) SYSTEM IN FERMILAB’S TEST BEAM FACILITYAnatoly Ronzhin, Mike Albrow, Erik Ramberg – Fermilab,Jerry Vavra – SLAC,Henry Frisch, Tyler Natoli, Camden Eartly, Heejong Kim, Andrew Kobach, Fukun Tang,Scott Wilbur, Jean-Francois Genat – University of Chicago,Ed May, Karen Byrum, John Anderson, Gary Drake – Argonne National Laboratory12 September, 2008


Optimization of lso for time of flight pet

Motivation

Reflector Optimization

LSO Optimization

PMT Optimization

Optimization of LSOfor Time-of-Flight PET

W. W. Moses1, M. Janecek1, M. A. Spurrier2, P. Szupryczynski2,3 ,W.-S. Choong1, C. L. Melcher2, and M. Andreaco3

1Lawrence Berkeley National Laboratory2University of Tennessee, Knoxville3Siemens Medical Solutions

October 21, 2008

Outline:

This work was supported by the NIH (NIBIB grant No. R01-EB006085).


Time of flight in pet

500 ps timing resolution

 7.5 cm localization

D

Time-of-Flight in PET

c = 30 cm/ns

  • Can localize source along line of flight.

  • Time of flight information reduces noise in images.

  • Variance reduction given by 2D/ct.

  • 500 ps timing resolution5x reduction in variance!

  • Time of Flight Provides a Huge Performance Increase!

  • Largest Improvement in Large Patients


Commercial tof pet w lso
Commercial TOF PET w/ LSO

~550 ps Coincidence Timing Achieved


Our goal demonstration tof pet camera
Our Goal:“Demonstration” TOF PET Camera

  • With better timing resolution (t), huge gains predicted(23x variance reduction for 100 ps timing)

  • Measure image improvement vs. timing resolution

  • Use LSO scintillator

    • Don’t change other factors that influence SNR(efficiency, scatter fraction, etc.)

Achieve the Best Timing Possible w/ LSO


What limits timing resolution
What Limits Timing Resolution?

Non-TOF Block Detector Module

Baseline 160 ps

Crystal

Geometry 326 ps

Light Sharing 454 ps

PMT 422 ps

PMT Array 274 ps

  • Many Factors

  • “Optical Geometry” Particularly Important


Proposed side coupled design
Proposed Side-Coupled Design

PMT

384 ps

(543 ps coinc.)

Conventional Geometry

(End-Coupled Crystal)

ScintillatorCrystal

218 ps

Proposed Geometry(Side-Coupled Crystal)

PMT

Shorter Optical Path Length & Fewer Reflections


Detector module design

Hole in ReflectorOn Top Face of Crystals

Two LSO Crystals

(each 6.15 x 6.15 x 25 mm3)

Detector Module Design

Reflector

(on all five faces of each crystal, including the face between the two crystals)

PMT

(HamamatsuR-9800)

Optical Glue

(between lower crystal faces and PMT)

Two Side-Coupled Scintillator Crystals per PMT


Detector ring geometry

Crystal ofInteraction

Detector Ring Geometry

  • Top face of each crystal (with hole in reflector) is coupled via a small (<1 mm) air gap to the edge of one opposing PMT.

  • Light seen by the opposing PMT is used to decode the crystal of interaction.

Exploded View

Crystals Decoded by Opposing PMT


Camera geometry
Camera Geometry

Section of Detector Ring

Lead Shielding

Modules

  • Detector ring is 825 mm diameter, 6.15 mm axial

  • 192 detector modules, 384 LSO scintillator crystals

  • Adjustable gap (6 – 150 mm) between lead shields allows “scatter-free” and “3-D” shielding geometries

“Real” Single-Ring PET Camera for Humans & Phantoms


Surface reflector optimization method
Surface & Reflector Optimization Method

  • 6.15 x 6.15 x 25 mm3

  • Reflector on 5 Sides

  • Optical Grease

  • No Hole on Top

  • Measure Timing of “Raw” Crystal(saw cut finish, Teflon tape reflector)

  • Apply Surface Treatment

  • Apply Reflector

  • Re-Measure Timing

  • Compute Percent Change

  • Repeat for 5 Crystals & Average Results

  • Do for All Surface / Reflector Combinations(>100 crystals, each measured twice)

R-9800

Same PMT forall measurements

Measure PercentageChange in Timing


Surface reflector results

Average

1.00

1.02

1.01

0.99

1.00

1.00

0.98

Average 1.01 0.96 1.03

Surface & Reflector Results

Reflector Saw Cut Chemically Mechanically Etched Polished

Air Gap

Teflon 1.00 ± 0.17 0.94 ± 0.10 1.06 ± 0.09

ESR 1.01 ± 0.08 0.96 ± 0.16 1.08 ± 0.08

Lumirror 1.03 ± 0.13 0.96 ± 0.06 1.04 ± 0.12

Glued

ESR 0.99 ± 0.09 0.98 ± 0.03 1.01 ± 0.18

Lumirror 1.04 ± 0.10 0.97 ± 0.10 0.98 ± 0.22

Melinex 1.01 ± 0.16 0.99 ± 0.06 1.01 ± 0.20

Epoxy 1.00 ± 0.16 0.95 ± 0.09 1.00 ± 0.15

Paint 0.96 ± 0.03


Optimization lso composition
Optimization: LSO Composition

I0

I(t) = I0 exp(-t/)

Light Output = I0 

  • Both Scintillators Have Same Light Output (photons/MeV)

  • Red Decay Time is 2x Longer Than Blue Decay Time

  • Predicted Timing Resolution  1/sqrt(I0)

  • Want High Total Light Output & Short Decay Time

  • Possible By Co-Doping LSO With Calcium


Optimization lso composition1

High Light Out

The Good Stuff!

Short 

0.1%

0.3%

0.4%

0.2%

= Ca-doped

Optimization: LSO Composition

Normal LSO

Ca-Doping Gives High Light Output & Short 


Measured results lso composition

0.1%

0.4%

0.3%

0.2%

= Ca-doped

Measured Results: LSO Composition

Normal LSO

Scaled by1/sqrt(I0)

  • Ca-Doping Gives Good Timing Resolution

  • ~15% Improvement Over Normal LSO


Optimization photomultiplier tube

Blue Sensitivity Index

Peak QE

Optimization: Photomultiplier Tube

  • Predicted Timing Resolution  1/sqrt(QE)

  • Want High Quantum Efficiency Version of PMT


Measured results high qe pmts

= “32% QE” PMTs

Measured Results: High QE PMTs

Normal (“28% QE”) PMTs

Scaled by1/sqrt(Blue Index)

  • Increased QE Improves Timing Resolution by 7%

  • Expect 10% Improvement with 35% SBA PMT


Summary
Summary

Hardware Single Coinc. TOF(ps fwhm) (ps fwhm) Gain

End-Coupled Crystal 384 544 4.3

Side-Coupled Crystal 218 309 7.6

Etched, Reflector Paint 227 321 7.3

Ca-Doped LSO 182 258 9.1

32% QE PMT 155 219 10.6

35% QE “SBA” PMT 148 209 11.1

  • TOF PET with Significantly Better Timing is Possible

  • To Achieve, We Must “Think Outside the Block Detector”


Future tof pet one layer for spect

Scintillator

Array

Thinned

SiPM Array

Future TOF-PET? (one layer for SPECT)

  • Depth of Interaction & 150 ps Timing Resolution

  • 11x Reduction in Variance in Practical Geometry


ad