GAMOS tutorial PET Exercises

1. GAMOS tutorialPETExercises Pedro Arce Dubois CIEMAT http://fismed.ciemat.es/GAMOS Introducción a GEANT4

2. Ex. 0: Installation Ex. 1: Basic example Ex. 2: Define PET geometry Obtain information about what is happening in a PET Ex. 3: Detector effects Ex. 4: Store results in file The exercises are sequential Use the commands of the previous exercise (only change what indicated PET simulation Exercises Introducción a GEANT4

3. Download installation scripts from http://wwwae.ciemat.es/~arce/GAMOS/download/GAMOS.1.9.0/scripts.tgz Uncompress it tar xvzf scripts.tgz Install it (under csh) cd scripts csh source installGamos.csh $HOME/gamos Exercise 0: installation Introducción a GEANT4

4. Geometry: Tube radius 100cm length 200cm of Water, axis along X inside Box 30cm X 30cm X 40cm of Aluminun Standard electromagnetic physics Primary particle: gamma 10 MeV at (0,0,0) in random direction Exercise 1: simple geometry Introducción a GEANT4

5. Visualize geometry and tracks Use OGLIX Use VRML2FILE Exercise 1b: visualisation Introducción a GEANT4

6. Use low energy electromagnetic Use Penelope (Make statistics on processes/particles) Exercise 1c: use different e.m. physics Introducción a GEANT4

7. 2 cm X 2 cm X 10 cm LSO crystals LSO: Lu 76.4016%, Si 6.1328%, O 17.4656% Block of 8X8 crystals 20 blocks in a ring of radius 60 cm Pace 5 rings blocks along Z separated 10 cm Water sphere of radius 2 cm at the centre of the rings Source of 511 keV photons at (0,0,0) towards the X axis PET Exercise 2a: PET geometry Introducción a GEANT4

8. Place F18 homogeneously distributed in the water sphere Activity: 1 milliCurie PET Exercise 2b: use F18 as source Introducción a GEANT4

9. Make info about the phsycis processes that occur Make the crystal sensitive detector and produce signals (hits) Obtain histograms about hits quantities (energy, position, …) Get detailed info about Compton and Photoelectric effect in crystals PET Exercise 2c: obtain information Introducción a GEANT4

10. Use GEANT4 low energy electromagnetic package, instead of standard electromagnetic package Observe differences in energy distribution Observe differences in processes occurring Observe differences in CPU time PET Exercise 2c: low energy physics Introducción a GEANT4

11. A PET event is the one that has two signals of energy about 511 keV in the crystals Classification is done looking at the reconstructed hits Define a RecHitBuilder that sums all the energy of the crystals in a block of 8X8, and assign the position as the centre of the crystal with biggest energy Count % of PET events How many are false coincidences In how many the line joining the two crystals passes too far from the F18 positron PET Exercise 2d: Classify events as PET events Introducción a GEANT4

12. Set crystal energy resolution as 20% Observe differences in hits energy Observe differences in number of PET events PET Exercise 3a: Energy resolution Introducción a GEANT4

13. Set the dead time of crystals as 1 microseconds When a crystal takes signal, full block of 8X8 crystal becomes dead for a time Observe differences in number of PET events PET Exercise 3b: Dead time Introducción a GEANT4

14. Set the measuring time of crystals as 1 microseconds Two signals in a crystal cannot be distinguised if they differe less than a given amount Observe differences in number of PET events Observe differences in recontructed hits PET Exercise 3b: Measuring time Introducción a GEANT4