RT Journal Article
SR Electronic
T1 PET monitoring based on Monte-Carlo simulation for proton therapy
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 2064
OP 2064
VO 52
IS supplement 1
A1 Claire Van Ngoc Ty
A1 Ludovic De Marzi
A1 Sebastien Jan
A1 Loic Lestand
A1 Claude Comtat
A1 Regis Ferrand
A1 Régine Trebossen
YR 2011
UL http://jnm.snmjournals.org/content/52/supplement_1/2064.abstract
AB 2064 Objectives Proton beams are used to treat cancers located in sensitive regions. Methods for monitoring proton irradiation have been proposed using PET [1], by measuring positron emitter distribution induced from nuclear reactions in patient (mainly O-15 and C-11). Nevertheless, a simulation of the expected positron-emitter distribution is required. The aim is to compare the PET measurement with the expected simulation obtained from the CT. Methods The physical parameters of the simulation have been selected to reproduce experimental measurements in PMMA phantoms (both single and spread-out Bragg Peak, SOBP). Fig. 1 shows a Rando-Alderson head phantom irradiated by a SOBP-width of 10 cm and 16 cm-water equivalent range. After irradiation, the phantom was acquired on the Biograph 6 TrueV PET/CT (Siemens). The PET/CT image spatial resolution is 5.5 mm.The Monte-Carlo simulation was performed using GATE v6p1[2]. Results The production rates for C-11 and O-15 at 110 MeV in PMMA were 1.71 and 0.78 per beam particle (%), coherent with ref [3].In homogeneous phantoms, the difference between the 50% of the distal fall-off of simulated and measured activity was around 1 mm. The head acquisition was performed with a delay of 11 min between the end of the irradiation and the beginning of the acquisition. For the head phantom, PET and simulated activities located in PMMA medium are superimposed. A small offset is observed, most probably due to CT HU-conversion into density. In air and bony structures, peaks in activity distribution corresponds. Conclusions The head phantom PET acquisition needs to be further investigated and analyzed, however these priliminary results confirmed the added value of PET for quality control in protontherapy