PROSPET First tests and results Gabriel Caizares Ledo

PROSPET: First tests and results Gabriel Cañizares Ledo Consejo Superior de Investigaciones Científicas Instituto de Instrumentación para Imagen Molecular (i 3 M)

Disclosure Nothing to disclosure 2

Index • Motivation • Position Emission Tomography (PET) • Two Panels Prototype • PROSPET System Configuration • Spatial Resolution. Sensitivity • Phantoms Studies. Patient Reconstruction • Summary and Conclusions 3

Motivation Prostate: Glandular organ. Seminal expulsion Ca. P: Most frequent tumour in men. No symptoms in early stadiums Random tissue extraction for study: Blind Biopsy. High probability for false negative test. What are we proposing? A dedicated PET system for Ca. P

Positron Emission Tomography (PET) Radiotracer: Molecule + Radioactive element. 18 F-FDG, 68 Ga. PSMA, etc… 511 ke. V gamma rays detectors. Scintillator cristal + Photodetectors Two coincidence gamma rays: Line of Response (LOR) Time of Flight (TOF). We need a very good time resolution (200 ps) We propose a specific PET system for Ca. P ▶Our goals: a) > 3 mm Spatial Resolution b) > 15% Energy Resolution c) DOI capabilities

Two panel prototype LYSO scintillator block 50 x 15 mm 3 50 m m 12 x 12 Si. PM photosensor, pitch 4. 2 mm Median Spatial Resolution: 1. 9 ± 0. 2 mm 50 mm Median Energy Resolution: 13 ± 1 % 15 mm Do. I Resolution: 3. 7 mm Patient Time resolution > 2 ns (required 0. 2 ns) We have simulated this device and we have observed artifacts 3 patients were measured. Result not satisfactory Simulation

PROSPET System Configuration 24 Module Detectors in a ring configuration 410 mm system aperture (300 mm FOV) Axial FOV: 80 mm (two steps) 1 to 13 coincidences allowed, against half ring Maximum Likelihood Estimation Method (MLEM). Iterative method Could allow molecular-imaging guided biopsy

Spatial Resolution. NEMA Protocol NEMA protocol source positions: 1 cm and 10 cm radial and CFOVaxial and 3/8 FOVaxial (17 mm) DOI information improves system performance at FOVedge Spatial resolution < 3 mm for the whole FOV

Sensitivity Following NEMA protocol, activity Source: 825 k. Bq. 0. 25 mm Source Diameter 22 Na CTR: 3 ns. TW: 5 ns. 1. 7 % (50% EW) vs 2. 3 % (Gate v 7. 2)

Phantoms Studies We can resolve 6 mm rods with 5: 1 activity ratio 11 x 11 Array 22 Na 4. 6 mm pitch

Patient results Patient > 70 years with clear hot-spots Ca. P (possible metastasis) 7. 48 m. Ci F-Choline, acquisition 2 hours later. 7 minutes for each axial FOV Normalization and attenuation (water elipsoid) corrections have been implemented 3 iterations, 2 subsets, voxel size 1 x 1 x 1 mm, virtual pixel 1 x 1 mm. No Normalization No Attenuation PROSPET Final Image Philips GEMINI TF

Summary and Conclusions ▶ Ca. P is the most frequent cancer in men > 50 years ▶ Even though, biopsies are made randomly and there is a chance for a false positive ▶ We are proposing a specific PET system in order to help in the diagnosis and in vivo biopsy ▶ Detector modules achieve less than 2 mm in spatial resolution and > 15% energy resolution ▶ With no time information, two panels configuration presents no reliable results ▶ For reconstruction process we are using a MLEM algorithm with 3 iteration ▶ Spatial resolution and sensitivity are the expected ▶ Patient image presents a good similarity with the PET system reference ▶ Next steps: CT attenuation correction + more phantoms (NECR) 12

Thanks! I 3 M Detectors for Molecular Imaging Laboratory (DMIL): Prof. J. M. Benlloch Ph. D F. Sanchez Ph. D A. J. Gonzalez Ph. D Andrea González-Montoro, Ph. D L. Moliner, Ph. D J. Barrio, Ph. D M. Freire E. Lamprou N. Cucarella K. Vidal V. Ilisie L. Hernández S. Aguilar Hospital La Fe (Valencia). Urology Department CD Vera-Donoso MD, F. Boronat Tormo MD, Laura Lorenzo MD Hospital La Fe (Valencia). Nuclear Medicine Irene Torres Ph. D, Pablo Sopena MD, Pilar Bello MD 13