Online proton therapy monitoring: clinical test of a Silicon-photodetector-based in-beam PET

Abstract

Particle therapy exploits the energy deposition pattern of hadron beams. The narrow Bragg Peak at the end of range is a major advantage but range uncertainties can cause severe damage and require online verification to maximise the effectiveness in clinics. In-beam Positron Emission Tomography (PET) is a non-invasive, promising in-vivo technique, which consists in the measurement of the β+ activity induced by beam-tissue interactions during treatment, and presents the highest correlation of the measured activity distribution with the deposited dose, since it is not much influenced by biological washout. Here we report the first clinical results obtained with a state-of-the-art in-beam PET scanner, with on-the-fly reconstruction of the activity distribution during irradiation. An automated time-resolved quantitative analysis was tested on a lacrimal gland carcinoma case, monitored during two consecutive treatment sessions. The 3D activity map was reconstructed every 10 s, with an average delay between beam delivery and image availability of about 6 s. The correlation coefficient of 3D activity maps for the two sessions (above 0.9 after 120 s) and the range agreement (within 1 mm) prove the suitability of in-beam PET for online range verification during treatment, a crucial step towards adaptive strategies in particle therapy.

Hybrid Imaging: Instrumentation and Data Processing

“…Positron emitters are generated inside the patient during treatment, and therefore, by using PET imaging the delivered dose can be indirectly measured [338,339]. This can be done during the irradiation (on-line or in-beam PET), which is beneficial when imaging short-lived emitters [340], or after the treatment in an off-site system (off-line), which can provide better counting statistics for relatively long-lived radionuclides [341]. In on-line systems, the integration of PET imaging into the treatment environment poses geometric constraints, conditioning the imaging performance.…”

Characterisation of Components of a Scintillation-fiber-based Compton Camera

“…Tracking of prompt-gamma, PET-gamma, and secondary protons and neutrons are examples [9][10][11]. Prototype systems for prompt-gamma and PET-gamma range monitoring were tested clinically and obtained satisfying precision of Bragg peak position monitoring on-line in the PBT treatment room [12][13][14]. At the Jagiellonian University in Kraków, a novel solution for diagnostic PET imaging, Jagiellonian-PET (J-PET) is being developed [15][16][17][18].…”

Investigations on Physical and Biological Range Uncertainties in Krak\'ow Proton Beam Therapy Centre

“…Tracking of prompt-gamma, PET-gamma and secondary protons and neutrons are examples [9,10,11]. Prototype systems for prompt-gamma and PET-gamma range monitoring were tested clinically and obtained satisfying precision of Bragg-peak position monitoring on-line in the PBT treatment room [12,13,14]. At the Jagiellonian University in Kraków, a novel solution for diagnostic PET imaging, Jagiellonian-PET (J-PET) is being developed.…”