Experimental demonstration of accurate Bragg peak localization with ionoacoustic tandem phase detection (iTPD)

Wieser, Hans-Peter ; Huang, Yuanhui; Schauer, Jannis; Lascaud, Julie ; Würl, Matthias ; Lehrack, Sebastian ; Radonic, D.; Vidal, Marie; Herault, Joel ; Chmyrov, Andriy; Ntziachristos, Vasilis ; Assmann, Walter; Parodi, Katia und Dollinger, Günther (16. Dezember 2021): Experimental demonstration of accurate Bragg peak localization with ionoacoustic tandem phase detection (iTPD). In: Physics in Medicine & Biology, Bd. 66, Nr. 24, 245020

Abstract

Accurate knowledge of the exact stopping location of ions inside the patient would allow full exploitation of their ballistic properties for patient treatment. The localized energy deposition of a pulsed particle beam induces a rapid temperature increase of the irradiated volume and leads to the emission of ionoacoustic (IA) waves. Detecting the time-of-flight (ToF) of the IA wave allows inferring information on the Bragg peak location and can henceforth be used for in-vivo range verification. A challenge for IA is the poor signal-to-noise ratio at clinically relevant doses and viable machines. We present a frequency-based measurement technique, labeled as ionoacoustic tandem phase detection (iTPD) utilizing lock-in amplifiers. The phase shift of the IA signal to a reference signal is measured to derive the ToF. Experimental IA measurements with a 3.5 MHz lead zirconate titanate (PZT) transducer and lock-in amplifiers were performed in water using 22 MeV proton bursts. A digital iTPD was performed in-silico at clinical dose levels on experimental data obtained from a clinical facility and secondly, on simulations emulating a heterogeneous geometry. For the experimental setup using 22 MeV protons, a localization accuracy and precision obtained through iTPD deviates from a time-based reference analysis by less than 15 μm. Several methodological aspects were investigated experimentally in systematic manner. Lastly, iTPD was evaluated in-silico for clinical beam energies indicating that iTPD is in reach of sub-mm accuracy for fractionated doses < 5 Gy. iTPD can be used to accurately measure the ToF of IA signals online via its phase shift in frequency domain. An application of iTPD to the clinical scenario using a single pulsed beam is feasible but requires further development to reach <1 Gy detection capabilities.

• Dokumententyp: Zeitschriftenartikel
• EU Funded Grant Agreement Number: 725539
• EU-Projekte: Horizon 2020 > ERC Grants > ERC Consolidator Grant > ERC Grant 725539: SIRMIO - Small Animal Ion Irradiator for Research in Molecular Image-Guided Radio-Oncology
• Publikationsform: Publisher's Version
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Sprache: Englisch
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 403225886
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 24819222