Experimental Medical Physics

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WP2b Ultrasound Imaging and Ionoacoustics


Ionoacoustics is a novel range verification method, which is based on the detection of thermoacoustic emissions induced by the therapeutic irradiation. The localized energy deposition of charged particles, delivered by a short-pulsed ion beam, generates measurable acoustic waves, whose characteristics primarily depend on the spatial heating function. These acoustic waves enhanced at the Bragg peak position allow range verification. The relative simplicity of this modality and the possibility to co-register anatomical ultrasound images, makes ionoacoustics a promising candidate for almost real-time in vivo dose monitoring. However, the main challenge is to detect the low-pressure (≤ 0.1 Pa) and low-frequency (≤ 100 kHz) waves usually observed for pre-clinical and clinical applications.

Such low frequency signals cannot be detected with conventional medical ultrasound systems. A second major challenge is the low pressure which requires the usage of high-sensitivity ultrasonic sensors (i.e., six order of magnitude lower compared to conventional ultrasound imaging). Because of that, we are actively developing dedicated instrumentation based either on Capacitive Micromachined Ultrasonic Transducers (CMUT) or polymer-based piezoelectric material (Polyvinylidene fluoride, PVDF), in a collaborative effort together with the Department of Engineering of the Roma Tre University (Rome, Italy) and the GREMAN UMR 7347 laboratory (University of Tours, France), respectively. Additionally to sensor improvement, the enhancement of the ionoacoustic signal through ultrasound (e.g., gas-filled microbubbles) and photoacoustic (e.g., India ink) contrast agents is also investigated aiming to increase the measurement sensitivity.


Optimal ionoacoustic detector design and Bragg peak localization strategies are investigated in-silico, and supported by experimental measurements at proton-beam facilities such as the MLL Tandem accelerator and the Centre Antoine Lacassagne (Nice, France), as well as by a dedicated in-house developed optoacoustic setup to mimic proton-induced pressure waves. Hereby, particular attention is paid to the influence of the sensor impulse response as well as tissue heterogeneities on the detected pressure and imaged proton beam, with the development of dedicated multimodal phantoms.



Dr. J. Lascaud


Beatrice Villata, Dominik Selzner, Pratik Dash, Ronaldo Kalunga, Dr. Julie Lascaud, Prof. Dr. Katia Parodi

Former members: Julia Müllner, Benjamin Wollant, Henri Carmigniani, Muhammad Safdar, Rafal Kowalewski, Edi Liang, Marita Oliv, Dr. Hans-Peter Wieser 


Peer-reviewed journals

Lascaud J., Dash P., Wieser H.-P., Kalunga R., Würl M., Assmann W., and Parodi K., Investigating the accuracy of co-registered ionoacoustic and ultrasound images in pulsed proton beams, Physics in Medicine & Biology, 2021, https://doi.org/10.1088/1361-6560/ac215e

Lascaud J., Dash P., Würl M., Wieser H.-P. , Wollant B., Kalunga R. , Assmann W., Clevert D.-A., Ferrari A., Sala P., Savoia A. S. and Parodi K., Enhancement of the ionoacoustic effect through ultrasound and photoacoustic contrast agents, Scientific Reports, 2021, https://doi.org/10.1038/s41598-021-81964-4

Conference contributions

Lascaud J., Pinto M., Dash P., Wieser H.-P., Rouffaud R., Certon D., Sitarz M., Poulsen P., N., Parodi K., Feasibility study of transient ionoacoustics-based proton beam monitoring for small animal irradiation at cyclotron-based clinical facilities under FLASH conditions. FLASH radiotherapy and particle therapy conference 2021, 1-3 December 2021, Online / Vienna. - Oral presentation

Dash P., Lascaud J., Pinto M., Wieser H.-P., Kurichiyanil N., Parodi K., Designing a detector array for ionoacoustics-based Bragg peak localization and dose reconstruction in a small animal during pulsed proton irradiation. Joint Conference of the ÖGMP, DGMP and SGSMP, 19-22 September 2021 – Poster, awarded “Best poster presentation in Medical Physics”.

Kalunga R., Wieser H.-P., Lascaud J., Dash P., Schmidt A.-K., Gerlach S., Haghani R., Riboldi M., Schreiber J., Assmann W., Parodi K., On the localization of the proton Bragg peak position in 3D using multilateration of ionoacoustic signals. Joint Conference of the ÖGMP, DGMP and SGSMP, 19-22 September 2021 - Oral presentation

Wieser H.-P., Schauer J., Huang Y., Lascaud J., Chmyrov A., Würl M., Bortfeldt J., Vidal M., Hérault J., Assmann W., Ntziachristos V., Dollinger G., Parodi K., Feasability study of correlated Bragg peak localization via ultrasound and ionoacoustics in abdominal imaging phantom. Joint Conference of the ÖGMP, DGMP and SGSMP, 19-22 September 2021 - Oral presentation

Lascaud J., Kowalewski R., Wollant B., Carmigniani H., Schnürle K., Dash P., Wieser H.-P., Borfeldt J., Kalunga R., Rouffaud R., Gérard A., Vidal M., Hérault J., Certon D., Parodi K., Optimization of the backing material of a low frequency PVDF detector for ion beam monitoring during small animal proton irradiation. Virtual IEEE IUS 2021 conference, 11-16 September 2021 - Poster

Lascaud J., Würl M., Dash P., Nitta M., Parodi K., Ionoacoustic treatment monitoring for radiosensitizers-enhanced carbon ion therapy: a feasibility study. Virtual 63rd annual meeting of the American Association of Physicists in Medicine (AAPM) 2021, 25-29 July 2021 - Oral presentation

Lascaud J., Wieser H.-P., Dash P., Kalunga R., Lehrack S., Assmann W., Parodi K., Investigation of the accuracy of co-registered ionoacoustic and ulrasound images in proton beams. Virtual 2020 IEEE Nuclear Science Symposium & Medical Imaging Conference (NSS/MIC), 2020 October 31 - November 7 - Oral presentation

Wieser H.-P., Dash P., Würl M., Savoia A.S., Assmann W., Parodi K. and Lascaud J., Simulation und Validierung der Detektorantwort f\"ur eine verbesserte Ionoakustik-basierte Bragg Peak Lokalisation. 51th Annual Meeting of the Deutsche Gesellschaft für Medizinische Physik. 2020 September 09-11, (Virtually) - Oral presentation

Dash P., Lascaud J., Wieser H.-P., Kalunga R., Wollant B., Assmann W., Botfeldt J., Pinto M., Kurichiyanil N., Würl M., Liubchenko G., Niepel K., Sabel B., Landry G., Lauber K., Savoia A.S., Parodi K., Investigating the co-registration of ionoacoustic and ultrasound signals along with possibilities of dose reconstruction in realistic small animal models for protonirradiation monitoring. 51th Annual Meeting of the Deutsche Gesellschaft für Medizinische Physik. 2020 September 09-11, (Virtually) - Oral presentation

Wieser H.-P., Huang Y., Schauer J., Lascaud J., Chmyrov A., Ntziachristos V., Dollinguer G., Assmann W., Parodi K., First experimental demonstration of accurate Bragg peak localization with ionoacoustic tandem phase detection (iTPD). Annual Conference of the American Association of Physicists in Medicine, 2020 July 12-16, Vancouver (Virtually) - Poster

Wieser H.-P., Dash P., Savoia A.S., Assmann W., Parodi K. and Lascaud J., Accurate simulation and validation of the detector response for improved Bragg peak localization via ionoacoustics. Annual Conference of the American Association of Physicists in Medicine, 2020 July 12-16, Vancouver (Virtually) - Poster

Lascaud J., Dash P., Bortfeld J., Wieser H.-P., Niepel K., Kalunga R., Wollant B., Würl M., Savoia A.S., Lauber K., Assman W., and Parodi K., Development of a multimodal 3D printed mouse phantom for quality assurance of ionoacoustics for range verification in precision preclinical proton radiation research. 5th Conference on small animal precision image-guided radiotherapy, 2020 March 9-11, Munich (Germany) - Oral presentation

Lascaud J., Lehrack S., Wieser H.-P., Kalunga R, Englbrecht S.F., Würl M., Assmann W., Savoia A.S., Parodi K., Applicability of Capacitive Micromachined Ultrasonic Transducers for the detection of proton-induced thermoacoustic waves. IEEE International Ultrasonics Symposium (IUS). 2019 October 6-9, Glasgow (UK) - Oral presentation

Wieser H.-P., Lascaud J., Lehrack S., Kalunga R., Würl M., Assmann W., Parodi K., Untersuchung des ionoakustischen effektes in heterogenen Medien zur Minimierung der reichweitenunsicherheit in der Partikeltherapie. 50th Annual Meeting of the Deutsche Gesellschaft für Medizinische Physik. 2019 September 18-21, Stuttgart (Germany) – Oral presentation