TY - JOUR
T1 - Ultrasound-assisted investigation of photon triggered vaporization of poly(vinylalcohol) phase-change nanodroplets
T2 - A preliminary concept study with dosimetry perspective
AU - Toumia, Yosra
AU - Miceli, Roberto
AU - Domenici, Fabio
AU - Heymans, Sophie V.
AU - Carlier, Bram
AU - Cociorb, Madalina
AU - Oddo, Letizia
AU - Rossi, Piero
AU - D'Angellilo, Rolando Maria
AU - Sterpin, Edmond
AU - D'Agostino, Emiliano
AU - Van Den Abeele, Koen
AU - D'hooge, Jan
AU - Paradossi, Gaio
N1 - Funding Information:
This work was funded by the European Union's Horizon 2020 research and innovation program under grant agreement n?766456 ("AMPHORA"). The authors acknowledge the financial support from INFN Istituto Nazionale di Fisica Nucleare (Rome, Italy), SR3T project.
Publisher Copyright:
© 2021 Associazione Italiana di Fisica Medica
PY - 2021/9
Y1 - 2021/9
N2 - Purpose: We investigate the vaporization of phase-change ultrasound contrast agents using photon radiation for dosimetry perspectives in radiotherapy. Methods: We studied superheated perfluorobutane nanodroplets with a crosslinked poly(vinylalcohol) shell. The nanodroplets' physico-chemical properties, and their acoustic transition have been assessed firstly. Then, poly(vinylalcohol)-perfluorobutane nanodroplets were dispersed in poly(acrylamide) hydrogel phantoms and exposed to a photon beam. We addressed the effect of several parameters influencing the nanodroplets radiation sensitivity (energy/delivered dose/dose rate/temperature). The nanodroplets-vaporization post-photon exposure was evaluated using ultrasound imaging at a low mechanical index. Results: Poly(vinylalcohol)-perfluorobutane nanodroplets show a good colloidal stability over four weeks and remain highly stable at temperatures up to 78 °C. Nanodroplets acoustically-triggered phase transition leads to microbubbles with diameters <10 μm and an activation threshold of mechanical index = 0.4, at 7.5 MHz. A small number of vaporization events occur post-photon exposure (6MV/15MV), at doses between 2 and 10 Gy, leading to ultrasound contrast increase up to 60% at RT. The nanodroplets become efficiently sensitive to photons when heated to a temperature of 65 °C (while remaining below the superheat limit temperature) during irradiation. Conclusions: Nanodroplets’ core is linked to the degree of superheat in the metastable state and plays a critical role in determining nanodroplet’ stability and sensitivity to ionizing radiation, requiring higher or lower linear energy transfer vaporization thresholds. While poly(vinylalcohol)-perfluorobutane nanodroplets could be slightly activated by photons at ambient conditions, a good balance between the degree of superheat and stability will aim at optimizing the design of nanodroplets to reach high sensitivity to photons at physiological conditions.
AB - Purpose: We investigate the vaporization of phase-change ultrasound contrast agents using photon radiation for dosimetry perspectives in radiotherapy. Methods: We studied superheated perfluorobutane nanodroplets with a crosslinked poly(vinylalcohol) shell. The nanodroplets' physico-chemical properties, and their acoustic transition have been assessed firstly. Then, poly(vinylalcohol)-perfluorobutane nanodroplets were dispersed in poly(acrylamide) hydrogel phantoms and exposed to a photon beam. We addressed the effect of several parameters influencing the nanodroplets radiation sensitivity (energy/delivered dose/dose rate/temperature). The nanodroplets-vaporization post-photon exposure was evaluated using ultrasound imaging at a low mechanical index. Results: Poly(vinylalcohol)-perfluorobutane nanodroplets show a good colloidal stability over four weeks and remain highly stable at temperatures up to 78 °C. Nanodroplets acoustically-triggered phase transition leads to microbubbles with diameters <10 μm and an activation threshold of mechanical index = 0.4, at 7.5 MHz. A small number of vaporization events occur post-photon exposure (6MV/15MV), at doses between 2 and 10 Gy, leading to ultrasound contrast increase up to 60% at RT. The nanodroplets become efficiently sensitive to photons when heated to a temperature of 65 °C (while remaining below the superheat limit temperature) during irradiation. Conclusions: Nanodroplets’ core is linked to the degree of superheat in the metastable state and plays a critical role in determining nanodroplet’ stability and sensitivity to ionizing radiation, requiring higher or lower linear energy transfer vaporization thresholds. While poly(vinylalcohol)-perfluorobutane nanodroplets could be slightly activated by photons at ambient conditions, a good balance between the degree of superheat and stability will aim at optimizing the design of nanodroplets to reach high sensitivity to photons at physiological conditions.
UR - http://www.scopus.com/inward/record.url?scp=85113654369&partnerID=8YFLogxK
U2 - 10.1016/j.ejmp.2021.08.006
DO - 10.1016/j.ejmp.2021.08.006
M3 - Article
AN - SCOPUS:85113654369
VL - 89
SP - 232
EP - 242
JO - Physica Medica
JF - Physica Medica
SN - 1120-1797
ER -