open access

https://hdl.handle.net/2115/93969

Technical note: Application of an optical hydrophone to ionoacoustic range detection in a tissue‐mimicking agar phantom

英語

spot‐scanning proton therapy

2024-07

Wiley

Medical Physics

51(7)

5130-5141

Background : Ionoacoustics is a promising approach to reduce the range uncertainty in proton therapy. A miniature-sized optical hydrophone (OH) was used as a measuring device to detect weak ionoacoustic signals with a high signal-to-noise ratio in water. However, further development is necessary to prevent wave distortion because of nearby acoustic impedance discontinuities while detection is conducted on the patient's skin. Purpose : A prototype of the probe head attached to an OH was fabricated and the required dimensions were experimentally investigated using a 100-MeV proton beam from a fixed-field alternating gradient accelerator and k-Wave simulations. The beam range of the proton in a tissue-mimicking phantom was estimated by measuring γ-waves and spherical ionoacoustic waves with resonant frequency (SPIRE). Methods : Four sizes of probe heads were fabricated from agar blocks for the OH. Using the prototype, the γ-wave was detected at distal and lateral positions to the Bragg peak on the phantom surface for proton beams delivered at seven positions. For SPIRE, independent measurements were performed at distal on- and off-axis positions. The range positions were estimated by solving the linear equation using the sensitive matrix for the γ-wave and linear fitting of the correlation curve for SPIRE; they were compared with those measured using a film. Results : The first peak of the γ-wave was undistorted with the 3 × 3 × 3-cm3 probe head used at the on-axis and 3-cm off-axis positions. The range positions estimated by the γ-wave agreed with the film-based range in the depth direction (the maximum deviation was 0.7 mm), although a 0.6–2.1 mm deviation was observed in the lateral direction. For SPIRE, the deviation was <1 mm for the two measurement positions. Conclusions : The attachment of a relatively small-sized probe head allowed the OH to measure the beam range on the phantom surface.

学術雑誌論文

Accepted Manuscript

This is the peer reviewed version of the following article: Shota Sueyasu, Koki Kasamatsu, Taisuke Takayanagi, Ye Chen, Yasutoshi Kuriyama, Yoshihiro Ishi, Tomonori Uesugi, Wolfgang Rohringer, Mehmet Burcin Unlu, Nobuki Kudo, Kohei Yokokawa, Seishin Takao, Naoki Miyamoto, Taeko Matsuura,Application of an optical hydrophone to ionoacoustic range detection in a tissue-mimicking agar phantom. Medical Physics. July 2024, 5130-5141, which has been published in final form at https://doi.org/10.1002/mp.16892. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

0094-2405

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