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Absorption Dependence of the X-Ray Induced Acoustic Waves

C Sanli1*, J Wang2 , M Unlu1,2,3 , (1) Bogazici University, Besiktas, Istanbul, (2) Global Station for Quantum Medical Science and Engineering, Sapporo, Hokkaido, (3) Stanford University, School of Medicine, Stanford, California


(Wednesday, 8/1/2018) 9:30 AM - 10:00 AM

Room: Exhibit Hall | Forum 6

Purpose: Our goal is to investigate the dependence of the X-ray acoustic waves on the absorption parameters.

Methods: We first obtained the pressure waveform due to a point dose absorption using a thermo-acoustic equation governing the heat absorption-pressure induction process. Then, X-ray induced acoustic signal at the detection point was obtained by generalizing point-dose-gradient induced acoustic signal to surface-dose-gradient of a uniform spherical 3D dose distribution. We used the reciprocity principle for pressure waves in fluid media. Therapeutic range of X-ray beam parameters dose rate, spot-size, pulse duration and repetition frequency are obtained from the literature to simulate the induced acoustic signal.

Results: X-ray beam of 1.7 mGy/pulse pulses each with duration of 1 μs with 5x5 cm2 field size on the water medium induces a pressure profile of two crest and troughs with the maximum pressure amplitude of 0.1 Pa at a 10 cm distance from the center of the assumed 3D spherical uniform dose distribution. Based on the power spectrum of the signal, the central frequency is determined as 45.8 kHz.

Conclusion: X-ray induced acoustic signals are observable in conventional cancer radiotherapy and the proposed analytic model achieves a very simple and practical way of predicting and interpreting these signals.


X Rays, Ultrasonics


IM- Ultrasound : Theory

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