(Sunday, 7/29/2018) 1:00 PM - 1:55 PM
Room: Room 202
Purpose: Our goal is to compare the acoustic waves generated in proton and carbon ion therapy
Methods: We developed a thermo-acoustic analytic model that assumes of instantaneous Gaussian heat deposition due to radiation exposure. Proton and carbon ion beam parameters were extracted from the literature. We used two types of accelerators to manipulate the heavy-ions: a synchrotron and a linac. For the synchrotron, pulse repetition frequency (PRF) was set to 5 Hz for both carbon ions and protons. Pulse duration was set to 1.5 µs and the dose rate was taken 5 Gy/min and 10 Gy/min for carbon and proton ions respectively. For the linac, the PRF was set as 30 Hz for the proton beam. For the carbon ions PRF was taken as 300 Hz. The dose per pulse was set to 0.28 mGy/pulse for the carbon ions. For the protons accelerated in a linac, the dose rate was 10 Gy/min.
Results: For the synchrotron, the amplitude of the carbon-acoustic wave is calculated as 350 µPa. In contrast, the proton acoustic waves have the amplitude of 700 µPa. For the linac, the proton acoustic signal is 120 µPa whereas the carbon ion induced acoustic wave has an amplitude of 5.8 µPa.
Conclusion: We show that short pulse durations and low pulse repetition frequencies strengthen the induced acoustic signal. While high PRF is important for fast scanning, it adversely effects the amplitude of the acoustic signals. The carbon ion induced acoustic waves are much more difficult to detect in both synchrotron and linac-based facilities. Proton acoustic waves can be detected with short pulse durations and low repetition frequencies especially in synchrotron-based facilities. Hence currently developing laser-driven ion acceleration technology and circular ion accelerators promise effective implementation of ion-acoustics as an indirect imaging modality.
Keywords
Not Applicable / None Entered.
Taxonomy
TH- External Beam- Particle therapy: Proton therapy - computational dosimetry-deterministic
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