Purpose: To demonstrate the feasibility and accuracy of X-Ray Induced Acoustic imaging for Absolute Radiation Dosimetry.
Methods: Dose distributions in a water phantom were calculated for simple field sizes using clinical Treatment Planning Software (TPS). The X-Ray induced acoustic pressure wave generated by the increase in temperature associated with the absorption of X-Rays were simulated, using an advanced numerical model for the time domain simulation of propagating acoustic waves. Through an iterative time reversal algorithm, we reconstructed the acoustic pressure distribution due to the X-Ray dose. X-Ray acoustic signals at varying depths were compared to the percent depth dose (PDD) curves calculated from the TPS.
Results: The acoustic pressure distribution due to the dose distribution in water phantom was reconstructed. The intensity of X-Ray acoustic pressure is similar to the radiation dose.We observed that although the acoustic PDD calculated from maximum acoustic pressure at each depth is proportional to clinical PDD, the maximum acoustic peak is shifted deeper by up to 25 mm from the maximum dose depth. The reason for this observation is illustrated.
Conclusion: X-Ray induced acoustic imaging has the potential to be used for absolute radiation dosimetry. However, due to the acoustic sensor geometry, there are discrepancies between the depth of maximum peak of acoustic pressure and the depth of maximum radiation dose, which depends on the distance of measurement. Thus, a three dimensional analysis of X-Ray acoustic signals is required for absolute dosimetry. Strategies such as senor geometry optimization and error analysis in the prior knowledge of acoustic properties of the medium are needed to improve the accuracy of X-ray acoustic imaging for radiation dosimetry.
Not Applicable / None Entered.