Speaker
Description
Barium sulfate (BaSO₄) contrast medium is widely used as a radiographic agent in gastrointestinal imaging. By coating and adhering to the gastrointestinal mucosa, it enhances radiographic contrast, facilitating improved visualization and the diagnosis of ulcers, tumors, and obstructions. This study aimed to assess the effects of barium sulfate contrast medium on dose evaluation in the linear accelerator (LINAC) radiotherapy treatment planning systems (TPS). Monte Carlo simulations and experimental measurements were performed to compare the TPS-calculated doses.
The results showed that, after the radiation beam passed through the contrast agent, the average discrepancy between the AAA algorithm calculations and the measured values was −4%, whereas the AXB algorithm exhibited an average discrepancy of −8%. Using a 200 w/v% contrast agent (physical density 2.553 g/cm³) as an example, the corresponding HU value was 1255 HU. After correcting the HU value in the TPS and recalculating the dose, the average error decreased to −2% for the AAA algorithm and −4% for the AXB algorithm. The effects of photon beam energy and field size, in combination with varying concentrations of barium sulfate contrast agent, on dose evaluation were also investigated and discussed.
This approach also enables estimation of the dosimetric impact of contrast agents at varying concentrations and positions during treatment, providing guidance for clinical decision-making and ensuring accurate dose documentation.