[Effects of Phantom Factor on Shape Differences in Tomotherapy Water-equivalent Phantoms]

Area of Science:

• Medical physics
• Radiation oncology
• Dosimetry

Context:

• Tomo-therapy is a sophisticated radiation therapy technique.
• Accurate dose verification is crucial for patient safety and treatment efficacy.
• Cheese phantoms are utilized for dose measurements in tomotherapy.

Purpose:

• To assess the impact of the phantom factor on measured dose verification in tomotherapy.
• To compare calculated and measured doses with and without the phantom factor.
• To evaluate the phantom factor under different tomotherapy delivery modes (TomoHelical/TomoDirect) and clinical scenarios.

Summary:

• A phantom factor of 1.007 was applied, leading to varied deviations between calculated and measured doses.
• The phantom factor's effect on dose verification differed based on the irradiation technique and field.
• Dose verification accuracy is influenced by phantom scattering characteristics.

Impact:

• Findings highlight the need to consider phantom scattering when applying phantom factors for dose verification.
• Results suggest that a single phantom factor may not be universally applicable across all tomotherapy conditions.
• This study informs more precise dose verification protocols in radiation therapy.