SU-E-T-532: Comparison of Dose Distributions Calculated Using Different Planning Systems with Radiochromic Film...

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Treatment Planning

Background:

• Accurate dose calculation in lung tumors is critical for effective radiotherapy.
• Traditional algorithms face challenges in modeling complex dose distributions within lung inhomogeneities.

Purpose of the Study:

• To compare the accuracy of four commercial dose calculation algorithms against radiochromic film measurements.
• To evaluate the performance of Raysearch, Pinnacle collapsed cone, Eclipse AAA, and Eclipse Acuros algorithms in a lung tumor phantom.

Main Methods:

• A lung tumor phantom with a thermoplastic cylinder inhomogeneity was constructed.
• Radiochromic films were used for dose measurements within the phantom.
• CT data was used to import the phantom into four treatment planning systems for dose calculation.

Main Results:

• All four algorithms demonstrated agreement within 3% of film measurements away from interfaces.
• The Acuros algorithm showed a peripheral dose deficit of up to 2% at the cylinder edge.
• This deficit may be attributed to the loss of lateral electron equilibrium.

Conclusions:

• All evaluated algorithms achieved good agreement with experimental measurements.
• The Acuros algorithm shows promise in accurately modeling peripheral dose deficits in lung tumors.
• Further investigation is recommended to confirm the Acuros algorithm's superior performance in this aspect.