Point Dose Measurement for Verification of Treatment Planning System using an Indigenous Heterogeneous Pelvis Phantom...

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Dosimetry

Background:

• Advanced radiotherapy planning relies on dose calculation algorithms.
• Accurate dose verification is crucial for effective radiotherapy.
• Commercial phantoms often lack patient-specific anatomical accuracy.

Purpose of the Study:

• To compare planned doses from different algorithms with measured doses.
• To validate an indigenous heterogeneous pelvic phantom for radiotherapy verification.

Main Methods:

• Developed an indigenous heterogeneous pelvic phantom simulating human pelvic anatomy.
• Created three dimensional conformal radiotherapy (3D-CRT) plans using various dose calculation algorithms.
• Delivered plans using a medical linear accelerator and measured doses with an ion chamber within the phantom.

Main Results:

• Pelvic phantom's relative electron densities closely matched actual pelvic tissues (bladder, rectum, fat, bone).
• Percentage deviations between planned and measured doses were within the acceptable ±5% range.
• Superposition algorithm showed highest deviations (3.09%), while Convolution had the least (-0.08%).

Conclusions:

• The indigenous heterogeneous pelvic phantom is a cost-effective tool for radiotherapy dose verification.
• Its anatomical and density accuracy makes it suitable for routine patient-specific quality assurance.
• This phantom can enhance the reliability of radiotherapy dose calculations.