Realization and verification of three-dimensional conformal radiotherapy with modulated fields

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy Technology

Background:

• Conventional conformal radiotherapy struggles to precisely target complex tumor shapes.
• Advanced modulation techniques are needed to improve dose conformity and spare healthy tissues.
• Multileaf collimators (MLCs) offer potential for dynamic dose shaping in radiotherapy.

Purpose of the Study:

• To experimentally demonstrate the delivery of 3D conformal radiotherapy dose distributions.
• To utilize in-field modulation of fixed-gantry beams for precise dose shaping.
• To evaluate the feasibility of using MLCs for complex target volume irradiation.

Main Methods:

• Quasi-dynamic MLCs were employed to create 2D in-field modulation profiles.
• Profiles were optimized for a prostate carcinoma target with invaginated and bifurcated geometry.
• Dose delivery was verified using films embedded within a custom-shaped polystyrene phantom.

Main Results:

• Achieved a higher degree of high-dose region conformation to the target shape compared to unmodulated therapy.
• Demonstrated the capability to conform dose distributions to complex, non-spherical target volumes.
• Identified spatial dose displacements, highlighting the critical need for accurate patient positioning.

Conclusions:

• Clinically relevant 3D conformal radiotherapy dose distributions can be delivered using MLC-modulated beams.
• This technique is feasible for treating complex, invaginated, and bifurcated target volumes.
• Precise patient positioning is essential for successful implementation of modulated radiotherapy.