Methodologies and tools for proton beam design for lung tumors

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Planning

Background:

• Proton beams offer precise dose delivery, sparing normal tissues by stopping within the target.
• Accurate lung tumor treatment with protons necessitates accounting for tissue motion and planning uncertainties.

Purpose of the Study:

• To evaluate different proton beam planning strategies for lung tumors.
• To determine the optimal method for achieving adequate tumor coverage and minimal normal tissue irradiation.
• To assess the simplicity of various planning approaches.

Main Methods:

• Generated proton beam treatment plans using three distinct strategies.
• Strategies involved designing apertures and boluses relative to the Planning Target Volume (PTV) and Clinical Target Volume (CTV).

Main Results:

• The Planning Target Volume (PTV) concept, as per ICRU Report 50, is insufficient for defining all beam margins due to uncertainties.
• Current planning tools led to unnecessary irradiation of normal tissues and complicated lung tumor planning.
• No single strategy perfectly balanced target coverage, normal tissue sparing, and planning simplicity.

Conclusions:

• Integrating target motion and setup uncertainties into the beam design step is crucial, superseding the creation of new targets.
• Development of new computerized treatment planning system tools is recommended.
• Improved tools will simplify lung tumor planning, allow abandonment of the PTV concept, enhance dose conformity, and improve avoidance of critical normal tissues.