HybridArc: a novel radiation therapy technique combining optimized dynamic arcs and intensity modulation

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Intensity-modulated radiation therapy (IMRT) and dynamic conformal arcs (DCA) are established radiation techniques.
• Optimizing radiation delivery is crucial for maximizing tumor control and minimizing normal tissue toxicity.
• Novel treatment planning approaches are continuously explored to improve therapeutic ratios.

Purpose of the Study:

• To evaluate the dosimetric and efficiency advantages of HybridArc, a combined IMRT and dynamic arc technique.
• To compare HybridArc plans against standard DCA and IMRT for cranial and prostate cancer cases.
• To assess improvements in target coverage, organ-at-risk sparing, and treatment efficiency.

Main Methods:

• HybridArc treatment plans were created for complex cranial and prostate tumors.
• Plans were compared to conventional dynamic conformal arc (DCA) and intensity-modulated radiation therapy (IMRT) plans.
• Comparisons focused on target dose conformity, homogeneity, organ-at-risk sparing, normal tissue dose, and monitor unit (MU) efficiency.

Main Results:

• HybridArc significantly improved dose conformity for cranial tumors compared to DCA and IMRT.
• For prostate cancer, HybridArc enhanced conformity versus DCA and improved planning target volume homogeneity versus IMRT.
• HybridArc reduced maximum bladder and rectal doses for prostate cases but increased peripheral dose volume compared to DCA.
• Monitor unit efficiency varied by site: 38% increase for cranial, 7% decrease for prostate compared to IMRT.

Conclusions:

• HybridArc offers improved target dose conformity for cranial tumors.
• For prostate cancer, HybridArc provides superior dose conformity and homogeneity compared to DCA and IMRT, respectively.
• The efficiency and normal tissue sparing benefits of HybridArc are site-specific, requiring careful consideration in treatment planning.