[Dose-volume histogram comparison among techniques of linac stereotactic radiosurgery]

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiosurgery Techniques

Background:

• Accurate three-dimensional dose distribution is crucial for effective radiosurgery.
• Various techniques exist, each with unique dose characteristics.
• Understanding these differences is key to optimizing treatment planning.

Purpose of the Study:

• To analyze and compare the 3D dose distributions of different radiosurgery techniques.
• To evaluate the impact of arc number, geometry, and field size on dose distribution.
• To assess the efficacy of dose-volume histograms (DVH) in characterizing these distributions.

Main Methods:

• Utilized dose-volume histograms (DVH) to analyze dose distributions.
• Measured off-center ratio and tissue-peak ratio for 6-MV X-rays.
• Employed diamond detectors and film dosimetry for small field characterization.
• Evaluated techniques including single-plane rotation, multiple non-coplanar arcs, dynamic rotation, and precessional converging radiotherapy (PCR) in a spherical phantom.

Main Results:

• Multiple non-coplanar convergent arcs (4 or 11 arcs) and PCR yielded similar DVH results.
• Single-plane rotation demonstrated dose falloffs considered almost unacceptably shallow.
• Dynamic rotation's DVH fell between single-plane rotation and the other evaluated methods.
• Most technique differences were within 40% of the maximum dose.

Conclusions:

• Multiple non-coplanar convergent arcs and PCR are effective radiosurgery techniques with comparable dose distributions.
• Single-plane rotation is less optimal due to shallow dose falloffs.
• DVH analysis effectively differentiates the performance of various radiosurgery techniques.