Reference dosimetry of modulated and dynamic photon beams

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Dosimetry

Background:

• Intensity-modulated radiotherapy (IMRT) has advanced photon beam delivery since the late 1980s.
• Techniques like helical tomotherapy and volumetric modulated arc therapy are standard in modern radiotherapy.
• Despite widespread clinical use, established guidelines for calibrating dynamic modulated photon beams are still lacking.

Purpose of the Study:

• To conduct a literature review on the dosimetry of nonstandard photon beams, including dynamic deliveries.
• To discuss the potential benefits and challenges of implementing the IAEA-AAPM formalism for dynamic photon beams.
• To highlight the need for updated dosimetry protocols for advanced radiotherapy techniques.

Main Methods:

• Literature review focusing on nonstandard photon beam dosimetry and calibration challenges.
• Analysis of the IAEA-AAPM formalism proposed by Alfonso et al. (2008).
• Discussion of the implications of IAEA Code of Practice TRS-483 and its limitations for dynamic beams.

Main Results:

• A significant gap exists in established guidelines for the calibration of dynamic modulated photon beams.
• The IAEA-AAPM formalism offers a new approach to reference dosimetry for nonstandard beams.
• IAEA TRS-483 addresses small static beams, but the broader formalism for dynamic beams requires clinical implementation.

Conclusions:

• Implementing the IAEA-AAPM formalism for dynamic photon beams represents a paradigm shift in radiotherapy calibration.
• Addressing the challenges of this implementation is crucial for accurate and safe IMRT delivery.
• Further research and clinical adoption are needed to establish robust dosimetry protocols for advanced radiotherapy techniques.