Real-time dosimetry in external beam radiation therapy

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Quality Assurance

Background:

• Modern radiotherapy, including intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), demands rigorous pre-treatment quality assurance (QA).
• Current pre-treatment QA for IMRT and VMAT ensures plan accuracy but may not predict clinically significant patient dose errors.
• Image-guided radiotherapy (IGRT) improves plan delivery accuracy but does not quantify the actual dose delivered to the tumor volume.

Purpose of the Study:

• To highlight the limitations of current radiotherapy quality assurance protocols.
• To emphasize the importance of real-time dosimetry for accurate dose delivery verification in complex radiotherapy treatments.
• To discuss the potential of real-time dosimetry in preventing major radiotherapy accidents and improving patient outcomes.

Main Methods:

• Review of current radiotherapy quality assurance practices, including pre-treatment checks and IGRT.
• Exploration of real-time dosimetry techniques and their application in external beam radiotherapy.
• Discussion of four established platforms for real-time dose information acquisition: Collimator, Patient, Couch, and Electronic Portal Imaging Device (EPID).

Main Results:

• Pre-treatment QA and IGRT do not fully capture the actual dose delivered to the patient, potentially leading to clinically relevant errors.
• Real-time dosimetry provides direct measurements of delivered dose, offering entrance, exit, or internal cavity doses.
• Various real-time dosimetry platforms exist, each with unique advantages and disadvantages, suggesting a combination may be optimal.

Conclusions:

• Real-time dosimetry is essential for verifying prescribed doses and ensuring treatment accuracy in complex radiotherapy.
• Implementing real-time dosimetry can avert major radiotherapy accidents by providing immediate feedback on dose delivery.
• A combination of different real-time dosimetric methods offers comprehensive information on the actual dose delivered to radiotherapy patients.