Patient-specific online dose verification based on transmission detector measurements

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Intensity-modulated radiation therapy (IMRT) requires rigorous patient-specific plan verification.
• Online dosimetry and 3D dose reconstruction are crucial for improving radiation therapy accuracy and safety.

Purpose of the Study:

• To investigate the clinical performance of the Dolphin transmission detector (DTD) for online dosimetry.
• To evaluate the DTD's accuracy in 2D and 3D dosimetric plan verification for IMRT.

Main Methods:

• The DTD's clinical performance was assessed using 18 IMRT sequences.
• Dosimetric plan verification was conducted in 2D and 3D, comparing DTD measurements with reference methods.
• Evaluations included gamma index, dose difference, and dose-volume histogram (DVH) analysis.
• The DTD's error detection capabilities were tested using leaf position uncertainties and linear accelerator (LINAC) output variations.

Main Results:

• DTD measurements showed excellent agreement with reference measurements in both 2D and 3D.
• A minor dose underestimation (<2%) was noted within the target volume during DVH analysis.
• The DTD successfully identified leaf bank positional errors exceeding 1mm and LINAC output errors greater than 2%.

Conclusions:

• The Dolphin transmission detector (DTD) provides accurate dose measurements for IMRT.
• The DTD is suitable for clinical routine due to its accuracy and error detection capabilities.