In vivo diode dosimetry for routine quality assurance in IMRT

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Quality Assurance

Background:

• Intensity-Modulated Radiation Therapy (IMRT) dosimetry is complex, often relying on phantom measurements for dose evaluation.
• In vivo dose reconstruction using electronic portal imaging devices or films is time-consuming and complicated.
• A need exists for a simplified and accurate method for IMRT dose delivery verification.

Purpose of the Study:

• To implement and evaluate routine diode dosimetry for in vivo IMRT dose verification.
• To compare diode measurements with planned doses for IMRT treatment fields.
• To simplify the IMRT quality assurance (QA) process.

Main Methods:

• Diode dosimetry was used for IMRT patients, mirroring procedures for standard radiation therapy.
• Dose contribution for each IMRT field at dmax depth was obtained from the treatment plan.
• Diode measurements were compared against planned doses for each treatment field.

Main Results:

• Approximately 90% (45/51 fields) of diode measurements agreed within +/- 10% of planned doses.
• A significant 63% (32/51 fields) achieved agreement within +/- 5% of planned doses.
• The method provided a uniform startup procedure for all patients.

Conclusions:

• Routine diode dosimetry is an effective and simplified method for in vivo IMRT dose verification.
• This approach enhances the quality assurance process for IMRT, ensuring accurate dose delivery.
• The study demonstrates the feasibility of integrating diode dosimetry into routine clinical practice for IMRT.