Low-Dose Image-Guided Pediatric CNS Radiation Therapy: Final Analysis From a Prospective Low-Dose Cone-Beam CT...

Area of Science:

• Radiotherapy
• Medical Imaging
• Pediatric Oncology

Background:

• Image-guided radiotherapy (IGRT) aims to improve treatment accuracy.
• Lower-dose imaging protocols are crucial for minimizing radiation exposure in pediatric patients.
• Cone-beam computed tomography (CBCT) is a key technology in IGRT.

Purpose of the Study:

• To evaluate a lower-dose CBCT protocol for central nervous system (CNS) IGRT in pediatric patients.
• To assess the setup accuracy and radiation dose of the lower-dose CBCT protocol.
• To determine the suitability of the protocol across a diverse pediatric population.

Main Methods:

• A prospective, multinational study involving seven institutions.
• A lower-dose CBCT protocol (0.7 mGy average dose) was used for patients ≤21 years.
• Setup accuracy was assessed by comparing table shifts from surface lasers versus CBCT, calculating vector magnitudes and estimating errors (group mean, interpatient, interinstitution, random).

Main Results:

• 96 patients with 2179 CBCT acquisitions were analyzed (median age 9 years).
• Setup accuracy vector magnitudes were 3.13 mm (group mean), 3.02 mm (interpatient), 1.64 mm (interinstitution), and 1.48 mm (random error).
• No significant clinical factors (age, gender, performance status, etc.) impacted setup accuracy; >99% of images were adequate for localization.

Conclusions:

• The lower-dose CBCT protocol achieved setup accuracy comparable to clinical target volume expansions in CNS radiotherapy.
• No significant clinical predictors of setup accuracy were identified, supporting broad applicability.
• This lower-dose CBCT protocol is suitable for diverse pediatric brain tumor patients, balancing accuracy and reduced radiation exposure.