Multicenter Study of Dose Accumulation for Reirradiation: Intercenter Variation in Radiobiological Dose Scaling...

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy

Background:

• Reirradiation dose accumulation is critical for effective cancer treatment.
• Variability in dose accumulation methods can impact patient outcomes.
• Standardization of image registration and radiobiological dose scaling is needed.

Purpose of the Study:

• To investigate intercenter variation in reirradiation dose accumulation.
• To assess the impact of image registration techniques and radiobiological dose scaling on dose accumulation.
• To analyze variations across eight patient cases and anatomical regions.

Main Methods:

• Eight centers performed dose mapping using rigid or deformable image registration.
• Doses were accumulated as physical dose and equieffective dose in 2 Gy fractions (EQD2).
• Dose scaling factors (DSFs) were applied to account for recovery; one dose-limiting organ at risk (OAR) was analyzed per case.

Main Results:

• Intercenter variation in accumulated dose (D1%) due to image registration alone ranged from 0.7 Gy to 9.5 Gy.
• EQD2 scaling increased intercenter variation for most OARs.
• DSFs significantly altered dose ranges, e.g., bladder (1.6 Gy to 5.8 Gy) and bowel bag (7.6 Gy to 10.9 Gy).

Conclusions:

• Discrepancies in radiobiological dose scaling methods are a major driver of intercenter variation.
• This variability is observed across a wide spectrum of tumor sites.
• A lack of consensus in dose scaling practices complicates consistent reirradiation dose accumulation.