Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA

*Corresponding author: CM Charlie Ma, Ph.D., Radiation Oncology Department, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA; Tel: (215) 728-2996; Fax: (215) 728-4789; Email: [email protected]

Received Date: March 3, 2024

Publication Date: March 17, 2024

Citation: Ma CMC, et al. (2024). Fraction-Modulated Dose Optimization for Advanced Radiation Therapy. Mathews J Cancer Sci. 9(1):47.

Copyright: Ma CMC, et al. © (2024)

ABSTRACT

The recent growth in technology of radiation treatment machines has resulted in advanced radiation therapy treatment techniques that deliver conformal dose distributions to cover treatment targets while sparing nearby critical structures. This has further facilitated clinical trials on dose escalation and fractionation to explore advanced treatment strategies for further improvement in tumor control and normal tissue toxicities. Radiobiological dose conversion plays an important role in conventionally fractionated radiation therapy (CFRT) that employs daily 2 Gy/fractions and stereotactic body radiotherapy (SBRT) that employs ablative doses (8-30Gy/fraction). This work investigates the radiobiological dose characteristics of CFRT and SBRT and the potential application of fraction-modulated dose optimization (FMDO) for advanced treatment planning. Physical dose distributions were converted to the biologically equivalent dose in 2-Gy fractions (EQD2) for tumors with an α/β ratio of 10 Gy and for normal tissues with an α/β ratio of 3 Gy. The Prowess Panther TPS was used for the EQD2 conversion and for FMDO-based plan optimization, in which the dose, fractionation and tissue radio-sensitivity are built in the planning objectives. The results showed that EQD2 in normal tissues immediately outside the target volume was much greater than EQD2 in the target, especially with fewer treatment fractions. The difference in EQD2 between the target and normal tissues decreased rapidly with the increasing distance from the target, and it reversed roughly outside V_50%Dp, the volume receiving 50% of the prescription dose. This is an important finding as the reversed EQD2 difference is the basis for SBRT parameters such as R50% and for FMDO-based treatment planning, which is beneficial to complex cases with multiple targets and overlapping target-OAR geometries. Realistic clinical cases demonstrated that doses to critical structures outside V_{50% Dp} could be reduced significantly (up to 50%) with SBRT compared with CFRT using the FMDO technique.

Keywords: Conventional fractionation radiation therapy (CFRT), stereotactic body radiation therapy (SBRT), radiobiology, EQD2, treatment planning, fraction-modulated dose optimization (FMDO)