Modelling responses to spatially fractionated radiation fields using preclinical image-guided radiotherapy

Spatially fractionated (GRID) radiation therapy using proton pencil beam scanning (PBS): Feasibility study and clinical implementation

“…2 Second, a significant tumor response can be achieved not only in high-dose regions but also in low-dose regions due to enhanced reoxygenation as well as possible radiation-induced bystander effects. 5,6 Clinical results have confirmed that GRID therapy is well tolerated by patients and is very effective in treating bulky tumors at various sites. [7][8][9] The standard delivery method for GRID therapy involves using collimating blocks with a distinctive transmission pattern mounted on a linear accelerator (Linac).…”

“…First, the existence of low‐dose regions reduces skin toxicity . Second, a significant tumor response can be achieved not only in high‐dose regions but also in low‐dose regions due to enhanced reoxygenation as well as possible radiation‐induced bystander effects . Clinical results have confirmed that GRID therapy is well tolerated by patients and is very effective in treating bulky tumors at various sites …”

Understanding High-Dose, Ultra-High Dose Rate, and Spatially Fractionated Radiation Therapy

“…A number of data sets were also presented to describe spatial fractionation and the biological response of solid tumors to this type of radiotherapy. Preclinical studies employing a small animal conformal irradiation system have suggested that some of the biological mechanisms of action are related to bystander killing as well as vascular damage and re-modeling leading to improved tumor oxygenation (2)(3)(4). These aspects of biological response by the tumor have been studied in both aerobic and hypoxic conditions, and it was found that hypoxia modifies the bystander killing in some cases.…”

The role of the spatially fractionated radiation therapy in the management of advanced bulky tumors

“…This model could accurately predict the SF of cells in modulated fields. In 2017, Butterworth et al 75 used this model to evaluate the impact of bystander signals on dose-volume histograms and EUD for a range of different GRID treatment plans. They concluded that incorporation of the intercellular signalling effect in the radiobiological model leads to the reduction in survival fraction within the low-dose region of GRID field and results in an increase in the EUD across the tumor.…”