Keywords:
Radiotherapy techniques, Biological effects, Radiobiology, Radiation therapy / Oncology, Cone beam CT, Radiation physics, Head and neck, Computer applications
Authors:
W. Harriss-Phillips, E. Bezak; ADELAIDE/AU
DOI:
10.1594/ranzcr2014/R-0162
Aim
Stereotactic body radiation therapy (SBRT) is an increasingly important treatment option for delivering large localised radiation doses to non-brain legions.
Non-conventional fractionation effects are a subject of radiobiological research; including issues such as non-LQ dose responses and the reduction of beneficial reoxygenation (ROx) effects. As such,
clinical trials (e.g.
RTOG phase III 1112 and phase II 0618) are being pursued and the technique is being applied at many centres to treat diseases such as lung,
liver and head and neck squamous cell carcinoma (HNSCC) metastases.
In this work,
tumour hypoxia during SBRT was investigated using the HYP-RT Monte Carlo model1-2,
for schedules delivering between 6 and 15 Gy per fraction,
which also were compared to conventional 2 Gy per fraction outcomes. Results were generated in the form of the total dose required to kill all cells and hence achieve tumour control.
Reoxygenation effects were investigated for hypoxic tumour simulations,
as well as expansion of embedded LQ cell kill equations to include a cubic “γ” term3,
which reduces cell kill at high doses.