How Can Tumor Effect and Normal Tissue Effect Be Balanced in Stereotactic Body Radiotherapy

Feasibility report of image guided stereotactic body radiotherapy (IG-SBRT) with tomotherapy for early stage medically inoperable lung cancer using extreme hypofractionation

“…Delivery of these high doses using conventional treatment planning comes at the price of increased toxicity [17,18]. Utilizing a highly conformal treatment planning technique such as IMRT or tomotherapy has two aims; increasing the dose to the tumor, and minimizing the dose to surrounding normal tissue by decreasing the volume of normal tissue receiving the prescribed dose as far as possible [12]. However, improvements in tumor localization and set-up reproducibility have to be integral components of these techniques, and become increasingly important as treatment fields decrease in size.…”

“…The treatment plans were reviewed, and mean normalized total doses (NTD ) were obtained for both the primary tumor and the total lung volume outside the PTV (residual lung) [11]. The plan was optimized so that the ratio of the prescription isodose volume (PIV) to the volume of residual healthy lung remained below the modeled toxicity threshold as published by us previously [12] and hence the residual mean lung NTD was less than 18.5 Gy 3 for all cases. The maximum FED for the avoidance structures was also obtained for each treatment plan.…”