Biologically Targeted Radiation Therapy :Increasing the Radiation Dose with Minimum Increasing Toxicity

Background: In radiation therapy, ۳۰ to ۵۰ % of patients have fail treatment due to local resistance and relapse۱,۲. Dose escalation (DE) is an option and related to both increasing tumor control probability (TCP) and normal tissue complication probability (NTCP) and can be challenging, especially for cancerous cells with low α/β ratio like prostate۳,۴. Advances in treatment approaches such as focal dose boost, image-guided radiotherapy (IGRT) and biology-guided radiotherapy (BgRT) have proper effects on the optimization delivery of the radiation but can still be improved in issues like precise contouring of organs at risk (OARs) and tumors, and toxicities of normal tissues۵. Biologically targeted radiotherapy (BiRT) with the promotion in identification of intra-tumoral heterogeneity, can be next generation of radiation therapy based on radiobiology and quantitative imaging and be utilized even for early recognition of cancers with high risk recurrence.Methods: This study is a narrative review based on articles available in scientific databases such as PubMed, Scopus, Google Scholar, Web of Science and our criteria for inclusion in the studies were the time and worthy quality of the publications, relevance, keywords and survey different aspects of this subject in the researches.Results: Multiparametric magnetic resonance imaging (mpMRI) techniques like DCE, BOLD, DWI and positron emission tomography (PET) besides modeling through voxel-wise mapping of biological characteristics, have the potential to quantitatively describe the extent and spatial distribution of hypoxia, angiogenesis, proliferation and metabolism in different cancers. Indeed, quantitative imaging with information derived from radiomics defines thespatial distribution of tumor heterogeneity resulted in personalizing radiation dose distribution in radiation therapy۶-۹.Conclusion: In summary, BiRT and quantitative imaging determine for clinicians where high doses of radiation and how much of dose should be delivered into target volume respectively, which the result of that is an increase in the therapeutic ratio and lower toxicities of normal tissues .

Keywords:

Biologically Targeted Radiation Therapy , TCP , NTCP , Quantitative Imaging