Spin Lattice Relaxation EPR pO2 Images May Direct the Location of Radiation Tumor Boosts to Enhance Tumor Cure

• Published in: Cell biochemistry and biophysics Vol. 75; no. 3-4; pp. 295 - 298
• Main Authors: Epel, Boris, Krzykawska-Serda, Martyna, Tormyshev, Victor, Maggio, Matthew C., Barth, Eugene D., Pelizzari, Charles A., Halpern, Howard J.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.12.2017; Springer Nature B.V
• Subjects: ABS resins; Acrylonitrile; Acrylonitrile butadiene styrene; Animal models; Beams (radiation); Biochemistry; Biological and Medical Physics; Biomedical and Life Sciences; Biophysics; Biotechnology; Cancer; Cell Biology; Computed tomography; Electron paramagnetic resonance; Fibrosarcoma; Hypoxia; Image enhancement; Legs; Life Sciences; Original Paper; Oxygen; Oxygenation; Pharmacology/Toxicology; Polymers; Radiation therapy; Rodents; Spatial discrimination; Spatial resolution; Styrene; Three dimensional printing; Tumors; Tungsten; Image-guided radiation therapy; Oxygen imaging; Radiation treatment; Spin lattice relaxation imaging; Electron paramagnetic resonance imaging
• ISSN: 1085-9195; 1559-0283; 1559-0283
• DOI: 10.1007/s12013-017-0825-2

Radiation treatment success and high tumor oxygenation and success have been known to be highly correlated. This suggests that radiation therapy guided by images of tumor regions with low oxygenation, oxygen-guided radiation therapy (OGRT) may be a promising enhancement of cancer radiation treatment. Before applying the technique to human subjects, OGRT needs to be tested in animals, most easily in rodents. Electron paramagnetic resonance imaging provides quantitative maps of tissue and tumor oxygen in rodents with 1 mm spatial resolution and 1 torr pO 2 resolution at low oxygen levels. The difficulty of using mouse models is their small size and that of their tumors. To overcome this we used XRAD225Cx micro-CT/ therapy system and 3D printed conformal blocks. Radiation is delivered first to a uniform 15% tumor control dose for the whole tumor and then a boost dose to either hypoxic tumor regions or equal volumes of well oxygenated tumor. Delivery of the booster dose used a multiple beam angles to deliver radiation beams whose shape conforms to that of all hypoxic regions or fully avoids those regions. To treat/avoid all hypoxic regions we used individual radiation blocks 3D-printed from acrylonitrile butadiene styrene polymer infused with tungsten particles fabricated immediately after imaging to determine regions with pO 2 less than 10 torr. Preliminary results demonstrate the efficacy of the radiation treatment with hypoxic boosts with syngeneic FSa fibrosarcoma tumors in the legs of C3H mice.