The pO{sub 2} in a murine tumor after irradiation: An in vivo electron paramagnetic resonance oximetry study
- Dartmouth-Hitchcock Medical Center, Lebanon, NH (United States); and others
Using electron paramagnetic resonance (EPR) oximetry with the oxygen-sensitive paramagnetic material, fusinite, we have measured the partial pressure of oxygen (pO{sub 2}) in the mouse mammary adenocarcinoma MTG-B. The average pO{sub 2} in untreated tumors was low (about 5 mm Hg) and decreased with tumor growth. Magnetic resonance imaging and histological examination were used to localize the position of the fusinite with respect to tumor margins and vascularization. The pO{sub 2} was generally higher in the periphery than in the center of the tumors, but there was considerable variation among tumors both during normal growth and after radiation treatment. After a single 20-Gy dose, a characteristic pattern of change in tumor pO{sub 2} was observed. In irradiated tumors, there was an initial reduction in pO{sub 2} (minimum occurred 6 h postirradiation). This work demonstrates postirradiation changes in pO{sub 2} of potential radiobiological significance. Compared to other oxygen assessment techniques, EPR oximetry is very useful because it can assess pO{sub 2} in the same region of the tumor over the course of tumor growth and during response to treatment. Thus EPR could be used to identify potentially radioresistant tumors as well as to identify tumors with slow reoxygenation. 43 refs., 5 figs., 1 tab.
- OSTI ID:
- 183329
- Journal Information:
- Radiation Research, Vol. 144, Issue 2; Other Information: PBD: Nov 1995
- Country of Publication:
- United States
- Language:
- English
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