THE SUCCESSFUL RADIATION THERAPY OF CANCER DEPENDS UPON THE THERAPEUTIC RATIO; THE RADIATION RESPONSE OF THE TUMOR COMPARED TO NORMAL TISSUES.

THE SUCCESSFUL RADIATION THERAPY OF CANCER DEPENDS UPON THE THERAPEUTIC RATIO; THE RADIATION RESPONSE OF THE TUMOR COMPARED TO NORMAL TISSUES. THROUGH THE USE OF PENETRATING BEAMS AND FRACTIONATED SCHEDULES THE ACUTE EFFECTS HAVE BEEN REDUCED; HOWEVER, THE LATE RESPONSE OF TISSUES, PARTICULARLY FIBROSIS, REMAINS AS A COMPLICATION. THERE IS LITTLE QUANTITATIVE INFORMATION ON THE DEVELOPMENT OF RADIATION INDUCED FIBROSIS AFTER SINGLE OR FRACTIONATED DOSES. IN THE PAST TWO YEARS METHODS HAVE BEEN DEVELOPED TO ASSAY FIBROTIC CHANGES IN TISSUES. TO TEST THE FEASIBILITY OF USING THESE ASSAYS TO MEASURE FRACTIONATED INDUCED FIBROSIS, ANIMALS WILL BE IRRADIATED UNDER THE FOLLOWING CONDITIONS: SINGLE DOSE, ANESTHETIZED AND PARTIAL BODY SHIELDED; LIMB SHIELDED; OR SEVERAL FRACTIONATED SCHEDULES IN UNANESTHETIZED MICE. FOUR MONTHS AFTER EXPOSURE THE SYNTHESIS OF COLLAGEN IN SKIN AND LUNG WILL BE MEASURED BY THE INCORPORATION OF 3H-PROLINE INTO OH-PROLINE (AN AMINO ACID ESSENTIALLY UNIQUE TO COLLAGEN). TOTAL COLLAGEN CONTENT WILL BE MEASURED IN FIXED, PARAFFIN-EMBEDDED TISSUES FROM THE SAME ANIMALS. THE RESULTS FROM THESE STUDIES WILL DEMONSTRATE WITHIN 6 MONTHS THE FEASIBILITY OF USING THE ASSAY SYSTEMS AND THE RADIATION SCHEDULES TO RAPIDLY MEASURE FRACTIONATED, RADIATION INDUCED FIBROSIS.