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The C15O2 and 15O2 steady state techniques have been used to quantitatively measure regional blood flow (RBF) and regional oxygen utilisation (ROU) in a rabbit tumour model. RBF values of 4.6 +/- 0.6 ml min/100 cc were measured for normal muscle tissue and 11.0 +/- 3.0 ml/min/100 cc for tumour surface. Corresponding values for ROU were 18.3 +/- 3.5 mumol/min/100 cc for normal tissue and 39.7 +/- 20.1 mumol/min/100 cc for tumour surface. 18F-2-fluoro-2-deoxy-D-glucose (2FDG) was used in the same tumour model to measure glucose metabolic rate. The values obtained were 4.3 +/- 2.1 mumol/min/100 cc for normal muscle tissue and 53.8 +/- 18.3 mumol/min/100 cc for tumour tissue. Tumour growth was followed with a series of measurements of blood flow, oxygen, and glucose metabolism at intervals of 1 week. Tumour-to-muscle ratios increased more rapidly with time for 2FDG than for oxygen utilisation and blood flow. The effect of radiation on tumour and normal tissue was followed by measurements of RBF and ROU. RBF values increased both in tumour and normal muscle tissue during radiation and decreased during one week after radiation. ROU-values decreased (30%) in tumour and increased (45%) in normal muscle tissue during radiation. Even at one week after radiation, ROU-values were 30% lower in tumour and 45% higher in normal muscle tissue than before radiation.

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An improved method for determining absorbed dose from internal gamma-photon emitters has been developed. This method rigorously considers the contribution to the absorbed dose from both direct and scattered radiation and gives results in terms of absorbed fractions, specific absorbed fractions and dose build-up factors. Appropriate equations that utilize these different quantities are given for absorbed dose calculations.Absorbed fractions for both point sources and uniformly distributed sources in different target shapes and sizes for various source energies are given in graphical form to enable accurate interpolation. Specific absorbed fractions and dose build-up factors for central point isotropic source are given for various energies and distances from the source, in both finite and infinite tissue equivalent media. The effect of a boundary on the values of specific absorbed fractions and build-up factors is discussed. Variation of these quantities with energy and size of the target is presented graphically.