Metabolism and pathophysiology of sodium and chlorine in tissue after neutron irradiation

Abstract

The photon emission of tissue was measured after radiotherapy with various doses of fission neutrons. Spectral analyses of the decay rates resulted in data for the exchange of sodium and chlorine between the irradiated tissue and the whole body. In 12 cases we found that about three fifths of Na and Cl exchange rapidly between the extravascular and vascular liquids with a turnover half-life of 13 +/- 2 min. Slowly exchangeable or non-exchangeable fractions are deposited in the soft tissue. New defined mass exchange rates for Na and Cl amount to an average of 0.8 mval min-1 kg-1 of soft tissue. The turnover of the electrolytes in tissue with large tumours is about twice that in tissues with small metastasis. Depending on dose, radiotherapy led in all cases to distinct variations of the metabolism. A maximum of the exchange of Cl combined with a minimum of Na occurs at about 85 Gy of conventional or at 10 Gy of lead-filtered fission neutron radiation. These results show directly for the first time the local response of the electrolyte metabolism to therapy.

Chlorine and sodium perfusion and electrolyte balance in human tissue and tumours before and during neutron and photon radiotherapy

“…As a radiation detector we used a Ge intrinsic diode with a high-energy resolution of about 2 keV. For details we refer to Koester et al (1994). The counting rates (per second), C(t), were measured over 1 h in periods of 2 min.…”

“…In order to eliminate these fractions we used the measured 49 Ca radioactivity to determine the mass of bone and its contents of Cl and Na in situ, by means of which the measured nonexchangeable fractions were corrected to yield the soft tissue values. Details may be found in the work by Koester et al (1994).…”

“…The size of non-exchangeable electrolyte fractions in the human body has been the subject of many studies by in vivo neutron activation analysis (see, for example, Koester et al 1994). About 30% of total Na and Cl in the body should be fixed in connective tissue and partly in cells.…”

“…During the irradiation period of T i minutes the activity concentrations in blood and tissue are of comparable magnitude (Koester et al 1994), so that the clearance of radioactivity in tissue by diffusion into the vascular volume may be ignored. In this case the electrolyte mass M is determined by the equation…”

“…It is the aim of the present work to supplement knowledge of vascularity and perfusion with new data on chlorine and sodium regional exchange in human tissue. The neutron activation in vivo analysis was introduced in a recent work by Koester et al (1994) as a side effect of the reactor neutron therapy (RENT). The regional exchange rates of the electrolytes Na and Cl could be determined with a measuring error also of the order of 10%.…”