Bone marrow scanning with52iron (52Fe)—Regeneration and extension of marrow after ablative doses of radiotherapy

Extensively irradiated patients were studied from 0 to 73 months after irradiation by 52Fe bone marrow scanning. Marrow regeneration was observed in most patients after intervals of 12 months or longer. The degree of recovery was not dose-related and the marrow ablative dose was not defined with doses of 4000-5000 rads. Degree of recovery depended more upon the antomic region and/or sequence of fields treated; the last field treated invariably showed poorer regeneration when recovery was uneven. Active erythropoisis expanded into distal inactive erthropoietic sites from 3-12 months after irradiation and then decreased thereafter. Blood count cytopenias were almost always restricted to the first year after irradiation.