Radioisotopic pulmonary lobectomy: feasibility study in dogs.

In search for an alternate treatment for inoperable cancer of the lung in humans, we investigated the possibility that introduction of radioactive material into a selected lobe of the canine lung would effectively destroy that lobe without systemic effects or radiation injury to adjacent organs. Ten million ion exchange microspheres labeled with 740 MBq of phosphorus-32 (32P) were injected through a catheter placed in a selected lobar branch of a pulmonary artery in 12 anesthetized dogs. Six additional dogs served as controls and received 10 million microspheres not labeled with 32P. Organs were harvested from 1 wk to 12 mo after injection and examined grossly and histologically. There was progressive organization and contraction of each necrosed 32P treated lobe which was reduced to a scarred remnant by 12 mo, whereas only minimal inflammatory changes occurred in controls. Of the 32P injected dose, 94% remained in injected lobe, 4%-5% in nontargeted lobes and less than 0.08% in blood. Radioactivity in liver, kidneys, spleen, heart, and bone marrow was less than 0.1% for each organ. Thus, large doses of radiation in the order of 1,500 Gy can be effectively delivered to a selected lobe to produce a "radioisotopic pulmonary lobectomy."

Collimator and xenon-127 for ventilation studies.

In comparison with xenon-133, the more energetic emissions from xenon-127 suffer less attenuation by tissues and should therefore provide images with better resolution in ventilation studies. However, the better resolution of the low-energy collimator used with xenon-133 may outweigh such advantages of the more energetic emission of xenon-127, which requires a medium or high-energy collimator.

The health physics of xenon-127.

Dosimetry calculations were performed for clinical ventilation studies in which xenon-127 was used in place of xenon-133. A graphical method for obtaining the maximum permissible concentrations for a facility that uses both isotopes is presented. Shielding requirements are also described.