HANDLING OF RADIOISOTOPES WITH ANIMALS AND PLANTS 



141 



SO that an accurately known volume of solution is administered. In some 

 instances it may be desirable to deliver all the radioactivity contained in 

 the syringe rather than a predetermined amoinit. This can be done with- 

 out removing the syringe from the site of injection by rinsing it repeatedly 

 with the wash solution, supplied under shght positive pressure from the 

 wash syringe. 



Shielding requirements are easily met for pure beta emitters by simple 

 Lucite shields that cover the body of the syringe (Fig. 4-19). When 



Fig. 4-19. Simple Lucite shield for 1-ml syringe; very convenient for beta emitters. 



gamma emitters are used, the shielding requirements are increased. A 

 syringe shield is available commercially which provides 3'^-in. lead shield- 

 ing and which has been satisfactory in operation at the multimillicurie 

 level. Its features are scale reflection and internal lighting which enable 

 one to read the liquid level in the syringe or check for air bubbles without 

 direct exposure to the radiation. The syringe can be handled without the 

 hand's coming in contact with the shielding directly over the barrel of the 

 syringe. The weight of this unit, however, makes it difficult to do injec- 

 tions requiring a delicate touch. 



Oral Dosage. For studies involving ingestion, the radioisotope can be 

 administered in the feed, in the drinking water, by capsule, or by stomach 



