autok\i)I()<;h\phy 



■7 ;' ■ v»-lf % 



,^ 



PARTtCfe€- -, 

 REAC; 



h-6Q0/i."i 



Fig. 8. Autoradiogram of lung section from 

 chronic Sr'''S04 inhalation experiment. Particulate 

 and diffuse distribution with heavy background 

 grain density of x-ray emulsion visible. (Courtesy 

 J. Biol. Phot. Assoc.^^). 



tological section is included, as Figure 9, for 

 comparison purposes. A noticeable back- 

 ground of grains, larger than in the NTA 

 and NTB emulsions, is observable. This is 

 due in part to the 25 ^ thickness of the x-ray 

 emulsion and in part to the greater sensitiv- 

 ity. Even greater sensitivity could have been 

 obtained had the film used been of the double 

 coated type. However, the image rendered 

 would have been more diffuse because the 

 emulsion layers are coated on either side 

 and separated by an acetate base. In this 

 case detail has been sacrificed to record low 

 activity density deposition of diffuse and 

 particulate Sr^". 



The next example is that of a beta emitter, 

 F'\ which has a 14.5 day half -life (8). A 

 gross, fast survey method for the detection 

 of P^- administered to rats by intraperitoneal 

 injection of 2.5 /xc per gram of body weight 



is outlined. The rats were sacrificed 24 hours 



following administration of the P^^ ^s Nao- 

 HP^^o^ 



The emulsion of choice in this case was 

 25 n, single layer, No-Screen x-ray emulsion 

 on 1 x 3 inch slides. Detail was sacrificed for 

 rough localization of P^^ by using an emulsion 

 with a grain size varing from 3 to 5 /i. The 

 increase in the sensitivity of the emulsion 

 and the thickness insured a positive record- 

 ing of the radioactive sites, with a minimum 

 exposure period. Noticeable disadvantages 

 with this techniciue are the large grain size 

 which makes cellular autoradiography im- 

 possible. The extreme thickness of the emul- 

 sion makes illustration of the recorded data 

 on the film difficult, except by macrographic 

 methods. 



Figure 10 is an autoradiogram of a rat 

 ovary section from an animal sacrificed 24 

 hours following intraperitoneal administra- 



'^W 



,»*-e<,y.4-" 



I'i't^?'. 



%. 





I— 500/i-li,, 



Fig. 9. Hematoxylin and eosin stained histo- 

 logical section adjacent to Fig. 8, for orientation 

 purposes. {Courtesy J . Biol. Phot. Assoc.^^). 



