168 



RADIATION BIOLOGY 



Table 2-2. Physical Data Pertaining to Radiation Dosage Resulting from 

 Radioelements Deposited in Biological Systems 



Z 



1 

 6 

 II 

 11 

 15 

 16 

 19 

 20 

 25'" 

 26* 

 26 

 27 

 29 

 30^ 

 33 

 35 

 38 

 38 

 39 

 53 

 53 

 79 



Radiation 



r,o 



r,o 

 r,o 



r,y 



/3-,0 



K,0 



li~,y 



^-,y 



^+/3-A',0 



(i^,K,y 



li~,y 



p-,y 



r,o 

 r,o 

 ti-,0 



r,y 



/3-,7 



r-y 



Half life, days 



4.49 X 10^ 

 2,03 X 10« 

 950 

 0.62 

 14.3 

 87.1 

 0.516 

 152 

 5.8 

 1060 



46.3 

 1940 



. 535 

 250 

 1.09 

 1.48 

 53 

 8800 

 2.7 

 0.525 

 8.0 

 2.69 



E^, Mev 



0.0057 



0.053 



0.21 



0.54 



0.69 



0.056 



1.40 



. 084 

 0.085 + 0.004 

 0.000 +0.0052 



0.130 



0.099 



0.120 



0.01 



1.06 



1.48 



0.56 



0.20 



0.87 



0.280 



0.200 



0.282 



I-, 



13.2 

 19.1 



1.95 



19.5 



[10]<= 



6.55 

 13.5 



1.2 

 .0 + [5] 



2.2 

 15.1 



13.0 



2.4 

 2.4 



Range" 



0.007 

 0.2 

 2.1 

 6.4 

 8.0 

 0.2 

 19.0 

 0.6 

 2.2 



1.5 



0.8 



2.6 



1.2 

 15.7 



9.4 



7 



2. 

 11.0 



4.5 



2. 



3. 



.0 



.2 



.2 

 ,8 



" Range of the most energetic 13 particle in millimeters of water. 

 '' In these elements E^ includes the energy of the localized X radiation following K 

 capture. 



" Values of ly in brackets pertain to the emission of iv-capture X rays. 



them for computational details on special problems (Richards and Rubin 

 1950; Rossi and Ellis, 1950; Bush, 1949; Oddie, 1951; Loevinger, 1950). 

 Final judgment as to the correctness of the published results, however, 

 must await the experimental determination of the ionization in a light, 

 homogenous medium as a function of distance from a point source 

 emitting /3 radiation over a rather wide range of energy, since in the refer- 

 ences mentioned, use has been made of simplified versions of /3-ray energy 

 loss through matter. Although the fundamental mechanisms involved in 

 this loss are well understood, the actual computations become unmanage- 

 ably complicated when attempts are made to account for the combined 

 effect of stopping power, of i8-ray-energy spectral distribution, and of 

 multiple scattering. Two types of experiments have been performed to 

 determine empirically the jS-ray ionization as a fimction of distance from 

 a point source (Brar, Clark, Marinelli, 1950; Loevinger, 1950; Munick 

 and Clark, 1950). Unfortunately, for the case of P^^ — the only isotope 

 measured by both methods — the results do not agree, and hence the 



