By G. M. CORNEY 
and H. M. CLEARE 
Research Laboratories 
Eastman Kodak Company 
Rochester, New York 
nucreonics DATA SHEET no. 6 
CS 
Dosimetry 
TABLE 1—Exposure in Roentgens of 1,000-kvp X-rays to 
Produce Various Densities 
Kodak Roentgens 
Kodak film developer D=0.6 =10 =16 =20 =26 =3.0 
Super Panchro- Kodak Rapid 
Press, Type B X-ray 1.3 4.3 1. 30. 85 280. 
DK-60a 1.7 736) 2% 87. 280 1,000. 
Super-XX Kodak Rapid 
X-ray 1.4 4.7 13 $5. 110 440. 
DK-60a 1.9 9.8 38 140. 470 1,300. 
Verichrome Kodak Rapid 
X-ray 1.9 5.4 14 a = = 
DK-60a 2.1 6.9 22 83. = = 
Kodalith Ortho, Kodalith 1,100. 1,400. — 1,700. — 1,900. 
Type 2 
Disaster Monitoring with Amateur 
and Commercial Photographic Films 
IN THE EVENT of an atomic disaster, 
widely distributed stand-by dosimeters 
might be extremely valuable, even if 
they gave only approximate indications. 
Photographic films ordinarily stored in 
commercial stocks and homes might 
fulfill this need. 
With this emergency in mind, the 
sensitivities to penetrating radiation 
were determined for several popular 
films: Kodak Super Panchro-Press 
Film, Type B; Kodak Super XX Pan- 
chromatic Film; Kodak Verichrome 
Film; and Kodalith Ortho Film, Type 
2. X-ray films were not included be- 
cause their sensitivities to penetrating 
radiation have been published (1-3). 
Film Calibration 
Film sensitivities, in roentgens, were 
determined for the unfiltered primary 
radiation from a 1,000-kvp resonant- 
transformer X-ray machine and were 
checked with radium gamma rays. 
These sensitivities also apply reason- 
206 
ably well to radiation generated at 
voltages up to several Mev and to the 
gamma rays of radium and cobalt-60, 
and therefore should also apply to 
atomic bomb prompt radiation (4). 
Photographic materials are less sensi- 
tive to these hard radiations, e.g., 
1,000-kvp X-rays, than to softer radi- 
ations. Therefore, calibrations made 
with 1,000-kvp X-rays would cause 
softer radiations to be overvalued. 
Specifically, such a calibration would 
cause overvaluation of any residual 
radiation from an atomic bomb (4) to 
which the film may have been exposed. 
The magnitude of the error would be 
difficult to estimate. The extent of 
the exposure to the residual radiation 
would, in general, be unknown. Fur- 
ther, different types of film vary in 
their relative sensitivities to hard and 
soft radiation. Silver-bromide photo- 
graphic materials would be expected 
to have a spectral sensitivity curve to 
X- or gamma rays similar to that given 
by Wilsey (1), but the ratio of maxi- 
mum to minimum sensitivity depends 
upon the specific material. Therefore, 
the dosage values obtained with re- 
covered film should be regarded as 
“approximate maximum dosages.” 
To calibrate the films, samples in 
light cardboard holders were placed at 
a series of distances from the X-ray 
focal spot and exposed simultaneously 
to 1,000-kvp X-rays. The intensity 
(r/min) for one film location was deter- 
mined to within 10% (5) with a Vic- 
toreen condenser-type r-meter. From 
this, the dosage to each film of a series 
could be computed. The films were 
developed in deep tanks, for the times 
shown in Table 1; fixation, washing, 
and drying followed normal procedure. 
A few points for each film were 
checked by exposing films to known 
radium gamma-ray dosages. These 
agreed with the X-ray measurements 
to within +15%. The difference be- 
tween the two determinations included 
