dS
BOND, CRONKITE, SONDHAUS, IMIRIE, ROBERTSON, AND BORG
—T
140
4
120
4
us
a
2 100
4
x
=
_
4 80
4
=<
<I
ox
a4
—
=
lad
60
—
ke
=
lid
oO
a
*
~
40}-
SN,
L{a)
250 KVP X-RAY
~~
XS
Z
me
(b)—--— 2000 KVP X-RAY
20}-(c }—— BOMB, INITIAL GAMMA
RADIATION
—{ d)----- Co®° GAMMA RADIATION
0
l
5
|
10
|
15
1
l
20..+»=«-25
4
7
t
30
DEPTH (cm)
Fig. 3. Unilateral exposure depth-dose curves in a Masonite phantomfor cifferent energy
radiations; depth dose expressed as per cent of entrance air dose,
it was desired to present depth-dose patterns as actually observed and since inverse square corrections can be applied by the reader, if desired.
RESULTS
The depth-dose curves obtained for the various exposure conditions are shown
in Figs. 3 and 4+. In these figures, the tissue dose is expressed as per cent of the
entrance air dose. Additional theoretical and analytical treatment of the several
exposure situations is given in reference 2.
Unilateral exposure. In Fig. 3, the depth-dose patterns obtained with 250- and
2000-kvp X-rays, Co, and the imitial bomb y-radiations are shown for com-
parison. In all cases the total dose is delivered in a single exposure from one side
of the phantom.’ It is apparent from the figure that marked nonuniformity of
* The term “unilateral” is applied for convenience to the exposure to the inittal +-radintion
from the stomie bomb, even though an appreciable component of the total dose undoubtedly
is received from the lateral and distal aspects of the phantom.