& eluilar computation for the dose index fran intoreert "5" zives the mich higher value 206, The total index at "P¥ is therefore 200, This means that for 10 negatons one would exrect an intezrated Lifotine dose of 220 roentgene in the vicinity of point "P*, _—_: It ds obviously time-consuming to compute the index for a large number ofpeinte in the Meld in the wy just deseribod, In order to speed up the computation of dose indices the nonogran in Pig, 2 was constructed from an altornate form of the dose index equation. « @ 8) = 7) R aT 5;HE Kn? He Tho most suitable form is -R (3e) in Fig. 2 has tw heisht lines, the curved ome corres- curve ia Selieved on, This height as it reduces the weicht of the beecanh move relists low and very bigh parts of the cloud and increases the weicht of the middie cloud. This rather general weighting is based tion and on observace and is not derived enalytically. With a very little experiense in the use ofthe namogr-m ome ¢- n from 16 the hedograph prepare the pict showm in Mg. 3 app roximately on The weighted heicht line bas Sean used im this pl oe e hour, 0-10