Economics of computer dosimetry

The literature concerning automatic dose planning methods contains sparse information about the time required and the cost. Bentley (1964) estimates the cost at 2 British Pounds ($5.60) for summation of digital dose-data from four fields in an array with 250 points on an ICT 1301, and states that the cost per plan will be lower if several plans are computed at the same time. With the analytical method described by Hope and Walters (1964) the summation time per field varies between 1/2 and 1 1/2 min on a Ferranti Sirius computer. The type of computer and the calculation method used strongly influence the time required for the computation. The cost per minute for a high-speed computer is, however, very much higher than for a slow computer, and the great variations in computing times between different machines will not necessarily be reflected in the final cost. This will, on the other hand, always be proportional to the number of dose-data to be handled and it is thus expensive to use arrays with a great number of points for the input-fields and for the resulting distributions. Variations in technique make it difficult to compare different computer methods. These difficulties are, however, small compared with those which arise when one tries to estimate and compare the manual techniques used at various hospitals