The Hospital Physicists' Association Diagrams and Data Scheme Calculated Isodose Curves

Abstract

The Hospital Physicists' Association Diagrams and Data Scheme Calculated Isodose CurvesPublished Online:28 Jan 2014https://doi.org/10.1259/0007-1285-30-350-111SectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail AboutAbstractThe Hospital Physicists' Association is publishing through its Diagrams and Data Scheme, sets of X-ray isodose curves based on the depth dose data given in The British Journal of Radiology, Supplement No. 5. It is intended to publish the charts for closed ended applicators at 50 cm F.S.D. and for qualities of radiation of 1·0, 1·5, 2·0 and 3·0 mm Cu H.V.L., although, if there is a reasonable demand for other conditions, this range will be extended. Thirty-nine separate charts for 2 mm Cu H.V.L. are already available and are listed in the Diagrams and Data Scheme, Catalogue D (Supplement 1).In calculating the curves, central axis depth dose data (Clarkson, 1953) were analysed into primary and secondary radiation components by the use of recently published back-scatter factors (Greening, 1954). The distributions of scattered radiation along radial axes parallel to the surface were then determined for depths 0, 1, 2, 3, 4, 5, 10, 15 and 20 cm with an optical integrator (Wheatley, 1951). The sensitivity of the integrator was adjusted at each depth so that the central axis scattered radiation intensity was always read as 100. Its magnitude at other points was then recorded as a percentage of the central axis value. Several advantages arise from this method of operation. In the first place, the values obtained are only slightly dependent on depth and hardly at all on H.V.L. so that self-consistency can easily be checked. Previous article Next article FiguresReferencesRelatedDetails Volume 30, Issue 350February 1957Pages: 57-112 © The British Institute of Radiology History Published onlineJanuary 28,2014 Metrics Download PDF