ISO INTERNATIONAL STANDARD 9236-3 First edition 1999-02-01 Photography Sensitometry of screen/film systems for medical radiography - Part 3: Determination of sensitometric curve shape, speed and average gradient for mammography Photographie - Sensitometrie des ensembles film/écran pour la radiographie médicale - Partie 3: Détermination de la forme de la courbe sensitométrique, de la sensibilite et du contraste moyen pour la mammographie Tso Reference number ISO9236-3:1999(E) Not for Resale ISO 9236-3:1999(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO member bodies). The work of preparing International Standards is normally carried out through isO technicalcommittees.Eachmemberbodyinterestedinasubjectforwhich atechnicalcommitteehasbeenestablishedhastherighttoberepresented on that committee. International organizations, governmental and non- governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. ISO/TC 42, Photography. ISO 9236 consists of the following parts, under the general title Photography - Sensitometry of screen/film systems for medical radio- graphy: Part 1: Determination of sensitometric curve shape, speed and average gradient Part 2: Determination of the modulation transfer function (MTF) Part 3: Determination of sensitometric curve shape, speed and Annexes A and B of this part of ISO 9236 are for information only @ISO1999 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International OrganizationforStandardization Casepostale56·CH-1211Geneve20·Switzerland Internet [email protected] Printed in Switzerland Copyright International Organization for Standardization from IHS Not for Resale @ ISO ISO 9236-3:1999(E) Introduction The sensitometric curve, which is also needed for the determination of other properties (as, for example, the modulation transfer function) is measured under low-scatter conditions via intensity scale X-ray sensito- metry, using a sensitometer which is mainly based on the photometric inverse square law. For the determination of the sensitometric curve shape, the irradiation of the screen/film/filmholder combination need be measured only in relative units. While the average gradient is determined from the sensitometric curve shape, speed has to be measured in a separate way, since the exposure conditions should simulate as closely as possible those which are used in practice. Therefore, scattered radiation is included, accompanied by a slight change of beam quality compared to the beam quality used for both an appropriate phantom and tube voltage. The screen/film/filmholder combination is exposed behind the phantom. The exposure shall be measured in absolute units (gray, Gy) in order to determine the speed radiation and the exposure time. Therefore, some variation in speed values may be expected under practical conditions. However, as the range of tube voltages applied in screen/film mammography is small, this part of ISO 9236 describes only one beam quality for speed measurement. The measurement conditions described in this part of iSO 9236 provide values under practical conditions. ili Not for Resale