XA9642869 IAEA-TECDOC-897 Review of data and methods recommendedthe in international code of practice IAEA Technical Reports Series No. 277, Absorbed Dose Determination in Photon Electronand Beams Proceedings of a consultants meeting held Vienna,in 8-11 December 1992 INTERNATIONAL ATOMIC ENERGY AGENCA / Y The originating Section of this publication in the IAEA was: Dosimetry Section International Atomic Energy Agency Wagramerstrasse 5 0 10 x P.OBo . A-1400 Vienna, Austria REVIEW OF DATA AND METHODS RECOMMENDED IN THE INTERNATIONAL CODE OF PRACTICE IAEA TECHNICAL REPORTS SERIES No. 277, ABSORBED DOSE DETERMINATION IN PHOTON AND ELECTRON BEAMS IAEA, VIENNA, 1996 IAEA-TECDOC-897 ISSN 1011-4289 ©IAEA, 1996 Printe IAEe th AustriAn y i d b a August 1996 The IAEA doe t normallsno y maintain stock f reportso thisn i s series. However, microfiche copies of these reports can be obtained from ClearinghousS I N I e International Atomic Energy Agency Wagramerstrasse 5 P.O. Box 100 A-1400 Vienna, Austria Orders should be accompanied by prepayment of Austrian Schillings 100,- in the form of a cheque or in the form of IAEA microfiche service coupons orderee whicb y dhma separatel ClearinghouseS I y N froI e mth . FOREWORD Repors Determinationn it o n I 4 2 t of Absorbed Dose Patienta n i Irradiated Beamsy b ofXor Gamma Rays Radiotherapyn i Procedures, Internationae th l Commissio Radiation no n Unit Measurementd san s (ICRU, 1976) concluded "althoug earlo to generalizeo ys t i t hi e th , available evidence for certain types of tumor points to the need for an accuracy of ±5% in the deliver absorben a f yo d dostargea o et t volum eradicatioe th f ei primare th f no y tumos i r sought". The limit was given in a context where uncertainties were estimated at 95% confidence limits, and therefore corresponds to approximately two standard deviations. It is considered today that the above goal of ±2.5% (one standard deviation) in dose deliver patiene th o figure yt tth strico mighd eto an te shoul b t d probabl increasede yb t bu , o definitn ther e ar ee recommendation n thii s s respect. What modem radiobiologs ha y confirme neee higr th dfo s di h accurac dosn yi e deliver techniquew ne f yi radiotherapyn si , includin e increasgth f prescribeeo d dose valueo t s s wit precedeno hn pase th t n i (dost e escalation in conformal radiotherapy), are to be applied. The present possibilities in radiotherapy, using modern diagnostic tools for determination of the target volume and advanced accelerator irradiationr sfo onln utilizee ca ,y b adequat n a therf i n d i y higs ei ewa h accuracy in absolute dose determination. There are many steps involved in the dosimetry of a patient undergoing radiotherapy treatment, starting with the determination of primary standards of absorbed dose or kerma at Primary Standard Dosimetry Laboratories (PSDLs), followed by the calibration of ionization chambers at Secondary Standard Dosimetry Laboratories (SSDLs) endind an , g with calculation irradiatiof so n tim accelerator eo r monitor patiene unitth r sfo t treatment differene th l Al . t steps include uncertainties gread an , t cars ei e procedureth neede l al n i do minimizt s e these uncertaintie orden i s o ensurt r e thae th t radiation treatmen acceptabln a s tha e quality. So-called dosimetry protocols, describing procedures to determine the absorbed dose in reference conditions at radiotherapy treatment facility, were published by various national medical physicist associations in the seventies and early eighties. These protocols improved the consistenc dosimetrn yi y withi ncountra t differenceybu s betwee protocole nth s resulted in deviations, in some cases of several per cent, among different countries. An International Cod f Practiceo publishes ewa IAEe th A198y n i db 7 (IAEA Technical Reports Serie. sNo 277) orden i , promoto t r worla e d wide consensu dosn i s e determinatio r radiotherapynfo . Authors were chosen who had already had been involved in writing the different national protocols and a large advisory group was consulted before the publication. The most up-to- date dat interaction ao n coefficient correctiod an s n factors were used repore Th . t therefore represented the highest possible accuracy in the field of dosimetry for ^Co y-beams and photon and electron beams from accelerators; for kilovoltage X rays the uncertainty was larger due to the intrinsic uncertainties in some correction factors not sufficiently known at that time. S 277Afte n initiaTR a ,r f researc o le fiel e f th perioradiotherap o dus n i hf o d y dosimetry indicated the need for a review of the data and procedures recommended in the International Code of Practice, and an analysis of the possible impact of new developments. An international working group was formed, which met at the end of 1992, to review the status of the Code of Practice. The working group surveyed scientific results on topics related to TRS 277, recommending that in certain cases important changes ought to be made, whereas in other situations it was considered that ignoring new developments would not significantly affect the dosimetry of radiotherapy patients. The dosimetry of kilovoltage X rays deserved special attention recommendatione th d ,an % 7 so t include p u 7 27 d S change date TR f th ao n si which could have important clinical consequences. In all cases the users of the Code of Practice should be made aware of the changes in dosimetry recommendations resulting from findingsw ne e th . A booklet entitled "Working material", which include a dsummar y with main recommendation reviewd san differenn so t topic f ionizatioso n chamber dosimetry (uses da source recommendations)e th r sfo prepares IAEe wa , th Ay db Dosimetry Section responsible preparatioe foth r publicatioe th f n o Internationae th f no l Cod Practicef eo orden .I expano rt d the dissemination of the changes to the recommendations of TRS 277 this material is now publishe presene th s da t IAEA-TECDOC. EDITORIAL NOTE In preparing this publication for press, staff of the IAEA have made up the pages from the original manuscripts as submitted by the authors. The views expressed do not necessarily reflect those governmentsofthe nominatingthe of Member nominating the States of or organizations. Throughout the text names of Member States are retained as they were when the text was compiled. The use of particular designations of countries or territories does not imply any judgement by the publisher, legal the IAEA, to the status as of such countries territories,or of their authoritiesand institutions or of the delimitation of their boundaries. The mention of names of specific companies or products (whether or not indicated as registered) does imply intentionnot any infringeto proprietary rights, should construednor be it an as endorsement recommendationor IAEA. partthe the of on The authors are responsible for having obtained the necessary permission for the IAEA to reproduce, translate or use material from sources already protected by copyrights. CONTENTS Review of data and methods recommended in the international code of practice IAEA Technical Reports Series No. 277, Absorbed Dose Determination in Photo Electrod nan n Beams .................................7 . Andreo,P. A.E. Nahum, Hohlfeld,K. SvenssonH. The status of high- energy photon and electron beam dosimetry five years after the publication of the IAEA Code of Practice (Abstract) ................ 11 P. Andreo Testin IAEe th Af go Cod Practicf eo gammo ^C t ea a rays ................3 1 . LeitnerA. The use of plane-parallel chambers for the dosimetry of electron beams in radiotherapy ......................................... 17 A.E. Nahum, D.I. Tkwdtes Testing of the IAEA code: Absorbed dose determination at '"Co gamma radiation . 37 HohlfeldK. In-phantom measuremen absorbef o t d dos wateo et mediun i r m energy X-ray beams ..............................................7 4 . K. Hohlfeld Lis Participantf o t s ........................................9 6 . Recent IAEA publications on radiation dosimetry ...................... 71 NEXTPAQE(S) I I toft BLANI K REVIE DATF W METHODO D AAN S RECOMMENDEE TH DN I INTERNATIONAL COD PRACTICF EO E IAEA TECHNICAL REPORTS SERIE . 277SNo , ABSORBED DOSE DETERMINATION IN PHOTON AND ELECTRON BEAMS P. Andreo, A. E. Nahum, K. Hohlfeld, H. Svensson The validity of the recommended procedures, data and dosimetry correction factors e Internationagiveth n i n l Cod f Practiceo e : IAEA Technical Reports Serie . 277No s , Absorbed Dose Determinatio Photon ni Electrod nan n Beams, were analyse workina y db g grou Decemben pi r 1992 maie Th .n conclusion recommendationd san changer S sfo TR n si 277 are summarized in this status report and categorized according to radiation quality. Detail recommendatione th n so paperfoune e b th n n di s ca following this summary. 1. HIGH ENERGY ELECTRONS absorbee Th d dos wateo et r ove ranga r electrof eo n energies determined accordino gt TRS 277 agrees within 1% with determinations based on non-ionometric methods. The values e fluencth f o e perturbation factor r cylindricafo s l chambers , havu p , e been e founb o t d somewhat too high, but the change in dose would be less than 0.4%. Possible changes in the basic stopping-power data due to alternative derivations of the density-effect correction have been found to have a minor effect (below 0.5%) on (s,,^,),,. Similarly, recomputations of swair(E0,z) using 3 different Monte Carlo codes have not revealed any significant differences fro date mth a bas f valuedespiteo 7 27 discovere sS eth give TR majoa n n i f yo r e erroth n i r particular Monte Carlo code used to derive these values.