INTERNATIONAL STANDARD ISO 16645 First edition 2016-10-01 Radiological protection — Medical electron accelerators — Requirements and recommendations for shielding design and evaluation Radioprotection — Accélérateurs médicaux d’électrons — Exigences et recommandations pour la conception et l’évaluation du blindage Reference number ISO 16645:2016(E) © ISO 2016 ISO 16645:2016(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2016, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2016 – All rights reserved ISO 16645:2016(E) Contents Page Foreword v Introduction vi Scope Normative references Terms and definitions 3.2 Quantities Definitions 4.1 4.2 Shielding design goals Shielding design assumptions 3.1 Shielding design goals and other design criteria Role o f the manu facturers, o f the radiation protection o fficer or qualified expert and interactions between stakeholders 5.1 5.2 5.3 5.4 5.5 5.6 Radiation fields around a linear electron accelerator 11 6.1 6.2 6.3 6.4 General 11 X-ray radiation 11 6.2.1 Primary X-ray beam 11 6.2.2 Primary electron beam bremsstrahlung 12 6.2.3 Secondary X-ray radiation 12 6.2.4 Tertiary X-ray radiation 13 Neutron radiation 13 6.3.1 General 13 6.3.2 Direct neutron radiation 14 6.3.3 Scattered and thermal neutron radiation 14 6.3.4 Primary barrier neutron radiation 15 γ radiation 15 6.4.1 General 15 6.4.2 Maze γ radiation 15 6.4.3 Door γ radiation 15 6.4.4 Primary barrier γ radiation 15 6.4.5 Air γ radiation 16 Shielding materials and transmission values 16 General formalism for shielding calculation 18 Shielding calculation for conventional devices 20 9.1 9.2 9.3 10 General Linear accelerator manufacturer Shielding material vendor Architectural firm/general contractor 10 Radiation protection o fficer or qualified expert 10 The licensee 11 General 20 Primary barriers 20 9.2.1 Radiation components 20 9.2.2 Barrier with a unique material 21 9.2.3 Barrier with multiple layers 21 Secondary barriers 22 9.3.1 Radiation components 22 9.3.2 Barrier with a unique material 23 9.3.3 Barriers with multiple layers 24 Doors and mazes 24 10.1 General 24 © ISO 2016 – All rights reserved iii ISO 16645:2016(E) 10.2 Radiation components 25 10.3 Standard maze 25 25 30 10.3.3 Maze neutron and capture gamma calculations 31 10.4 Two legged maze 33 10.5 No maze - Direct-shielded doors 34 10.5.1 General 34 10.5.2 Shielding at the far side of a direct-shielded door entrance 35 10.5.3 Shielding at the near side of a direct-shielded door entrance 37 10.6 No door at maze entrance 39 10.7 Door Calculations 40 10.7.1 General 40 10.7.2 Maze door calculations 40 10.7.3 Direct Shielded Door Calculations 41 1 H elical intens ity mo dulated radio therapy 1 D edicated device o r intra o p erative radio therapy with electro ns Ducts 43 12.1 Duct impact on radiation protection 43 43 12.3 Additional shielding 44 12.3.1 General 44 12.3.2 Neutron and capture gamma radiation passing through the interior of the shielded duct 44 12.3.3 X scattered radiation passing through the interior of the shielded duct 45 12.3.4 Scattered radiation passing through the walls of the duct shielding 46 12.3.5 Dose equivalent at HVAC duct exterior opening 46 2 Reco mmended lo catio n and geo metry Special considerations 46 13 46 13.1.1 General 46 46 48 13.2 Groundshine radiations 49 13.3 Joints and junctions 49 S kys hine 15 A n n e x A n n e x A n n e x B i b l i o X- ray s kys hine radiatio n 3 N eutro n s kys hine radiatio n 49 14.1 General 49 50 14.3 Evaluation 50 Indication, warning signs, interlocks 52 (informative) Tenth value layers for the most common shielding materials 53 (informative) Supporting data for shielding calculations 66 (informative) f f 68 74 S h i e l d iv X- ray direct Leakage 11.1 General 41 11.2 Robotic arm accelerator 41 42 42 f 12 M aze X- ray s catter calculatio ns 0.3 Shielding calculations for special devices 41 11 1 0.3 A B C g n g e v a l u p h a t i o n ( e x p e r i m e n t a l v e r i f i c a t i o n ) M eas uring equip ment and metho lo gy r a i E x a m p l e o c a l c u l a t i o n o r c o nv e n t i o n a l d e v i c e a n d s t a n d a r d m a z e y © ISO 2016 – All rights reserved ISO 16645:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented 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 o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the di fferent approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules o f the ISO/IEC Directives, Part www.iso org/directives Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received www.iso org/patents Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the following URL: Foreword - Supplementary in formation The committee responsible for this document is ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection , Subcommittee SC 2, Radiological protection © ISO 2016 – All rights reserved v ISO 16645:2016(E) Introduction Radiotherapy uses external beam radiation to kill cancer cells and shrink tumours The use o f electron linear accelerators to administer external beam radiation has spread during recent decades and is now common throughout the world These accelerators deliver high energy electron and photon beams with increasingly high dose rates Although the use o f radiotherapy is well established, irradiation techniques have continued to evolve and are becoming increasingly complex Examples include modulation o f beam intensity, availability o f high dose rate modes, arctherapy, helical intensity modulated radiotherapy, robotic arm accelerators, and dedicated devices for intra-operative radiotherapy The shielding design o f treatment rooms has been evolving with these changes The higher radiation workload associated with most of these techniques can impact the shielding materials used The irradiation technique can also impact the geometry to be considered in the shielding calculations IEC 60601-2-1 relates to the design and the construction of the accelerators in order to ensure the In addition, several national[2][3] or international (IAEA Sa fety Reports Series Report No 47, 2006) reports propose recommendations concerning the installation and the exploitation o f these accelerators, the sa fety devices, the design and the calculation o f protections, the radiological control and monitoring National standards have been established in certain countries[4] [5] Moreover national regulations impose particular rules of protection against radiation, in particular sa fety o f their operation[1] relating to the definition o f the controlled areas and the calculation o f shielding Taking into account the developments o f new irradiation techniques and o f new designs o f treatment room facilities on the one hand, and the variety o f guides or normative documents on the other hand, it appeared judicious to establish an international standard to be used as a general framework This standard is intended to be complementary to the other international standards (IEC and IAEA) The following items are discussed in the standard: — types o f accelerators: conventional accelerators with and without flattening filter (FF and FFF operating modes), devices for helical intensity modulated radiotherapy and robotic arm accelerator, dedicated machines for intra-operative radiotherapy; — radiation fields: electrons, X photons and neutrons (direct, scattered, leakage), neutron capture gamma rays; — Treatment room geometry: maze without and with door, no maze with direct door; — materials o f protection: concrete (ordinary or high density), metals, laminated barriers (concrete and metal), hydrogenated materials, earth and others; — design o f the radiotherapy facility: — calculation methods o f the shielding, including neutrons, various types o f installations and shielding geometries; — evaluation o f the impact o f the maze and calculation o f the protection o f the entrance door; — evaluation o f the impact o f the ducts (ventilation and air-conditioning, high voltage and fluids) and additional protections; — shielding design assumption and goals; — Radiation survey o f the completed installation to ensure national requirements have been met and the shielding and design is fit for purpose a fter installation o f the accelerator vi © ISO 2016 – All rights reserved INTERNATIONAL STANDARD ISO 16645:2016(E) Radiological protection — Medical electron accelerators — Requirements and recommendations for shielding design and evaluation Scope This International Standard is applicable to medical electron linear accelerators i.e linear accelerators with nominal energies of the beam ranging from MV to 30 MV, including particular installations such as robotic arm, helical intensity modulated radiotherapy devices and dedicated devices for intra operative radiotherapy (IORT) with electrons The cyclotrons and the synchrotrons used for hadrontherapy are not considered The radiation protection requirements and recommendations given in this International Standard cover the aspects relating to regulations, shielding design goals and other design criteria, role of the manu facturers, o f the radiation protection o fficer or qualified expert and interactions between stakeholders, radiations around a linear accelerator, shielding for conventional and special devices (including shielding materials and transmission values, calculations for various treatment room configurations, duct impact on radiation protection) and the radiological monitoring (measurements) NOTE NOTE NOTE Annex A provides transmission values for the most common shielding materials Annex B provides supporting data for shielding calculation Annex C provides an example of calculation for conventional device and standard maze Normative references The following documents, in whole or in part, are normatively re ferenced in this document and are indispensable for its application For dated re ferences, only the edition cited applies For undated re ferences, the latest edition o f the re ferenced document (including any amendments) applies IEC 60976, Medical electrical equipment — Medical electron accelerators — Functional performance characteristics IAEA Sa fety Reports Series Report No 47, Radiation protection in the Design of Radiotherapy Facilities (2006) Terms and definitions For the purposes o f this document, the terms and definitions given in IEC 60976 and the following apply 3.1 Quantities 3.1.1 absorbed dose D quotient of dε D= by dm, where dε is the mean energy imparted to matter o f mass dm thus dε dm © ISO 2016 – All rights reserved ISO 16645:2016(E) No te to entr y: I n th i s c u ment, the ab s orb e d s e i s defi ne d for rad iation pro duce d b y a l i ne ar accelerator at a s p e ci fic lo c ation: the ab s orb e d s e to water at the i s o centre (at m from the s ou rce for conventiona l device s) at a reference depth in water in electron equilibrium conditions (for example at the depth of maximum absorbed dose) N o te to entr y: T he u n it o f ab s orb e d s e i s j o u le p er ki lo gra m ( J · kg−1 ) , a nd its s p e c i a l n a me i s gray (Gy) [SOURCE: ISO 12749-2:2013, 4.1.6.7] [6] 3.1.2 absorbed dose rate output rate DRo dose absorbed per unit of time N o te to entr y: I n th i s I ntern ation a l Sta nda rd , i n the ab s ence o f s p e c i fic i nd ic ation , the ab s o rb e d s e rate i s de fi ne d fo r rad iation p ro duce d b y a l i ne a r accelerator at a s p e c i fic lo c ation: the ab s o rb e d s e rate to water at the isocentre (at m from the source for conventional devices) at a reference depth in water in electron equilibrium conditions (for example at the depth of maximum absorbed dose) f ) The usual unit for medical accelerators ) N o te to entr y: T he u n it o ab s orb e d s e rate i s gray p er s e cond (Gy· s −1 i s gray p er ho u r (Gy· h −1 3.1.3 dose equivalent H product of D and Q at a point in tissue, where D is the absorbed dose (3.1.1) and Q f H= D× Q i s the qua l ity fac tor or the s p e ci fic rad iation at th i s p oi nt, thu s: N o te to entr y: T he u n it o f s e e qu i va lent i s j ou le p er ki lo gra m ( J· kg−1 [SOURCE: ISO 12749-2:2013, 4.1.6.8] [6] ), and its special name is sievert (Sv) 3.1.4 IMRT ratio CI ratio of the average monitor unit per unit prescribed absorbed dose needed for IMRT (MUIMRT ) and the monitor unit per unit absorbed dose for conventional treatment (MUconv) C = I MU MU I M RT CONV 3.1.5 instantaneous dose-equivalent rate IDR “ambient/p ers ona l” s e - e qu iva lent rate (S v· h the absorbed dose rate DRo (Gy· h –1) –1) as measured with the linear accelerator operating at N o te to entr y: T h i s i s the d i re c t re ad i ng o f the rateme ter that give s a s tab le re ad i ng i n s e - e qu iva lent p er ho u r IDR i s s p e c i fie d at a re ference p o i nt (3 c m) b e yond the p ene trate d b a rr ier 3.1.6 effective dose E s u m mation o f a l l the ti s s ue e qui va lent s e s , e ach mu ltipl ie d b y the appropriate ti s s ue weighti ng fac tor 3.1.7 occupancy factor T frac tion o f ti me the are as adj acent to the tre atment ro om a re o cc upie d b y a n i nd ividua l or group du ri ng linear accelerator operation © ISO 2016 – All rights reserved ISO 16645:2016(E) 3.1.8 orientation or use factor U fraction of the time during which the radiation under consideration is directed at a particular barrier 3.1.9 α r e f l e c t i o n c o e f f i c i e n t raction o f radiation (e.g., fluence, energy fluence) expressed by the ratio o f the amount backscattered f to that incident 3.1.10 shielding design goal P practical values o f dose equivalent, for a single radiotherapy source or set o f sources, evaluated at a re ference point beyond a protective barrier Note to entry: The shielding design goals ensure that the respective annual values for e ffective dose limit defined by national regulation or IAEA/ICRP for controlled and uncontrolled areas are not exceeded 3.1.11 (patient) scatter fraction a(θ) ratio of absorbed dose at m from a tissue-equivalent scattering object to the absorbed dose measured at the isocentre with the object removed Note to entry: This quantity is a function o f the scatter angle (θ ), incident beam quality, and beam area A scattering phantom is typically a water-equivalent volume representing a standard human being 3.1.12 tenth-value distance TVD distance that a specified radiation travels under broad beam condition in order to reduce the radiation field intensity to one-tenth o f its original value 3.1.13 tenth-value layer TVL thickness o f a specific material that reduces a specified radiation field intensity by a factor o f 10 o f its original value, under broad beam condition Note to entry: TVL is expressed in m or cm o f a defined material or in kg/m (thickness × density) Note to entry: TVL1 and TVL2 are the first and the second tenth-value layer thicknesses, respectively Note to entry: TVL e is the equilibrium tenth-value layer, thickness for each subsequent tenth-value layer in the region in which the directional and spectral distributions o f the radiation field are practically independent o f thickness Note to entry: TVL c is the cumulative tenth-value layer, approximate value based on large attenuation measurements: for a given thickness t, TVL c = - t/log(B) 3.1.14 time averaged dose-equivalent rate TADR barrier attenuated dose-equivalent rate averaged over a specified period o f accelerator operation Note to entry: TADR is proportional to instantaneous dose-equivalent rate (IDR), and depends on the values of workload (W) and orientation or use factor (U) © ISO 2016 – All rights reserved ISO 16645:2016(E) 3.1.15 transmission factor (or barrier transmission) B ratio o f radi ation field i nten s ity at a lo c ation b eh i nd the b arrier on wh ich rad iation i s i ncident to the field i nten s ity at the s ame lo cation without the pres ence o f the sh ield, N o te to entr y: for a given rad iation typ e and qual ity B is a measure of the shielding effectiveness of the barrier 3.1.16 workload W average ab s orb ed s e to water o f radiation pro duced by a li near accelerator, at the i s o centre at a re ference dep th in water i n elec tron equi librium conditions , over a s p e ci fied p erio d average d over a year N o te to entr y: T he worklo ad i s s p e c i fie d i n Gray (Gy) N o te to entr y: T he ti me p er io d s hou ld b e s i s tent b e twe en s h ield i n g de s ign go a l s a nd worklo ad N o te to entr y: T he i s o centre i s at m from the s ou rce N o te to entr y: T he re ference dep th i n water i s for fo r convention a l de vice s e xa mp le the dep th o f m a xi mu m ab s orb e d s e 3.2 Definitions 3.2.1 barrier (or protective barrier) protective wall of radiation attenuating material(s) used to reduce the dose equivalent on the side guidance b eyond the rad iation s ou rce to an accep table level comp atible with nationa l legi sl ation or i nternationa l 3.2.2 primary barrier wa l l , cei l i ng , flo or or o ther s truc tu re de s igne d to attenuate the d i re c t rad i ation em itte d from the ta rge t or source that passes though the collimator opening (useful beam) to an acceptable level compatible with national legislation or international guidance 3.2.3 secondary barrier wa l l , cei l i ng , flo or or o ther s truc tu re no t s truck b y the pri ma r y b e a m a nd de s igne d to attenuate the le a kage and s c attere d rad i ation s to an accep table level comp atible with nationa l le gi s lation or international guidance 3.2.4 controlled area defi ne d are a i n wh ich s p e c i fic pro te c tion me a s ure s and s a fe ty provi s ion s a re or cou ld b e re qui re d for control l i ng e xp o s ure s or preventi ng the s pre ad o f contam i nation i n norma l worki ng cond ition s , and preventi ng or l i m iti ng the l i kel i ho o d a nd magn itude o f p o tenti a l exp o s u re s N o te to entr y: This protection purposes i mp l ie s th at acce s s , o cc up a nc y, a nd worki n g cond itio n s a re co ntro l le d fo r rad iation [SOURCE: IAEA BSS] [7] 3.2.5 geometrical field size geometrical projection as seen from the centre of the front surface of the radiation source on a plane perpendicular to the axis of the beam of the distal end of the beam limiting device or collimator N o te to entr y: T he field i s thu s o f the s a me s h ap e a s the ap er tu re o f the b e a m l i m iti n g de vice N o te to entr y: T he proj e c te d field s i z e i s s p e c i fie d at a p a r tic u l a r d i s ta nce m from the target or at the reference distance of the device from the ta rge t, e g at the i s o centre © ISO 2016 – All rights reserved ISO 16645:2016(E) Table A.6 — Patient scattered photon TVL values (cm) for a scattering angle of 30°, for ordinary concrete (density 2,35 g·cm−3 ), steel and lead E (MV) 10 15 18 20 24 Scattered X at 30° Ordinary concrete IAEA 47 NCRP151 Table 11 TVL1 24,8 26,1 27,5 28,5 28,8 29 29,3 Table B.5a 25 26 28 31 32 33 36 Lead NCRP151 Table B.5b TVL2 3,7 4,4 4,5 NOTE If TVL be used in that nation In other cases, for conservative calculations, the use of the largest d ata a re p ro vide d b y the n atio n a l re g u l ato r y autho r it y, the n the s e s h a l l TVL va lue fo r a g i ven energ y a nd a g i ve n m ate r i a l i s re co m mende d Table A.7 — Patient scattered photon TVL values (cm) for a scattering angle of 45°, for ordinary concrete (density 2,35 g·cm−3 ), steel and lead E (MV) 10 15 18 20 24 Scattered X at 45° Ordinary concrete IAEA 47 NCRP151 Table 11 TVL1 22,3 22,9 23,3 23,7 23,8 23,9 24 Table B.5a 22 23 25 26 27 27 29 Lead NCRP151 Table B.5b TVL2 3,1 3,4 3,6 NOTE If TVL be used in that nation In other cases, for conservative calculations, the use of the largest d ata a re p ro vide d b y the n atio n a l re g u l ato r y autho r it y, the n the s e s h a l l TVL 62 va lue fo r a g i ven energ y a nd a g i ve n m ate r i a l i s re co m mende d © ISO 2016 – All rights reserved ISO 16645:2016(E) Table A.8 — Patient scattered photon TVL values (cm) for a scattering angle of 90°, for ordinary concrete (density 2,35 g·cm−3 ), steel and lead E (MV) Scattered X at 90°a Ordinary concrete Lead IAEA 47 NCRP151 DIN/DFI NCRP151 DIN/DFI b Table 11 Table B.5a Table Table B.5b Table TVL1 TVL2 / Tab le 4 10 15 18 20 24 16,9 17,1 17,3 17,4 17,4 17,4 17,5 17 17 18 18 19 19 19 NOTE If TVL for conservative calculations, the use of the largest TVL 16 16 16 16 16 16 16 / Tab le 1,3 1,5 1,6 Steel DIN/DFI Table 1,5 1,5 1,5 1,5 1,5 1,5 1,5 / Tab le 4,9 4,9 4,9 4,9 4,9 4,9 4,9 d ata a re p ro vide d b y the n atio n a l re g u l ato r y autho r i ty, then the s e s h a l l b e u s e d i n th at n atio n I n o ther c a s e s , a b N o a ng u l a r dep endence fo r D en s i t y s c a le d u s i ng d ata s c atte re d p ho to n s fro m fo r de n s i ty , g· c m va lue fo r a g i ven e ne rg y a nd a g i ven m ater i a l i s re co m me nde d D I N/ D I F −3 concrete Table A.9 — TVL values for radiations passing through the maze (one or two-legged maze) and reaching the door, scattered X-rays, neutrons and capture γ, for concrete (ordinary concrete: density 2,35 g·cm−3 ), lead, steel and hydrogenated materials: polyethylene and borated polyethylene (BPE), para ffin and water TVL for maze scattered X-rays (cm) Ordinary concrete Average NCRP 151 DIN/DFI energy (MeV) a b c d 0,3 a 0,2 b Figure A.1 16 13 Lead Steel NCRP 151 DIN/DFI NCRP 151 DIN/DFI Table Table c 16 16 / / L e a kage s c atter (one i nterac tio n) [19] Patient and wall scatter (two interactions) [2] D en s ity s c a le d u s i n g data from den s ity , g· c m −3 concrete D en s ity s c a le d u s i n g N C RP 51 co nc re te d ata (B PE den s ity: ,9 g· c m −3 Concrete (ordinary or high density) a b c d Table Figure A.1 Table c Figure A.1 0,8 1,5 3,9 0,5 1,5 2,6 Average NCRP 79 See References [15][29] NCRP 151 Figure A.1 NCRP 151 Table B.2 DIN/DFI : pri mar y 10 M V TVL for maze neutrons (cm) Lead Steel DIN/DFI DIN/DFI TVL1 D e n s it y s c a le d u s i n g N C RP 51 co nc re te d ata ( B PE den s i t y: ,9 g c m − NOTE If TVL for conservative calculations, the use of the largest TVL Table Table c 4,9 4,9 BPE d / 39,6 32,2 ) Polyethylene, BPE para ffin, water IAEA 47/NCRP 151 DIN/DFI ) d ata a re p ro vide d b y the n atio n a l re g u l ato r y autho r i t y, the n the s e s h a l l b e u s e d i n th at n atio n I n o ther c a s e s , © ISO 2016 – All rights reserved va lue fo r a g i ven e nerg y a nd a g i ve n m ate r i a l i s re co m me nde d 63 ISO 16645:2016(E) Table A.9 (continued) Ordinary concrete Average NCRP 151 D energy ( e M n a b e e V r g y ( M 0,1 a e V N / D F I D Table / Table c Table 3/ Table 13 Figure A.1 ) I TVL for maze scattered X-rays (cm) Lead Steel NCRP 151 NCRP 151 ) 16,1 b I N D F I D I N / D F P E d I Table 2/ Table 2/ Figure A.1 Table c Figure A.1 Table c Table 3/ Table 3/ Table 3/ Table Table Table 37 37 4,5 Energy at the maze entrance [IAEA 47/NCRP 151] Calculated according to: TVL (cm) = 15,5 + 5,6 × E (MeV), where E is the average neutron energy[15] TVL f Ordinary concrete NCRP 151 Energya a b c d / B ( M e V ) 3,6 (average energy) 10 (maximum energy) See References[15][29] NCRP 151 Figure A.1 NCRP 151 Table B.2 : primary 10 MV TVL1 33 b 41 c o r m a z e c a p t u r e γ ( c Lead I A E A / N C R P (conservative) 6,1 6,1 m ) Steel NCRP 151 9,5 b 11 d B P E d 81,7 101,5 Density scaled using NCRP 151 concrete data (BPE density: 0,95 g.cm−3 ) NOTE If TVL data are provided by the national regulatory authority, then these shall be used in that nation In other cases, for conservative calculations, the use of the largest TVL value for a given energy and a given material is recommended a) 64 © ISO 2016 – All rights reserved ISO 16645:2016(E) b) Key X E (MeV) Y TVL (cm) concrete s p herical s hell geo metry p o lyethylene p o lyethylene (mo no energetic) Key X E (MeV) Y TVL (cm) concrete NOTE Figure A.7 is reprinted from NCRP 79 (Figures 33 and 36) with permission of the National Council on Radiation Protection and Measurements, lo ng ro o m geo metry p o lyethylene http: // N C RP pub l ic atio n s org Figure A.7 — Dose equivalent TVL f room shielding as a function of the average energy of neutron source (a) and for a geometry a p p r o x i m a t i n g a s h i e l d i n g d o o r a t t h o e r e s p n h d e o r f i c a a l m s a h z e e l a l s s h a i f e u l d n c neutrons at the door (b) [26] © ISO 2016 – All rights reserved i n t i g o a n p o p f r t o h x e i m a a v e t i r n a g g e a e t r n e e a r t g m y e o n f t t h e 65 ISO 16645:2016(E) (informative) A n n e x B Supporting data for shielding calculations T a b s l i e z e B , a t — d e P p a t t h Angle θ (degree) i e n 10 20 30 45 60 90 135 150 t s m M c a m t t e f o r r f e r n a e c r t g i o y n r e M l a V V 1,04 10 −2 6,73 10 −3 2,77 10 −3 1,39 10 −3 8,24 10 −4 4,26 10 −4 3,00 10 −4 2,87 10 −4 t a i v e n d M t o p r m i m m a f o r r y a h i t g h m e r V d e 1,66 10 −2 5,79 10 −3 3,18 10 −3 1,35 10 −3 7,46 10 −4 3,81 10 −4 3,02 10 −4 2,74 10 −4 i n s e t r M a g n i c e V 1,42 10 −2 5,39 10 −3 2,53 10 −3 8,64 10 −4 4,24 10 −4 1,89 10 −4 1,24 10 −4 1,20 10 −4 e s , [ a I θ), for a 0,04 m ( A E A S R S , T a M b l e f i e l d ] V 1,78 10 −2 6,32 10 −3 2,74 10 −3 8,30 10 −4 3,86 10 −4 1,74 10 −4 1,20 10 −4 1,13 10 −4 NOTE The data given in this table are computed data from Monte Carlo simulations[13] , reproduced in IAEA SRS 47, Table T a b l e B — W a l l r e f l e c t i o n c o e f ) for ordinary concrete and 45° incident angle [IAEA SRS 47, Table 6] 1) f i − c i e n t R Incident energy 24 MV 20 MV 18 MV 15 MV 10 MV MV MV 0,5 MeV 0,25 MeV 75 3,37 10 −3 3,75 10 −3 4,01 10 −3 4,48 10 −3 5,75 10 −3 7,69 10 −3 9,36 10 −3 1,70 10 −2 1,82 10 −2 ( m e 45 f l e c 3,91 10 −3 4,20 10 −3 4,41 10 −3 4,78 10 −3 5,75 10 −3 7,35 10 −3 9,01 10 −3 2,15 10 −2 3,05 10 −2 t i o n a n g l e ( d e g r e e ) 15 3,91 10 −3 4,14 10 −3 4,32 10 −3 4,56 10 −3 5,38 10 −3 6,71 10 −3 8,19 10 −3 2,10 10 −2 3,50 10 −2 3,74 10 −3 3,95 10 −3 4,11 10 −3 4,34 10 −3 5,10 10 −3 6,35 10 −3 7,77 10 −3 2,03 10 −2 3,39 10 −2 1) Reproduced from International Atomic Energy Agency, Radiation Protection in the Design o f Radiotherapy Facilities, Safety Reports Series No 47, IAEA, Vienna (2006) with permission 66 © ISO 2016 – All rights reserved ISO 16645:2016(E) Table B.3 — Wall reflection coe fficient (m−2 ) for ordinary concrete and normal incidence [IAEA SRS 47, Table 7] 2) Incident energy 24 MV 20 MV 18 MV 15 MV 10 MV MV MV 0,5 MeV Reflection angle (degree) 75 1,47 10 1,57 10 −3 1,62 10 −3 1,75 10 −3 2,06 10 −3 2,60 10 −3 3,16 10 −3 7,54 10 −3 −3 60 2,30 10 2,43 10 −3 2,51 10 −3 2,69 10 −3 3,15 10 −3 3,92 10 −3 4,77 10 −3 1,26 10 −2 −3 45 2,82 10 2,98 10 −3 3,07 10 −3 3,29 10 −3 3,83 10 −3 4,76 10 −3 5,81 10 −3 1,58 10 −2 −3 30 3,15 10 3,31 10 −3 3,42 10 −3 3,65 10 −3 4,24 10 −3 5,28 10 −3 6,46 10 −3 1,78 10 −2 −3 3,20 10 −3 3,34 10 −3 3,46 10 −3 3,66 10 −3 4,25 10 −3 5,35 10 −3 6,62 10 −3 1,82 10 −2 2) Reproduced from International Atomic Energy Agency, Radiation Protection in the Design o f Radiotherapy Facilities, Safety Reports Series No 47, IAEA, Vienna (2006) with permission © ISO 2016 – All rights reserved 67 ISO 16645:2016(E) (informative) A E x a m p l e o f c a l c u l a t i o n f o r c o n n n v e e n x t i C o n a l d e v i c e a n d s t a n d a r d m a z e Dimensions in metres F T r a a i g b d l i u e a t r C i Energy 15 MV e o C n — p — r A o c t V c e i e c e l t w e i r o o a n Field size at isocentre 0,40 × 0,40 m f t t o o f h r f i e c c p h e l a r a r n a o r n c t q e e u d r i a f a s l i t c i f i i c e l s i d calculations t y a n e x w d p i t p e h a r r t e a t s t m o i m e d t e a e t t r e e s r d a m w c i c n a o e l r s l t d h i i h n e i c g l d k t i n o n e t g s h s e a c e s s c p o b e r e c d f o i i f i n r c g e a s t t o h e l d i n f g Figure C.1 i i o n s o t h e Leakage fraction W IMRT ratio CI FIMRT WL 1·10 −3 Gy/patient ,5 MU/cGy 0,5 WL 39 375 Gy/year 22 500 Gy/year 68 © ISO 2016 – All rights reserved ISO 16645:2016(E) T a b l e C — C a o Location l c c c u u l a p i t e i o d Type of barrier n a d r t a a s i t o n d t h e e f i n c a e l s c h u l i e a t l i d o i n n g e f x o a Scatter Distance source to angle protected point m (Concrete) A B C D H a e (m) 6,7 6,8 5,3 8,4 - P rimar y P rimar y S e co nd a r y 29° S e co nd a r y 90° S e conda r y 48 ° r t m h p l e e d a i c ff e c o r r e d n i Shielding design goal P ( m S v / y e a t n r g a t d o i a t i o n c o m p o n e n t s a n d Figure C.1 Orientation or use factor Occupancy factor T 0,25 0,25 1 1 0,2 1 U r ) 1 1 Table C.3 — Primary barrier (see Figure C.1) Parameter Unit Distance source to protected point d (including distance from wall 0,30 m) Shielding design goal P Orientation or use factor U O cc up a nc y Worklo ad fac tor T W m m S v/ye a r - Formula and data references Location Location A - 6,7 0,25 1 0,25 0,2 Gy/ye a r Primary Hu,p X-ray u n s h ielde d s e e qu iva lent Bp Maximum transmission TVL c concrete m S v/ye a r W·U/d2 - P/(T· Hu,p) m m M i n i mu m b a rr ier th ickne s s t m m B a r r ier th ickne s s Fi n a l p ro p o s e d th ickne s s S h ielde d s e e qu i va lent rate fo r fi n a l p ro p o s e d (9) (3) Table A.1 (IAEA value) - TVL c Log (Bp) (7) and (8) t + 0,3 TVL c m S v/ye a r B 22 500 ,1 ·10 ,71·10 − 2,19 1,25 10 ,9 ·10 −5 0,432 2,32 2,40 0,35 1,90 2,03 2,10 0,345 th ickne s s Table C.4 — Secondary barrier (see Figure C.1) Parameter Distance source to protected point dsec Shielding design goal P Orientation or use factor U O cc up a nc y fac tor T Leakage W IMRT ratio CI FIIMRT Wo rklo ad IMRT factor L e a kage worklo ad Unit m m S v/ye a r - Gy/ye a r WL © ISO 2016 – All rights reserved Gy/ye a r Formula and data ref Location C Location D - (5) (6) 6,8 1 5,3 1 22 500 2,5 0,5 1,75 39 375 69 ISO 16645:2016(E) Table C.4 (continued) Parameter X-ray le a kage Unit Formula and data ref Location C Location D - frac tio n Hu,L (13) m S v/ye a r X-ray le a kage u n s h ielde d s e e qu iva lent m m BL TVL c le a kage fo r conc re te M i n i mu m b a r r ier th ickne s s t Shielded dose equivalent rate for each component 1·10 −3 , 51·10 P/(T·Hu,L) Table A.5 (IAEA value) - TVL c Log (B ) ,4 ·10 ,17·10 −3 7,1 ·10 − 0,97 0,979 1,04 0,989 l m S v/ye a r 0,33 a nd m i n i mu m th ickne s s Patient scatter Target to isocentre distance dSCA m m2 M a xi mu m field a re a at i s o centre S c atter a ngle θ P atient s c atter frac tio n fo r field , m 0,16 Table B.1 (15) ° a (θ) Hu ps m S v/ye a r , X-ray u n s h ielde d p atient s c atter s e e qu iva lent m Bps TVL c patient scatter for concrete M i n i mu m b a r r ier th ickne s s ,9 7·10 90° −3 ,78 ·10 P/(T· Hu ps) , Tables A.6, A.8 (NCRP value) - TVL c Log (B ) m t Shielded dose equivalent rate for each component 30° , 61·10 − , ·10 ,7 ·10 − , ·10 −3 1,17 0,972 0,53 0,950 0,31 ps m S v/ye a r 0,18 a nd m i n i mu m th ickne s s Table C.5 — Secondary barrier dose equivalent rate and thicknesses for a shielding design goal f Figure C.1) o m S v / y e a r ( s e e Location C 8,51 10 0,33 Patient scatter 5,78 10 0,31 1,26 1,18 L e a kage Unshielded dose equiva lent rate (m S v/ye a r) TVL Concrete (m) M i n i mu m th ickne s s required to achieve the shielding goal for each component (m) a ness (m) b Shielded dose equivalent rate for each comFi n a l p rop o s e d th ick Location D 1,40 10 0,33 Patient scatter 8,36 10 0,18 1,11 0,60 L e a kage 1,36 1,20 0,064 0,237 0,323 10 −4 p onent (m S v/ye a r) a Shielded dose equivalent rate 0,301 m C a lc u l atio n ne b y co n s ide r i n g S v / fo r y e a 0,324 r b 70 H i ghe r th ickne s s fo r fo r S v / y e a r e ach co mp o ne nt the p ro duc t o f the re l ati ve u n s h ielde d s e e qu i va lent (the s e e qu i va le nt o f the s e e qu i va lents m fo r the co mp o ne nt d i vide d b y the s u m a l l co mp o nents) b y the s h ield i n g go a l lo c atio n p lu s , × TVL , i f co nc re te den s i t y i s u ncer ta i n © ISO 2016 – All rights reserved ISO 16645:2016(E) Dimensions in metres F i g u r e C — V i e w o f t h e p l a n n e d f a c i l i t y a n d m a z e d i s t a n c e s ( w i t h e s t i m a t e d w a l l t h i c k n e s s e s ) Table C.6 — Maze and Door (see Figure C.2) Parameter Workload W Unit Formula and data ref - - 22 500 1 m m - 1 6,7 Gy/year mSv/year Shielding design goal P Occupancy factor T Patient scatter 10.3.1.2 Orientation or use factor U Target to isocentre distance dsca Distance from isocentre to the wall at the end of maze dsec Maze length d zz Area maze back wall Scatter angle θ Patient scatter fraction a(θ) for field 400 cm © ISO 2016 – All rights reserved m m2 ° A = w1 · h Table B.1 (interpolation) V a l u e 10 11,22 = 3,4 × 3,3 50° 8,44·10 −4 71 ISO 16645:2016(E) Table C.6 (continued) Parameter Unit Formula and data ref 3,85 m m - 4,3 6,4 m m2 - 6,2 11,22 Orientation or use factor U A z = wm · h = 3,4 × 3, 1st reflection angle 1st reflection coe fficient α0 Area at fist reflection A Reflection coe fficient scatter by primary wall αz ° 1/m m2 1/m Hu, s wall scatter unshielded dose equivalent at mSv/year (18) 3,39 10 −1 (6) - 39 375 Gy/year Distance from isocentre to wall maze end dsec Distance from wall maze at end to door dzz Wall width seen from door w1 Room height h Maze scatter area A1 w1 x h Table B.2 for 1/m 1st reflection coe fficient α1 Hu,LS Leakage scatter unshielded dose equiv- (20) mSv/y X-ray direct leakage unshielded dose 10.3.2 Distance from the average target location (isocentre) to the protected point dL Barrier slant (42°) thickness (concrete) Transmission a z e n e u t r o Vendor Head shielding transmission factor (lead) β Distance from isocentre to maze opening (point A) d1 Treatment room total reflection sur face Sr Neutron source strength Qn 72 n f l u e n 6,7 10 3,4 3,3 11,22 7,77 10 −3 0,765 m 8,4 m 1,62 1,28 10 −5 7,14 10 −3 Hu,L X Ray direct leakage dose equivalent M 2,96 1·10 −3 MV - 45° and 0° Orientation or use factor U alent rate 7,54·10 −3 0,5 MeV - 75° m m m m m2 75° 1,75·10 −3 Table B.3 for 15 MV - 75° A = (dh / dsca) x 0,16 Table B.3 for Leakage scatter unshielded 10.3.1.4 Leakage workload WL X-ray leakage fraction e (17) 0,5 MeV, 0° scatter angle mSv/year inside door u 2,03·10 −2 Wall scatter (plane of rotation parallel to inner maze wall) 10.3.1.3.1 Distance from source to primary barrier dH Distance from primary barrier to the inner maze entrance dr Distance from inner maze entrance dz Cross section of inner maze entrance A z l Table B.2 Reflection coe fficient α1 Hu, ps Patient scatter unshielded dose equivalent V a c e c a l c u l a t i o n 10.3.3 (21) ELEKTA 5,9 m m2 neutron/Gy (23) 222,4 1,44 10 11 © ISO 2016 – All rights reserved ISO 16645:2016(E) Table C.6 (continued) Leakage scatter unshielded 10.3.1.4 (22) 1,02 10 2,06 x S1/2 (25) 7,1 3,35 7,26 5,55 6,29 neutron/m ·Gy Neutron fluence at point A φA per Gy Maze neutron unshielded dose 10.3.3 Distance from maze opening d2 Inner maze cross section S0 Maze cross section area S Tenth value distance for neutrons TVDn m m2 m2 m mSv/y Hu,n Entrance neutron unshielded dose equivalent Capture Gamma unshielded dose rate 10.3.3 Tenth value distance for neutrons TVDɣ m Ratio capture gamma dose equivalent to neutron Sv·m /neutron Capture gamma unshielded dose equivalent Hu,γ mSv/y fluence K 6,9 10 −16 (24) 2,08 Table C.7 — Maze door shielded dose equivalent and thickness of each layer for a shielding Figure C.2) f d e s i g n g o a l o m S v / y e a r ( s e e Patient scatter Wall scatter Leakage scatter Direct leakage Capture gamma Neutrons 3,85 3,39 10 −1 0,765 7,14·10 −3 2,08 6,29 0,29 0,03 0,06 5·10 −4 0,16 0,47 component at the door (MeV) TVL (mm) Lead 0,2 0,2 0,3 15 3,6 0,1 - - - 47 - 61 - 45 required to achieve the shielding goal for each component and Lead mm Lead mm Lead mm Lead 53 mm Lead Polyethylene 69 mm 51 mm Shielded dose equivalent for each component 10 −14 10 −15 2,03 10 −9 2,5 10 −4 1,56 10 −1 0,472 Unshielded dose equivalent (mSv/year) Shielded dose equivalent goal for the compo- nent (mSv/year) a Energy o f radiation Para ffin/polyethylene Minimum thickness specified material (mSv/year) Shielded dose equivalent (mSv/year) 0,63 mSv/year For 51 mm polyethylene + 69 mm lead a Calculation done by considering for each component the product o f the relative unshielded dose equivalent (the dose equivalent for the component divided by the sum o f the dose equivalents for all components) by the shielding goal © ISO 2016 – All rights reserved 73 ISO 6645 : 01 6(E) Bibliography [1] IEC 60601-2-1, Medical electrical equipment — Part 2-1: Particular requirements for the basic [2] Report No NCRP 151, Structural shielding design and evaluation for megavoltage X- and [3] IPEM report No 75, The design o f Radiotherapy Treatment Room Facilities (1998) [4] [5] safety and essential performance of electron accelerators in the range MeV to 50 MeV gamma-ray radiotherapy facilities (2005) Ordonnance du DFI sur la radioprotection 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