General Guidelines for the Assessment of Internal Dose from Monitoring Data (Project IDEAS)

Transcription

1 General Guidelines for the Assessment of Internal Dose from Monitoring Data H. Doerfel, FZK, Karlsruhe A Andrasi, KFKI, Hungary M Bailey, J Marsh, J Stather, NRPB, UK V Berkovski, RPI, Ukraine C-M Castellani, ENEA, Italy C Hurtgen, SCK CEN, Belgium J-R Jourdain, E Blanchardon, I Laniece, IRSN, France B LeGuen, EDF, France I Malatova, RPI Czech Rep. (corresponding member) R Cruz-Suarez, J Zeger, IAEA (corresponding members) IM2005, Vienna, April

2 Background Monitoring data Intake & Committed Dose Assumptions: Pathway of of intake Time course of of intake General experience: Biokinetic Model(s) Parameter values When for fora material set set of of bioassay & subject data data is is given to to two two different assessors, it it is is likely that that different Influencing factors: assumptions will will be be made, and and perhaps and that Amount and and quality different of of methods data data applied and therefore that will be Skill and and experience different of of results the thedosimetrist will be obtained. Computational tools toolsavailable IM2005, Vienna, April

3 What we have learned from recent intercomparison exercises There is a clear need to develop guidelines on assessments of intake and internal doses, in order to promote harmonisation in assessments, especially, but not only, across the EU. Such guidelines have formed the core of the IDEAS project. IM2005, Vienna, April

4 Presentation to Intercomparison Workshop 18 April : The IDEAS Project 2: The IDEAS guidelines IM2005, Vienna, April

5 The project: Cost-shared action in in 5th 5th FP FP Months: October March (extended to to June June2005, to to co-ordinate intercomparison exercise with withiaea and and this thisworkshop with withim 2005) The aims: To To develop guidelines to to standardise assessments of of internal doses By Byapplication of of such such guidelines, different assessors should obtain the thesame result from the thesame data data IM2005, Vienna, April

6 Work package 1 Collection of incorporation cases (C. Hurtgen) Survey of open literature Survey of open literature Contacts with industry and research institutions Contacts with industry and research institutions Bibliographic database Compilation of of references (author, year, year, title, title, journal) Content: references (mainly (mainlyhealth Phys. Phys. (229), (229), Rad. Rad. Prot. Prot. Dos. Dos. (60)) (60)) Incorporation case casedatabase Detailed information (case (casedescription, monitoring results, results, dose dose assessment) Content: cases cases Selection of of cases for forassessment by byconsortium (WP3) IM2005, Vienna, April

7 Work package 1 Collection of incorporation cases Work package 2 Preparation of evaluation software (V. Berkovski) Investigate improved mathematical methods to to assess intakes from monitoring data data Implement in in existing software (IMIE: RPI) RPI) Implementation of of new newfeatures: Mixed Mixed fractions of of pathway of of intake intake (inhalation, ingestion, injection) Mixed Mixed fractions of of absorption types types (F, (F, M and and S) S) Wound Wound simulated as as chronic chronic injection and/or and/or multiple injection AMADs up up to to micron micron Import Import of of individual retention and and excretion functions IM2005, Vienna, April

8 Work package 1 Collection of incorporation cases Work package 2 Preparation of evaluation software Evaluation of of cases cases (29 (29 of of them them by by 2 or or more more evaluators) Application of of both both IMIE IMIE and and IMBA IMBA Expert Expert TM TM Selection of of the the best best estimates Identification of of important issues issues related related to to the the guidelines Work package 3 Evaluation of Evaluation incorporation database cases Compilation (C-M. Castellani) of of all all information (Word (Word and and Excel Excel files) files) Content: independent evaluations of of cases cases Identification of of factors and and assumptions for forwhich guidance is isneeded IM2005, Vienna, April

9 Develop Workcommon package 1approach for forevaluation of of monitoring Collection data data of incorporation cases Consider data data handling (intake pattern, multiple data data sets, sets, errors, rogue data etc.) Work data package etc.) 3 Evaluation of Develop draft guidelines based incorporation on on Workshop cases discussions Work package 4 Development of general guidelines (H. Doerfel) Discuss Workwith package experts 2 in in open open Virtual Workshop Preparation (1) (1) on on of the theinternet evaluation software Prepare report on on draft guidelines IM2005, Vienna, April

10 Work package 4 (Development of general guidelines) Details and discussion in Part 2 of presentation (later) IM2005, Vienna, April

11 Virtual workshop for discussion of the guidelines with the community Special webpage ( for posting the guidelines Special webpage ( for posting the guidelines Discussion forum forumfor forevery everystage stageof of the theguidelines where whereanyone anyonecould couldplace placehis his (or (or her) her) comments Announcement of of the theworkshop through contacts, relevant national and and international organisations etc. etc. (including IRPA IRPA Madrid) Start of the workshop on 31 May 2004; end is still open Start of the workshop on 31 May 2004; end is still open IM2005, Vienna, April

12 Virtual workshop for discussion of the guidelines with the community Statistics of the visits of the website ( Statistics of the visits of the website ( Month May 2004 June 2004 July 2004 August 2004 September 2004 Number of Visits IM2005, Vienna, April

13 Virtual workshop for discussion of the guidelines with the community Statistics of the visits of the discussion forum Statistics of the visits of the discussion forum Subject Visits Comments 1 First check of data Check of statistical significance Standard procedure Special procedure definition of pathways 5 ( ) Special procedure for inhalation 6 ( ) Special procedure for ingestion 7 ( ) Special procedure for inhalation and ingestion Total IM2005, Vienna, April

14 Virtual workshop for discussion of the guidelines with the community Special webpage ( for posting the guidelines Special webpage ( for posting the guidelines Start Start of of the theworkshop on on May May 2004; 2004; end end is isstill still open, open, Continuation, linked linkedto to CONRAD FP6 FP6 Project Project (Carlo-Maria Castellani & Hans Hans Doerfel) Develop guidelines further Develop guidelines further Information exchange for internal dosimetry community Information exchange for internal dosimetry community IM2005, Vienna, April

15 Organise Work package Joint Intercomparison 1 Exercise on on Internal Collection Dose Dose of Assessment together with withiaea Prepare, incorporation distribute cases cases & guidelines Compile results Work package 3 Workshop (2) (2) with with participants Evaluation to to discuss of incorporation cases results Modify Workdraft package guidelines 2 according to to results of of discussion Preparation of evaluation software Publish report and and General Guidelines Work package 4 Development of general guidelines Work package 5 Practical testing of general guidelines IM2005, Vienna, April

16 Work package 4 (Development of general guidelines) General philosophy based on on the theevaluation (Work package 3) 3) Levels of of task task based on on general philosophy General guidelines for forthe theevaluation based on on Level of of task structure IM2005, Vienna, April

17 General philosophy Harmonisation: by by following the the procedures any any two two assessors should obtain the the same estimate of of dose dose from a given data data set set Discussion point? Best Best estimate: the the best estimate of of dose dose should be be obtained from the the available data data Sometimes there is conflict between these principles. Which has priority? Proportionality: the the effort applied to to the the evaluation should be be proportionate to to the the dose dose the the lower the the dose, the the simpler the the process should be. be. IM2005, Vienna, April

18 The general guidelines provide Detailed information about data handling Detailed information about data handling processing processing of of data data before before use, use, handling handling of of single single data data and and multiple multiple data data sets, sets, number number and and type type of of data data required required for for the the dose dose assessment assessment assessment assessment of of the the uncertainty uncertainty on on data, data, handling handling of of data data below below the the limits limits of of detection, detection, handling handling of of data data influenced influenced by by chelation chelationtherapy therapy and and the the identification identification of of rogue rogue data data General information about about the the evaluation of of the the monitoring data data reflecting the the general general philosophy Structured approach to the dose assessment reflecting the levels of task. Structured approach to the dose assessment reflecting the levels of task. IM2005, Vienna, April

19 Levels of task Level Level 0: 0: Annual Annual dose dose < msv msv evaluation of of dose dose needed. needed. (German & Swiss Swiss Guidelines, external doses doses rounded) Level Level 1: 1: Dose Dose from from the the intake intaketypically msv msv Simple, Simple, reference evaluation, with with ICRP ICRP defaults used used for for all all parameter values, values, except except where where there there is is better better a priori priori information available Level Level 2: 2: Dose Dose from from the the intake intake typically 1 6 msv msv Sophisticated evaluation using using additional information to to give give more more realistic assessment of of dose: dose: Adjustment of of AMAD, absorption type type or or the the time time of of intake intake if if unknown (A (A posteriori: using using measurement data) data) Level Level 3: 3: Dose Dose from from the the intake intake typically > 6 msv msv More More sophisticated evaluation, which which applies applies to to cases cases where where there there are are comprehensive data data available: Systematic adjustment of of the the model model parameter values values ( step-by-step approach), until until the the fit fit is is acceptable (not (not rejected) IM2005, Vienna, April

20 1 (Level 0) Single routine measurement, M Compare with tabulated value M C If If measurement M< M C implies Annual dose (committed effective dose from intakes in in year) <0.1 msv; assuming similar intakes in in all monitoring intervals. Record dose = 0.0 msv. Record measurement. STOP IM2005, Vienna, April

21 1 Structured approach to dose assessment 1: 1: 1.1 Check Check of of the theneed needfor forevaluation Identify monitoring value M 1.2 M < Mc(1) no yes Level 0: evaluation needed End 1.3 Above Level 0: Evaluation needed 2 IM2005, Vienna, April

22 1 (Level 0) Step 1.1 Identify measurement (M) and duration of of monitoring interval (T) Data treatment (if needed) Other radionuclides present as as well as as Indicator that was measured? IM2005, Vienna, April

23 1 1.1 Identify monitoring value M 1.2 M < Mc(1) no yes Level 0: evaluation needed End 1.3 Above Level 0: Evaluation needed 2 IM2005, Vienna, April

24 Step 1.2: Example of the critical monitoring quantity M c Radionuclide Absorption type (chemical form) Type of monitoring H-3 HTO Urine Co-60 M Whole body Sr-90 F Urine I-131 F Thyroid Cs-137 F Whole body U-235 S Lungs Pu-239 M Urine Monitoring interval (d) Critical monitoring value M C 4400 Bq/d 5500 Bq/d 3900 Bq/d 160 Bq 230 Bq 290 Bq 0.4 Bq/d 0.2 Bq/d 0.2 Bq/d 18 Bq 26 Bq 26 Bq 1200 Bq 1800 Bq 2000 Bq 0.2 Bq < LLD 0.3 Bq < LLD 0.5 Bq < LLD mbq/d < LLD mbq/d < LLD mbq/d < LLD IM2005, Vienna, April

25 2 (Level 1) Measurement M>M C Check whether M is is significant: Need realistic estimate of of uncertainty If so so reference procedure (ICRP 78): Default values, a priori parameter values, route of of intake, etc. If annual dose <1 msv (record dose) STOP IM2005, Vienna, April

26 Structured approach of the dose assessment 1: 1: Check Check of of the theneed needfor forevaluation Assessment of uncertainty on measured value M (or application of default uncertainty) 2.2 Calculation of contributions from previous intakes (P) 2.3 M > SF*P 2: 2: Check of the of Check of the significance of measurement and and consistency with withprevious evaluations 2.4 P/SF < M < P*SF There is a new significant intake; calculation of net measured value N = M - P There is no new significant intake (confirmation of previous assessments) 3 End 2.5 There is a discrepancy with previous evaluations 2.6 Value is reliable Special evaluation of previous intakes needed 4 IM2005, 2.7 Vienna, April Make corrections on the measured value, if possible; otherwise repeat measurement

27 2 (Level >0) Step 2.1 Assess overall uncertainty on measurement: New intake? Consistent with previous intakes? (Rogue point: inconsistent with other data?) (Weighting in in fitting more than one measurement) (Objective criteria to to determine whether model fits data) (Objective criteria to to choose between models) IM2005, Vienna, April

28 2 (Level >0) Step 2.1 Assess overall uncertainty on measurement for comparison with model (Scattering Factor, SF): Type A (Poisson counting statistics) and Type B (other) Measurement of of activity in in sample (or in in organs) and its use to to estimate modelled activity (e.g. daily excretion rate), sampling errors, biological variability IM2005, Vienna, April

29 2 (Level >0) Step 2.1 Guidance on estimating SF: Log-normal. t exact, but pragmatic (approximate better than nothing, or oronly some contributions) Some details available for in in vivo measurements General defaults (Table 2.3, Guthrie Miller) excretion etc. based on plutonium. IM2005, Vienna, April

30 Step 2.1: Default values for the components of log-normal uncertainty for various types of measurement Quantity SF true 24-hr urine 1.1 Discussion point!!! simulated 24-hr urine, specific gravity normalization 1.3 excretionspot etc. urine basedsample on plutonium. 2.0 Need more: fecal typical sample SF for other radionuclides 3 to 7- contributions chest please!!! count 1.2 to 1.6 nasal swipe 3 to 7 room air monitor 7 to 20 IM2005, Vienna, April

31 2 2.1 Assessment of uncertainty on measured value M (or application of default uncertainty) 2.2 Calculation of contributions from previous intakes (P) 2.3 M > SF*P There is a new significant intake; calculation of net measured value N = M - P 3 Discussion Point! P/SF 2 <M<P*SF P/SF < M < P*SF There is no new significant intake (confirmation of previous assessments) End chance of false intakes or inconsistency >30% Use eg SF 2? 2.5 There is a discrepancy with previous evaluations 2.6 Value is reliable Special evaluation of previous intakes needed Make corrections on the measured value, if possible; otherwise repeat measurement IM2005, Vienna, April

32 2 2.1 Assessment of uncertainty on measured value M (or application of default uncertainty) 2.2 Calculation of contributions from previous intakes (P) 2.3 M > SF*P There is a new significant intake; calculation of net measured value N = M - P P/SF < M < P*SF There is no new significant intake (confirmation of previous assessments) End 2.5 There is a discrepancy with previous evaluations 2.6 Value is reliable Special evaluation of previous intakes needed 4 IM2005, 2.7 Vienna, April Make corrections on the measured value, if possible; otherwise repeat measurement

33 3 (Level > 0) Standard evaluation Measurement M due to to new intake Confirm routine (not special, 4) 4) Reference assumptions, as as ICRP 78, eg. single intake (inhalation) at at mid-point Parameter values related to to material (eg AMAD) if if known before (a (a priori) If annual dose <1 msv record and STOP IM2005, Vienna, April

34 Structured approach of the dose assessment 1: 1: Check Check of of the theneed needfor forevaluation Routine monitoring? Assume pathway of intake 2: 2: Check of the of 3.3 Check of the significance of measurement and and consistency with withprevious evaluations Assign a priori parameters (default or site-specific) 3: 3: Standard reference evaluation procedure 3.4 Estimate intake and dose 3.5 Annual dose < 1 msv Record intake and dose End 4 IM2005, Vienna, April

35 4 4.1 Pure inhalation? Special evaluation for inhalation 5 Structured approach of the dose assessment 1: 1: 4.2 Pure ingestion? Check Check of of the theneed needfor forevaluation Special evaluation for ingestion 6 2: 2: Check of the 4.3 of Check of the significance of measurement and and consistency with withprevious evaluations Inhalation and Special evaluation for inhalation and ingestion? ingestion 3: 3: Standard reference evaluation procedure 4.4 Injection or skin absorption? Special evaluation for Injection 4: 4: Special Special evaluation procedure: Identification of of pathway of of intake intake Wound involved? The wound pathway not considered by the guidelines at the present state. IM2005, Vienna, April End

36 4 4.1 Pure inhalation? 4: Special Assessment Special evaluation for inhalation 5 Room air contamination (Default) 4.2 Pure ingestion? Special evaluation for ingestion 6 External contamination 4.3 Inhalation and ingestion? Special evaluation for inhalation and ingestion 7 Room air and external contamination AND justification 4.4 Injection or skin absorption? Special evaluation for Injection 8 Discussion point! 4.5 Wound involved? The wound pathway not considered by the guidelines at the present state. IM2005, Vienna, April End Understand the case: Plot graph of data Hand calculation?

37 5 5A (Steps ) Initial assessment with a priori parameter values 5: 5: Special Special Assessment from incorporation [Inhalation] monitoring data 5A: 5A: Initial Initial evaluation using usinga priori priori (Project parameters IDEAS) 5.6 Dose < 1 msv End 5B (Steps ) Special evaluation for intake by inhalation selecting AMAD, absorption Type and/or time of intake by comparison of model predictions with data (a posteriori) 5B: 5B: Varying the theamad, absorption type typeand/or time time of of intake, intake, if ifnot known, known, using usingthe thedata 5.15 Dose < 6 msv and good Fit End 5C (Steps ) 5C Vary HRTM, HATM tract and systemic model parameter values in specified order (a posteriori) 5C: 5C: Systematic adjustment of of model modelparameters (HRTM, HAT) HAT) until untilfit fit is isacceptable Goodness of fit is acceptable End 5.23 Consult other experts IM2005, Vienna, April

38 5A 5.1 Identification of all measured data representing the case General guidelines 5A: for the Special estimation assessment of committed dose Inhalation: Standard evaluation As 3, but >1 measurement 5.4: Routine measurement inconsistent with previous or standard evaluation, dose >1 msv 5.2 Assessment of contributions from previous intakes and calculation of net values of measured data 5.3 Assign a priori parameters (default or site-specific) 5.4 Time of intake is known 5.5 Calculate the dose with a priori parameters 5.5: Calculate intake (dose?) I i from each measurement M i Best estimate = mean (I i ) 5.6: If dose from intake <1 msv, (for every measurement type) (for every radionuclide) Record and STOP 5.6 Dose from intake < 1 msv Record dose with a priori parameters End 5B IM2005, Vienna, April

39 s 5A & 5B: select parameter values by fitting model predictions to the data Dose from intake < 6 msv 5B 5.7 There are suffcient relevant data 5.8 Time of intake is known 5.9 Early lung and faeces data available 5.10 Derive effective AMAD from early lung and faeces data 5.11 Assessment of dose by fitting of the absorption type Goodness of fit is acceptable General guidelines for the estimation 5B: of committed dose 5A Special assessment Inhalation: vary AMAD, F/M/S, Time of intake Get additional dose relevant data 5.12 Assessment of dose by simultaneous fitting of both the time of intake and the absorption type Goodness of fit is acceptable Dose from intake < 6 msv Procedure stops when model fits, i.e. data do not reject model. Easy if few data, hence steps 5.6, , : Are there enough data? Depends on dose Check the number of data required for evaluation at this level and get more data, if necessary (Table) Check the number of data required for evaluation at this level and get more data, if necessary (Table) Record dose with all parameters 5.13 Assessment of dose by fitting of the mixture of default absorption types (F,M,S) 5.14 Assessment of dose by simultaneous fitting of both the time of intake and the mixture of default absorption types (F,M,S) Record dose with all parameters End 5C End IM2005, Vienna, April

40 Criteria for rejecting fit: Discussion Point!!! Model should fit fit data for unbiased estimate Proposed criteria for rejecting fit: Chi-squared test statistic: 1% level if ifdose <6 msv; 5% level if ifdose >6 msv; OR Fit looks unreasonable by eye (series of of data underorover-estimatedor IM2005, Vienna, April

41 Radionuclide Number and type of data needed for assessment of dose for selected radionuclides and monitoring procedures Discussion point!!! Type of monitoring Required monitoring data D < 1 msv 1 msv < D < 6 msv D > 6 msv Number Time range Number Time range Number Time range (days) (days) (days) This is only a start ( place-holder ) H-3 Urine Help is needed to: Co-60 W hole body Sr-90 Urine Faeces Ag-110m I-125 confirm (or improve) I-131 Thyroid Urine Cs-137 W hole body extend to other situations U-235 Urine Faeces Lungs Pu-239 Urine n.a Hopefully Faeces workplace monitoring 3 will 30 ensure 5 that 30 Am-241 Urine Faeces sufficient Lungs data are available Skeleton 1 30 IM2005, Vienna, April

42 5B 5.7 There are suffcient relevant data 5.8 Time of intake is known General guidelines for the estimation 5B: of committed dose 5A Special assessment Inhalation: vary AMAD, F/M/S, Time of intake Get additional dose relevant data 5.9 Early lung and faeces data available 5.10 Derive effective AMAD from early lung and faeces data Step 5.8 Procedure splits based on time of intake: known ( ) or 5.11 Assessment of dose by fitting of the absorption type 5.12 Assessment of dose by simultaneous fitting of both the time of intake and the absorption type unknown (5.12, 5.14) Dose from intake < 6 msv Goodness of fit is acceptable Goodness of fit is acceptable Dose from intake < 6 msv Check the number of data required for evaluation at this level and get more data, if necessary (Table) Check the number of data required for evaluation at this level and get more data, if necessary (Table) Record dose with all parameters 5.13 Assessment of dose by fitting of the mixture of default absorption types (F,M,S) 5.14 Assessment of dose by simultaneous fitting of both the time of intake and the mixture of default absorption types (F,M,S) Record dose with all parameters End 5C End IM2005, Vienna, April

43 General guidelines for the estimation 5B: of committed dose from Special incorporation assessment monitoring Inhalation: data vary AMAD, F/M/S (Time of intake) Step 5.8: time of intake known Main effect of AMAD is partition between: upper respiratory tract (ET, BB, bb) mostly early fecal excretion lower respiratory tract (AI) mostly lung retention Hence estimate effective AMAD IM2005, Vienna, April

44 General guidelines for the estimation 5B: of committed dose from Special incorporation assessment monitoring Inhalation: data vary AMAD, F/M/S (Time of intake) Cumulative activity in faeces from 1 to 3 days / activity in lung on day AMAD, µm Relatively insoluble materials Ratio of early fecal excretion to lung retention (day 3) for Am-241 Could extend to other situations Type M Type S Main effect of AMAD is partition between: upper respiratory tract (ET, BB, bb) mostly early fecal excretion lower respiratory tract (AI) mostly lung retention Hence estimate effective AMAD IM2005, Vienna, April

45 General guidelines for the estimation 5B: of committed dose from Special incorporation assessment monitoring Inhalation: data vary AMAD, F/M/S (Time of intake) Step 5.8: time of intake known Step 5.11 Fit absorption type A priori assignment based on chemical form (Step 5.3) Check goodness of fit (Step ). If fit rejected try other Types (F/M/S) IM2005, Vienna, April

46 General guidelines for the estimation 5B: Special of committed assessment dose from incorporation Inhalation: monitoring data vary AMAD, F/M/S (Time of intake) Step 5.8: time of intake known Steps &2 Model fits data, if dose <6 msv record dose and stop. Steps Enough data for 6 msv? Step 5.13 If fit rejected or additional data, try mixture of Types (F/M/S) IM2005, Vienna, April

47 Discussion point!!! If model fits, then probably several sets of parameter values (intake times and mixtures of absorption Types) will fit. t straightforward to harmonise best fit with two variables. Needs more work. General guidelines 5B: for Special the estimation assessment of committed Inhalation: dose vary (AMAD), F/M/S Time (Project of intake IDEAS) Step 5.8: time of intake unknown (Cannot determine effective AMAD) Step 5.12 Simultaneous fit of time of intake and absorption. If model fits data, and if dose <6 msv record dose and stop. Step Enough data for 6 msv? Step 5.14 If fit rejected or additional data, try mixture of Types (F/M/S) IM2005, Vienna, April

48 5C: Advanced evaluation Vary parameter values in in order: check fit fit after each step HRTM absorption parameters (f (f r r,, s r r,, s s s ) GI tract absorption ff 1 HRTM particle transport parameters GI tract transit Systemic biokinetic model IM2005, Vienna, April

49 Development of Guidelines 1. IDEAS: refine from outcome of the exercise, and discussions at the Workshop. Publish summer : ICRP Guidance Document to accompany revision of publications 30/54/68/78. Publish 2007? 3: IDEAS web site. CONRAD FP7? Another exercise around ? IM2005, Vienna, April