The Work Package 4 of the ORAMED project, a collaborative project (2008-11) supported by the European Commission within its seventh Framework Programme, is concerned with the optimisation of the extremity dosimetry of medical staff in nuclear medicine. To evaluate the extremity doses and dose distributions across the hands of medical staff working in nuclear medicine departments, an extensive measurement programme has been started in 32 nuclear medicine departments in Europe. This was done using a standard protocol recording all relevant information for radiation exposure, i.e. radiation protection devices and tools. This study shows the preliminary results obtained for this measurement campaign. For diagnostic purposes, the two most-used radionuclides were considered: 99mTc and 18F. For therapeutic treatments, Zevalin® and DOTATOC (both labelled with 90Y) were chosen. Large variations of doses were observed across the hands depending on different parameters. Furthermore, this study highlights the importance of the positioning of the extremity dosemeter for a correct estimate of the maximum skin dose

Baechler, S.

Barth, I.

Carnicer, A.

Donadille, L.

Ferrari, P.

Fulop, M.

Ginjaume, M.

Gualdrini, G.

Krim, S.

Mariotti, F.

Ortega, X.

Rimpler, A.

Ruiz, N.

Sans Merce, M.

Vanhavere, F.

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EXTREMITY EXPOSURE IN NUCLEAR MEDICINE:PRELIMINARY RESULTS OF A EUROPEAN STUDYM. Sans Merce 1,*, N. Ruiz 1, I. Barth 2, A. Carnicer 3, L. Donadille 4, P. Ferrari 5, M. Fulop 6, M. Ginjaume 3,G. Gualdrini 5, S. Krim 7, F. Mariotti 5, X. Ortega 3, A. Rimpler 2, F. Vanhavere 7 and S. Baechler 11Institute of Radiation Physics, University Hospital Center of Lausanne, Grand-pre´ 1, 1007 Lausanne,Switzerland2Bundesamt fu¨r Strahlenschutz, Ko¨penicker Allee 120-130, 10318 Berlin, Germany3Universitat Politecnica de Catalunya (UPC), Diagonal 647, 08028 Barcelona, Spain4Institut de Radioprotection et de Suˆrete´ Nucle´aire (IRSN), BP17, 92262 Fontenay-aux-Roses, France5Ente per le Nuove Tecnologie, l’Energia e l’Ambiente (ENEA), Via dei Colli 16, 40136 Bologna, Italy6Slovak Medical University, Limbova 12, 83303 Bratislava, Slovakia7Belgian Nuclear Research Centre (SCK†CEN), Boeretang 200, 2400 Mol, Belgium*Corresponding author: marta.sans-merce@chuv.chThe Work Package 4 of the ORAMED project, a collaborative project (2008–11) supported by the European Commissionwithin its seventh Framework Programme, is concerned with the optimisation of the extremity dosimetry of medical staff innuclear medicine. To evaluate the extremity doses and dose distributions across the hands of medical staff working in nuclearmedicine departments, an extensive measurement programme has been started in 32 nuclear medicine departments in Europe.This was done using a standard protocol recording all relevant information for radiation exposure, i.e. radiation protectiondevices and tools. This study shows the preliminary results obtained for this measurement campaign. For diagnostic purposes,the two most-used radionuclides were considered: 99mTc and 18F. For therapeutic treatments, Zevalinw and DOTATOC (bothlabelled with 90Y) were chosen. Large variations of doses were observed across the hands depending on different parameters.Furthermore, this study highlights the importance of the positioning of the extremity dosemeter for a correct estimate of themaximum skin doses.INTRODUCTIONAs a consequence of the definition that the dose limitfor the skin has to be applied to ‘the dose averagedover any area of 1 cm2 regardless of the areaexposed’, it is advisable to measure the local skindose at the location with presumably the highestexposure. This requirement is the central dilemma ofextremity dosimetry and causes severe practical diffi-culties. In daily practice, in nuclear medicine, it isoften not known which part of the hand will receivethe highest dose. Moreover, the dose distribution overthe hand may vary during a single process as well aswhen several people perform the same procedure(1).To tackle, amongst other things, these problems, theORAMED project (a collaborative project supportedby the European Commission within its seventhFramework Programme) was started at the beginningof 2008. The Work Package 4 of this project aims atoptimising radiation protection of medical staff innuclear medicine. The goal of the present work was tomeasure skin doses Hp (0.07) at different positions onthe hands for several nuclear medicine proceduresusing the appropriate measuring tools. The procedureswere selected according to their frequency of use, thedelivered doses and the three types of radionuclidescommonly used in nuclear medicine, i.e. positron,beta and gamma emitters.. For diagnostic purposes,two radionuclides are considered: 18F is used for posi-tron emission tomography (PET) examinations and99mTc is used for planar and single photon emissioncomputed tomography (SPECT) examinations. Thetwo most frequently used therapeutic agents are 90Y-labelled Zevalinw and DOTATOC. Other treatmentsbased on drugs labelled with other radionuclides (32P,177Lu, etc.) were also registered, but the results willnot be reported in this paper.MATERIALS AND METHODSAn extensive measurement programme is being per-formed in 32 nuclear medicine departments distribu-ted among hospitals in seven different countriesacross Europe with a unified protocol, where allrelevant information for radiation exposure (i.e. radi-ation protection devices and tools, dominant hand,staff experience) were recorded. Using the same pro-tocol, the measurements are harmonised and alldata can be compared and evaluated. The protocolincludes preparation and administration, indepen-dently, both for diagnostic and therapeutic appli-cations. The skin dose on the hands was measuredwith high-sensitivity thermoluminescent dosemeters(TLDs) specific for beta- and gamma-radiation.Figure 1 shows their placement on gloves at 11different positions for each hand.. Moreover, TLDs# The Author 2011. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.comRadiation Protection Dosimetry (2011), Vol. 144, No. 1–4, pp. 515–520 doi:10.1093/rpd/ncq574Advance Access publication 12 January 2011were welded in thin plastic bags to reduce the thick-ness on top of the TLD and adequately measure thequantity Hp(0.07).An intercomparison between the participating lab-oratories was performed at IRSN to assess andcompare the methods used for the calibration of thedosemeters. The main goal of this intercomparisonwas to establish a common basis for the measure-ment campaign among all participants. Two differ-ent reference irradiation fields were used: 137Cs and85Kr, defined in compliance with the ISO 4037-1(2)and 6980-1(3) standard. Standard TLDs(LiF:Mg:Cu:P and LiF:Mg:Ti, up to 240 mg cm22),used for gamma-ray measurements, were irradiatedwith 137Cs and thin TLDs (8–10 mg cm22), usedfor positron and beta pharmaceuticals(4), were irra-diated with 85Kr. All participants reported resultswithin 10 % of the reference value (2 mSv).RESULTS AND DISCUSSIONPreliminary results from the measurement campaignare shown in Tables 1 and 2. At the moment, 115workers from 32 nuclear medicine departments havebeen monitored. The aim is that every worker is mon-itored at least five times for the same diagnostic pro-cedure. For this study, all measurements have beenconsidered even when the number is smaller than five(for 50 % of the workers). To compare measurementsfrom different departments, for each procedure, thedose equivalent to the hands Hp(0.07) was measuredand normalised to the respective manipulatedactivity. In general, there is a large spread of results,due to the influence of many factors, such as the typeof protections used and the experience of the workers.The complete statistical analysis of the results isunder progress. The uncertainties associated to thedifferent values are not given for simplification ofreading the tables and figures.The maximum normalised doses in Tables 1 and 2correspond to the maximum values among allworkers and all measuring positions in the hands.Mean and median dose values correspond to themean and median value at the position where themaximum dose is most frequently found, usuallythe index tip/nail and the thumb.Normalised doses are higher for 18F than for99mTc, as shown in Table 1. However, diagnostic pro-cedures using 99mTc are more frequent than thoseusing 18F. Thus, the activities manipulated areusually higher for 99mTc than for 18F. ComparingTable 1 with Table 2, the doses obtained for diagnos-tics procedures were found to remain much lowerthan the values measured for therapeutic procedureswith 90Y. Usually preparation delivers higher dosesthan the administration of the radiopharmaceutical.Three main reasons contribute to this effect. First,the activities manipulated for preparation are higherthan those manipulated for the administration of theradiopharmaceutical. Second, some of the prep-aration steps are performed with an unshieldedsource, while the administration of the radiopharma-ceutical to the patient is usually performed with ashielded syringe. Finally, the time needed to preparea radiopharmaceutical is longer than the timeneeded for administering it.Mean normalised doses per positionThe mean normalised doses found for each moni-tored hand position are shown in Figures 2 and 3for diagnostic and therapeutic procedures,respectively.From Figures 2 and 3, it is clearly seen that thetips and nails of the fingers are the most exposedareas in the hands. The two most exposed fingers arethe index and the thumb usually of the non-domi-nant hand, followed by the middle and the ring. Thewrist position, even if used in some countries asroutine monitoring position(5), is the least exposedposition in the hand.Position of the dosemeter for extremity monitoringTo comply with the definition of dose limit for theskin, the recommended position for extremity moni-toring is the position where the maximum dose canbe found.Figure 1. TLDs positioning in the hands.Table 1. Maximum, median and mean normalised doses forthe two radionuclides most commonly used for diagnostics.Diagnostic radionuclidesA-99mTc P-99mTc A-18F P-18FMaximum (mSv GBq21) 1.50 2.06 3.67 4.43Median (mSv GBq21) 0.07 0.17 0.33 0.64Mean (mSv GBq21) 0.07 0.32 0.71 0.77‘A’ stands for administration and ‘P’ for preparation.M. SANS MERCE ET AL.516Table 2. Maximum, median and mean normalised doses for 90Y Zevalinw and DOTATOC therapies.Therapeutic radionuclidesA-90Y Zevalinw P-90Y Zevalinw A-90Y Dotatocw P-90Y DotatocwMaximum (mSv GBq21) 11.17 32.05 6.27 5.84Median (mSv GBq21) 2.16 2.07 0.56 0.34Mean (mSv GBq21) 2.46 3.52 0.65 1.65‘A’ stands for administration and ‘P’ for preparation.Figure 3. Mean normalised doses in each position of the hands for both preparation and administration for the twotherapies (Zevalinw and DOTATOC) considered.Figure 2. Mean normalised doses in each position of the hands for the radionuclides used in diagnostics and for bothprocedures—preparation and administration.EXTREMITY EXPOSURE IN NUCLEAR MEDICINE517Figures 4 and 5 show for each radionuclide andfor each procedure, the frequencies of the positionwhere the maximal dose was measured. The mostfrequent positions correspond to the index tip/nailand thumb of the non-dominant hand.The impact of placing the routine monitoring dose-meter at a different position than the one correspond-ing to the maximal hand dose has been estimated bycalculating correction factors as ratios between theindex tip or maximum in the hand and the positionusually used for routine monitoring, i.e. the base ofthe index or the ring finger, as shown in Figure 6.The values used to compute the correction factorsare the mean dose values obtained by averagingamong all workers; so individual values can be evenmuch higher. Those factors vary from 1 to 7 depend-ing on the radionuclide and the procedure. The correc-tion factors with respect to the ring finger are usuallyhigher than those with respect to the base of the indexfinger. Indeed, the index finger, specially the tip, isusually one of the most-exposed fingers, in accordanceto what has already been observed in the literature(6).CONCLUSIONSPreliminary results show that large variations of skindoses were observed across the hands, from 0.07 to32.05 mSv GBq21, depending on the radionuclideand procedure, but also on the worker and the radi-ation-protection measures. Further analyses will bedone on these influences in the future.The positioning of the dosemeter used in routinemonitoring strongly affects the estimates of the extre-mity doses meaning that in some cases, the limit onequivalent dose for the skin (0.5 Sv y21) could besurpassed. For example, a worker manipulating anannual realistic activity of 1500 GBq of 99mTc couldbe receiving an annual dose of 150 mSv at the baseof the ring finger; in this case, the dose at themaximum (factor 4 higher) will exceed the annuallimit of 500 mSv. From the available results, it canbe concluded that the position of the dosemeter onthe hand is important to obtain a correct estimate ofthe extremity dose. Neither the wrist nor the ringpositions, ordinarily used as routine monitoring pos-itions, are adequate for this purpose. A more correctposition will be the tip of the index finger on thenon-dominant hand. However, since this is difficultto accomplish in daily practice, a ring dosemeterplaced on the base of the index finger of the non-dominant hand might be a better alternative. In thiscase, radiation protection officers must be aware thatthe measured dose in such case will be around afactor of 2.5 smaller than the maximum skin dose.Figure 4. Frequencies of the position where the maximum dose was obtained for preparation and administration of 99mTcand 18F. (The regions highlighted in grey and with capital letters correspond to the dominant hand, while that in whitecorrespond to the non-dominant hand. Positions where values are under 7 % are not labelled.)M. SANS MERCE ET AL.518Figure 5. Frequencies of the position where the maximum dose was obtained, for 90Y Zevalinw and 90Y DOTATOC, forpreparation and administration. (The regions highlighted in grey and with capital letters correspond to the dominanthand, and white to the non-dominant hand. Positions where values are under 7 % are not labelled.)Figure 6. Correction factors computed for the non-dominant hand, i.e. usually the most-exposed hand. ‘Prep.’ stands forpreparation and ‘Adm.’ for administration.EXTREMITY EXPOSURE IN NUCLEAR MEDICINE519FUNDINGThis work was supported by the European AtomicEnergy Community’s Seventh Framework Programme(FP7/2007–2011) under grant agreement no. 211361.REFERENCES1. Vanhavere, F., Carinou, E., Donadille, L., Ginjaume,M., Jankowski, J., Rimpler, A. and Sans Merce, M. Anoverview of extremity dosimetry in medical applications.Radiat. Prot. Dosim. 129, 350–355 (2008).2. International Organization for Standardization. X andgamma reference radiation for calibrating dosemeters anddose rate meters and for determining their response as afunction of photon energy—part I: characteristics of theradiations and their methods of production. ISO 4037–1(ISO) (1996).3. International Organization for Standardization. Nuclearenergy—reference beta-particle radiation—part 1: methodof production. ISO 6980–1 (ISO) (2006).4. Ginjaume, M. et al. Extremity ring dosimetry intercom-parison in reference and workplace fields. Radiat. Prot.Dosim. 131, 67–72 (2008).5. Donadille, L., Carinou, E., Ginjaume, M., Jankowski,J., Rimpler, A., Sans Merce, M. and Vanhavere, F. Anoverview of the use of extremity dosemeters in someEuropean countries. Radiat. Prot. Dosim. 131, 62–66(2008).6. Wrzesien, M., Olszewski, J. and Jankowski, J. Handexposure to ionising radiation of nuclear medicineworkers. Radiat. Prot. Dosim. 130, 325–330 (2008).M. SANS MERCE ET AL.520

Extremity exposure in nuclear medicine: preliminary results of a European study

Extremity exposure in nuclear medicine: preliminary results of a European study

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