Bei der Vorbereitung und der Applikation von Radiopharmaka in der Nuklearmedizin sind vor allem an den Händen des betreffenden Personals Überschreitungen des Grenzwertes für die Organdosis der Haut von 500 mSv/a nicht auszuschließen. Im Rahmen des EU-Projekts ORAMED (Optimization of Radiation Protection in Medicine) erfolgten Untersuchungen zur Hautexposition bei der Diagnostik mit Tc-99 m und F-18 sowie bei Radionuklidtherapien mittels Y-90-markierter Radiopharmaka. In 7 europäischen Ländern und 32 Einrichtungen wurden Erhebungsmessungen zur Hautdosis an 124 Mitarbeitern durchgeführt. Ziel war die Ermittlung der individuellen maximalen lokalen Hautdosis, HP (0,07)max. Die gefundenen Mittelwerte der aktivitätsnormierten Dosiswerte, H P (0,07)max/A, umfassten erwartungsgemäß einen großen Bereich, von 0,23 mSv/GBq bei der Administration von Tc-99 m bis zu 11 mSv/GBq bei der Markierung von Y-90/Zevalin®. Dabei war die Strahlenbelastung bei der Markierung der radioaktiven Substanzen und der Vorbereitung der Spritzen grundsätzlich höher als bei deren Administration am Patienten. Die individuelle Dosis hängt entscheidend davon ab, ob adäquate Abschirmungen für Spritzen und ­Vorratsfläschchen (Vials) sowie abstandsvergrößernde Hilfsmittel verwendet werden. Untersuchungen zur Dosisverteilung an den Händen geben Anlass, die bisherige Praxis beim Tragen amtlicher Teilkörperdosimeter kritisch zu hinterfragen. Es wird empfohlen, Ringdosimeter in der Nuklearmedizin grundsätzlich am Grundglied des Zeigefingers der nicht-dominanten Hand zu tragen, mit palmar ausgerichteter Dosimetersonde. Auch bei dieser Kompromisslösung wird die zu limitierende maximale Hautdosis systematisch unterschätzt, im Mittel um einen Faktor 5, jedoch weniger als bei allen anderen zumutbaren Dosimetertrageorten. Die Untersuchungen zeigten, dass in den meisten Einrichtungen Möglichkeiten zur Reduzierung der Hautexposition des Personals bestehen.

The increase in the use of radionuclide therapies (RNT) requires establishing adequate protective standards to avoid high radiation doses to the occupationally exposed technical and medical staff. Due to the particular working conditions when using unsealed radionuclides in RNT, predominantly exposure to the skin on the hands may occur. First of all, the use of nuclides emitting high-energetic beta radiation, such as Y-90, is a challenge to health physicists. This chapter provides the basic physical characteristics, explains the fundamental principles of radiation protection and describes the key components of a dedicated radiation protection regime in nuclear medicine in order to minimise radiation exposure. The radiation protection measures are based on well-known rules: the use of adequate shields, keeping distance to the sources and limiting the exposure time. These provisions have to be completed by routine monitoring of skin exposure using appropriate ring dosimeters and regular contamination checks. A review of the most important recent literature on exposure and radiation safety related to special therapy procedures is included. Besides the exposure of staff during preparation and administration of radiopharmaceuticals in RNT, protection of members of the public, such as relatives and caregivers of RNT patients, is also a matter of concern. Some precautionary measures have to be observed, especially after the patient's release from the hospital.

Depth-dose curves in LiF detectors of different effective thicknesses, together with their responses, were calculated for typical nuclear medicine radiation fields with Tc-99m, F-18 and Y-90 sources. Responses were analysed in function of the radionuclide, detector effective thickness and irradiation geometry. On the other hand the results of the nuclear medicine measurement campaign of the ORAMED project were presented focussing on the dose distribution across the hand and on the appropriate position to wear the dosimeter. According to the results, thin LiF detectors provide better responses in all cases. Its use is essential for F-18, since thick dosimeters can underestimate H-p(0.07) up to a 50% because of the very inhomogeneous dose deposition on the active layer. The preliminary results of the measurement campaign showed that the index tip of the non-dominant hand is usually the most exposed position among the 22 monitored positions. It was also found that, in average, wrist dosimeters are likely to underestimate the maximum skin dose by a factor of the order of 20. This factor is reduced to around 6 for a ring dosimeter worn on the base of the index of the non-dominant hand. Thus, for typical nuclear medicine procedures, the base of the index of the non-dominant hand is recommended as the best monitoring option. (C) 2011 Elsevier Ltd. All rights reserved.

Workers performing preparation and administration of radiopharmaceuticals in NM departments are likely to receive high local skin doses to the hands which may even surpass the dose limit of 500 mSv whenever radiation protection standards are insufficient. A large measurement campaign was organised within the framework of the ORAMED project to determine the dose distribution across the hands received during preparation and administration of F-18- and Tc-99m-labelled radiopharmaceuticals. The final data, collected over almost 3 years, include 641 measurements from 96 workers in 30 NM departments from 6 European countries. Results have provided levels of reference doses for the considered standard NM diagnostic procedures (mean maximum normalised skin dose of 230 mu Sv/GBq, 430 mu Sv/GBq, 930 mu Sv/GBq and 1200 mu Sv/GBq for the administration of Tc-99m, preparation of Tc-99m, administration of F-18 and preparation of F-18, respectively). Finger dose was analysed as a function of the potential parameters of influence showing that shielding is the most efficient means of radiation protection to reduce skin dose. An appropriate method for routine monitoring of the extremities is also proposed: the base of the index finger of the non-dominant hand is a suitable position to place the ring dosemeter, with its sensitive part oriented towards the palm side; its reading may be multiplied by a factor of 6 to estimate the maximum local skin dose. Finally, results were compared to earlier published data, which correspond mostly to individual works with a reduced number of workers and measurements. (C) 2011 Elsevier Ltd. All rights reserved.

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: (99m)Tc and (18)F. For therapeutic treatments, Zevalin(®) and DOTATOC (both labelled with (90)Y) 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 doses.

The optimization of the extremity dosimetry of medical staff in nuclear medicine was the aim of the Work Package 4 (WP4) of the ORAMED project, a Collaborative Project (2008–2011) supported by the European Commission within its 7th Framework Programme. Hand doses and dose distributions across the hands of medical staff working in nuclear medicine departments were evaluated through an extensive measurement program involving 32 hospitals in Europe and 139 monitored workers. The study included the most frequently used radionuclides, 99mTc- and 18F-labelled radiopharmaceuticals for diagnostic and 90Y-labelled Zevalin® and DOTATOC for therapy. Furthermore, Monte Carlo simulations were performed in different predefined scenarios to evaluate separately the efficacy of different radiation protection measures by comparing hand dose distributions according to various parameters. The present work gives recommendations based on results obtained with both measurements and simulations. This results in nine practical recommendations regarding the positioning of the dosemeters for an appropriate skin dose monitoring and the best protection means to reduce the personnel exposure.

90Y-labelled radiopharmaceuticals offer promising prospects for radionuclide therapies of tumours, e.g. radioimmunotherapies (RIT), (EANM, 2007), peptide receptor radiotherapies (PRRT), (Otte et al., 1998), and selective internal radiotherapies (SIRT), (Salem and Thurston, 2006). 90Y, an almost pure high-energy beta radiation emitter (Eβ,max = 2.28 MeV), is a favourable radionuclide for therapeutic purposes. However, when preparing and performing these therapies, high activities of 90Y (>1 GBq) are to be manipulated and technicians, physicians and nurses may receive high skin exposures to the hands. If radiation protection standards are low, the exposure of staff can exceed the annual skin dose limit of 500 mSv. Within a particular work package (WP4) of the ORAMED project, comprehensive measurements in nuclear medicine departments of several hospitals in 6 European countries were carried out. The study focussed on 90Y-labelled substances such as Zevalin® and DOTATOC to achieve a representative database on staff exposure. This paper summarises the most important results and conclusions for individual monitoring of skin exposure of staff.

Neben der seit vielen Jahren erfolgreich angewandten Radiosynoviorthese (RSO) von entzündlichen Gelenkerkrankungen mit Betastrahlern (Er-169, Re-186, Y-90) haben in den letzten Jahren neue Therapieverfahren in die nuklearmedizinische Praxis Einzug gehalten. Bei der Radioimmuntherapie (RIT) mit Y-90/Zevalin, der palliativen Therapie mit Sm-153 und der Radiopeptidtherapie mit Lu-177 und Y-90 werden die speziellen Eigenschaften von Betastrahlern z.B. zur Abtötung von Tumorgewebe bei weitestgehendem Schutz des umgebenden gesunden Gewebes ausgenutzt. Die große Ionisierungsdichte hochenergetischer Betastrahlung hat aber zur Folge, dass die Haut des Personals im Vergleich zur Gammastrahlung, z.B. von Tc-99m, bei gleicher Aktivität einem deutlich höheren Expositionsrisiko ausgesetzt ist. Mit speziellen Thermolumineszenzdosimetern ermittelte maximale lokale Hautdosen an den Fingerspitzen des Personals zeigten, dass der Grenzwert für die Organdosis der Haut beruflich strahlenexponierter Personen von 500 mSv pro Jahr bei unsachgemäßer Arbeitsweise deutlich überschritten werden kann. Im Vortrag wird auf gravierende Fehler beim Umgang mit Betastrahlern eingegangen und Strahlenschutzmaßnahmen werden vorgestellt. Die untersuchten Therapieverfahren können jedoch aus strahlenhygienischer Sicht sicher betrieben werden, wenn geeignete Strahlenschutzmittel verwendet und die empfohlenen Strahlenschutzmaßnahmen beachtet werden. Entgegen der vorherrschenden Meinung in der Literatur zeigten Untersuchungen des Bundesamts für Strahlenschutz, dass in der Nähe des Patienten kurz nach der Therapie nicht Bremsstrahlung sondern Betastrahlung vorherrscht. Die Dosisleistung der Betastrahlung ist ein bis zwei Größenordnungen höher als die der Bremsstrahlung. Da die Patienten meist ambulant behandelt werden, sind daher von ihnen bestimmte Regeln zum Umgang mit Angehörigen einzuhalten.

Radioimmunotherapies (RITs) and peptide receptor radiotherapies (PRRTs) with (90)Y-labelled compounds offer promising prospects for tumor treatment in nuclear medicine. However, when preparing and performing these therapies, which require manipulations of high activities of (90)Y (>1 GBq), technicians and physicians may receive high exposures, mainly to the skin of the hands. Even non-occupationally exposed persons, such as caregivers and family members, receive external exposures in the initial period after therapy, arising from the (90)Y in the patient. The local skin doses of the individual staff members, measured during RITs and PRRTs with thermoluminescence detectors fixed with tapes to the fingers, vary considerably. The exposure of staff can exceed the annual permissible dose limit of 500 mSv if radiation protection standards are low. Thus, adequate safety measures are needed. Measurements of the dose rate around patients, made using survey meters with sufficient response to beta particles, indicate that the exposure of caregivers and family members is considerably higher than previously assumed, and was dominated by primary beta radiation instead of bremsstrahlung. Nevertheless, under normal circumstances, the annual dose limits for the public (effective dose: 1 mSv, skin dose: 50 mSv) will be complied with.

Sealed and unsealed beta radiation sources come into use to a greater extent in radiation therapy, e.g. for treating inflammatory joint diseases by radiosynoviorthesis (RSO), by injecting 90Y, 186Re or 169Er-solutions. Sealed 90Sr/90Y and 32P-sources or 188Re-liquid-filled balloon catheter are applied in vascular brachytherapy. Recently, 90Y-labelled antibodies are being successfully used in radioimmunotherapy (RIT) of malign lymphoma. Such practices require handling of high activities at small distances to the skin. Thus, the medical staff may be exposed to high beta doses. Investigations of the extremity exposure were performed at several workplaces, in particular during RSO treatments. The local skin dose (LSD), Hp(0,07), was measured with thin-layer TLD (LiF:Mg,P,Cu) fixed to the fingers (TLD-tapes). The findings indicate that the exposure of the staff can exceed the annual dose limit of 500 mSv when working at low protection standard. Routine monitoring of the extremity exposures with ring dosemeters appropriate to beta radiation and provided by the approved German dosimetry services was found to be needed. But even monitoring with these official 'beta-dosemeters' does mostly not give suitable results to demonstrate compliance with the dose limit. A study was conducted at RSO-workplaces in order reveal a correlation between doses measured with ring dosemeters and the maximum LSD obtained from the TLD-tapes. The results are discussed and conclusions for routine monitoring are drawn.

Summary Aim of this study was the assessment of the radiation exposure from preparation and application of 90Y-Zevalin, the measurement of the dose rate at the patient, the exposure of family members as well as the determination of the activity concentration in urine of patients. Methods: Overall data from 31 therapeutic administrations carried out in four institutions were evaluated. During preparation and application of 90Y-Zevalin the finger exposures of radiochemists, technicians, and physicians were measured. The dose rate of the patient was measured immediately after radioimmunotherapy. In patients treated in a nuclear medicine therapy unit, urine was collected over a two day period and the corresponding activity was determined. Family members of outpatients were asked to wear a dosimeter over a seven day period. Results: During the preparation we found a maximum skin dose of 6 mSv at the average, and during application of 3 mSv, respectively. After administration of 90Y the dose rate was 0.4±0.1 μSv/h at 2 m distance. Urine measurements yielded a cumulated 24 h excretion of 3.9±1.4% and 4.4±1.4% within 48 h, respectively, that is equivalent to 43±18 and 50±20 MBq of 90Y, respectively. Family members received a radiation exposure of 40±14 μSv over seven days. Conclusion: During preparation and application of 90Y-Zevalin appropriate radiation shielding is necessary. For family members as well as nursing staff no additional special radiation protection measures beyond those being common for other nuclear medicine procedures are necessary.

UNLABELLED AIM of this study was the assessment of the radiation exposure from preparation and application of (90)Y-Zevalin, the measurement of the dose rate at the patient, the exposure of family members as well as the determination of the activity concentration in urine of patients. METHODS Overall data from 31 therapeutic administrations carried out in four institutions were evaluated. During preparation and application of (90)Y-Zevalin the finger exposures of radiochemists, technicians, and physicians were measured. The dose rate of the patient was measured immediately after radioimmunotherapy. In patients treated in a nuclear medicine therapy unit, urine was collected over a two day period and the corresponding activity was determined. Family members of outpatients were asked to wear a dosimeter over a seven day period. RESULTS During the preparation we found a maximum skin dose of 6 mSv at the average, and during application of 3 mSv, respectively. After administration of (90)Y the dose rate was 0.4 +/- 0.1 microSv/h at 2 m distance. Urine measurements yielded a cumulated 24 h excretion of 3.9 +/- 1.4% and 4.4 +/- 1.4% within 48 h, respectively, that is equivalent to 43 +/- 18 and 50 +/- 20 MBq of (90)Y, respectively. Family members received a radiation exposure of 40 +/- 14 microSv over seven days. CONCLUSION During preparation and application of (90)Y-Zevalin appropriate radiation shielding is necessary. For family members as well as nursing staff no additional special radiation protection measures beyond those being common for other nuclear medicine procedures are necessary.

In der Nuklearmedizin werden zunehmend offene und umschlossene Beta-Strahler angewendet. Dies ist teilweise für das Personal mit hohen Strahlenexpositionen, insbesondere der Hände, verbunden. Es ist anzunehmen, dass der Grenzwert für die Organdosis der Haut beruflich strahlenexponierter Personen von 500 mSv pro Jahr überschritten werden kann. Deshalb wurden vom Bundesamt für Strahlenschutz (BfS) Untersuchungen zur Strahlenschutzsituation an Arbeitsplätzen und Erhebungsmessungen der Teilkörperexposition bei folgenden Therapieverfahren durchgeführt:- Radiosynoviorthese (RSO) mit 90Y, 169Er und 186Re- Radioimmuntherapie (RIT) von Non-Hodgkin-Lymphomen mit 90Y-Zevalin®- palliative Schmerztherapie (PST) mit 153SmTätigkeiten bei diesen Therapien sind gekennzeichnet durch den Umgang mit hohen Aktivitäten, sehr kleine Abstände der Hände zu den Quellen sowie ein hohes Kontaminationsrisiko, da mit offenen Radionukliden umgegangen wird. Zur Ermittlung der Teilkörperexposition, insbesondere an den Händen, wurden Dünnschicht-Thermolumineszenzdosimeter (TLD) eingesetzt. Den Schwerpunkt der Untersuchungen bildete die Radiosynoviorthese. Hier wurden an einigen Arbeitsplätzen maximale lokale Hautdosen Hp (0,07) an den Fingerspitzen durch Direktstrahlung von mehr als 100 mSv (bis zu 210 mSv) pro Arbeitstag ermittelt. In einigen Fällen traten zusätzlich Expositionen durch Kontaminationen in der gleichen Größenordnung auf. Maßnahmen und Strahlenschutzmittel, deren Praxiseinführung zu einer beträchtlichen Verringerung der beruflichen Exposition führt, werden beschrieben und Therapie übergreifende Empfehlungen zur Verbesserung der Strahlenschutzsituation bei nuklearmedizinischen Therapien gegeben. Die Verwendung von amtlichen Beta-/Photonen-Fingerringdosimetern wird empfohlen und die Abhängigkeit des Dosismesswertes von der Trageweise diskutiert.

Beta-emitters are increasingly used in medicine in unsealed and sealed form. Therapeutic applications benefit from the fact that the beta-energy can be totally absorbed in a small delimited tissue volume. The occupational beta-radiation exposure was determined for the personnel at different workplaces in the following fields of medicine: Radiosynoviorthesis (Y-90, Er-169, Re-186) a therapy of inflammatory joint diseases Preparation and application of Re-188 liquid-filled balloon catheter for vascular brachytherapy Use of the Beta-Cath system (Sr-90/Y-90) in the therapy of in-stent-restenosis patients Change of the P-32-Source at a Galileo system for vascular brachytherapy Treatment of an eye tumour with Ru-106/Rh-106 eye applicator and Treatment of Non-Hodgkin lymphomas by radioimmunotherapy with Zevalin (Y-90). Practices in these fields are characterized by handling high activities, very small distances between source and skin as well as high risk of contamination when using unsealed sources and unsatisfactory area and personal dosemeters. Very sensitive thin-layer thermoluminescence dosemeters (TLD) were used to determine the skin exposure to the hands due to beta-radiation. At some workplaces local skin doses Hp(0,07) at the fingertips due to direct radiation of more than 100 mSv up to about 700 mSv per working day were determined. In addition, exposures in the same order of magnitude were sometimes caused by contamination of the skin. Thus, several simple radiation protection measures have been introduced, leading to a considerable reduction of occupational exposure. Some examples of such measures will be presented. Furthermore, the application of an authorized partial body personal betadosemeter with workplace-specific correction factor is proposed.

ZusammenfassungZiel: Der Anstieg der Therapiezahlen bei der Radio-synoviorthese (RSO) und die neue Strahlenschutzverordnung (StrSchV) erfordern, die -Strahlenbelastung, HP(0,07), des Personals bei der RSO zu dokumentieren. Methode: Da die amtlichen Teilkörperdosimeter (TLDFingerringdosimeter) die -Strahlenbelastung bei der RSO ungenügend wiedergeben, wurden Thermolumineszenzdosimeter (TLD) auf allen Fingerkuppen des Therapeuten, Radiochemikers und der assistierenden Schwester platziert. An 6 Therapietagen mit insgesamt 155 behandelten Gelenken erfolgte die Messung der HP(0,07) für die Nuklide 169Er, 186Re, 90Y. Ergebnisse: Die höchste Dosis zeigten linker Zeigefinger- (ZF li.) und Daumenkuppe (Daumen li.) des Therapeuten (Rechtshänder). Für drei Therapiesitzungen mit 52 Finger- (1204 MBq 169Er), 31 großen Gelenken (2405 MBq 186Re) sowie 15 Kniegelenken (3100 MBq 90Y) betrug die kumulative Dosis für den ZF li. 190 mSv , für den Daumen li. 48 mSv. Als maximale Ortsdosen ergeben sich: 0,56 Sv/MBq (169Er) bzw. 1,52 Sv/MBq (186Re) am ZF li. Durch Einsatz eines Manipulators für die Fixierung der Injektionsnadel konnte die Fingerbelastung für 90Y am li. ZF von 22,09 auf 0,42 Sv/MBq reduziert werden. Die kumulative Fingerbelastung betrug 119 mSv am Daumen li. (Radiochemiker) und 16 mSv am ZF li. (Assistenz). Schussfolgerung: Bei üblicher Durchführung der RSO wird der größte Teil der HP(0,07) durch 90Y verursacht. Besonders am ZF li. besteht die Gefahr, den Grenzwert der Organdosis für die Haut §55 StrlSchV zu überschreiten. Mit einem Manipulator zur Fixierung der Injektionsnadel kann die maximale Fingerbelastung um den Faktor 50 reduziert und der gesetzlich vorgeschriebene Grenzwert eingehalten werden.