[Incorporation Monitoring of Staff using I-131 and Lu-177 in a Nuclear Medicine Ward]. / Inkorporationsüberwachung des Personals einer nuklearmedizinischen Therapiestation mit Einsatz von I-131 und Lu-177.

OBJECTIVES: In addition to the well-established therapy with iodine-131, treatments with lutetium-177 are increasingly being performed on an inpatient basis in Germany. All of these treatments have be taken into account when assessing the potential internal dose and for incorporation monitoring of personnel. This article describes the experience with and the results of incorporation monitoring of staff of a nuclear medicine ward of a university hospital in Germany. METHODS: Personnel working in a nuclear medicine ward was regularly measured using a whole body counter. In total, 234 measurements were performed over a period of 12 months. Incorporation factors were determined considering activities handled or applied to patients in the respective time period. RESULTS: In approx. 74 % of measurements, no incorporations was found. In the remaining measurements, activity was detected. Assuming incorporation, the maximum effective dose would be less than 0.15 mSv per measurement. The incorporation factors determined in this work were in the order of magnitude of 10-7 for all groups except for personnel performing radiochemical quality control. For this group, only an upper limit of the incorporation factor of 10-5 can be specified. CONCLUSION: The risk of incorporating radiactivity can be considered low for personnel working in a nuclear medicine ward. An incorporation factor of 10-7 is appropriate for medical, nursing, and cleaning staff and personnel performing radiochemical syntheses.

Assessment of the radiation exposure of relatives and caregivers of patients treated with Ra-223 - Results of a German multicenter study.

A multicenter study was conducted to assess the radiation exposure of relatives and caregivers of patients suffering from castration resistant prostate cancer with bone metastases and treated with Ra-223 dichloride in an outpatient setting. As Ra-223 and most of its progeny emit alpha particles, especially the internal exposure of persons in the patient's vicinity had to be evaluated. METHODS: The external radiation was measured in distances of 1 m and 2 m. Wipe-tests were taken in the patients' homes to identify significant contaminations and evaluated by liquid scintillation counting. Samples of saliva and sweat were taken and measured using gamma spectrometry. RESULTS: The external exposure from the patients measured 10-20min post injection (p. i.) was<0.080µSv/h in median in 1 m distance (range: below decision threshold (

Measurement of Rn-219 with Alphaguard radon monitors.

The alpha-emitting radionuclide Ra-223 is used in nuclear medicine in form of the commercially available radiopharmaceutical "Xofigo". The direct progeny of Ra-223 is Rn-219, a noble gas with a half-life of approx. four seconds, that might be exhaled by patients treated with Ra-223. For assessing the exhalation of Rn-219, a radon monitor calibrated for this isotope is necessary. This work investigates on the response of the commercially available Alphaguard radon monitor to Rn-219 and proposes for the first time a factor for the calculation of the Rn-219-concentration in the instrument's measurement chamber from the instrument reading suitable for estimating patients exhalations.

[Disposal of radioactive contaminated waste from Ga-68-PET - calculation of a clearance level for Ge-68]. / Entsorgung radioaktiv kontaminierter Reststoffe aus der Ga-68-PET ­ Berechnung eines Freigabewertes für Ge-68.

Ga-68-labeled radiotracers, particularly used for the detection of neuroendocrine tumors by means of Ga-68-DOTA-TATE or -DOTA-TOC or for the diagnosis of prostate cancer by means of Ga-68-labeled antigens (Ga 68-PSMA), become increasingly important. In addition to the high sensitivity and specificity of these radiopharmaceuticals, the short-lived radionuclide Ga-68 offers almost ideal nuclear characteristics for use in PET. Ga-68 is obtained from a germanium-gallium-generator system, so that the availability of Ga-68-labeled radiotracers is independent of an on-site-cyclotron regardless of the short half-life of Ga-68 of about 68minutes. Regarding the disposal of the radioactively contaminated waste from the preparation of the radiopharmaceutical, the eluted Ga-68 has to be considered to be additionally contaminated with its parent nuclide Ge-68. Due to this production-related impurity in combination with the short half-life of Ga-68, the radioactive waste has to be considered to be contaminated with Ge-68 and Ga-68 in radioactive equilibrium (hereafter referred to as Ge-68+). As there are no clearance levels for Ge-68+ given in the German Radiation Protection Ordinance, this work presents a method to calculate the missing value basing on a recommendation of the German Radiation Protection Commission in combination with simple geometric models of practical radiation protection. Regarding the relevant exposure scenarios, a limit value for the unrestricted clearance of Ge-68+ of 0.4 Bq/g was determined.

[Conservative calibration of a clearance monitor system for waste material from nuclear medicine]. / Konservative Kalibrierung eines Freimesssystems für Reststoffe aus dem nuklearmedizinischen Betrieb.

Clearance monitor systems are used for gross gamma measurements of waste potentially contaminated with radioactivity. These measurements are to make sure that legal requirements, e.g. clearance criteria according to the german radiation protection ordinance, are met. This means that measurement results may overestimate, but must not underestimate the true values. This paper describes a pragmatic way using a calibrated Cs-137 point source to generate a conservative calibration for the clearance monitor system used in the Medizinische Hochschule Hannover (MHH). The most important nuclides used in nuclear medicine are considered. The measurement result reliably overestimates the true value of the activity present in the waste. The calibration is compliant with the demands for conservativity and traceability to national standards.

A portable TDCR system.

The triple-to-double-coincidence ratio method (TDCR) is an important method for activity standardization in metrology institutes worldwide. There is an increasing interest in portable systems that allow activity determination outside of specialized laboratories with high accuracy. Within the framework of the EMRP "MetroFission" project, several portable systems using different designs were developed. The PTB system described here is based on channel photomultipliers incorporated in a portable detection module, a separate electronics bin and a computer for data acquisition and storage. This miniature TDCR system was extensively tested and compared to the PTB reference TDCR system that is very well characterized and has been used in several intercomparisons.

Investigations on TDCR measurements with the HIDEX 300 SL using a free parameter model.

The Triple to Double Coincidence Ratio (TDCR) method requires a special counting system with three photodetectors. The systems currently used by National Metrology Institutes for activity standardizations are custom built, and up to now the HIDEX 300 SL counter is the only TDCR counter commercially available. At PTB, measurements with a special metrology version of this counter were carried out to investigate its applicability for activity standardizations. The activity results of measurements with the HIDEX counter are compared to those obtained with a PTB-TDCR counter, as such a comparison reduces the model dependence. In addition, a spectrometry method was applied to measure (109)Cd samples and a new TDCR-Cerenkov method was tested with (32)P samples.

Activity standardization and decay data of 64Cu.

The activity of a solution of (64)Cu was measured by 4pibeta(PC)-gamma coincidence counting and liquid scintillation counting using the CIEMAT/NIST method. In addition, 4pi ionization chambers were used to establish and preserve calibration factors for secondary standardizations and for a determination of the half-life, for which a value of 12.704(5)h was measured. The photon emission probabilities were determined using gamma-ray spectrometry, finding values of p(511 keV)=0.3512(22) and p(1346 keV)=0.00474(5). The results were checked for consistency, and an ampoule was submitted to the BIPM to have the activity result entered into the database of the International Reference System (SIR), yielding the first entry for this radionuclide.