Finger doses due to Ga-68-labelled pharmaceuticals in PET departments-results of a multi-centre pilot study

Introduction: Although the use of Ga-68 has increased substantially in nuclear medicine over the last decade, there is limited information available on occupational exposure due to Ga-68. The purpose of this study is to determine the occupational extremity exposure during the preparation, dispensing and administration of Ga-68-labelled radiopharmaceuticals. Method: Workers in eight centres wore a ring dosimeter for all tasks involving Ga-68-labelled radiopharmaceuticals for a minimum of one month. Additionally, the fingertip dose was monitored in two centres and the hand with the highest ring dose during Ga-68 procedures was also identified in one centre. Results: The median normalised ring dose for Ga-68 procedures was found to be 0.25 mSv GBq(-1) (range 0.01-3.34). The normalised Ga-68 ring doses recorded in this study are similar to that found in the literature for F-18. This study is consistent with previous findings that the highest extremity dose is found on the non-dominant hand. A limited sub study in two of the centres showed a median fingertip to base of the finger dose ratio of 4.3. Based on this median ratio, the extrapolated annual Ga-68 fingertip dose for 94% of the workers monitored in this study would be below Category B dose limit (150 mSv) and no worker would exceed Category A dose limit (500 mSv). Conclusion: When appropriate shielding and radiation protection practices are employed, the extremity dose due to Ga-68 is comparable to that of F-18 and is expected to be well below the regulatory limits for the majority of workers

Intercomparison of Gafchromic™ films, TL detectors and TL foils for the measurements of skin dose in interventional radiology

Several passive solid state dosemeters, such as GafchromicTM films and thermoluminesscence (TL) detectors, are used to estimate and monitor patient skin doses in interventional radiology. To determine the suitability of XR-TypeR GafchromicTM films and of detectors based on TL materials: pellets, chips and foils to measure skin dose, an intercomparison exercise has been organized within European Dosimetry Radiation Group - Working Group 12 “European Medical ALARA Network” (EURADOS WG12). To test response detectors were exposed to X-ray beams of energies and qualities applied clinically. A blind test was also performed to investigate the accuracy of the dose estimate by detectors exposed to unknown doses. We found the response of films to be strongly dependent on beam quality and filtration (increasing by up to 80 % with respect to reference beam quality). The response of TL detectors was found to be less dependent on beam quality (less than 25% variation), with TL foils showing less than 10% variation with respect to reference beam quality. To accurately estimate patient skin doses in interventional radiology it is important to choose the quality of the calibration beam to be as close as possible to the quality of beams actually applied in clinical work

Independent isotopic fission yields of Cf-252 spontaneous fission via mass measurements at the FRS Ion Catcher

We present first preliminary results of a novel method for measuring independent isotopic fission yields (IIFYs) of spontaneous fission (SF) via direct mass measurements, at the FRS Ion Catcher (FRS -IC) at GSI. Fission products were generated from a Cf-252 source installed in a cryogenic stopping cell, and were identified and counted with the multiple-reflection time-of-flight mass spectrometer (MR-TOR-MS) of the FRS-IC, utilizing well-established measurement and data analysis methods. The MR-TOR-MS resolves isobars unambiguously, even with limited statistics, and its non-scanning nature ensures minimal relative systematic uncertainties amongst fission products. The analysis for extracting IIFYs includes isotope-dependent efficiency corrections for all components of the FRS -IC. In particular, we applied a self-consistent technique that takes into account the element-dependent survival efficiencies in the CSC, due to chemical reactions with the buffer gas. Our IIFY results, which cover several tens of fission products in the less -accessible high-mass peak (Z = 56 to 63) down to fission yields at the level of 10(-5), are generally similar to those of the nuclear database ENDF/B-VII.O. Nevertheless, they reveal some structures that are not observed in the database smooth trends. These are the first results of a planned campaign to investigate IIFY distributions of spontaneous fission at the FRS-IC. Upcoming experiments will extend our results to wider Z and N ranges, lower fission yields, and other spontaneously-fissioning actinides