Finger doses due to68Ga-labelled pharmaceuticals in PET departments-results of a multi-centre pilot study.

INTRODUCTION: Although the use of68Ga has increased substantially in nuclear medicine over the last decade, there is limited information available on occupational exposure due to68Ga. The purpose of this study is to determine the occupational extremity exposure during the preparation, dispensing and administration of68Ga-labelled radiopharmaceuticals. METHOD: Workers in eight centres wore a ring dosimeter for all tasks involving68Ga-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 during68Ga procedures was also identified in one centre. RESULTS: The median normalised ring dose for68Ga procedures was found to be 0.25 mSv GBq-1(range 0.01-3.34). The normalised68Ga ring doses recorded in this study are similar to that found in the literature for18F. 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 annual68Ga 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 to68Ga is comparable to that of18F and is expected to be well below the regulatory limits for the majority of workers.

RADIATION DETECTOR FOR THE ISRAELI FIRST RESPONDERS-METHODOLOGY OF SELECTION.

This paper presents the rationale and development of a methodology of selection of a radiation detector that can be used by first responders arriving to a terror event scene, not knowing if the event involves any radioactive materials. This detector can be used to detect and quantify the presence of gamma radiation. The role of this detector in a radiological terror event is reviewed via the operational concept for handling radiological terror in Israel. The development of the methodology of selection included a literature survey of relevant radiation detector categories, followed by a user-side survey of requirements based on the first responders' experience along with the Israeli Ministry of Defense perspective on the management of radiological events, supplemented by the input from experts in aspects of radiation detection, radiation protection and dosimetry from the Israel Atomic Energy Commission's Soreq Nuclear Research Center. The general qualitative characterisation of requirements was then quantified using a scoring method, enabling the methodological evaluation and numerical ranking of available detectors. Plans to evaluate candidate detector models according to the developed methodology are outlined. The detectors evaluation will be conducted as part of the procurement procedure of future detectors for first responders.

IMPROVEMENT OF DOSE ESTIMATION PROCESS USING ARTIFICIAL NEURAL NETWORKS.

We present here for the first time a fast and reliable automatic algorithm based on artificial neural networks for the anomaly detection of a thermoluminescence dosemeter (TLD) glow curves (GCs), and compare its performance with formerly developed support vector machine method. The GC shape of TLD depends on numerous physical parameters, which may significantly affect it. When integrated into a dosimetry laboratory, this automatic algorithm can classify 'anomalous' (having any kind of anomaly) GCs for manual review, and 'regular' (acceptable) GCs for automatic analysis. The new algorithm performance is then compared with two kinds of formerly developed support vector machine classifiers-regular and weighted ones-using three different metrics. Results show an impressive accuracy rate of 97% for TLD GCs that are correctly classified to either of the classes.

STUDY OF THE SUITABILITY OF ISRAELI HOUSEHOLD SALT FOR RETROSPECTIVE DOSIMETRY.

The first results of an in-depth evaluation of the practical potential of common household Israeli salt as a retrospective dosemeter in the event of a nuclear accident or terror attack are presented. Ten brands of salt were investigated with emphasis on four of the bestselling brands that constitute 76 % of the total consumer market. Eight of the ten brands show similar glow curves with two main glow peaks at maximum temperatures of ∼176°C and ∼225°C measured at a heating rate of 1°C s(-1) Chemical analysis of three major brands indicates substantial impurity levels of 200-500 ppm of Ca, K, Mg and S and significant differences of additional ppm trace impurities, which lead to an ∼50 % difference in the TL response of the three major brands. Fading in the dark is in significant but under room light is of the order of 35 % per day. The dose response is linear/supralinear with the threshold of supralinearity at ∼0.01 Gy reaching maximum value of ∼4 at 0.5-1 Gy for two of the major brands. The precision of repeated measurements is ∼10 % (1 SD), but the accuracy of dose assessment under field conditions requires further study.

The additional dose to radiosensitive organs caused by using under-collimated X-ray beams in neonatal intensive care radiography.

Radiographic technique and exposure parameters were recorded in five Israeli Neonatal Intensive Care Units for chest, abdomen and both chest and abdomen X-ray examinations. Equivalent dose and effective dose values were calculated according to actual examination field size borders and proper technique field size recommendations using PCXMC, a PC-based Monte Carlo program. Exposure of larger than required body areas resulted in an increase of the organ doses by factors of up to 162 (testes), 162 (thyroid) and 8 (thyroid) for chest, abdomen and both chest and abdomen examinations, respectively. These exposures increased the average effective dose by factors of 2.0, 1.9 and 1.3 for the chest, abdomen and both chest and abdomen examinations, respectively. Differences in exposure parameters were found between the different neonatal intensive care units-tube voltage, current-time product and focal to skin distance differences up to 13, 44 and 22%, respectively. Reduction of at least 50% of neonate exposure is feasible and can be implemented using existing methodology without any additional costs.