Use of real-time electronic extremity dosimeters for monitoring and optimisation of radiopharmacy technique.

Radiopharmacy staff members are subject to extremity radiation doses, particularly to the fingertips. Dosemeters, such as, thermoluminescent detectors (TLDs) are currently used for monitoring fingertip doses. This study aimed to use real-time dosemeters to monitor radiopharmacy extremity doses to identify specific procedural steps associated with higher fingertip doses and, subsequently, reduce dose through promotion of optimised radiation protection practises. Five radiopharmacy operators were monitored using an ED3 active extremity dosemeter with a detector attached to each tip of the index fingers. Dose rate and accumulated dose data were matched to the handled radioactivity data, of99mTc-labelled radiopharmaceuticals only, with the dose per activity (µSv MBq-1) calculated for each step. Once baseline dose data was established, an educational session identified technique adjustments toward improved radiation protection. A subsequent monitored session was undertaken with the dose data compared to quantify changes in operator doses. Radiopharmacy steps which significantly contributed to extremity doses were identified. The average accumulated dose per activity across all procedural steps for the99mTc-labelled radiopharmaceuticals for all operators before the educational session was 0.042 ± 0.045µSv MBq-1and 0.042 ± 0.041µSv MBq-1(n= 89) for non-dominant and dominant index fingertips, respectively, and 0.030 ± 0.044µSv MBq-1and 0.031 ± 0.032µSv MBq-1(n= 97), respectively, afterwards. Overall, there was an average 40.7% reduction in the total extremity dose received after the educational session. Real-time electronic extremity dosemeters for monitoring radiopharmacy extremity dose presented as a useful tool for incorporation into radiation protection education and training, towards optimised radiopharmacy technique.

Low Dose Radiation Therapy, Particularly with 0.5 Gy, Improves Pain in Degenerative Joint Disease of the Fingers: Results of a Retrospective Analysis.

Low-dose radiation therapy (LDRT) has been successfully established for decades as an alternative analgesic treatment option for patients suffering from chronic degenerative and inflammatory diseases. In this study, 483 patients were undergoing LDRT for degenerative joint disease of the fingers and thumb at the University Hospital Erlangen between 2004 and 2019. Radiotherapy was applied according to the German guidelines for LDRT. Several impact factors on therapeutic success, such as the age and gender, the number of affected fingers, the single and cumulative dose, as well as the number of series, were investigated. In summary, 70% of the patients showed an improvement of their pain following LDRT. No significant impact was found for the factors age, gender, the number of series or the cumulative dosage. Patients with an involvement of the thumb showed a significantly worse outcome compared to patients with an isolated affection of the fingers. In this cohort, patients receiving a single dose of 0.5 Gy reported a significantly better outcome than patients receiving 1.0 Gy, strongly suggesting a reduction in the total dose. In summary, LDRT is a good alternative treatment option for patients suffering from degenerative and inflammatory joint disease of the fingers.

Mobile phone antenna-matching study with different finger positions on an inhomogeneous human model.

The human head and hand being in the near-field zone of a mobile phone antenna can drastically influence the antenna matching with free space. The goal of the presented research is to study this phenomenon on an inhomogeneous human model for different relative positions and distances of hand and fingers when using a mobile phone. The only safety criteria commonly used to estimate RF exposure impact on humans is the specific absorption rate (SAR). Its limits are determined by the Federal Communication Commission (FCC) in the USA and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in Europe. The maximal values of SAR for a mobile handset are determined for each model by the manufacturer. In this paper, it is shown that the peak values provided by the manufacturers and their understanding may need refinement. It is almost impossible to consider all parameters, such as the dependence of SAR on antenna communication matching, with a variety of shapes and forms and other details during physical measurements or numerical estimation. The premise for such assumptions is based on the analysis of S11 dependency on the exposure scenario and the fact that the Automatic Gain Control (AGC) increases power when the signal strength at the base station drops.

Radiation exposure to eye lens and operator hands during endovascular procedures in hybrid operating rooms.

OBJECTIVE: The purpose of this study was to evaluate the radiation exposure of vascular surgeons' eye lens and fingers during complex endovascular procedures in modern hybrid operating rooms. METHODS: Prospective, nonrandomized multicenter study design. One hundred seventy-one consecutive patients (138 male; median age, 72.5 years [interquartile range, 65-77 years]) underwent an endovascular procedure in a hybrid operating room between March 2012 and July 2013 in two vascular centers. The dose-area product (DAP), fluoroscopy time, operating time, and amount of contrast dye were registered prospectively. For radiation dose recordings, single-use dosimeters were attached at eye level and to the ring finger of the hand next to the radiation field of the operator for each endovascular procedure. Dose recordings were evaluated by an independent institution. Before the study, precursory investigations were obtained to simulate the radiation dose to eye lens and fingers with an Alderson phantome (RSD, Long Beach, Calif). RESULTS: Interventions were classified into six treatment categories: endovascular repair of infrarenal abdominal aneurysm (n = 65), thoracic endovascular aortic repair (n = 32), branched endovascular aortic repair for thoracoabdominal aneurysms (n = 17), fenestrated endovascular aortic repair for complex abdominal aortic aneurysm, (n = 25), iliac branched device (n = 8), and peripheral interventions (n = 24). There was a significant correlation in DAP between both lens (P < .01; r = 0.55) and finger (P < .01; r = 0.56) doses. The estimated fluoroscopy time to reach a radiation threshold of 20 mSv/y was 1404.10 minutes (90% confidence limit, 1160, 1650 minutes). According to correlation of the lens dose with the DAP an estimated cumulative DAP of 932,000 mGy/m(2) (90% confidence limit, 822,000, 1,039,000) would be critical for a threshold of 20 mSv/y for the eyes. CONCLUSIONS: Radiation protection is a serious issue for vascular surgeons because most complex endovascular procedures are delivering measurable radiation to the eyes. With the correlation of the DAP obtained in standard endovascular procedures a critical threshold of 20 mSv/y to the eyes can be predicted and thus an estimate of a potential harmful exposure to the eyes can be obtained.

Occupational radiation exposure of medical staff performing 9°Y-loaded microsphere radioembolization.

PURPOSE: Radioembolization of liver cancer with (90)Y-loaded microspheres is increasingly used but data regarding hospital staff exposure are scarce. We evaluated the radiation exposure of medical staff while preparing and injecting (90)Y-loaded glass and resin microspheres especially in view of the increasing use of these products. METHODS: Exposure of the chest and finger of the radiopharmacist, nuclear medicine physician and interventional radiologist during preparation and injection of 78 glass microsphere preparations and 16 resin microsphere preparations was monitored. Electronic dosimeters were used to measure chest exposure and ring dosimeters were used to measure finger exposure. RESULTS: Chest exposure was very low for both products used (<10 µSv from preparation and injection). In our experience, finger exposure was significantly lower than the annual limit of 500 mSv for both products. With glass microspheres, the mean finger exposure was 13.7 ± 5.2 µSv/GBq for the radiopharmacist, and initially 17.9 ± 5.4 µSv/GBq for the nuclear medicine physician reducing to 13.97 ± 7.9 µSv/GBq with increasing experience. With resin microspheres, finger exposure was more significant: mean finger exposure for the radiopharmacist was 295.1 ± 271.9 µSv/GBq but with a reduction with increasing experience to 97.5 ± 35.2 µSv/GBq for the six most recent dose preparations. For administration of resin microspheres, the greatest mean finger exposure for the nuclear medicine physician (the most exposed operator) was 235.5 ± 156 µSv/GBq. CONCLUSION: Medical staff performing (90)Y-loaded microsphere radioembolization procedures are exposed to safe levels of radiation. Exposure is lower than that from treatments using (131)I-lipiodol. The lowest finger exposure is from glass microspheres. With resin microspheres finger exposure is acceptable but could be optimized in accordance with the ALARA principle, and especially in view of the increasing use of radioembolization.

Strategies for assessment of doses to the tips of the fingers in nuclear medicine.

Staff manipulating radiopharmaceuticals in radiopharmacies and nuclear medicine departments can receive significant radiation doses to the tips of their fingers. However, dosemeters for monitoring the fingers are frequently attached to a ring worn at the base of the finger and the doses recorded are significantly lower. Therefore a correction factor is required to estimate the dose to the finger tip from that recorded by a ring dosemeter. A survey of practices in UK nuclear medicine departments has been undertaken via a questionnaire, results of studies in the literature reporting ratios of doses to the tip and base of the finger reviewed, and patterns of finger exposure studied using an electronic dosemeter. The survey indicates that UK staff use vial and syringe shields for the majority of manipulations. Ratios between doses to the tip and base of the index finger reported in the literature vary between 2 and 6. Higher ratios appear to be associated with poor protection practices including not using syringe shields and use of a finger to support a syringe needle. Staff are recommended to wear dosemeters on the palmar side of the index finger of each hand. Dosemeters worn at the finger tips are ideal, but doses to the tips can be estimated from ring dosemeters worn on the index fingers, and factors that can be used for this are proposed. For staff who always use vial and syringe shields and never touch the syringe needle or vial a factor of 3 is appropriate. For staff who mostly use syringe shields and may occasionally support a needle during an injection, a factor of 4 can be used, while for others a factor of 6 should be applied.

Possibilities of the exposure reduction of hands during the preparation and application of radiopharmaceuticals.

BACKGROUND: The current routinely used methods of estimating the skin equivalent dose relies on the finger dosimetry which usually largely underestimates the real maximum exposure and thus appropriate correction factors have to be used. METHODS: The group under the investigation consisted of 10 workers preparing and 5 workers administering radiopharmaceuticals labelled with 18F. The monitoring was carried out using 12 pairs of thermoluminiscent dosimeters (TLDs) placed on each hand of the worker. A total of 46 measurements were completed. The maximum exposure of the skin of hands, defined in terms of the quantity of the personal dose equivalent Hp(0.07), was related to the unit activity of radiopharmaceutical with which the worker came into the contact during the measurement. RESULTS: The exposure of the hands of workers handling 18F-labelled radiopharmaceuticals showed significant inhomogeneity. Out of 15 workers, in 53 % of cases, the maximum skin exposure was observed on the tip of their index finger. It was estimated that in about 60 % of the cases (during the preparation and administration of radiopharmaceuticals), the exposure may exceed the 3/10 of the annual dose limit. Moreover, in 40 % of all cases, the exposure may even be higher than this dose limit. The established relevant correction factors reached the values up to 8 (as for preparations) and 13 (as for administrations). CONCLUSIONS: The study resulted in the establishment of the appropriate correction factors and in the recommendations of procedures aimed at the further reduction of the exposure of extremities (Tab. 3, Fig. 2, Ref. 17).

Radiation safety education reduces the incidence of adult fingers on neonatal chest radiographs.

A previous audit revealed a high frequency of adult fingers visualised on neonatal intensive care unit (NICU) chest radiographs-representing an example of inappropriate occupational radiation exposure. Radiation safety education was provided to staff and we hypothesised that the education would reduce the frequency of adult fingers visualised on NICU chest radiographs. Two cross-sectional samples taken before and after the administration of the education were compared. We examined fingers visualised directly in the beam, fingers in the direct beam but eliminated by technologists editing the image, and fingers under the cones of the portable x-ray machine. There was a 46.2% reduction in fingers directly in the beam, 50.0% reduction in fingers directly in the beam but cropped out, and 68.4% reduction in fingers in the coned area. There was a 57.1% overall reduction in adult fingers visualised, which was statistically significant (Z value - 7.48, P < 0.0001). This study supports radiation safety education in minimising inappropriate occupational radiation exposure.

Radiation exposure during liver surgery after treatment with (90)Y microspheres, evaluated with computer simulations and dosimeter measurements.

PURPOSE: Two patients with liver tumours were planned for a combined treatment, including surgery with preceding injections of ß(-) radiation emitting (90)Y microspheres (SIRTEX(®)). The aim of this paper is to present a method of pre-surgical computer simulations of the absorbed dose rate on the surface of tumour tissue, combined with measurements of the actual absorbed dose rate on resected tissue, in order to estimate the absorbed dose to a surgeon's fingers during such surgery procedures. METHODS AND MATERIALS: The dose rates from ß(-) radiation on the surface of tumour tissue were simulated with the software VARSKIN(®) Mod 2. The activity concentrations in tumours were estimated, based on SPECT/CT distribution studies of (99m)Tc-MAA and confirmed by SPECT/CT bremsstrahlung studies of (90)Y microspheres. The activity distributions were considered as homogeneous within the tumour regions. The absorbed dose rates at different tumour tissue spots were calculated based on measurements with thermo-luminescent dosimeters (TLD) fastened on resected tissue. RESULTS: The simulations showed a good agreement with the averaged absorbed dose rates based on TLD measurements performed on resected tissue, differing by 13% and 4% respectively. The absorbed dose rates at the measured maximum hotspots were twice as high as the average dose rates for both patients. CONCLUSION: The data is not sufficient in order to draw any general conclusions about dose rates on tumour tissue during similar surgeries, neither about the influence of dose rate heterogeneities nor about average dose rates. However, the agreement between simulations and measurements on these limited data indicate that this approach is a promising method for estimations of the radiation exposure to the surgeons' fingers during this kind of surgery procedure. More data from similar surgeries are necessary in order to validate the method.

The response of the human circulatory system to an acute 200-µT, 60-Hz magnetic field exposure.

PURPOSE: Recent research by the authors on the effects of extremely low-frequency (ELF) magnetic field (MF) exposure on human heart rate (HR), heart rate variability (HRV), and skin blood perfusion found no cardiovascular effects of exposure to an 1,800-µT, 60-Hz MF. Research from our group using rats, however, has suggested a microcirculatory response to a 200-µT, 60-Hz MF exposure. The present pilot study investigated the effects of 1 h of exposure to a 200-µT, 60-Hz MF on the human circulation. Microcirculation (as skin blood perfusion) and HR were measured using laser Doppler flowmetry. Mean arterial pressure was monitored with a non-invasive blood pressure system. METHODS: Ten volunteers were recruited to partake in a counterbalanced, single-blinded study consisting of two testing sessions (real and sham exposure) administered on separate days. Each session included four consecutive measurement periods separated by rest, allowing assessment of cumulative and residual MF effects. RESULTS: A within-subjects analysis of variance did not reveal session by time period interactions for any of the parameters which would have been suggestive of a MF effect (p > 0.05). Perfusion, HR, and skin surface temperature decreased over the course of the experiment (p < 0.05). CONCLUSIONS: The MF used in this experiment did not affect perfusion, HR, or mean arterial pressure. Decreasing perfusion and HR trends over time were similar to our previous results and appear to be associated with a combination of inactivity (resulting in decreasing body temperatures) and reduced physiological arousal.

Radiation exposure of the operators in the preparation and administration of yttrium-90 microspheres in the treatment of malignant hepatic lesions: What is the risk?

Liver radioembolization is an emerging treatment against liver primary and secondary tumours. The whole procedure of radioembolization involves different health care specialists with different expertise. During the fractionation and infusion phases, the personnel manipulates high activities of 90Y. In our centre, the number of radioembolization treatments per year is increasing; the aim of this study is to monitor the dose to the operators and to estimate the radiological risk for the operators involved in the RE. At present, two medical devices are approved: Sir-Sphere® and Therasphere™, both loaded with 90Y. The dosimeters used were TLDs placed over the fingertips, for a total of 4 dosimeters for each phase; the selected dose descriptor was Hp0.07. The study concerned 17 patients affected by malignant hepatic lesions, treated from September 2017 to March 2018. We performed 27 procedures: 10 fractionations (with Sir-Sphere®) and 17 infusions to the patients (10 with Sir-Spheres®, 7 with Theraspheres™). For fractionation phase, the average activity of each preparation was 3.34 GBq, the average value of Hp0.07 was 0.50mSv. For infusion phase, the average activity was 1.51 GBq for Sir-Sphere® and 2.10 GBq for Theraspheres™, the average value of Hp0.07 was 0.10mSv. No significant differences were found between senior (Hp0.07 = 0.08mSv) and young operators (Hp0.07 = 0.09mSv), respectively. Similarly, no significant differences were found between the right and left hand, with the same average value of Hp0.07 (0.01mSv). In conclusion, the results are encouraging, since fingertips reported doses very low. The handling of 90Y microspheres and the radioembolization procedure can be carried out under safe conditions.

Time course and local distribution of skin exposure of hand and fingers from [68Ga]Ga-DOTA-NOC synthesis using a self-shielded module.

AIM: The study examined the local dose distribution as well as the time course of skin exposure of hand and fingers from [68Ga]Ga-DOTA-NOC synthesis using a self-shielded synthesis module. METHODS: A compact calibrated electronic dosimeter (ED) with a miniaturized probe was used for real-time measurements of skin dose equivalent Hp (0.07) (reference point: left and right index finger). A time resolved assessment of exposure during radiotracer production was performed. Additionally, thermoluminescence dosimeters (TLD) were used to determine local dose distribution for five different positions (e. g. fingertips). Cumulated Hp (0.07) estimated by ED was analysed and correlated with the measurements obtained by a TLD positioned close to the ED. RESULTS: The cumulative skin exposure from the production process measured by ED, was 74.7 ±â€Š32.7 µSv/GBq and 40.1 ± 14.3 µSv/GBq for the right and left hand, respectively. The exposure recorded by the ED was in the average 19.4 % ±â€Š40.0 % (median = 21.3 %) lower compared to the results from TLD. Highest exposure was recorded during synthesis (guided hand: 24.5 ±â€Š12.2 µSv/GBq) and measuring of product yield including preparation of probes for quality control (guided hand: 36.1 ±â€Š12.7 µSv/GBq). The highest local exposure was measured by a TLD close to the tip of the index finger of the guiding hand (range: 773-1257 µS/GBq). CONCLUSION: The chosen methodology using ED, proved to be a good concept for identifying procedure steps with an increased exposure level and to determine the time course of skin exposure and to identify procedure steps for further optimization of handling. Furthermore, miniaturized electronic dosimeters may be used for online surveillance of local exposure rates at hands and fingers.

Exposure of treating physician to radiation during prostate brachytherapy using iodine-125 seeds: dose measurements on both hands with thermoluminescence dosimeters.

BACKGROUND AND PURPOSE: Only sparse reports have been made about radiation exposure of the treating physician during prostate seed implantation. Therefore, thermoluminescence dosimeter (TLD) measurements on the index fingers and the backs of both hands were conducted. MATERIAL AND METHODS: Stranded iodine-125 seeds with a mean apparent activity of 27.4 MBq per seed were used. During application, the treating physician manipulated the loaded needle with the index fingers, partially under fluoroscopic control. Four physicians with varying experience treated 24 patients. The radiation exposure was determined with TLD-100 chips attached to the index fingertips and the backs of hands. Radiation exposure was correlated with the physician's experience. RESULTS: The average brachytherapy duration by the most experienced physician was 19.2 min (standard deviation sigma = 1.2 min; novices: 34.8 min [sigma = 10.2 min]). The mean activity was 1,703 MBq (sigma = 123 MBq), applied with 16.3 needles (sigma = 2.5 needles; novices: 1,469 MBq [sigma = 229 MBq]; 16.8 needles [sigma = 2.3 needles]). The exposure of the finger of the "active hand" and the back of the hand amounted to 1.31 mSv (sigma = 0.54 mSv) and 0.61 mSv (sigma = 0.23 mSv), respectively (novices: 2.07 mSv [sigma = 0.86 mSv] and 1.05 mSv [sigma = 0.53 mSv]). CONCLUSION: If no other radiation exposure needs to be considered, an experienced physician can perform about 400 applications per year without exceeding the limit of 500 mSv/year; for novices, the corresponding figure is about 200.

Radiation exposure to the orthopaedic surgeon during periacetabular osteotomy.

The objective of this study was to directly measure the radiation exposure to the orthopaedic surgeon and to measure dose points to the surgeon's fingers, thyroid gland, and forehead during intraoperative fluoroscopy in periacetabular osteotomy (PAO). In a series of 23 consecutive periacetabular osteotomy procedures, exposure monitoring was carried out using thermo luminescent dosimeters. The effective dose received by the operating surgeon was 0.008 mSv per operation which adds up to a yearly dose of 0.64 mSv from PAO. The median point equivalent dose (mSv) exposure under PAO was 0.009 for the forehead and thyroid gland, 0.045 for the right index finger, and 0.039 for the left index finger. The effective estimated yearly dose received by the operating surgeon was very low. Wearing a lead collar reduces radiation exposure to the thyroid gland while the lead gloves did not protect the surgeon's fingers.

Reduction of Operator Hand Exposure in Interventional Radiology With a Novel Finger Sack Using Tungsten-containing Rubber.

The purpose of this study was to evaluate the x-ray shielding ability of a novel tungsten-particle-containing rubber-based finger sack for use in interventional radiology. Shielding rates for the air kerma (mGy m) were measured using a semiconductor dosimeter with and without the finger sack and commercial lead gloves, at a 20 cm distance from the field of view. A C-arm digital angiography system was used with x-ray tube voltages of 60, 80, 100, and 120 kVp. In addition, the 70 µm dose equivalent to the operator's finger was measured using fluorescent glass dosimeters with and without the finger sack during interventional radiology examinations. The x-ray shielding rates for 60, 80, 100, and 120 kV x rays were 98.0 ± 0.03%, 94.8 ± 0.05%, 92.3 ± 0.12%, and 90.1 ± 0.03%, respectively, with the finger sack and 69.8 ± 0.39%, 61.0 ± 0.53%, 52.3 ± 0.52%, and 47.0 ± 0.69% with the lead gloves. The x-ray shielding rates for the fluoroscopy and cine mode with the finger sack were 91.3 ± 0.21% and 56.5 ± 0.58%, respectively, while with the lead gloves they were 96.5 ± 0.04% and 67.6 ± 0.33%. The 70 µm dose equivalent for the operator's finger exposure dose was reduced by approximately 39.4% using the finger sack. The finger shields were more user friendly, had excellent radiation shielding ability against x rays, and should reduce finger exposure in interventional radiology.

Changes in slow and fast alpha bands in subjects submitted to different amounts of functional electrostimulation.

OBJECTIVE: To examine the changes in slow (8-10Hz) and fast (10-12Hz) alpha bands of EEG in three groups of subjects submitted to different amounts of functional electrostimulation (FES). Our hypothesis is that different amounts of electrostimulation may cause different patterns of activation in the sensorimotor cortex. In particular, we expect to see an increase in alpha power due to habituation effects. We examine the two bands comprised by alpha rhythm (i.e., slow and fast alpha), since these two sub-rhythms are related to distinct aspects: general energy demands and specific motor aspects, respectively. METHODS: The sample was composed of 27 students, both sexes, aging between 25 and 40 years old. The subjects were randomly distributed in three groups: control (n=9), G24 (n=9) and G36 (n=9). A FES equipment (Neuro Compact-2462) was used to stimulate the right index finger extension. Simultaneously, the electroencephalographic signal was acquired. We investigated the absolute power in slow and fast alpha bands in the sensorimotor cortex. RESULTS: The G36 indicated a significant increasing in absolute power values in lower and higher alpha components, respectively, when compared with the control group. Particularly, in the following regions: pre-motor cortex and primary motor cortex. DISCUSSION: FES seems to promote cortical adaptations that are similar to those observed when someone learns a procedural task. FES application in the G36 was more effective in promoting such neural changes. The lower and higher components of alpha rhythms behave differently in their topographical distribution during FES application. These results suggest a somatotopic organization in primary motor cortex which can be represented by the fast alpha component.

Hand exposure to ionising radiation of nuclear medicine workers.

The specific nature of work in nuclear medicine departments involves the use of isotopes and handling procedures, which contribute to the considerable value of an equivalent dose received, in particular, by the fingertips. Standard nuclear medicine department uses ring dosemeters placed usually at the base of the middle finger. The main aim of the study was to find out whether a relationship exists between the doses recorded by thermoluminescent detectors placed at various locations on the radiopharmacists' hands and the doses recorded by the ring detectors, and to determine the character of that relationship. The correction factor represents a correction value to be used to calculate the doses which might be received by locations on the hand from the dose recorded by the ring dosemeter. The dose recorded by the ring dosemeter is on the average five times lower than that received by the fingertips of thumb, index and middle fingers.

[Trial manufacture of a plunger shield for a disposable plastic syringe].

A syringe-type radiopharmaceutical being supplied by a manufacturer has a syringe shield and a plunger shield, whereas an in-hospital labeling radiopharmaceutical is administered by a disposable plastic syringe without the plunger shield. In cooperation with Nihon Medi-Physics Co. Ltd., we have produced a new experimental plunger shield for the disposable plastic syringe. In order to evaluate this shielding effect, we compared the leaked radiation doses of our plunger shield with those of the syringe-type radiopharmaceutical (Medi shield type). Our plunger shield has a lead plate of 21 mm in diameter and 3 mm thick. This shield is equipped with the plunger-end of a disposal plastic syringe. We sealed 99mTc solution into a plastic syringe (Terumo Co.) of 5 ml with our plunger shield and Medi shield type of 2 ml. We measured leaked radiation doses around syringes using fluorescent glass dosimeters (Dose Ace). The number of measure points was 18. The measured doses were converted to 70 microm dose equivalent at 740 MBq of radioactivity. The results of our plunger shield and the Medi shield type were as follows: 4-13 microSv/h and 3-14 microSv/h at shielding areas, 3-545 microSv/h and 6-97 microSv/h at non-shielding areas, 42-116 microSv/h and 88-165 microSv/h in the vicinity of the syringe shield, and 1071 microSv/h and 1243 microSv/h at the front of the needle. For dose rates of shielding areas around the syringe, the shielding effects were approximately the same as those of the Medi shield type. In conclusion, our plunger shield may be useful for reducing finger exposure during the injection of an in-hospital labeled radiopharmaceutical.

Receptive field properties of the macaque second somatosensory cortex: representation of orientation on different finger pads.

Orientation tuning has been studied extensively in the visual system, but little is known about it in the somatosensory system. Here we investigate tuning in the second somatosensory (SII) region using a motorized stimulator that presented a small oriented bar to the 12 finger pads of digits 2-5 (D2-D5) of the macaque monkey. A subset (23%; n = 218) of the 928 SII region neurons [the same 928 neurons studied by Fitzgerald et al. (2004, 2006)] exhibited tuning, and most of these were tuned on one or two finger pads. All eight 22.5 degrees separated orientations were represented as the preferred orientation of multiple neurons, although not necessarily in equal numbers. A measure of bandwidth indicated that tuning in the SII region is sharp and is similar to the tuning observed in visual cortical areas. In addition, two-dimensional Gaussians that were fit to the tuning curves had very high r2 values, indicating that most tuning curves are both unimodal and symmetrical with respect to their preferred orientation. Most tuned neurons had additional untuned pads, although the responsiveness of these pads tended to be less than the responsiveness of tuned pads. Neurons with multiple tuned pads tended to have similar preferred orientations on their tuned pads, which can be interpreted as evidence for integration of information across fingers or as a form of positional invariance. Finally, comparison of the tuning properties showed that there are small but significant differences between the posterior, central, and anterior fields of the SII region.

Using wavelet analysis to detect the influence of low frequency magnetic fields on human physiological tremor.

The influence of extremely low frequency magnetic fields (ELF-MFs) on human physiological processes and, in particular, on motor activity is still not established with certainty. Using the wavelet-transform approach, changes in the characteristics of human finger micromovement are studied in the presence of a low intensity MF centred at the level of the head. Different approaches to nonstationary signal analysis involving real as well as complex wavelet functions are considered. We find evidence that ELF-MFs lead to more regular postural tremor and more homogeneous energy distribution.