Ring Dosimeters Research Articles

TH-AB-BRA-11: Fear Not the Y-90 Surgical Staff Dose

Purpose: Patients with hepatic malignancies treated with ⁹⁰Y-microsphere brachytherapy are often precluded from liver transplantation for 4-weeks (∼10 half-lives) following therapy. This delay protects surgical staff from potential radiation dose but negatively impacts patients who could benefit from early transplantation post-therapy. We investigated the potential radiation dose to surgical staff performing early liver transplantation. Methods: Measured data from 30 treated patients were used to determine an average liver ⁹⁰Y-radioactivity concentration (Cavg= 60 µCi/cm3) and average maximum patient surface exposure rate (Ravg_max = 5.9 mR/h). Beta and bremsstrahlung dose rates at the liver surface were calculated from Cavg and Ravg_max respectively. These surface dose rates were compared with Monte Carlo (Geant4) simulated dose rates for a voxelized 1600 cm3 liver (Cliver = Cavg) containing a 5 cm diameter tumor (Ctumor = 3Cavg). The radiation dose to the hands of a transplant surgeon (Dhand) handling a radioactive liver for 2-hours was estimated using the calculated and Monte Carlo derived liver surface dose rates. Dhand was determined at different time-points post ⁹⁰Y-therapy. Results: Transplantation performed at 1-day and at 1-week post ⁹⁰Y-therapy resulted in Dhand<100 mSv and Dhand<20 mSv, respectively. At 1-week post-therapy, Dhand was less than 5% of the annual occupational dose limit to the hand (500 mSv). Calculated Dhand and Monte Carlo derived Dhand agreed within 20%. At the liver surface, bremsstrahlung dose rates were less than 1% of beta dose rates. Location of the liver tumor did not have a significant effect on Dhand. Conclusion: Potential radiation dose to surgical staff is low (<5% of annual limit) when performing liver transplantation in patients as early as 1-week after ⁹⁰Y microsphere brachytherapy. Future work aims to improve dosimetry by incorporating patient specific imaging data of the ⁹⁰Y radioactivity distribution and by measuring dose to surgical staff via ring and body dosimeters.

Correction factors for the ISO rod phantom, a cylinder phantom, and the ICRU sphere for reference beta radiation fields of the BSS 2

The International Organization for Standardization (ISO) requires in its standard ISO 6980 that beta reference radiation fields for radiation protection be calibrated in terms of absorbed dose to tissue at a depth of 0.07 mm in a slab phantom (30 cm x 30 cm x 15 cm). However, many beta dosemeters are ring dosemeters and are, therefore, irradiated on a rod phantom (1.9 cm in diameter and 30 cm long), or they are eye dosemeters possibly irradiated on a cylinder phantom (20 cm in diameter and 20 cm high), or area dosemeters irradiated free in air with the conventional quantity value (true value) being defined in a sphere (30 cm in diameter, made of ICRU tissue (International Commission on Radiation Units and Measurements)). Therefore, the correction factors for the conventional quantity value in the rod, the cylinder, and the sphere instead of the slab (all made of ICRU tissue) were calculated for the radiation fields of 147Pm, 85Kr, 90Sr/90Y, and, 106Ru/106Rh sources of the beta secondary standard BSS 2 developed at PTB. All correction factors were calculated for 0° up to 75° (in steps of 15°) radiation incidence. The results are ready for implementation in ISO 6980-3 and have recently been (partly) implemented in the software of the BSS 2.

Radiation Exposure to Hand Surgeons’ Hands: A Practical Comparison of Large and Mini C-Arm Fluoroscopy

To determine and compare the radiation exposure to surgeons' hands with large and mini C-arm fluoroscopy in a practical, clinically based model. Two hand surgeons monitored radiation exposure to their hands with a ring dosimeter over a 14-month period using large and mini C-arm fluoroscopic units. One surgeon performed all cases with a large C-arm unit in a hospital setting, and the other performed all cases with mini C-arms in surgical centers. For each case, fluoroscopic time, the output displayed by the unit, radiation by time, and ring dosimeter absorption were recorded and analyzed. A total of 160 consecutive cases were reviewed with 71 cases and 89 cases in the large and mini C-arm groups, respectively. The median output displayed by the large C-arm was 0.7 mGy/case, and the median output displayed by the mini C-arm was 10.0 mGy/case. With output as a product of time, the median calculated values were 0.02 mGy/s for the large C-arm group and 0.28 mGy/s for the mini C-arm group. Cumulative ring dosimeter absorption to the surgeons' hands was found to be 380 mrem for 71 cases in the large C-arm group versus 1,000 mrem for 89 cases in the mini C-arm group. In our model, the use of the mini C-arm resulted in more than a 10-fold increase in the rate of output and approximately double the dosimeter absorption to the surgeon's hand compared with the large C-arm. Although it has been shown that the mini C-arm produces less radiation scatter, in a practical model, it may not be a safer alternative with respect to the surgeon's hands. Based on these findings, we recommend that surgeons be more aware of radiation exposure risk, know their C-arm unit's specifications, and try to minimize radiation exposure. Prognostic II.

Occupational exposure to the whole body, extremities and to the eye lens in interventional radiology in Poland, as based on personnel dosimetry records at IFJ PAN

Abstract We report results of measurements of Hp(10) from whole body dosimeters (about 53 thousand readouts), of Hp(0.07) from finger ring dosimeters (23 thousand readouts) and of Hp(3) from eye lens dosimeters (100 readouts), issued in the years 2010–12 to over 150 medical departments in Poland which apply X-rays in radiology, interventional radiology (haemodynamic, angiology, cardiac surgery), urology, orthopaedics, electrophysiology or electro-cardiology. In all measurements thermoluminescence detectors (TLD) were used: the well-known standard MTS-N (LiF:Mg, Ti) for whole body and extremity dosimetry, and the high-sensitivity MCP-N (LiF:Mg, Cu, P) for eye lens dosimetry and environmental monitoring. We analysed the data base of the accredited Laboratory of Individual and Environmental Dosimetry (LADIS) at the Institute of Nuclear Physics PAN which offers its dosimetry service to these departments on a regular basis. We found that in the population of radiation workers that studied over the years 2010–2012 in 84%, 87%, and 34% of Hp(10), Hp(0.07) and Hp(3) measurements, respectively, the level of 0.1 mSv/quarter did not exceed, indicating lack of their occupational exposure. In the remaining 16%, 13% and 66% of individual cases, the 0.1 mSv/quarter exceeded, occasionally reaching several hundreds of mSv/quarter.

MP12-10 RADIATION EXPOSURE TO MEDICAL STAFF IN THE UROLOGY OPERATING THEATRE – A PROSPECTIVE STUDY

You have accessJournal of UrologyImaging/Radiology III1 Apr 2014MP12-10 RADIATION EXPOSURE TO MEDICAL STAFF IN THE UROLOGY OPERATING THEATRE – A PROSPECTIVE STUDY Peter Sauermann, Gabriel Schell, Julia Johannsen, Joerg Binder, Thomas Leippold, Neff Thomas, and Guido Tenti Peter SauermannPeter Sauermann More articles by this author , Gabriel SchellGabriel Schell More articles by this author , Julia JohannsenJulia Johannsen More articles by this author , Joerg BinderJoerg Binder More articles by this author , Thomas LeippoldThomas Leippold More articles by this author , Neff ThomasNeff Thomas More articles by this author , and Guido TentiGuido Tenti More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.445AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Fluoroscopic screening is essential in urological standard surgery. However, there is only limited and inconsistent data available on the level of radiation exposure to the medical staff in the operating theatre, thus raising concerns about immediate and late effects of exposure to X-rays. METHODS In this prospective analysis, cumulative radiation doses were measured in a three months period from January to March 2013 in the urology operating theatre. All surgical procedures requiring fluoroscopic screening (Uroskop Access, Siemens) were included. Dosimeters (Dosilab®) were attached to the surgeon’s forehead and to the ring finger of the left hand. Radiation exposure of anesthesia staff was captured by a dosimeter that was placed on the surface of the respirator. In addition, general patient exposure in the areas outside the X-ray field was measured by a dosimeter positioned laterally of the patient’s pelvis. RESULTS A total of 108 surgical procedures, among them 41 ureterorenoscopies, 34 ureteral stent insertions, and 33 not further specified procedures, were evaluated. The surgeon’s cumulative exposure to radiation during the entire study period and as measured via finger ring dosimeter was 6.2 mSv, at the forehead (cornea level) 1.1 mSv were measured. The general cumulative patient exposure amounted to 0.3 mSv. At the anesthesia work place, which is in about 3 meters distance from the fluoroscope, no radiation exposure was detected (0.0 mSv). CONCLUSIONS Despite the regular need of fluoroscopic screening for diagnostic and therapeutic procedures in the urology operating theatre, cumulative radiation exposure to the surgeon’s cornea and fingers reached only one-hundredth of the maximum permissible annual dose. For the anesthesia staff as well as for the patient, no significant increase in cumulative dose was detected as compared to the natural background radiation. However, a responsible handling of the radiation source is an immediate requirement. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e109 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Peter Sauermann More articles by this author Gabriel Schell More articles by this author Julia Johannsen More articles by this author Joerg Binder More articles by this author Thomas Leippold More articles by this author Neff Thomas More articles by this author Guido Tenti More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Évaluation de l’exposition des travailleurs du service de radioimmunoanalyse du Bénin aux rayonnements ionisants de l’iode 125

Occupational radiation dose of staff handling 125I assessment at the Benin radioimmunoassay laboratory, have been undertaken from October 2012 to April 2013 to determine level of radiation safety. Equivalent dose to skin, whole body and extremities, were measured by the mean of thermoluminescence dosimetry. Firstly, three permanent workers and two students were provided with finger ring dosimeters to wear at index finger base of both hands. Ring dosimeters were used for four months. Secondly, three permanent workers and three students were provided with badge dosimeters to wear at the chest level. Badge dosimeters were renewed monthly for six months. The exposed ring and badge dosimeters were evaluated in Ghana. Permanent workers highest average equivalent dose received at index finger base of both hands was 142.75±89.54, microSV/2 months and that of students was 34.69±29.23, microSV/2 months. Workers skin exposure was below one third of prescribed dose limits for permanents workers (500mSv/yr) and students (150mSv/yr). Whole body exposure, expressed in mSv/month, of permanent workers and students, respectively ranged from 0.12 to 0.23 and from 0.11 to 0.16. Radio-immuno-assay laboratory workers are weakly exposed to ionizing radiation. They are safe from deterministic effect risk.

POMIAR INDYWIDUALNEGO RÓWNOWAŻNIKA DAWKI PROMIENIOWANIA X I GAMMA ZA POMOCĄ DOZYMETRU PIERŚCIONKOWEGO - WYNIKI PORÓWNAŃ MIĘDZYLABORATORYJNYCH

The aim of the study was to present the results of the interlaboratory comparisons for ring dosimeters and to confirm that the applied method is suitable for measuring the personal dose equivalent H(p)(0.07). In addition, calibration procedures used in dosimetric measurements in persons occupationally exposed to ionizing photon radiation X and gamma were presented. Ring dosimeters made of flexible plastics with the diameter of approximately 20 mm, equipped with two thermoluminescence (TL) detectors type MTS-N, were the subject of interlaboratory comparisons. Irradiated detectors were red out using a new manual TLD's reader (FIMEL, France). All TLD exposures were done for validation of TLD readers and were performed using the reference X-ray and gamma beams with the ISO rod phantom. The methodology of performed exposures corresponded with the methods applied by the European Radiation Dosimetry Group (EURADOS), the European organizer ofinterlaboratory comparisons. The energy, dose and angular characteristics of the ring dosimeter allowed to elaborate the formula for estimating and verifying the personal dose equivalent H(p)(0.07). The test was performed to check and confirm the correctness of the estimated characteristics. The test results were satisfactory, and thus the readiness to implement TLD reader in the used method and to participate in interlaboratory comparisons was confirmed. According to the requirements of the Polish Centre for Accreditation, the laboratory was participating in the interlaboratory comparison organized by EURADOS in terms of the personal dose equivalent H(p)(0.07). The result of the comparison was satisfactory, therefore the correctness of the testing procedure was confirmed.

2013 Young Investigator Award Winner

Prospective in vivo radiation exposure study. To assess surgeon exposure to ionizing radiation in the setting of lateral lumbar interbody fusion (LLIF). Minimally invasive spine surgery relies heavily on image guidance. Rapid popularization of minimally invasive spine surgery procedures, such as LLIF, is appropriately accompanied by concern regarding occupational radiation exposure related to intraoperative fluoroscopy. Optically stimulated luminescence technology dosimeters were used to record radiation exposure prospectively at 5 anatomic locations during 18 LLIF procedures: (1) eye, (2) thyroid, (3) chest, (4) axilla, and (5) gluteal region. Additionally, a ring dosimeter was worn during 13 of the LLIF cases. Average fluoroscopy time was 88.7 ± 36.8 seconds and skin dose to the patient was 25.2 ± 21.1 mGy. The chest dosimeter protected by lead recorded the lowest readings per procedure (0.44 ± 0.49 mrem). The gluteal dosimeter recorded an average exposure of 2.31 ± 4.50 mrem and the dosimeter at the axilla recorded an average of 4.20 ± 7.76 mrem per procedure. Exposure to the thyroid and eye were 2.19 ± 2.07 mrem and 2.64 ± 2.76 mrem, respectively. With the exception of the gluteal region, dosimeter readings from all unprotected areas were significantly higher than those from the chest dosimeter (P < 0.0125). In the course of 13 procedures, 190 mrem of exposure to the hand was recorded by the ring dosimeters. More than 2700 LLIF procedures may be performed annually before occupational limits are exceeded. Prolonged exposure to "low-level" radiation as an occupational risk remains a concern for medical personnel. Radiation exposures to unprotected, radiosensitive locations, such as the axilla or eye, are worrisome. However, following radiation safety guidelines, 2700 LLIF procedures can be performed per year before exceeding occupational dose limits. Adherence to radiation safety guidelines is necessary to avoid sequelae related to an invisible but potentially deadly risk of minimally invasive spine surgery procedures.

Mesure de l’exposition externe du personnel du service de médecine nucléaire de l’hôpital Ibn Sina de Rabat au cours de la manipulation des radiopharmaceutiques

The nuclear medicine department of Ibn Sina hospital was created in 1965. Its first location was in radiology department, and then it was transferred in 1977 to the old emergency unit. The conception was not originally dedicated for a nuclear medicine department. To reassure the medical staff about their exposition during radiopharmaceutical manipulation, a dosimetric study was performed in collaboration with the National center of radiation protection (CNRP). Dosimetric monitoring was conducted for 3months with the use of passive thermoluminescent dosimeters, (Harshow, 6600 plus), covering all categories of staff. The administration of 153 Samarium has been also studied. Other cases of people concerned our study: a pregnant woman doctor, whose exposure of the unborn child must be reduced as much as possible, and a woman from a private company, working occasionally in the department. To control the conditions imposed on all activities requiring exposure to ionizing radiation, we evaluated the dose at the extremities of operators with the use of ring dosimeters (Harshow 6600 plus) and the dose on the ambient environment of staff. This experiment has shown exposure levels below legal limits, without been negligible for some workstations. Technicians equivalent doses results justify the wearing of dosimeter rings as a complementary dosimeter in nuclear medicine department. Finally, monitoring ambient dosimetry showed that the environment measurements are in keeping with national and international norms. The Medical staff was very interested by this study, which demonstrates that radiation protection standards are respected through awareness, basic training, continuing education and information. The first author is particularly involved in the practical procedures in order to respect radiation protection recommendations for restraining staff annual chest and extremities dosimetry figures within regulations values.

SU-E-T-308: Dosimetry of a New Minimally Invasive Episcleral Brachytherapy Device.

Describe the dosimetry of an episcleral brachytherapy device. The SMD-I device is designed to treat exudative age-related macular degeneration (AMD) and employs a Sr-90/Y-90 source encapsulated in a stainless steel cylinder. The source is welded to a flexible wire allowing it to travel from a shielded vault in the SMD-I handle to the distal end of a curved cannula to deliver a therapeutic dose of radiation through the sclera to the neovascular target in the subchoroidal space. The SMD-I handle and vault are comprised of Ultem, a lightweight radiation tolerant plastic, which shields the surgeon. Dose calculations were performed using the MCNPX radiation transport code. The absolute dose rate was determined using radiochromic film (GAFChromatic© MD-55) at a point in solid water 2.0mm from the source center perpendicular to the cannula. Dose rates at several depths were measured using Kodak EDR2 film in water equivalent phantoms to compare with the absolute dose rate measurement and MCNPX calculations. The surgeon's hand dose received while manipulating the device with the source in the vault was measured using standard TL (thermoluminescence) finger ring dosimeters, TL ChipstratesTM, and calculated with MCNPX. The absolute dose rate 2.0mm from the source center is 0.45 Gy/min/mCi. The EDR2 film results agree with the absolute dose measurement and the MCNPX calculations. The dose rate decreases rapidly with depth so that the dose at the target depth (3mm) is approximately 8 times less than at 1mm depth (sclera). The dose distribution is sensitive to the angle between the cannula and the neovascular plane. Both TL methods yield a maximum dose rate of 6 μSv/min mCi to the surgeon's fingers consistent with the MCNPX calculation. The SMD-I device permits accurate delivery of a therapeutic radiation dose for the treatment of exudative AMD. Russell J. Hamilton is a founder and currently serves on the Scientific Advisory Board of Salutaris Medical Devices, Inc. Wendell Lutz and Thomas Cetas serve on the Scientific Advisory Board of Salutaris Medical Devices, Inc. All authors have received financial support from Salutaris Medical Devices, Inc.

Occupational Radiation Dose:Percutaneous Interventional Procedures on Hemodialysis Arteriovenous Fistulas and Grafts

To evaluate operator radiation exposure during percutaneous interventions on hemodialysis arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs). Seventy-seven procedures were performed in 57 patients while the interventional radiologist wore two ring dosimeters, two thermoluminescent dosimeters at the lower legs, and a thermoluminescent dosimeter on the forehead. Dose-area product, fluoroscopy time, total procedure time, and radiation exposures to eye lens, hands, and legs were recorded. Variables were procedure type, access site side, and angiography equipment. Statistical analysis was performed with the signed-rank and Mann-Whitney U tests. Mean operator radiation doses for the left hand, right hand, eye lens, left leg, and right leg were 0.28, 0.28, 0.03, 0.11, and 0.12 mSv, respectively. Radiation exposure to the hands was significantly higher compared with that to the legs (P<.0001). In recanalization procedures, fluoroscopy time, total procedure time, and mean number of angiographic runs were higher (all P<.001) than those for percutaneous transluminal angioplasty (PTA), as were radiation exposures to the hands and left leg (all P<.05). Left-sided access interventions resulted in higher doses to the right hand and leg (both P<.05). For right-sided access interventions, doses to the left hand and leg were higher (P<.0001). Eye lens radiation dose was significantly higher for procedures with the flat-panel detector system (P=.002). Operator radiation exposure to the hands, legs, and eyes during percutaneous interventional procedures performed on hemodialysis AVFs and AVGs is relatively low. Radiation exposure to the hands was higher than that to the legs, and the hand and leg closest to the AVF or AVG received a higher dose. Recanalization procedures resulted in higher doses to the hands and left leg than did PTA. Eye lens radiation dose may be higher with a flat-panel detector system.

Hand exposure in diagnostic nuclear medicine with 18F- and 99mTc-labelled radiopharmaceuticals - Results of the ORAMED project

Abstract 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 18 F- and 99m Tc-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 μSv/GBq, 430 μSv/GBq, 930 μSv/GBq and 1200 μSv/GBq for the administration of 99m Tc, preparation of 99m Tc, administration of 18 F and preparation of 18 F, 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.

CORRECTION FACTORS APPLIED TO FINGER DOSIMETRY: A THEORETICAL ASSESSMENT OF APPROPRIATE VALUES FOR USE IN HANDLING RADIOPHARMACEUTICALS

United States Nuclear Regulatory Commission (USNRC) regulations limit the dose to the skin to 500 mSv per year. This is also the dose limit recommended by the International Commission on Radiological Protection (ICRP). The operational quantity recommended by ICRP for quantifying dose to the skin is the personal dose equivalent, Hp(0.07) and is identical to NRC's shallow dose equivalent, Hs, also measured at a skin depth of 7 mg cm-2. However, whereas ICRP recommends averaging the dose to the skin over an area of 1 cm regardless of the size of the exposed area of skin, USNRC requires the shallow dose equivalent to be averaged over 10 cm. To monitor dose to the skin of the hands of workers handling radioactive materials and particularly in radiopharmaceutical manufacturing facilities, which is the focus of this work, workers are frequently required to wear finger ring dosimeters. The dosimeters monitor the dose at the location of the sensitive element, but this is not the dose required to show compliance (i.e., the dose averaged over the highest exposed contiguous 10 cm of skin). Therefore, it may be necessary to apply a correction factor that enables estimation of the required skin dose from the dosimeter reading. This work explored the effects of finger ring placement and of the geometry of the radioactive materials being handled by the worker on the relationship between the dosimeter reading and the desired average dose. A mathematical model of the hand was developed for this purpose that is capable of positioning the fingers in any desired grasping configuration, thereby realistically modeling manipulation of any object. The model was then used with the radiation transport code MCNP to calculate the dose distribution on the skin of the hand when handling a variety of radioactive vials and syringes, as well as the dose to the dosimeter element. Correction factors were calculated using the results of these calculations and examined for any patterns that may be useful in establishing an appropriate correction factor for this type of work. It was determined that a correction factor of one applied to the dosimeter reading, with the dosimeter placed at the base of the middle finger, provides an adequate estimate of the required average dose during a monitoring period for most commonly encountered geometries. Different correction factors may be required for exceptional or unusual source geometries and must be considered on a case-by-case basis.

The use of different types of thermoluminescent dosimeters to measure extremity doses in nuclear medicine

Abstract Depth–dose curves in LiF detectors of different effective thicknesses, together with their responses, were calculated for typical nuclear medicine radiation fields with 99mTc, 18F and 90Y 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 18F, since thick dosimeters can underestimate Hp(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.

Radiation Exposure to the Surgeon During Percutaneous Pedicle Screw Placement

In-vitro radiation exposure study. To determine the radiation exposure to the eyes, extremities, and deep tissue during percutaneous pedicle screw placement. Image-guided minimally invasive spinal surgery is typically performed with the use of fluoroscopy, exposing the surgeon and patient to ionizing radiation. The radiation dose to the surgeon has not been reported and risk to the surgeon performing this procedure over the long term is uncertain. Percutaneous pedicle screws were placed in a cadaveric specimen from L2-S1 bilaterally using a cannulated pedicle screw system. Two fluoroscopes were used in the anteroposterior and lateral planes. The surgeon wore a thermolucent dosimeter ring on the right hand and badge over the left chest beneath the lead apron. Complete surgical time was recorded and a computed tomography scan was performed to assess screw placement. Radiation exposure was measured for total time of fluoroscopy use; average exposure per screw, surgical level, and dose to the eyes was calculated. This data was used to define the safety of percutaneous pedicle screw placement. Total fluoroscope time for placement of 10 percutaneous pedicle screws was 4 minutes 56 seconds (29 s per screw). The protected dosimeter recorded less than the reportable dose. The ring dosimeter recorded 103 mREM, or 10.3 mREM per screw placed. All screws were within the bone confines with acceptable trajectory. Exposure to the eyes was 2.35 mREM per screw. On the basis of this data, percutaneous pedicle screw placement seems to be safe. A surgeon would exceed occupational exposure limit for the eyes and extremities by placing 4854 and 6396 screws percutaneously, respectively. Lead protected against radiation exposure during screw placement. The "hands-off" technique used in this study is recommended to minimize radiation exposure. Lead aprons, thyroid shields, and leaded glasses are recommended for this procedure.

Hand and Body Radiation Exposure With the Use of Mini C-Arm Fluoroscopy

To determine whole body and hand radiation exposure to the hand surgeon wearing a lead apron during routine intraoperative use of the mini C-arm fluoroscope. Four surgeons (3 hand attending surgeons and 1 hand fellow) monitored their radiation exposure for a total of 200 consecutive cases (50 cases per surgeon) requiring mini C-arm fluoroscopy. Each surgeon measured radiation exposure with a badge dosimeter placed on the outside breast pocket of the lead apron (external whole body exposure), a second badge dosimeter under the lead apron (shielded whole body exposure), and a ring dosimeter (hand exposure). Completed records were noted in 198 cases, with an average fluoroscopy time of 133.52 seconds and average cumulative dose of 19,260 rem-cm(2) per case. The total measured radiation exposures for the (1) external whole body exposure dosimeters were 16 mrem (for shallow depth), 7 mrem (for eye depth), and less than 1 mrem (for deep depth); (2) shielded whole body badge dosimeters recorded less than 1 mrem; and (3) ring dosimeters totaled 170 mrem. The total radial exposure for 4 ring dosimeters that had registered a threshold of 30 mrem or more of radiation exposure was 170 mrem at the skin level, for an average of 42.5 mrem per dosimeter ring or 6.3 mrem per case. This study of whole body and hand radiation exposure from the mini C-arm includes the largest number of surgical cases in the published literature. The measured whole body and hand radiation exposure received by the hand surgeon from the mini C-arm represents a minimal risk of radiation, based on the current National Council on Radiation Protection and Management standards of annual dose limits (5,000 mrem per year for whole body and 50,000 mrem per year to the extremities).

Radiation exposure to nuclear medicine personnel handling positron emitters from Ge-68/Ga-68 generator

Objective:To measure the radiation exposure to nuclear medicine personnel during synthesis and injection to the patients of Ga-68 1,4,7,10-tetraazacyclododecane-N,N′,N″,N″′-tetraacetic acid (DOTA)-1-Nal3-octreotide (NOC)- (DOTA-NOC) using ring thermoluminescence dosimeters (TLDs).Materials and Methods:Synthesis of Ga-68 DOTA-NOC was done on a semi-automated system. Finger doses were measured during synthesis and injection of Ga-68 DOTA-NOC. The occupational workers wore TLDs at the base of ring finger of both hands. The finger doses of two radio chemists were measured during synthesis of Ga-68 DOTA-NOC while that of a physician during its injection to the patients.Results:Duration of the study was eight months and a total of 20 samples were prepared. During synthesis, the mean dose to base of left ring finger was 3.02 ± 1.01 mSv and to base of right ring finger was 1.96 ± 0.86 mSv. Mean dose to base of left ring finger was 1.26 ± 0.35 mSv while that to base of right ring finger was 1.03 ± 0.13 mSv during injection. The mean dose was observed to be higher during synthesis than injection. However, the difference was not significant (P = 0.27 and P = 0.18, respectively). Overall mean finger dose of left hand was 2.43 ± 1.21 mSv, whereas for the right hand the same was 1.65± 0.82 mSv.Conclusion:Finger doses to radio chemists during semi-automated synthesis of Ga-68 DOTA-NOC and that to the physician involved in injection of Ga-68 DOTA-NOC were found to be within permissible limits. Ring dosimeters must be worn for the safety of the nuclear medicine personnel involved in synthesis and injection of Ga-68 DOTA-NOC.

Radiation Exposure of Patient and Physician during Implantation and Upgrade of Cardiac Resynchronization Devices

Cardiac resynchronization therapy (CRT) is often associated with extended fluoroscopic exposure during placement of the devices. The objective of this study was to measure the radiation exposure sustained by different parts of the body of patients and operators during fluoroscopically guided cardiac resynchronization device implantation. Dosimetry data were prospectively recorded in a series of 104 consecutive patients, who underwent resynchronization device implantation or upgrade in our cardiac catheterization laboratory. Five Chipstrate dosimeters were fixed to the patient's skin around the thorax (right and left paravertebral, right and left parasternal, and sternal positions), one dosimeter was attached to the forehead, and one to the pubis. The operator was equipped with one dosimeter on the forehead at eye level and a ring dosimeter was worn on the right hand. Based on the maximum radiation dose of 9.2 mSv measured at the operator's hand in a single implantation session, it might be recommended to conservatively limit the number of implantations to four per month (an annual limit value of 500 mSv). At a mean dose of 1.2 mSv, this number can be increased sevenfold. In patients, incipient deterministic radiation effects can theoretically be observed at dose area product >400 Gy*cm(2), a dose applied in 2.9% of CRT implantation procedures. Special follow-up programs are considered necessary for these patients and for operators, as the latter may be exposed over many years given the unknown long-term impact of chronic radiation exposure and the nature of current complex electrophysiology and device procedures.

Performance testing and dose verification for extremity ring dosimetry

Abstract The paper describes the testing performed on an extremity dosimetry system to measure the personal dose equivalent H p (0.07) in photon and beta reference fields. This research refers to the American National Standard Institute (ANSI) N13.32 standard (1995) to organize the performance testing for the INER's TLD-100H extremity ring dosimeters. The results show that tolerance level ( L ), absolute of bias (| B |) and standard deviation ( S ) for all categories of performance testing meet the ANSI N13.32 performance testing criteria. The performance testing results were suggested to be an important step of an accreditation procedure for the extremity ring dosimetry system in Taiwan. Besides, the dose evaluation of extremity ring dosimeters to measure H p (0.07) in realistic fields of nuclear medicine is also verified. The reference values of H p (0.07) were calculated using the Monte Carlo method normalized by the measured activity of the radioactive solution. For nuclear medicine irradiations the relative response to 201 Tl and 99m Tc radionuclides produced by INER are also satisfactory.

Dose estimation of the radiation workers in the SK cyclotron center using dual-TLD method

Abstract The Cyclotron Center in Shin Kong Wu Ho-Su Memorial Hospital (SK Cyclotron Center) produced the 18 F-FDG compound and provided it to the Positron Emission Tomography (PET) center for diagnosis services. The works in SK Cyclotron Center are distinguished into three procedures including production, dispensation, and carry of the compound. As the medical cyclotron was operated to produce the radioactive compounds, secondary radiations such as neutrons and γ -rays were also induced. To estimate the exposure for the staffs working in the SK Cyclotron Center, the dual-TLD (TLD-600/700) chips were used to measure the doses contributed from photons and neutrons during the operation of the cyclotron, and the doses contributed from photons during dispensation and carry of the nuclear compounds. In the results, the mean H p (10) and H p (0.07) of the finger for a worker were 2.11 mSv y −1 and 96.19 mSv y −1 , respectively. Results estimated by the regular personal chest badges and finger ring dosimeters which considered only the doses of photons were compared. By means of the results of this work, doses contributed from different working procedures and from different types of radiation to the workers in the SK Cyclotron Center were realized.