Real-time Radiation Monitoring Device Research Articles

Effect of a real-time radiation monitoring device on operator radiation exposure during cardiac catheterization: the radiation reduction during cardiac catheterization using real-time monitoring study.

The Radiation Reduction During Cardiac Catheterization Using Real-Time Monitoring study sought to examine the effect of a radiation detection device that provides real-time operator dose reporting through auditory feedback (Bleeper Sv; Vertec Scientific Ltd; Berkshire, UK) on patient dose and operator exposure during cardiac catheterization. Between January 2012 and May 2014, 505 patients undergoing coronary angiography, percutaneous coronary intervention, or both were randomized to use (n=253) or no use (n=252) of the Bleeper Sv radiation monitor. Operator radiation exposure was measured in both groups using a second, silent radiation exposure monitoring device. Mean patient age was 65±8 years, most patients (99%) were men, and 30% had prior coronary artery bypass graft surgery. Baseline clinical characteristics were similar in the 2 study groups. Radial access was used in 18% and chronic total occlusion percutaneous coronary intervention constituted 7% of the total procedures. Median procedure time was 17 (12-27) minutes for diagnostic angiography, 42 (28-70) minutes for percutaneous coronary intervention, and 27 (14-51) minutes in the overall study population, with similar distribution between the study groups. First (9 [4-17] versus 14 [7-25] μSv; P<0.001) and second (5 [2-10] versus 7 [4-14] μSv; P<0.001) operator radiation exposure was significantly lower in the Bleeper Sv group. Use of the device did not result in a significant reduction in patient radiation dose. The effect of the Bleeper Sv device on operator radiation exposure was consistent among various study subgroups. Use of a real-time radiation monitoring device that provides auditory feedback can significantly reduce operator radiation exposure during cardiac catheterization. http://www.clinicaltrials.gov. Unique identifier: NCT01510353.

Measurement of Linear Energy Transfer Distribution at CERN-EU High-Energy Reference Field Facility with Real-Time Radiation Monitoring Device III and Its Comparison with Dosimetric Telescope

The distributions of linear energy transfer for LET (LETwater) in front of the 80-cm-thick concrete side shield at the CERN-EU high-energy reference field (CERF) facility were measured with a Si detector telescope named real-time radiation monitoring device-III (RRMD-III) covered with and without a 1 cm-thick acrylic plate. In these measurements, a difference of about 20% in the absorbed dose between the two LETwater distributions was observed as a result of protons, deuterons and tritons recoiled by neutrons. The LETwater distribution obtained using RRMD-III without the 1-cm-thick acrylic plate is compared with lineal energy distributions obtained using the dosimetric telescope (DOSTEL) detector under the same conditions. These dose equivalents are also compared with that obtained using HANDI TEPC which is used as the standard at the CERF facility.

Measurements of LET-distribution, dose equivalent and quality factor with the RRMD-III on the Space Shuttle Missions STS-84, -89 and -91

Dosimetric measurements on the Space Shuttle Missions STS-84, -89 and -91 have been made by the real-time radiation monitoring device III (RRMD-III). Simultaneously, another dosimetry measurement was made by the Dosimetry Telescope (DOSTEL) on STS-84 and by the tissue-equivalent proportional counter (TEPC) on STS-91. First, the RRMD-III instrument is described in detail and its results summarized. Then, the results of DOSTEL and TEPC are compared with those of the RRMD-III. Also, the absorbed doses obtained by TLD (Mg 2SiO 4) and by RRMD-III on board STS-84 and -91 are compared.

Application of real-time radiation dosimetry using a new silicon LET sensor

A new type of real-time radiation monitoring device, RRMD-III, consisting of three double-sided silicon strip detectors (DSSDs), has been developed and tested on-board the Space Shuttle mission STS-84. The test succeeded in measuring the linear energy transfer (LET) distribution over the range of 0.2 keV/μm to 600 keV/μm for 178 h. The Shuttle cruised at an altitude of 300 to 400 km and an inclination angle of 51.6° for 221.3 h, which is equivalent to the International Space Station orbit. The LET distribution obtained for particles was investigated by separating it into galactic cosmic ray (GCR) particles and trapped particles in the South Atlantic Anomaly (SAA) region. The result shows that the contribution in dose-equivalent due to GCR particles is almost equal to that from trapped particles. The total absorbed dose rate during the mission was 0.611 mGy/day; the effective quality factor, 1.64; and the dose equivalent rate, 0.998 mSv/day. The average absorbed dose rates are 0.158 mGy/min for GCR particles and 3.67 mGy/min for trapped particles. The effective quality factors are 2.48 for GCR particles and 1.19 for trapped particles. The absorbed doses obtained by the RRMD-III and a conventional method using TLD (Mg 2SiO 4), which was placed around the RRMD-III were compared. It was found that the TLDs showed a lower efficiency, just 58% of absorbed dose registered by the RRMD-III.

LET distribution measurement with a new real-time radiation monitoring device-III onboard the Space Shuttle STS-84

Abstract A new type of Real-time Radiation Monitoring Device, RRMD-III, consisting of three double-sided silicon strip detectors (DSSDs) has been constructed and used onboard the Space Shuttle mission STS-84. The Space Shuttle cruised at an altitude of 300–400 km and an inclination angle of 51.6° for 221.3 h. RRMD-III succeeded in measuring the linear energy transfer (LET) distribution over the range of 0.2– 600 keV / μ m for 178 h . The obtained LET distribution of particles was investigated in detail by classifying it into galactic cosmic ray (GCR) particles and trapped protons in the South Atlantic Anomaly (SAA) region. The result shows that GCR particles contribute 60% to the total dose equivalent. The total absorbed dose rate during the mission was 0.516 mGy / day , the effective quality factor was 1.81 by ICRP-Pub.26, and the dose equivalent rate was 0.935 mSv / day . The average absorbed dose rates are 0.120 μGy / min for GCR particles and 4.80 μGy / min for trapped protons. The effective quality factors are 3.16 for GCR particles and 1.19 for trapped protons. RRMD-III data were also compared with the data of the tissue equivalent proportional counter (TEPC), proving that RRMD-III is a reliable device for deriving the true-LET distribution in real time for evaluating space radiation.

Space radiation enhancement linked to geomagnetic disturbances

Space radiation dosimetry measurements have been made on board the Space Shuttle. A newly developed active detector called “Real-time Radiation Monitoring Device (RRMD)” was used (Doke et al., 1995; Hayashi et al., 1995). The RRMD results indicate that low Linear Energy Transfer (LET) particles steadily penetrate around the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent and some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions (Doke et al., 1996). We also have been analyzing the space weather during the experiment, and found that the anomalous high-energy particle enhancement was linked to geomagnetic disturbance due to the high speed solar wind from a coronal hole. Additional analysis and other experiments are necessary for clarification of these phenomena. If a penetration of high-energy panicles into the low altitude occurs by common geomagnetic disturbances, the prediction of geomagnetic activity becomes more important in the next Space Station's era.

Inhibition in a microgravity environment of the recovery of Escherichia coli cells damaged by heavy ion beams during the NASDA ISS phase I program of NASA Shuttle/Mir mission no. 6.

We participated in a space experiment, part of the National Space Development Agency of Japan (NASDA) Phase I Space Radiation Environment Measurement Program, conducted during the National Aeronautics and Space Administration (NASA) Shuttle/Mir Mission No. 6 (S/MM-6) project. The aim of our study was to investigate the effects of microgravity on the DNA repair processes of living organisms in the <Realtime Radiation Monitoring Device III (RRMD III)> in orbit. Heavy ion beam radiation- or ç-irradiation-damaged biological samples of Escherichia coli and the radioresistant bacterium Deinococcus radiodurans were prepared and placed in a biospecimen box, which was loaded into the RRMD III sensor unit of the Space Shuttle. Two identical sets of samples were left in the Spacehab's Payload Processing Facility (SPPF) in Florida, USA, as a control. (flight No. STS-84) was launched from NASA John F. Kennedy Space Center (KSC) in Florida, USA, on May 15, 1997. The mission duration was 9.22 days. An astronaut activated the biological samples in the biospecimen box in the Spacehab during orbit in order to start repair of the DNA damaged by heavy ion beams or ç-irradiation and the samples were incubated for 19 h 35 min at about 22ûC, the cabin temperature. The control specimens in the SPPF were subjected to the same treatment under terrestrial gravity. After returned to earth, we investigated cell recovery by comparing the repair of the radiation-damaged DNA of E. coli and D. radiodurans in the microgravity environment in space with that on Earth. The results indicated that the DNA repair process of E. coli, but not of D. radiodurans, cells was inhibited in a microgravity environment.

Radiation Dosimetry Measurements with Real Time Radiation Monitoring Device (RRMD)-II in Space Shuttle STS-79

The real-time measurement of radiation environment was made with an improved real-time radiation monitoring device (RRMD)-II onboard Space Shuttle STS-79 (S/MM#4: 4th Shuttle MIR Mission, at an inclination angle of 51.6° and an altitude of 250–400 km) for 199 h during 17–25 September, 1996. The observation of the detector covered the linear energy transfer (LET) range of 3.5–6000 keV/µm. The Shuttle orbital profile in this mission was equivalent to that of the currently planned Space Station, and provided an opportunity to investigate variations in count rate and dose equivalent rate depending on altitude, longitude, and latitude in detail. Particle count rate and dose equivalent rate were mapped geographically during the mission. Based on the map of count rate, an analysis was made by dividing whole region into three regions: South Atlantic Anomaly (SAA) region, high latitude region and other regions. The averaged absorbed dose rate during the mission was 39.3 µGy/day for a LET range of 3.5–6000 keV/µm. The corresponding average dose equivalent rates during the mission are estimated to be 293 µSv/day with quality factors from International Commission on Radiological Protection (ICRP)-Pub. 60 and 270 µSv/day with quality factors from ICRP-Pub. 26. The effective quality factors for ICRP-Pub. 60 and 26 are 7.45 and 6.88, respectively. From the present data for particles of LET > 3.5 keV/µm, we conclude that the average dose equivalent rate is dominated by the contribution of galactic cosmic ray (GCR) particles. The dose-detector depth dependence was also investigated.

Cancer risk in space due to radiation assessed by determining cell lethality and mutation frequencies of prokaryotes and a plasmid during the Second International Microgravity Laboratory (IML-2) Space Shuttle experiment.

We participated in a space experiment conducted during the 2nd International Microgravity Laboratory Mission (IML-2) project. The aim of our study was to investigate the effects of space radiation, i.e., high-LET (linear energy transfer) cosmic radiation, on living organisms in the 'Realtime Radiation Monitoring Device (RRMD)'. The biological samples, dried E. coli DNA repair-deficient mutant cells and shuttle vector plasmid pZl89 DNA, were prepared and placed in a biospecimen box sandwiched between 'Harzlas' plastic radiation detectors. This box was then loaded into the RRMD sensor unit in the Space Shuttle 'Columbia' and an identical box was left in the NASA John F. Kennedy Space Center (KSC) as a control. 'Columbia' (flight No. STS-65) was launched from KSC in Florida, USA on July 8, 1994. The mission duration was 14.75 days and after 'Columbia' returned to earth, we studied (i) the lethal and mutagenic effects of high-LET cosmic radiation on E. coli mutants and (ii) the relationship between high-LET cosmic radiation and the mutation frequency of pZ189 DNA. There were virtually no differences between the cell viabilities of the space and control samples of Escherichia coli KMBL3835 (wild-type), KY383 (lexA-), KY385 (recA-) and KY386 (uvrA-), nor between the mutation frequency ratios of the space and control E. coli mutant samples. Furthermore, the survival and mutation frequency of the supF gene of pZ189 DNA space samples did not differ from those of the control samples. We concluded there was no cancer risk during this Space Shuttle flight.

DIP angle dependence on track formation sensitivity in antioxidant doped CR-39 plates

Recently, space radiation dosimetry measurements were made by passive and active detectors inside the Spacelab [STS-47 (FMPT): 300km, 57°, STS-65 (IML-2 mission): 300km, 28.5°]. The LET distributions obtained by antioxidant doped CR-39 inside the Spacelab were compared with those measured by the tissue equivalent proportional counter (TEPC) and the real time radiation monitoring device (RRMD) consisting of eight silicon detectors. While both distributions by CR-39 are in good agreement with those obtained by active detectors over the region of LET of several tens to 200 keV/μm, a significant difference in the LET region of smaller than several tens keV/μm is seen. It is considered to be caused by the dip angle dependence of track formation sensitivity in CR-39. The track formation sensitivity for different dip angle were measured for several high heavy energy ions. Using these results, the correction for the dip angle was made for the LET distribution. The corrected result is consistent with the results obtained by active detectors.

Space radiation enhancement linked to geomagnetic disturbances.

Space radiation dosimetry measurements have been made on board the Space Shuttle. A newly developed active detector called "Real-time Radiation Monitoring Device (RRMD)" was used (Doke et al., 1995; Hayashi et al., 1995). The RRMD results indicate that low Linear Energy Transfer (LET) particles steadily penetrate around the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent and some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions (Doke et al., 1996). We also have been analyzing the space weather during the experiment, and found that the anomalous high-energy particle enhancement was linked to geomagnetic disturbance due to the high speed solar wind from a coronal hole. Additional analysis and other experiments are necessary for clarification of these phenomena. If a penetration of high-energy particles into the low altitude occurs by common geomagnetic disturbances, the prediction of geomagnetic activity becomes more important in the next Space Station's era.

Measurement of LET distribution and dose equivalent on board the space shuttle STS-65

Space radiation dosimetry measurements have been made on board the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called “Real-time Radiation Monitoring Device (RRMD)” utilizing silicon semi-conductor detectors and others are conventional detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. Using the RRMD detector, the first attempt of real-time monitoring of space radiation has been achieved successfully for a continuous period of 251.3 h, giving the temporal variations of LET distribution, particle count rates, and rates of absorbed dose and dose equivalent. The RRMD results indicate that a clear enhancement of the number of trapped particles is seen at the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent, while some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions for galactic cosmic ray particles (GCRs). Therefore, the main contribution to dose equivalent is seen to be due to GCRs in this low altitude mission (300 km). Also, the dose equivalent rates obtained by TLDs and CR-39 ranged from 146.9 to 165.2 μSv/day and the average quality factors from 1.45 to 1.57 depending on the locations and directions of detectors inside the Space-lab at this highly protected orbit for space radiation with a small inclination (28.5°) and a low altitude (300 km). The LET distributions obtained by two different detectors, RRMD and CR-39, are in good agreement in the region of 15–200 keV/mm and difference of these distributions in the regions of LET < 15 keV/mm and LET > 200 keV/mm can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks.

Real time measurement of LET distribution in the IML-2 Space-Lab (STS-65)

The real time monitoring of environmental radiation in the Space-Lab of STS-65 (IML-2: inclination 28.5°, mitude 300 km) has been achieved successfully through the flight by a new silicon detector telescope called “Real time Radiation Monitoring Device” (RRMD). It consists of two 2-dimensional position sensitive silicon detectors and six diode type silicon detectors. In this monitoring, the temporal variation of rates of particle flux, together with the dose equivalent and the LET distribution at three locations in the Space-Lab, were reasonably given in real time. The LET distribution obtained by the RRMD and CR-39 track detectors measured at the same location is in good agreement except at the highest LET region >200 keV/μm and the lowest LET region <5 keV/μm.