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Geiger counter [keywords]
- Comprehensive data on ionising radiation from Fukushima Daiichi nuclear power plant in the town of Miharu, Fukushima prefecture: The Misho Project. [JOURNAL ARTICLE]
- J Radiol Prot 2014 Aug 15; 34(3):675-698.
Data related to radioactivity released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on 15 March 2011 gathered by residents of Miharu, Fukushima Prefecture, and by Tohoku University are presented. These data sets consist of (1) the earliest radiation monitoring by a Geiger counter in the town, (2) ratios of radioactivity between (132)Te and (137)Cs for a wide area between Fukushima and Tokyo, (3) radiation measurement of soil samples collected from 18 school grounds, and (4) external radiation exposure of 1400 students using OSL badges. By combining and analysing these various data sets, a curve for the cumulative total external exposure as a function of time, with 16 : 00 h on 15 March 2011 being time zero, is obtained. The average cumulative external dosage is estimated to be 10 mSv (σ = 4.2 mSv) over 10 years. In addition, the initiative that the residents of Miharu took in response to the FDNPP accident, which became known as The Misho Project (MP), is documented; in particular, the time at which the municipality instructed the immediate ingestion of iodine tablets by those under the age of 40, 13 : 00 h on 15 March 2011, is assessed.
- Assessment of individual dose equivalents Hp(0.07) of medical staff occupationally exposed to ionizing radiation in 2012. [Journal Article]
- Med Pr 2014; 65(2):167-71.
The paper presents the Nofer Institutes of Occupational Medicine in Łódź's results of the assessment of individual dose equivalents Hp(0.07) of medical staff exposed to X-rays in Poland in 2012. In addition, the collected data was analysed in terms of types of medical units performing medical procedures and the categorization of personnel.Dosimetric service was provided for medical staff of interventional radiology departments occupationally exposed to ionizing radiation in terms of individual dose equivalents Hp(0.07). In 2012, personal dosimetry Hp(0.07) determinations were performed by the Nofer Institute of Occupational Medicine in Łódź and covered 2044 employees from 174 health facilities. The determinations were performed using thermoluminescence dosimetry according to the procedure accredited by the Polish Centre for Accreditation (document number AB 327). The measurements were performed using ring-dosimeters in the periods of 1 or 2 months.Mean annual individual dose equivalent Hp(0.07) in 2012 was equal to 3.3 mSv (annual limit for Hp(0.07) is 500 mSv). The average value of annual individual dose equivalent Hp(0.07) decreased comparing to the previous year. In 2012, no single case of exceeding the annual limit for Hp(0.07) was reported. Data stored in the file indicates that more than 96% of all of the annual doses did not exceed the level of 10 mSv.The analysis of data on occupational exposure to ionizing radiation confirms a stable level of exposure and satisfactory radiological protection in interventional radiology facilities monitored by the Nofer Institute of Occupational Medicine in Łódź in Poland in 2012.
- [Results of measuring neutrons doses and energy spectra inside Russian segment of the International Space Station in experiment "Matryoshka-R" using bubble detectors during the ISS-24-34 missions]. [English Abstract, Journal Article]
- Aviakosm Ekolog Med 2014; 48(2):52-6.
The paper presents the results of calculating the equivalent dose from and energy spectrum of neutrons in the right-hand crewquarters in module Zvezda of the ISS Russian segment. Dose measurements were made in the period between July, 2010 and November, 2012 (ISS Missions 24-34) by research equipment including the bubble dosimeter as part of experiment "Matryoshka-R". Neutron energy spectra in the crewquarters are in good agreement with what has been calculated for the ISS USOS and, earlier, for the MIR orbital station. The neutron dose rate has been found to amount to 196 +/- 23 microSv/d on Zvezda panel-443 (crewquarters) and 179 +/- 16 microSv/d on the "Shielding shutter" surface in the crewquarters.
- Failure rate of contemporary low-dose radiosurgical technique for vestibular schwannoma. Clinical article. [Journal Article]
- J Neurosurg 2013 Dec.:840-4.
The decline in cranial nerve morbidity after radiosurgery for vestibular schwannoma (VS) correlates with dose reduction and other technical changes to this procedure. The effect these changes have had on tumor control has not been well documented.The authors performed a retrospective review of 293 patients with VSs who underwent radiosurgery between 1990 and 2004 and had a minimum of 24 months of imaging follow-up (90% of the entire series). The median radiation dose to the tumor margin was 13 Gy. Treatment failure was defined as progressive tumor enlargement noted on 2 or more imaging studies. The mean postradiosurgical follow-up was 60.9 ± 32.5 months.Tumor growth was noted in 15 patients (5%) at a median of 32 months after radiosurgery. Radiographically demonstrated tumor control was 96% at 3 years and 94% at 7 years after radiosurgery. Univariate analysis revealed 2 factors that correlated with failed radiosurgery for VS: an increasing number of isocenters (p = 0.03) and tumor margin radiation doses ≤ 13 Gy (p = 0.02). Multivariate analysis showed that only an increasing number of isocenters correlated with failed VS radiosurgery (hazard ratio 1.1, 95% CI 1.02-1.32, p < 0.05). The tumor margin radiation dose (p = 0.22) was not associated with tumor growth after radiosurgery.Distortion of stereotactic MR imaging coupled with increased radiosurgical conformality and progressive dose reduction likely caused some VSs to receive less than the prescribed radiation dose to the entire tumor volume.
- Radiation exposure of normal temporal bone structures during stereotactically guided gamma knife surgery for vestibular schwannomas. [Journal Article]
- J Neurosurg 2013 Dec.:800-6.
The dosimetry of radiation exposure of healthy inner, middle, and external ear structures that leads to hearing loss, tinnitus, facial weakness, dizziness, vertigo, and imbalance after gamma knife surgery (GKS) for vestibular schwannomas (VSs) is unknown. The authors quantified the dose of radiation received by these structures after GKS for VS to assess the likelihood that these doses contributed to postradiosurgery complications.A retrospective study was performed using a prospectively acquired database of a consecutive series of 54 patients with VS who were treated with GKS during a 3.5-year period at an "open unit" gamma knife center. Point doses were measured for 18 healthy temporal bone structures in each patient, with the anatomical position of each sampling point confirmed by a fellowship-trained neurootologist. These values were compared against single-dose equivalents for the 5-year tolerance dose for a 5% risk of complications and the 5-year tolerance dose for a 50% risk of complications, which were calculated using known 2-Gy/fraction thresholds for chronic otitis, chondromalacia, and osseous necrosis, as well as the tumor margin dose and typical tumor margin prescription doses for patients in whom hearing preservation was attempted. External and middle ear doses were uniformly low. The intratemporal facial nerve is susceptible to unintentionally high radiation exposure at the fundus of the internal auditory canal, with higher than tumor margin doses detected in 26% of cases. In the cochlea, the basal turn near the modiolus and its inferior portion are most susceptible, with doses greater than 12 Gy detected in 10.8 and 14.8% of cases. In the vestibular labyrinth, the ampulated ends of the lateral and posterior semicircular canals are most susceptible, with doses greater than 12 Gy detected in 7.4 and 5.1% of cases.Doses delivered to middle and external ear structures are unlikely to contribute to post-GKS complications, but unexpectedly high doses may be delivered to sensitive areas of the intratemporal facial nerve and inner ear. Unintentional delivery of high doses to the stria vascularis, the sensory neuroepithelium of the inner ear organs and/or their ganglia, may play a role in the development of post-GKS tinnitus, hearing loss, dizziness, vertigo, and imbalance. Minimizing treatment complications post-GKS for VS requires precise dose planning conformality with the three-dimensional surface of the tumor.
- Increased preservation of functional hearing after gamma knife surgery for vestibular schwannoma. [Journal Article]
- J Neurosurg 2013 Dec.:204-6.
Gamma knife surgery (GKS) for vestibular schwannoma is still associated with an additional hearing loss of approximately 30%. The purpose of this study was to record the effect on hearing preservation of maintaining a margin dose of 13 Gy while reducing the maximum dose to 20 Gy.Seventy-eight of 95 patients who entered a prospective protocol with a follow up of at least 12 months (mean 22 months) were evaluated. The mean tumor volume was 2.28 cm3. After a mean follow-up duration of 22 months, the magnetic resonance imaging--based tumor control rate was 87%. In two cases a second procedure (surgery) was necessary. Thus, the clinical control rate was 97.5%. In two cases there was an increase in trigeminal dysesthesia. One patient suffered transient facial nerve impairment. Functional hearing was preserved in 83.4% of the patients with functional hearing preoperatively.Reducing the maximum dose to 20 Gy seems to be an effective treatment, which probably increases preservation of functional hearing without sacrificing the high tumor control rates achieved in radiosurgery. Post-radiosurgery tumor swelling occurred in 25% of the cases and was not correlated with hearing deterioration.
- Predictors of hearing preservation after stereotactic radiosurgery for acoustic neuroma: clinical article. [Journal Article]
- J Neurosurg 2013 Dec.:863-73.
Many patients with acoustic neuromas (ANs) have hearing function at diagnosis and desire to maintain it. To date, radiosurgical techniques have been focused on conformal irradiation of the tumor mass, with less attention to inner ear structures for which there was scant radiobiological information. The authors of this study evaluated tumor control and hearing preservation as they relate to tumor volume, imaging characteristics, and nerve and cochlear radiation dose following stereotactic radiosurgery (SRS) using the Gamma Knife.Seventy-seven patients with ANs had serviceable hearing (Gardner-Robertson [GR] Class I or II) and underwent SRS between 2004 and 2007. This interval reflected more recent measurements of inner ear dosimetry during the authors' 21-year experience. The median patient age was 52 years (range 22-82 years). No patient had undergone any prior treatment for the ANs. The median tumor volume was 0.75 cm3 (range 0.07-7.7 cm3), and the median radiation dose to the tumor margin was 12.5 Gy (range 12-13 Gy). At diagnosis, a greater distance from the lateral tumor to the end of the internal auditory canal correlated with better hearing function.At a median of 20 months after SRS, no patient required any other additional treatment. Serviceable hearing was preserved in 71% of all patients and in 89% (46 patients) of those with GR Class I hearing. Significant prognostic factors for maintaining the same GR class included (all pre-SRS) GR Class I hearing, a speech discrimination score (SDS) ≥ 80%, a pure tone average (PTA) < 20 dB, and a patient age < 60 years. Significant prognostic factors for serviceable hearing preservation were (all pre-SRS) GR Class I hearing, an SDS ≥ 80%, a PTA < 20 dB, a patient age < 60 years, an intracanalicular tumor location, and a tumor volume < 0.75 cm3. Patients who received a radiation dose of < 4.2 Gy to the central cochlea had significantly better hearing preservation of the same GR class. Twelve of 12 patients < 60 years of age who had received a cochlear dose < 4.2 Gy retained serviceable hearing at 2 years post-SRS.As currently practiced, SRS with the Gamma Knife preserves serviceable hearing in the majority of patients. Tumor volume and anatomy relate to the hearing level before radiosurgery and influence technique. A low radiosurgical dose to the cochlea enhances hearing preservation.
- Irradiation of cochlear structures during vestibular schwannoma radiosurgery and associated hearing outcome. [Journal Article]
- J Neurosurg 2013 Dec.:733-9.
The purpose of this study was to measure the dose of radiation delivered to the cochlea during a Gamma knife surgery (GKS) procedure for treatment of patients with vestibular schwannomas (VSs), and to analyze the relationship between cochlear irradiation and the hearing outcome of these patients.Eighty-two patients with VSs were treated with GKS using a marginal dose of 12 Gy. No patient had neurofibromatosis Type 2 disease, and all had a Gardner-Robertson hearing class of I to IV before treatment, and a radiological and audiological follow-up of at least 1-year after GKS. The dosimetric data of the volume of the cochlea were retrospectively analyzed and were correlated with the auditory outcome of patients.The mean radiation dose delivered to the cochlear volume ranged from 1.30 to 10.00 Gy (median 4.15 Gy). The cochlea received significantly higher radiation doses in patients with worsening of hearing after GKS. A highly significant association between the cochlear and the intracanalicular dose of radiation delivered during GKS was found.During GKS for VSs, relatively high doses of radiation can be delivered to the cochlea. Worsening of hearing after GKS can be the consequence of either radiation injury to the cochlea or the irradiation dose delivered into the auditory canal, or both.
- Noninvasive in-vehicle alcohol detection with wavelength-modulated differential photothermal radiometry. [Journal Article]
- Biomed Opt Express 2014 Jul 1; 5(7):2333-40.
This study describes the potential of wavelength-modulated differential photothermal radiometry (WM-DPTR) for non-invasive in-vehicle alcohol detection which can be of great importance in reducing alcohol-impaired driving. Ethanol content in the range of concern, 0-100 blood alcohol concentration (BAC) in water phantoms and blood serum diffused in human skin in vitro were measured with high sensitivity. The results show that the WM-DPTR system can be optimized for alcohol detection with the combination of two sensitivity-tuning parameters, amplitude ratio R and phase shift ΔP. WM-DPTR has demonstrated the potential to be developed into a portable alcohol ignition interlock biosensor that could be fitted as a universal accessory in vehicles.
- PERFORMANCE OF RADIATION SURVEY METERS IN X- AND GAMMA-RADIATION FIELDS. [JOURNAL ARTICLE]
- Radiat Prot Dosimetry 2014 Jul 25.
The aim of this work was to investigate the different types of radiation detectors commonly used for radiation protection purposes as survey meters. The study was performed on survey meters that use different detectors as ionisation chamber, Geiger Mueller (GM) counter and scintillation detector. For each survey meter, energy dependence and angular response in X- and gamma-radiation fields was tested. The following commercially available survey meters were investigated: ionisation chambers Victoreen 451P, Babyline 31 and VA-J-15A, Geiger counter MRK-M87, 6150 AD6 and FAG FH 40F2 and scintillation counter 6150 ADB. As a source of gamma radiation, (137)Cs and (60)Co were used whereas X-ray radiation fields were generated using an X-ray unit. The radiation characteristics of the survey meters were mostly in compliance with references estimated by standard IEC 1017-2. However, some of them showed larger deviation at lower energies. GM counters exhibit strong energy dependence for low-energy photons.