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At least 379 records · Page 21Linked to original sources
PubMed2005

Patient doses in multi-slice CT and the importance of optimisation.

Substantive surveys of patient doses arising from CT examinations have been conducted in our Hospital. In the first instance doses were measured on a single-slice Siemens Plus 4 scanner. A similar survey was conducted initially following commissioning of a Siemens multi-slice Sensation scanner and subsequently after some effort was made to optimise scanning protocols. Doses are reported in terms of dose-length products (DLPs) and as effective doses. The optimisation process on the multi-slice scanner resulted in a reduction in DLP values by between 14% and 58%. With two exceptions, significantly lower or comparable DLP values were obtained when meaningful comparisons were made with results previously obtained with the single-slice scanner. Specific results for the multi-slice scanner in terms of the median DLP in mGy.cm (and median effective dose in mSv) are: routine brain, 660 (1.5); routine chest, 195 (4.0); chest with portal liver phase, 370 (7.2); routine chest with high resolution component, 250 (5.1); chest/abdomen/pelvis with contrast, 560 (11.0); routine abdomen without contrast, 145 (2.4); routine abdomen with contrast 215 (3.6); routine abdomen/pelvis without contrast, 230 (4.4); routine abdomen/pelvis with contrast, 345 (6.3); abdomen/pelvis triple phase, 715 (13.3); renal scan, 260 (4.6); lumbar spine, 445 (7.2); cerebral angiography, 240 (0.58); pulmonary angiography, 165 (3.4); aortic angiography, 305 (5.7). Based on the survey findings possible values for CT examination local diagnostic reference levels (LDRLs) are suggested.

Australia↗
PubMed2005

Neutron activation of patients following boron neutron capture therapy of brain tumors at the high flux reactor (HFR) Petten (EORTC Trials 11961 and 11011).

BACKGROUND AND PURPOSE: At the High Flux Reactor (HFR), Petten, The Netherlands, EORTC clinical trials of Boron Neutron Capture Therapy (BNCT) have been in progress since 1997. BNCT involves the irradiation of cancer patients by a beam of neutrons, with an energy range of predominantly 1 eV to 10 keV. The patient is infused with a tumor-seeking, (10)B-loaded compound prior to irradiation. Neutron capture in the (10)B atoms results in a high local radiation dose to the tumor cells, whilst sparing the healthy tissue. Neutron capture, however, also occurs in other atoms naturally present in tissue, sometimes resulting in radionuclides that will be present after treatment. The patient is therefore, following BNCT, radioactive. The importance of this induced activity with respect to the absorbed dose in the patient as well as to the radiation exposure of the staff has been investigated. MATERIAL AND METHODS: As a standard radiation protection procedure, the ambient dose equivalent rate was measured on all patients following BNCT using a dose ratemeter. Furthermore, some of the patients underwent measurements using a gamma-ray spectrometer to identify which elements and confirm which isotopes are activated. RESULTS: Peak levels, i.e., at contact and directly after irradiation, are of the order of 40-60 muSv/h, falling to < 10 muSv/h 30-50 min after treatment. The average ambient dose equivalent in the first 2 h at a distance of 2 m from the patient is in the order of 2.5 muSv. The ambient dose equivalent rate in 2 m distance from the patient's head at the earliest time of leaving the reactor center (20 min after the end of treatment) is far less than 1 muSv/h. The main radioisotopes were identified as (38)Cl, (49)Ca, and (24)Na. Furthermore, in two patients, the isotopes (198)Au and (116m)In were also present. The initial activity is predominantly due to (49)Ca, whilst the remaining activity is predominantly due to (24)Na. CONCLUSION: The absorbed dose resulting from the activated isotopes in the irradiated volume is in the order of < 1% of the prescribed dose and therefore does not add a significant contribution to the absorbed dose in the target volume. In other parts of the patient's body, the absorbed dose by induced activity is magnitudes smaller and can be neglected. The levels of radiation received by staff members and non-radiation workers (i.e., accompanying persons) are well below the recommended limits.

Body Burden↗
PubMed2006

[Radiation protection. Implications for clinical practice on the new regulations governing roentgen ray irradiation and radioprotection].

In 2001 or 2002, the legislator made substantial alterations to the "Röntgenverordnung" [regulations governing use of roentgen ray radiation] and "Strahlenschutzverordnung" [regulations governing radiation protection]. This was done to bring German law in line with EU Directives 96/29/Euratom (basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionizing radiation) and 97/43/Euratom (health protection of individuals against the dangers of ionizing radiation in relation to medical exposure). Proper use of radiation in medicine requires that those involved in its application are aware of the biological effect of radiation. When staff and others are protected good organization and appropriate technology at the workplace can achieve a great deal. In the new directives, the radiation protection for the patient is quantified and the responsibility of the physician is clearly pointed out. The most important aim is uniform quality throughout Europe in radiological diagnosis and radiation protection.

Clinical Medicine↗
PubMed2005

The Elbmarsch leukemia cluster: are there conceptual limitations in controlling immission from nuclear establishments in Germany?

The childhood leukemia cluster in the proximity of the German nuclear establishments of Geesthacht is unique in its spatial and temporal concentration. After a steep increase in cases in 1990, the cluster continues to show a significant increase up to the present. Early investigations of blood samples from a casual sample of local residents showed an increase in dicentric chromosomes in lymphocytes, indicating exposure exceeding dose limits. Analyses of the immission data revealed several unexpected deliveries of fission and activation products in the environment but provided no explanation of the source. Because of the observed overdispersion of dicentric chromosomes in cells, the idea of a contribution by densely ionizing emitters was compelling. The routine programs, however, do not include alpha emitters. These were measured in specific studies that proved contamination by transuranic nuclides. As shown in the present investigation, routine environmental surveillance programs support the occurrence of an accidental event near Geesthacht in September 1986. Until now, neither the cause nor the complete scenario of the activity release could be established. The ongoing discussion highlights limitations in the immission-control concept, which is predominantly based on gamma-radiation monitoring.

Air Pollutants, Radioactive↗
PubMed2005

Pediatric patient surface doses in neuroangiography.

BACKGROUND: Neuroangiographic techniques (diagnostic and interventional) can be lengthy and complex and can be associated with high radiation entrance skin doses from fluoroscopy and digital subtraction angiography (DSA). OBJECTIVE: To measure entrance surface doses received by pediatric patients undergoing neuroangiographic procedures and to (1) compare these doses with thresholds for deterministic effects, (2) compare these doses with those reported in adults, and (3) to understand the dose relationships among diagnostic and interventional procedures, DSA and fluoroscopy. MATERIALS AND METHODS: A neurobiplane unit with fluoroscopic and DSA capabilities was used for all neuroangiographic procedures. An automated patient dosimeter, installed on both planes of the unit, calculated maximum surface dose. The dosimeter also recorded the number of angiographic frames and the length of fluoroscopy time for each procedure. RESULTS: This retrospective study analyzed entrance surface doses to 100 pediatric patients, 76 of whom underwent neuroangiographic diagnostic procedures and 24 of whom underwent neuroangiographic interventional procedures. The DSA acquisitions ranged from 44 frames to 1,428 frames per procedure and fluoroscopy times ranged from 1.1 to 85.6 min per procedure. The mean surface dose from fluoroscopy was 68.1 mGy (max: 397.1 mGy) in the frontal (PA) plane; in the lateral (LAT) plane, the mean surface dose was 40.9 mGy (max: 418.5 mGy). The mean surface doses from DSA were 263.1 and 126.9 mGy in the frontal and lateral planes, with maximum doses of 924.4 and 410.1 mGy, respectively. Mean fluoroscopy dose rates were 5.4 mGy/min in the PA plane and 4.7 mGy/min in the LAT plane. The DSA largely contributed to the overall procedural surface dose, accounting for 82% of the combined surface dose in the each of the imaging planes. CONCLUSION: The surface dose for each procedure measured in this study was found to be below thresholds for deterministic effects. Interventional procedures consistently yield the highest doses.

Adolescent↗
PubMed2005

Radiation exposure to family members of patients with thyrotoxicosis treated with iodine-131.

PURPOSE: The purpose of this study was twofold: (1) to measure the radiation exposure to family members of out-patients with thyrotoxicosis treated with radioiodine, 131I, using the recommendations from the European Commission (EC) guidance and age-specific periods for behaviour restrictions; (2) to use the results to identify necessary restrictions to ensure recommended dose constraints. METHODS: The study population comprised 76 family members (46 adults and 30 children below the age of 18) of 42 patients. The patients were treated with an average activity of 417 MBq (range 260-600 MBq). They received oral and written EC recommendations about behaviour restrictions (translated into Norwegian). On the day of treatment we repeated the oral instructions to the patient and an adult family member. The time periods for restrictions were 14 days for children aged 0-10 years, 7 days for persons aged 11-59 years and 3 days for persons aged 60 years and older. Family members wore a thermoluminescent dosimeter (TLD) on each wrist day and night for 2 weeks. The doses received were adjusted to give an estimate of the expected values if the TLDs had been worn indefinitely. RESULTS: Radiation doses well below the recommended dose constraints were measured for all adult family members and children, except one 2-year-old child; in the latter case the mother probably did not comply with the instructions given. CONCLUSION: The radiation dose to family members of thyrotoxic patients treated with up to 600 MBq of radioiodine is well below recommended dose constraints if EC instructions are given and compliance is adequate. The duration of restrictions for various age groups used in this study may be considered when establishing guidelines in Norway.

Administration, Oral↗
PubMed2006

Radiation protection in radionuclide therapies with (90)Y-conjugates: risks and safety.

PURPOSE: The widespread interest in (90)Y internal radionuclide treatments has drawn attention to the issue of radiation protection for staff. Our aim in this study was to identify personnel at risk and to validate the protection devices used. METHODS: (90)Y-MoAb (Zevalin, 15 cases, 1.1 GBq/patient) and (90)Y-peptide ((90)Y-DOTATOC) systemic (i.v., 50 cases, 3.0 GBq/patient) and locoregional (l.r., 50 cases, 0.4 GBq/patient) treatments were considered. Radiolabelling was carried out in a dedicated hot cell. Tele-tongs, shielded (PMMA: polymethylmethacrylate) syringes/vials and an automatic dose fractionating system were used. Operators wore anti-X-ray and anti-contamination gloves, with TLD dosimeters placed over the fingertips. For i.v. administration, activity was administered by a dedicated system; for l.r. administration, during activity infusion in the brain cavity, tongs were used and TLDs were placed over the fingertips. The air kerma-rate was measured around the patients. RESULTS: The use of devices provided a 75% dose reduction, with mean fingertip doses of 2.9 mGy (i.v. MoAbs), 0.6 mGy (i.v. peptides)/radiolabelling procedure and 0.5 mGy/l.r. administration. The mean effective dose to personnel was 5 microSv/patient. The air kerma-rate around the patients administered i.v. (90)Y-peptides were 3.5 (1 h) and 1.0 (48 h) microGy/h at 1 m. Patient hospitalisation of 6 h (l.r.)/48 h (i.v.) guaranteed that the recommended limits of 3 mSv/year to family members and 0.3 mSv/year to the general population (Council Directive 97/43/Euratom) were respected. CONCLUSIONS: When specific procedures are adopted, a substantial improvement in (90)Y manipulation is attainable, reducing doses and increasing safety. For the widespread clinical use of (90)Y-conjugates, a completely automatic labelling procedure is desirable.

Italy↗
PubMedDate not supplied

Radiation dose to the radiologist's hand during continuous CT fluoroscopy-guided interventions.

Computed tomography fluoroscopy (CT fluoroscopy) enables real-time image control over the entire body with high geometric accuracy and, for the most part, without significant interfering artifacts, resulting in increased target accuracy, reduced intervention times, and improved biopsy specimens [1--4]. Depending on the procedure being used, higher radiation doses than in conventional CT-supported interventions might occur. Because the radiologist is present in the CT room during the intervention, he is exposed to additional radiation, which is an important aspect. Initial experience with CT fluoroscopically guided interventions is from the work of Katada et al. in 1994 [5] and only relatively few reports on radiation aspects in CT fluoroscopy are found in the literature [1, 2, 6--11]. To date, there are no reported injuries to patients and radiologists occurring with CT fluoroscopy. The time interval since the wide use of CT fluoroscopy is too short to have data on late effects to the operator using CT fluoroscopy on a daily basis. In addition, the spectrum of CT fluoroscopically guided interventional procedures will expand and more sophisticated procedures requiring longer fluoroscopy times will be performed. Thus, effective exposure reduction is very important. The purpose of our study was to assess the radiation dose to the operator's hand by using data from phantom measurements. In addition, we investigated the effect of a lead drape on the phantom surface adjacent to the scanning plane, the use of thin radiation protective gloves, and the use of different needle holders.

Adult↗
PubMed2005

Thoron levels in traditional Chinese residential dwellings.

A survey on radon (222Rn), thoron (220Rn) and its decay products (220RnD) was conducted in Chinese traditional residential dwellings constructed with loam bricks or soil wall. The activity concentrations in 164 dwellings under investigation were 72.4+/-59.2 (arithmetic mean, AM) and 57.5+/-2.0 Bq m-3 (geometric mean, GM) for 222Rn, and 318+/-368 and 162+/-3.7 Bq m-3 for 220Rn, respectively. For 220RnD, 67 dwellings were studied. The AM of the 220RnD equilibrium equivalent concentration was 3.8+/-3.3 Bq m-3 with a maximum value of 15.8 Bq m-3. On the basis of these results, the average annual effective doses to the local residents due to radon and thoron exposure were 1.44-4.62 mSv. Thoron contributes 12.9-56.6% to the total doses. Preliminary results show that there is a relation between 220RnD in air and 232Th in soil. The correlation factors of outdoor and indoor were 0.88 and 0.40. The 232Th activity content of Chinese soil is estimated to be about two times the world average. The traditional residential dwellings with soil construction are still common in China. Further investigations on the 220Rn level in these dwelling with the aim of dose reduction are proposed.

Air Pollution, Indoor↗
PubMed1998

Measurements of radioactivity in environmental samples from the southern Urals.

A region between Chelyabinsk and Ekaterinburg in the Southern Urals has been heavily contaminated due to operational and accidental releases from the first Soviet plutonium production facility Mayak. In 1992 and 1993, the German Federal Office for Radiation Protection organized a measuring campaign involving two Russian institutes to assist with the validation of former Soviet measurement data. The results of this measuring campaign are reported here. Environmental samples were collected from areas affected by significant radioactive releases into the Techa river, which started in 1948, and by fallout from the explosion of a fission product storage tank in 1957. Soil, sediment, water, milk and food samples were independently analysed for 90Sr, 137Cs and plutonium by the three institutes involved. This paper presents data on the present levels of environmental radioactivity. The highest contamination of areas accessible to the local population was found in the vicinity of the Techa river around Muslumovo. Activity concentration of floodplain samples reached up to 37,000 Bq.kg-1 137Cs, 5,600 Bq.kg-1 90Sr and 9.9 Bq.kg-1 Pu. Milk and potatoes from private farms in Muslumovo showed low activity in the range from 0.7 Bq.kg-1 to 25 Bq.kg-1 90Sr. The results of the three independent measurement teams showed sufficient agreement. One Russian laboratory obtained plutonium activities that exceeded the results of the other laboratories by about 20%. Contrary to the International Chernobyl Project, there was no overestimation of 90Sr activities in the Russian analyses. Therefore, the validity of earlier data sets acquired with same methodology and quality control can be considered a valuable basis for further assessments and for dose reconstruction in epidemiological projects.

Animals↗
PubMed2005

Techniques and parameters for estimating radiation exposure and dose in cardiac computed tomography.

With increasing clinical use of cardiac CT imaging it is important that all health care providers referring for or administering such examinations are familiar with the concepts and values of radiation dosimetry in CT as well as with the basic principles of radiation protection. There are important technical differences pertinent to radiation dose between the CT scanner types that are currently being used for imaging of the heart and coronary arteries. As a result of these differences, the radiation dose typically is higher when a cardiac examination is performed with multidetector-row CT (MDCT) than when it is performed with electron beam CT. Several techniques have been described to reduce radiation dose of MDCT imaging by varying the X-ray tube current during a CT examination. The volume computed tomographic dose index (CTDIvol), the dose length product (DLP), and the effective dose (E) are the most useful parameters to describe and compare radiation doses received from cardiac CT examinations. When comparing radiation doses between scanning protocols and scanner types, the degree of image noise must be considered. Diagnostic, rather than aesthetic, quality of images should be the most important factor guiding the development of scanning protocols for cardiac CT imaging. Cardiac CT examinations should be ordered only by qualified health care providers, and the ordering clinicians should be aware of their responsibility of weighing risks of the radiation exposure against the expected benefits.

Heart↗
PubMed2006

Sustainability in the cardiac cath lab.

Use of radiation for medical examinations and test is the largest man-made source of radiation exposure. Interventional procedures are only 2% of all radiological procedures, but contribute to about 20% of the total collective dose per head per year. On average, a left ventriculography and coronary angiography corresponds to a radiation exposure for the patient of about 300, a coronary stent to 1,000, a peripheral artery intervention to 1,500 to 2,500, and a cardiac radiofrequency ablation to 900-1,500 chest x-rays. Invasive cardiology procedures increased tenfold in the last ten years and growth in the field has been accompanied by concern for the safety of the staff. Interventional cardiologists have an exposure per-head per year two- to three times higher than that of radiologists, with an annual exposure equivalent to around 250 chest x-rays per head. A reduction of occupational doses by a factor of ten can be achieved simply by and intensive training program. The awareness of radiation effects may be suboptimal in the medical community. It is recommended by professional guidelines and reinforced by the European law that the responsibility of all physicians is to minimize the radiation injury hazard to their patients, to their professional staff and to themselves.

Cardiac Catheterization↗