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Biomedical subjects

Sören Mattsson

Publications and source records attributed to Sören Mattsson.

At least 19 recordsLinked to original sources
PubMed2006

Assessment of the environmental contamination with long-lived radionuclides around an operating RBMK reactor station.

The presence of man-made gamma emitting radionuclides in the region within 32km radius of the Ignalina NPP/Lithuania has been investigated during the period 2001-2004, prior to the closure of the first of the two operating RBMK 1500-type reactors. Gamma spectrometric measurements of various terrestrial and aquatic plants as well as of soil samples showed moderate environmental contamination with the fission product (137)Cs and with the neutron activation products (60)Co and (54)Mn. Traces of the activation products (65)Zn and (110m)Ag were found in the nearest vicinity of the NPP. Activity concentrations were inhomogeneously distributed in the area of interest. Moss and algae samples showed the highest uptake of radionuclides. In addition to the gamma spectrometric measurements, the levels of (14)C were determined in the same bio-indicator samples using accelerator mass spectrometry.

Ecosystem↗
PubMed2006

Development of methods for body composition studies.

This review is focused on experimental methods for determination of the composition of the human body, its organs and tissues. It summarizes the development and current status of fat determinations from body density, total body water determinations through the dilution technique, whole and partial body potassium measurements for body cell mass estimates, in vivo neutron activation analysis for body protein measurements, dual-energy absorptiometry (DEXA), computed tomography (CT) and magnetic resonance imaging (MRI, fMRI) and spectroscopy (MRS) for body composition studies on tissue and organ levels, as well as single- and multiple-frequency bioimpedance (BIA) and anthropometry as simple easily available methods. Methods for trace element analysis in vivo are also described. Using this wide range of measurement methods, together with gradually improved body composition models, it is now possible to quantify a number of body components and follow their changes in health and disease.

Algorithms↗
PubMed2006

Combination of pre-operative radiotherapy and surgery suppresses local accumulation of collagen and TGF-beta1 in rats.

BACKGROUND: The systemic and local tissue repair responses of radiation in combination with surgery are still unclear. We have studied the effect of fractionated pre-operative radiotherapy with or without subsequent laparotomy on collagen accumulation using a rodent model. MATERIALS AND METHODS: Thirty-two male Sprague-Dawley rats were divided into four groups (eight rats per group): 1) sham radiation and sham laparotomy (control); 2) sham radiation and laparotomy; 3) radiation and sham laparotomy; and 4) radiation followed by laparotomy. Expanded polytetrafluoroethylene (ePTFE) tubes were implanted subcutaneously in the abdominal wall in the radiotherapy field and on the back outside the radiotherapy field day 0. The abdomen (3 cm x 4 cm) was irradiated day 3 (10 Gy) and again day 7 (10 Gy). On day 10, implants were extirpated, laparotomy undertaken in groups 2 and 4 and new ePTFE tubes implanted subcutaneously. The second implants were extirpated on day 20. Implants were analyzed for hydroxyproline, total protein and transforming growth factor-beta1 (TGF-beta1) levels. RESULTS: On day 10, hydroxyproline (P < 0.05) and TGF-beta1 (P < 0.001) were lower in ePTFE tubes in irradiated compared with non-irradiated rats. On day 20, the abdominal ePTFE hydroxyproline remained low (P < 0.001) in animals subjected to laparotomy and pre-operative irradiation while hydroxyproline levels of rats subjected to irradiation only were similar to controls. The effects of radiation on hydroxyproline were confined to the irradiated abdominal area. There was a positive correlation between hydroxyproline and TGF-beta1 levels in the abdominal wall implant day 20 (r = 0.53, P < 0.005). CONCLUSION: A clinically relevant fractionated radiation scheme reduced subcutaneous collagen accumulation pre-operatively and profoundly within the radiation field post-operatively after laparotomy, possibly because of lowered TGF-beta1 levels.

Animals↗
PubMed2006

Radioactive iodine in thyroid medicine--how it started in Sweden and some of today's challenges.

In Sweden, radioactive iodine for thyroid diagnostics and therapy was introduced by Jan Waldenström (1906-1996) and Bengt Skanse (1918-1963). The paper describes the start of the clinical use of radioiodine, the various iodine isotopes available, measurement techniques and dosimetry. There are still problems to solve in relation to an optimal clinical use of radioiodine. One of the remaining challenges is to get consensus about the goal of the treatment of hyperthyreosis, as well as about a method for individual absorbed dose calculations. Careful dose estimates will prevent unnecessary radiation exposure and constitute a base for a future optimised radioiodine therapy. For the dose calculation, it is important to understand if there is any clinically significant temporary reduction in the ability of thyroid tissue to trap or retain 131I-iodide following prior administration of a diagnostic activity of 131I-iodide (stunning of the thyroid). This may be of special concern in connection with treatment of thyroid cancer and its metastases. Finally, the production capacity, availability and delivery of 123I have to be improved to increase clinical access to this radionuclide, which is optimal for diagnostic imaging and which gives lower absorbed dose and therefore also less risk for thyroid stunning than 131I.

History, 20th Century↗
PubMed2006

"Distributed proton radiation therapy"--a new concept for advanced competence support.

The increased interest in high precision radiation therapy is to a large extent driven by the potential of modern imaging technology. The aim of this project was to analyse how an expensive proton facility best could support a multi-centre health care system. We have developed a model for distributed expert collaboration where all clinical experts will work close to their patients in regional centres. Patients who are candidates for proton therapy will be examined and dose-planned at their regional clinic, discussed in a fully information supported video conference and digitally made available at the proton treatment facility. The proton facility itself will be placed near a communication centre easily reached by all patients where they will be treated under full responsibility of their own physician at the home clinic. This concept has been analysed in detail both with respect to the overall functionality and with respect to possible weaknesses. It was found that the concept of distributed radiation therapy, as proposed here, will offer a stable clinical solution for advanced radiation therapy. It will support the spread of knowledge, serve as a fully developed backup system and the concept will further serve as an efficient base for clinical research.

Ambulatory Care Facilities↗
PubMed2006

Comparative renal, hepatic, and bone marrow toxicity of Cisplatin and radioactive Cisplatin (191Pt) in Wistar rats.

The aim of the study was to investigate the possibility to increase the therapeutic gain of the cytotoxic agent, cisplatin, by incorporation of radioactive platinum. In this study, we investigated how organs at risk (i.e., kidneys, bone marrow, and liver) are affected by treatment with 191Pt-cisplatin, compared to treatment with conventional cisplatin. Rats (total, n = 69) were divided into three groups and given 5 mg/kg 191Pt-cisplatin and 5 mg/kg nonradioactive cisplatin or saline. The weight of the animals and blood samples, including analysis of creatinine, bilirubin, alanine and aspartate aminotransferases and platelet count, was followed for 6 weeks after treatment. Histopathology examinations of kidney and liver tissues were performed. An initial decrease in weight gain was seen from 3 days after treatment with cisplatin and 191Pt-cisplatin and for 1 week onward; thereafter, the weight gain continued, following the same pattern as for the control group. Concentration of plasma creatinine was increased for both cisplatin groups but with no significant difference between treatment groups. No other significant differences in effect parameters were found. There was no increase in toxicity for radioactive cisplatin on liver, kidneys, and bone marrow, compared to conventional cisplatin. Further experimental and clinical studies on preparations of this type are thus warranted.

Animals↗
PubMed2005

Lead in finger bone, whole blood, plasma and urine in lead-smelter workers: extended exposure range.

OBJECTIVES: To assess the historical exposure and to study the relationships between lead concentrations in whole blood (B-Pb), plasma (P-Pb), urine (U-Pb), finger bone (Bone-Pb) and duration of employment in workers at a secondary lead smelter and to compare the relationships between B-Pb and P-Pb with results from previous studies of populations with a wide range of lead exposure. METHODS: In 39 lead workers (29 active, ten retired), recruited from those with the highest exposure at a German secondary lead smelter, levels of B-Pb, P-Pb and U-Pb were determined by inductively coupled plasma mass spectrometry (ICP-MS). Bone-Pb was determined by in vivo X-ray fluorescence (XRF). Results were compared with data from a previous study on 90 workers (71 active, 19 retired) with lower exposure, from a Swedish secondary lead smelter, as well as with previously collected data from 42 active Russian lead workers and 34 Ecuadorian lead-exposed subjects. RESULTS: The median values in the active/retired German lead workers were: age 44/59 years, duration of employment 20/38 years, Bone-Pb 71/150 microg/g, B-Pb 500/330 microg/l, P-Pb 2.7/1.1 microg/l, and U-Pb 25/13 micromol/mol creatinine. Bone-Pb increased with duration of employment by 4.2 microg/g per year and 1.6 microg/g per year in German and Swedish workers, respectively. The median Bone-Pb was three times higher in both active and retired German workers than in Swedish smelter workers with essentially the same age distribution and duration of employment. The linear regression equation between B-Pb and log P-Pb in the combined group of Ecuadorian, German, Russian and Swedish lead-exposed subjects (n=176) was B-Pb=545 x log[P-Pb] + 258 (r(s)=0.94; P<0.001). CONCLUSIONS: The high Bone-Pb values recorded for the German smelters implied a historical lead exposure of considerable magnitude. The long-term high lead exposure also showed up in the B-Pb levels for both active and retired workers, leading to the implementation of necessary industrial safety measures in order to respond to biological threshold limits. The suggested equation describing the relationship between B-Pb and P-Pb in the combined group of subjects with a wide range of lead exposure can be useful in future cross-sectional and longitudinal studies of lead-exposed populations, relating, e.g., lead exposure to adverse health outcomes.

Adult↗
PubMed2005

Inter-observer variation in masked and unmasked images for quality evaluation of clinical radiographs.

PURPOSE: To investigate the influence of masking on the inter-observer variation in image quality evaluation of clinical radiographs of chest and lumbar spine. BACKGROUND: Inter-observer variation is a big problem in image quality evaluation since this variation is often much bigger than the variation in image quality between, for example, two radiographic systems. In this study, we have evaluated the effect of masking on the inter-observer variation. The idea of the masking was to force every observer to view exactly the same part of the image and to avoid the effect of the overall 'first impression' of the image. A discussion with a group of European expert radiologists before the study indicated that masking might be a good way to reduce the inter-observer variation. METHODS: Five chest and five lumbar spine radiographs were collected together with detailed information regarding exposure conditions. The radiographs were digitised with a high-performance scanner and five different manipulations were performed, simulating five different exposure conditions. The contrast, noise and spatial resolution were manipulated by this method. The images were printed onto the film and the individual masks were produced for each film, showing only the parts of the images that were necessary for the image quality evaluation. The quality of the images was evaluated on ordinary viewing boxes by a large group of experienced radiologists. The images were examined with and without the masks with a set of image criteria (if fulfilled, 1 point; and not fulfilled, 0 point), and the mean score was calculated for each simulated exposure condition. RESULTS: The results of this study indicate that-contrary to what was supposed-the inter-observer variation increased when the images were masked. In some cases, especially for chest, this increase was statistically significant. CONCLUSIONS: Based on the results of this study, image masking in studies of fulfilment of image criteria cannot be recommended.

Computers↗
PubMed2005

A software tool for increased efficiency in observer performance studies in radiology.

Observer performance studies are time-consuming tasks, both for the participating observers and for the scientists collecting and analysing the data. A possible way to optimise such studies is to perform them in a completely digital environment. A software tool-ViewDEX (Viewer for Digital Evaluation of X-ray images)-has been developed in Java, enabling it to function on almost any computer. ViewDEX is designed to handle several types of studies, such as visual grading analysis (VGA), image criteria scoring (ICS) and receiver operating characteristics (ROC). The results from each observer are saved in a log file, which can be exported for further analysis in, for example, a special software for analysing ROC results. By using ViewDEX for an ROC experiment, an evaluation rate of approximately 200 images per hour can be achieved, compared to approximately 25 images per hour using hard copy evaluation. The results are obtained within minutes of completion of the viewing. The risk of human errors in the process of data collection and analysis is also minimised. The viewer has been used in a major trial containing approximately 2700 images.

Computer Simulation↗
PubMed2005

Evaluation of image quality of lumbar spine images: a comparison between FFE and VGA.

PURPOSE: The aim of the present study is to compare two different methods for evaluation of the quality of clinical X-ray images. METHODS: Based on fifteen lumbar spine radiographs, two new sets of images were created. A hybrid image set was created by adding two distributions of artificial lesions to each original image. The image quality parameters spatial resolution and noise were manipulated and a total of 210 hybrid images were created. A set of 105 disease-free images was created by applying the same combinations of spatial resolution and noise to the original images. The hybrid images were evaluated with the free-response forced error experiment (FFE) and the normal images with visual grading analysis (VGA) by nine experienced radiologists. RESULTS: In the VGA study, images with low noise were preferred over images with higher noise levels. The alteration of the MTF had a limited influence on the VGA score. For the FFE study, the visibility of the lesions was independent of the sharpness and the noise level. No correlation was found between the two image quality measures. CONCLUSIONS: FFE is a precise method for evaluation of image quality, but the results are only valid for the type of lesion used in the study, whereas VGA is a more general method for clinical image quality assessment. The results of the FFE study indicate that there might be a potential to lower the dose levels in lumbar spine radiography without losing important diagnostic information.

Calibration↗
PubMed2005

Nodule detection in digital chest radiography: summary of the RADIUS chest trial.

As a part of the Europe-wide research project 'Unification of physical and clinical requirements for medical X-ray imaging'-governed by the Radiological Imaging Unification Strategies (RADIUS) Group-a major image quality trial was conducted by members of the group. The RADIUS chest trial aimed at thoroughly examining various aspects of nodule detection in digital chest radiography, such as the effects of nodule location, system noise, anatomical noise, and anatomical background. The main findings of the RADIUS chest trial concerning the detection of a lung nodule with a size in the order of 10 mm can be summarised as: (1) the detectability of the nodule is largely dependent on its location in the chest, (2) the system noise has a minor impact on the detectability at the dose levels used today, (3) the disturbance of the anatomical noise is larger than that of the system noise but smaller than that of the anatomical background and (4) the anatomical background acts as noise to a large extent and is the major image component affecting the detectability of the nodule.

Artifacts↗
PubMed2005

Nodule detection in digital chest radiography: introduction to the RADIUS chest trial.

Most digital radiographic systems of today have wide latitude and are hence able to provide images with a small constraint on dose level. This opens up for an unprejudiced dose optimisation. However, in order to succeed in the optimisation task, good knowledge of the imaging and detection processes is needed. As a part of the European-wide research project 'unification of physical and clinical requirements for medical X-ray imaging'-governed by the Radiological Imaging Unification Strategies (RADIUS) Group-a major image quality trial was conducted by members of the group. The RADIUS chest trial was focused on the detection of lung nodules in digital chest radiography with the aims of determining to what extent (1) the detection of a nodule is dependent on its location, (2) the system noise disturbs the detection of lung nodules, (3) the anatomical noise disturbs the detection of lung nodules and (4) the image background and anatomical background act as pure noise for the detection of lung nodules. The purpose of the present paper is to give an introduction to the trial and describe the framework and set-up of the investigation.

Artifacts↗
PubMed2005

Priorities in optimisation of medical X-ray imaging--a contribution to the debate.

A simplistic approach to optimising medical imaging is to use the lowest effective dose to the patient that does not jeopardise a correct diagnosis. With limited resources and over 1000 different types of X-ray examinations, it is not always easy to set the right priorities and to decide how to perform the optimisation. Recent research shows that the 'Rose model' for the detection of specific structures does not hold for realistic backgrounds. A reasonable conclusion regarding methods for optimisation is therefore not to use contrast-detail phantoms. Phantoms producing clinically realistic background images or real clinical images-modified with respect to quantum noise levels-are preferred. The images should be evaluated using visual grading or receiver operating characteristic methods. The quality of many common X-ray investigations, performed with projection techniques, is not limited by quantum noise. For these, the radiation dose to the patient can be lowered without seriously affecting the outcome of the detection task. For computed tomography (CT) investigations, the obscuring effect of anatomical structures and anatomical noise is less pronounced than in projection techniques. For CT, true optimisation in terms of a trade-off between radiation dose and image quality is therefore more likely to be effective. Both the number of CT examinations performed per year and the effective dose per examination are increasing owing to the technical advances in CT--jointly leading to a steady increase in the collective dose from CT examinations. Moreover, the smaller influence of the anatomical background in CT gives a high correlation between detection tasks and radiation dose. Thus, a reasonable view to take on which examinations to optimise is to give priority to CT examinations. The recommended distribution of a full working week for optimisation, based on the relative lifetime risk of lethal cancer from diagnostic X rays and the total collective dose from CT, is to use three out of five days to optimise CT examinations, of which one day should be devoted to paediatric CT.

Adult↗
PubMed2004

Real-time optical-fibre luminescence dosimetry for radiotherapy: physical characteristics and applications in photon beams.

A new optical-fibre radiation dosimeter system, based on radioluminescence and optically stimulated luminescence from carbon-doped aluminium oxide, was developed and tested in clinical photon beams. This prototype offers several features, such as a small detector (1 x 1 x 2 mm3), high sensitivity, real-time read-out and the ability to measure both dose rate and absorbed dose. The measurements describing reproducibility and output dependence on dose rate, field size and energy all had standard deviations smaller than 1%. The signal variation with the angle of incidence was smaller than 2% (1 SD). Measurements performed in clinical situations suggest the potential of using this real-time system for in vivo dosimetry in radiotherapy.

Aluminum Oxide↗
PubMed2004

Excess radiation absorbed doses from non-optimised radioiodine treatment of hyperthyroidism.

Radioiodine therapy is often the method of choice for treatment of hyperthyroidism because it is considered safe, is relatively inexpensive, and is convenient for the patient and except for occasional hypothyroidism, almost without side effects. Even though radioiodine treatment has been performed for over 50 years, the method of treatment differs from country to country and even from hospital to hospital within the same country. To illuminate such differences 187 radioiodine treatments for Graves' disease at Malmö University Hospital in Sweden have been analysed. Comparative dose calculations were carried out assuming that the individual patients had also been treated according to a number of other protocols in current use. The results show that the protocol used for calculating the administered activity in radioiodine therapy is far from optimised in many hospitals. Following the protocols where the absorbed dose to the thyroid is calculated without any uptake measurements after administration of a test activity, most of the patients were treated with an unnecessarily high activity, as a mean factor of 2.5 times too high and in individual patients up to eight times too high, leading to an unnecessary radiation exposure both for the patient, the family and the public. This is not in accordance with generally accepted radiation protection principles. Using higher activity than necessary will also prolong the patient's stay at the hospital and thus increase the costs for the care. Unnecessarily high activity will also necessitate more long-lasting radiation protection restriction relative to family members when the patient is back home.

Absorption↗
PubMed2003

Biokinetics and radiation dosimetry for patients undergoing a glycerol tri[1-14C]oleate fat malabsorption breath test.

The glycerol tri[1-14C]olein test for fat malabsorption was carried out in two male volunteers and measurements of the loss of 14C in expired air, urine and faeces and the retention of 14C in biopsy samples of abdominal fat were made using accelerator mass spectrometry. Exhalation accounted for 73% and 55% of the administered activity and could be described by three-component exponential functions with halftimes of about 1h, 2 days and 150 days, respectively. Urinary excretion accounted for 24% of the administered activity, almost all during the first 24h after administration; about 2% was excreted in the faeces in 48h. The halftime of retention of 14C in fat ranged from 137 to 620 days. Absorbed dose calculations indicate that for a normal adult the largest dose, 1.5-7.0mGy/MBq is received by the adipose tissue, and that the effective dose is 0.3-0.5mSv/MBq. It is concluded that no restrictions need to be placed on radiation safety grounds on the administration of 0.05-0.1MBq 14C-triolein for the triolein breath test.

Adipose Tissue↗
PubMed2003

Radiation therapy dose delivery.

In an investigation by the Swedish Cancer Society, the present status critical issues and future aspects and potentials in each of nine major areas of radiation therapy research were described by an expert group. The report presented here deals with radiation therapy dose delivery. dose distributions, beam shaping and intensity modulation.

Humans↗