| 1. |
- Almén, Anja, et al.
(författare)
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Challenges assessing radiation risk in image-guided treatments-implications on optimisation of radiological protection
- 2018
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 38:3, s. 1064-1076
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Tidskriftsartikel (refereegranskat)abstract
- The present work explores challenges when assessing organ dose and effective dose concerning image-guided treatments. During these treatments considerable x-ray imaging is employed using technically advanced angiographic x-ray equipment. Thus, the radiation dose to organs and the related radiation risk are relatively difficult to assess. This has implications on the optimisation process, in which assessing radiation dose is one important part. In this study, endovascular aortic repair treatments were investigated. Organ dose and effective dose were assessed using Monte Carlo calculations together with a detailed specification of the exposure situation and patient size. The resulting normalised organ dose and effective dose with respect to kerma-area product for patient sizes and radiation qualities representative for the patient group were evaluated. The variability and uncertainty were investigated and their possible impact on optimisation of radiation protection was discussed. Exposure parameters, source to detector distances etc varied between treatments and also varied between image acquisitions during one treatment. Thus the derived normalised organ dose and effective dose exhibited a large range of values depending greatly on used exposure parameters and patient configuration. The derived normalised values for effective dose varied approximately between 0.05 and 0.30 mSv per Gy.cm(2) when taking patient sizes and exposure parameters into consideration, the values for organ doses exhibited even larger variation. The study shows a possible systematic error for derived organ doses and effective dose up to a factor of 7 if detailed exposure or patient characteristics are not known and/or not taken into consideration. The intra-treatment variability was also substantial and the normalised dose values varied up to a factor of 2 between image acquisitions during one treatment. The study shows that the use of conversion factors that are not adapted to the clinic can cause the radiation dose to be exaggerated or underestimated considerably. A conclusion from the present study is that the systematic error could be large and should be estimated together with random errors. A large uncertainty makes it difficult to detect true differences in radiation dose between methods and technology-a prerequisite for optimising radiation protection for image-guided treatments.
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| 2. |
- Almén, Anja, 1964, et al.
(författare)
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OPTIMISATION OF OCCUPATIONAL RADIATION PROTECTION IN IMAGE-GUIDED INTERVENTIONS: EXPLORING VIDEO RECORDINGS AS A TOOL IN THE PROCESS
- 2016
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 425-429
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Tidskriftsartikel (refereegranskat)abstract
- The overall purpose of this work was to explore how video recordings can contribute to the process of optimising occupational radiation protection in image-guided interventions. Video-recorded material from two image-guided interventions was produced and used to investigate to what extent it is conceivable to observe and assess dose-affecting actions in video recordings. Using the recorded material, it was to some extent possible to connect the choice of imaging techniques to the medical events during the procedure and, to a less extent, to connect these technical and medical issues to the occupational exposure. It was possible to identify a relationship between occupational exposure level to staff and positioning and use of shielding. However, detailed values of the dose rates were not possible to observe on the recordings, and the change in occupational exposure level from adjustments of exposure settings was not possible to identify. In conclusion, the use of video recordings is a promising tool to identify dose-affecting instances, allowing for a deeper knowledge of the interdependency between the management of the medical procedure, the applied imaging technology and the occupational exposure level. However, for a full information about the dose-affecting actions, the equipment used and the recording settings have to be thoroughly planned.
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| 3. |
- Almén, Anja, 1964, et al.
(författare)
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Optimisation of occupational radiological protection in image-guided interventions: potential impact of dose rate measurements.
- 2015
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Ingår i: Journal of radiological protection : official journal of the Society for Radiological Protection. - : IOP Publishing. - 1361-6498. ; 35:1, s. 47-62
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Tidskriftsartikel (refereegranskat)abstract
- The optimisation of occupational radiological protection is challenging and a variety of factors have to be considered. Physicians performing image-guided interventions are working in an environment with one of the highest radiation risk levels in healthcare. Appropriate knowledge about the radiation environment is a prerequisite for conducting the optimisation process. Information about the dose rate variation during the interventions could provide valuable input to this process. The overall purpose of this study was to explore the prerequisite and feasibility to measure dose rate in scattered radiation and to assess the usefulness of such data in the optimisation process.Using an active dosimeter system, the dose rate in the unshielded scattered radiation field was measured in a fixed point close to the patient undergoing an image-guided intervention. The measurements were performed with a time resolution of one second and the dose rate data was continuously timed in a data log. In two treatment rooms, data was collected during a 6month time period, resulting in data from 380 image-guided interventions and vascular treatments in the abdomen, arms and legs. These procedures were categorised into eight types according to the purpose of the treatment and the anatomical region involved.The dose rate varied substantially between treatment types, both regarding the levels and the distribution during the procedure. The maximum dose rate for different types of interventions varied typically between 5 and 100mSvh(-1), but substantially higher and lower dose rates were also registered. The average dose rate during a complete procedure was however substantially lower and varied typically between 0.05 and 1mSvh(-1). An analysis of the distribution disclosed that for a large part of the treatment types, the major amount of the total accumulated dose for a procedure was delivered in less than 10% of the exposure time and in less than 1% of the total procedure time.The present study shows that systematic dose rate measurements are feasible. Such measurements can be used to give a general indication of the exposure level to the staff and could serve as a first risk assessment tool when introducing new treatment types or x-ray equipment in the clinic. For example, it could provide an indication for when detailed eye dose measurements are needed. It also gives input to risk management considerations and the development of efficient routines for other radiological protection measures.
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| 4. |
- Engström, Andreas, 1983, et al.
(författare)
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A case study of cost-benefit analysis in occupational radiological protection within the healthcare system ofSweden
- 2021
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Ingår i: Journal of Applied Clinical Medical Physics. - : Wiley. - 1526-9914. ; 22, s. 295-304
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to demonstrate cases of cost-benefit analysis within healthcare, of how economic factors can be considered in occupational radiological protection, in agreement with the as low as reasonably achievable principle and present Swedish legislations. In the first part of the present study, a comparison of examples within health economics used by authorities and institutes in Sweden was made. The comparison focused on value of a statistical life, quality-adjusted life year, and monetary cost assigned to a unit of collective dose for radiation protection purposes (α-value). By this comparison, an α-value was determined as an interval between $45 and $450 per man-mSv, for the Swedish society in 2021. The α-value interval can be interpreted as following:. Less than $45 per man-mSv is a good investment. From $45 to $450 per man-mSv, other factors than costs and collective dose are important to consider. More than $450 per man-mSv is too expensive. In the second part of the present study, seven cases of cost-benefit analyses in occupational radiological protection were provided. The present study focused specifically on cases where the relevant factors were costs and collective dose. The present case study shows a large variation in costs per collective dose from different types of occupational radiological protection, used at Skaraborg Hospital in Sweden.
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| 5. |
- Engström, Andreas, 1983, et al.
(författare)
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How much resources is it reasonable to spend on occupational radiological protection in Sweden?
- 2024
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Ingår i: European Congress of Radiology.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A cost-benefit analysis can show that a specific intervention in occupational radiological protection is reasonable in terms of cost effectiveness, which can be helpful for decision-makers in the healthcare system. In other cases, interventions can be shown not to be reasonable in terms of cost effectiveness, and resources would then be better invested elsewhere within the healthcare system.
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| 6. |
- Engström, Andreas, 1983, et al.
(författare)
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Lead aprons and thyroid collars: to be, or not to be?
- 2023
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Ingår i: Journal of radiological protection : official journal of the Society for Radiological Protection. - 1361-6498. ; 43:3
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Tidskriftsartikel (refereegranskat)abstract
- Wearing lead aprons and thyroid collars for long periods of time has a subjective component: to balance the effective dose reduction with the effort of carrying a heavy load. Occupational radiation exposure has decreased dramatically in the last century within the health care system. During the same period the use of lead aprons and thyroid collars has also gone up. Therefore, a question that may be raised is: how safe is safe enough? In order to promote stakeholder involvement, the aim of the present study was to investigate staff's experience of discomforts associated with wearing lead aprons and thyroid collars for long periods of time, and also to investigate staff's willingness to tolerate personal dose equivalent (expressed as radiation dose) and the corresponding increase in future cancer risk to avoid wearing these protective tools. A questionnaire was developed and given to staff working in operating or angiography rooms at Skaraborg Hospital in Sweden. The results from the 245 respondents showed that 51% experienced bothersome warmth, 36% experienced fatigue and 26% experienced ache or pain that they believed was associated with wearing lead aprons. One third of the respondents would tolerate a personal dose equivalent of 1 mSv per year to avoid wearing lead aprons, but only a fifth would tolerate the corresponding increase in future cancer risk (from 43% to 43.2%). In conclusion, discomforts associated with wearing lead aprons and thyroid collars for long periods of time are common for the staff using them. At the same time, only a minority of the staff would tolerate a small increase in future cancer risk to avoid wearing them. The present study gives an example of stakeholder involvement and points at the difficulties in making reasonable decisions about the use of these protective tools.
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| 7. |
- Engström, Andreas, 1983, et al.
(författare)
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Lead aprons: to be, or not to be?
- 2024
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Ingår i: European Congress of Radiology.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The present study shows that discomforts associated with wearing lead aprons for long periods of time are problematic for the staff using them. At the same time, only a minority of the staff would tolerate a small increase in future cancer risk to avoid wearing them. The present study gives an example of stakeholder involvement and points at the difficulties in making reasonable decisions about the use of radiation protective tools.
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| 8. |
- Ivarsson, Jonas, 1976, et al.
(författare)
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Aligning Video-And Structured Data for Imaging Optimisation.
- 2021
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 195:3-4, s. 134-138
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Tidskriftsartikel (refereegranskat)abstract
- Imaging optimisation can benefit from combining structured data with qualitative data in the form of audio and video recordings. Since video is complex to work with, there is a need to find a workable solution that minimises the additional time investment. The purpose of the paper is to outline a general workflow that can begin to address this issue. What is described is a data management process comprising the three steps of collection, mining and contextualisation. This process offers a way to work systematically and at a large scale without succumbing to the context loss of statistical methods. The proposed workflow effectively combines the video and structured data to enable a new level of insights in the optimisation process.
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| 9. |
- Larsson, Maria, 1972, et al.
(författare)
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Evaluation of novel radiation protection devices during radiologically guided interventions
- 2024
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Ingår i: CVIR ENDOVASCULAR. - 2520-8934. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIn radiologically guided interventions, medical practitioners are subjected to radiation exposure, which may lead to radiation-induced diseases. In this study, novel radiation shields for the head and neck were evaluated for their potential to reduce radiation exposure.MethodAn anthropomorphic phantom was exposed on its left side to scattered radiation from beneath to simulate the exposure of an operator in a x-ray operating room. Thermoluminescent dosimeters (TLDs) were positioned at different depths in five slices in the phantom, measuring personal dose equivalent. Two different set up situations were evaluated: a head protector designed to reduce radiation in the upper section of the head; and a novel thyroid protector prototype extended in the front and on both sides, designed to reduce radiation in the lower and middle sections of the head. A standard thyroid collar prototype and a ceiling mounted lead glass shield were used as comparisons.Furthermore, the head protector was evaluated in a clinical study in which TLDs were positioned to measure scattered radiation exposure to the heads of operators during endovascular interventions.MethodAn anthropomorphic phantom was exposed on its left side to scattered radiation from beneath to simulate the exposure of an operator in a x-ray operating room. Thermoluminescent dosimeters (TLDs) were positioned at different depths in five slices in the phantom, measuring personal dose equivalent. Two different set up situations were evaluated: a head protector designed to reduce radiation in the upper section of the head; and a novel thyroid protector prototype extended in the front and on both sides, designed to reduce radiation in the lower and middle sections of the head. A standard thyroid collar prototype and a ceiling mounted lead glass shield were used as comparisons.Furthermore, the head protector was evaluated in a clinical study in which TLDs were positioned to measure scattered radiation exposure to the heads of operators during endovascular interventions.ResultsThe extended thyroid protector reduced the scattered radiation in the throat, chin, and ear slices. Some shielding effect was seen in the brain and skull slices. The head protector showed a shielding effect in the skull slice up to two cm depth where it covered the phantom head. As expected, the ceiling mounted lead glass shield reduced the scattered radiation in all measuring points.ConclusionsA ceiling mounted lead glass shield is an effective radiation protection for the head, but in clinical practice, optimal positioning of a ceiling mounted lead shield may not always be possible, particularly during complex cases when radiation protection may be most relevant. Added protection using these novel guards may compliment the shielding effect of the ceiling mounted lead shield. The head protector stand-alone did not provide sufficient protection of the head. The extended thyroid protector stand-alone provided sufficient protection in the lower and middle sections of the head and neck.
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| 10. |
- Lundh, Charlotta, 1977, et al.
(författare)
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A model for evaluating the use of imaging in image-guided interventional procedures-possible implications on optimisation of radiation protection.
- 2021
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 195:3-4, s. 139-144
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Tidskriftsartikel (refereegranskat)abstract
- The present study focuses on introducing the concept of optimisation and proposing a model, including evaluation of image quality, to be used in the clinical routines where image-guided intervention is being performed. The overall aim of the study was to develop a model for evaluating the use of imaging in X-ray-guided interventional procedures and its possible implications on optimisation of radiation protection. In the search for an adequate evaluation model, data from endovascular interventions of the aorta (EVAR procedures) were used. The procedure was schematically described in steps. Every imaging event was connected to the steps in the medical procedure and was also described with the purpose of the imaging event. Available technical, as well as procedural parameters, were studied and analysed. Data were collected from the X-ray equipment for 70 EVAR procedures and, out of these, 12 procedures were randomly selected to be recorded on video to understand the procedure better. It was possible to describe the EVAR procedures in a general way with explanations of the clinical purpose connected to each imaging event. Possible quality parameters of the procedure were identified for the imaging events (radiation dose, image quality). The model method still needs to be refined and will then be applied to clinical data and to other clinical procedures to test the validity.
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| 11. |
- Lundh, Charlotta, 1977, et al.
(författare)
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Biodistribution of free 211At and 125I- in nude mice bearing tumors derived from anaplastic thyroid carcinoma cell lines.
- 2006
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Ingår i: Cancer biotherapy & radiopharmaceuticals. - : Mary Ann Liebert Inc. - 1084-9785 .- 1557-8852. ; 21:6, s. 591-600
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Tidskriftsartikel (refereegranskat)abstract
- Free 211At has been proposed for therapy of anaplastic thyroid carcinoma (ATC). However, no extensive biodistribution study comparing tumor-bearing and nontumor-bearing mice has previously been performed. The aim of this study was to perform a complete evaluation of the biodistribution of 211At, both for normal and ATC-bearing mice. For comparison, the biodistribution of 125I- was simultaneously studied. Dosimetric evaluations were performed to investigate if (211)At can be used for therapy of ATC. METHODS: Athymic nude mice were subcutaneously injected with either of two human ATC cell lines, HTh83 and KAT-4. Tumor-bearing and nontumor-bearing mice were injected intravenously with 0.3 MBq 211At and 0.3 MBq 125I- simultaneously. The mice were sacrificed 4-24 hours after injection, and the activity concentrations in tissues were determined. RESULTS: Except for the thyroid, the concentration of 211At was higher than that of 125I- in the tissues. The uptake of 211At was primarily high in NIS-expressing organs. Furthermore, the absorbed doses to these organs were higher than both tumor types. CONCLUSIONS: The biodistribution of 211At and 125I- differed in this animal model. The higher mean absorbed dose from 211At in several organs than in tumor tissue restricts the possibility of using free 211At for therapy of ATC.
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| 12. |
- Lundh, Charlotta, 1977, et al.
(författare)
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Optimisation of radiological protection in a complex hybrid environment using detailed dose rate information
- 2015
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Ingår i: Optimisation in X-ray and Molecular Imaging 2015 - the Fourth Malmö Conference on Medical Imaging, Gothenburg, Sweden, 28-30 May 2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: Physicians performing image-guided interventions are exposed to one of the highest radiation risk levels in healthcare. Hybrid environments combine the imaging technology of the image-guided interventions with operation environments, engaging more medical specialties to the use of advanced imaging devices. This complicates the risk management of radiological protection. The aim of this study was to explore the possibilities of using dose rate data for risk assessment in a multi-purpose hybrid room. Method: Dose rate data was collected for three types of image guided interventions in a hybrid room at Sahlgrenska University Hospital. The three procedure types studied were EndoVascular Aortic Repair (EVAR), Transcatheter Aortic Heart Valve (TAVI) and an orthopedic procedure of the back (Ort Back). Dose rate data for scattered radiation was collected using an active dosimeter system, giving dose rate data with a time resolution of 1 second in a fixed unshielded point on the C-arm. Data was analysed and visualized as histograms. Results: The dose rates varied substantially between the three types of procedures studied. The median dose rates were 2.3 mSv/h (EVAR), 1.4 mSv/h (TAVI) and 0.1 mSv/h (Ort back). During EVAR-procedures the absolute majority of the dose rates were between 1 and 10 mSv/h while it during Ort Back-procedures was dominated by dose rates below 0.1 mSv/h. Conclusions: A multi-purpose hybrid room have dose rates that vary substantially between the different areas of use, both regarding dose rate levels and dose rate distribution. The use of dose rate information adds important information that can improve the management of risk in these environments.
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| 13. |
- Lundh, Charlotta, 1977, et al.
(författare)
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Radiation-induced thyroid stunning: differential effects of (123)I, (131)I, (99m)Tc, and (211)At on iodide transport and NIS mRNA expression in cultured thyroid cells.
- 2009
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Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505. ; 50:7, s. 1161-7
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Tidskriftsartikel (refereegranskat)abstract
- Recent clinical and experimental data demonstrate that thyroid stunning is caused by previous irradiation and may influence the efficacy of (131)I radiation therapy of thyroid cancer and possibly hyperthyroidism. To avoid stunning, many clinics have exchanged (131)I for (123)I for pretherapeutic diagnostic imaging and dose planning. Furthermore, recent in vitro studies indicate that (131)I irradiation reduces iodide uptake by downregulating the expression of the sodium iodide symporter (NIS). The rationale for this study was therefore to study effects on iodide transport and NIS messenger RNA (mRNA) expression in thyrocytes exposed to both (123)I and (131)I in addition to some other potentially interesting radionuclides. METHODS: Thyrotropin-stimulated thyroid cell monolayers were exposed to 0.5 Gy of (123)I, (131)I, (99m)Tc, or (211)At, all being radionuclides transported via NIS, in the culture medium for 6 h, or to various absorbed doses of (123)I or (131)I for 48 h. NIS mRNA expression was analyzed using quantitative reverse-transcriptase polymerase chain reaction. RESULTS: Iodide transport and NIS mRNA expression were reduced by all radionuclides. At the same absorbed dose, iodide transport was reduced the most by (211)At, followed by (123)I and (99m)Tc (equally potent), whereas (131)I was least effective. The onset of NIS downregulation was rapid (<1 d after irradiation) in cells exposed to (123)I or (211)At and was delayed in cells irradiated with (131)I or (99m)Tc. Iodide transport and NIS expression were recovered only for (211)At. (123)I reduced the iodine transport and the NIS mRNA expression more efficiently than did (131)I at an equivalent absorbed dose, with a relative biological effectiveness of about 5. CONCLUSION: The stunning effect per unit absorbed dose is more severe for (123)I than for (131)I. Despite the lower absorbed dose per unit activity for (123)I than for (131)I, stunning by (123)I cannot be excluded in patients. The degree to which iodide transport capacity and NIS mRNA expression are reduced seems to be related to the biological effectiveness of the type of radiation delivering the absorbed dose to the target, with (211)At (which has the highest relative biological effectiveness) causing the highest degree of stunning per unit absorbed dose in the present study.
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| 14. |
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| 15. |
- Lundh, Charlotta, 1977, et al.
(författare)
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Reduced iodide transport (stunning) and DNA synthesis in thyrocytes exposed to low absorbed doses from 131I in vitro.
- 2007
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Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - 0161-5505. ; 48:3, s. 481-6
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Tidskriftsartikel (refereegranskat)abstract
- Thyroid stunning refers to reduced uptake of (131)I in the thyroid tissue (or tumor) during radioiodine ((131)I) therapy compared with the uptake measured after the previous administration of (131)I for diagnostic purposes. The phenomenon is clinically important, as it can potentially lead to the undertreatment of thyroid cancer or to unnecessarily high absorbed doses in critical organs. Previous clinical and experimental studies indicated that thyroid stunning is absorbed dose dependent. The aim of this study was to investigate the effects of (131)I irradiation on (125)I(-) transport and cell proliferation at low absorbed doses in vitro. METHODS: Primary cultured porcine thyroid cells were grown to form a confluent monolayer of epithelial cells on a filter in a bicameral culture system. The cells were continuously irradiated with (131)I in the culture medium for 48 h to obtain 0.0015-1.5 Gy. At 3 d after irradiation was stopped, the transepithelial iodide transport capacity was evaluated by measuring (125)I(-) transport from the basal chamber compartment to the apical chamber compartment. The effect of (131)I irradiation on DNA synthesis was estimated by pulse labeling with (3)H-thymidine of both subconfluent and confluent cells irradiated with up to 9 Gy. Total DNA content was measured to quantify cell numbers. RESULTS: A statistically significant reduction in (125)I(-) transport was seen at absorbed doses of >or=0.15 Gy, with a 50% reduction at 1.5 Gy, compared with the results observed for nonirradiated control cells. (3)H-Thymidine incorporation was already statistically significantly reduced at absorbed doses of 0.01-0.1 Gy, but 0.15-0.3 Gy did not affect DNA synthesis. However, absorbed doses of >or=1 Gy again resulted in reduced DNA synthesis. A 50% reduction was obtained at 4 Gy. Total DNA measurements revealed a statistically significant reduction in cell numbers at 8 Gy. CONCLUSION: The lowest absorbed dose from (131)I that reduced iodide transport was 0.15 Gy. Because stunning was found at low absorbed doses, it might occur for (131)I treatment not only of thyroid cancer but also of thyrotoxicosis. On the basis of differences in dose responses, radiation-induced thyroid stunning and cell cycle arrest may be independent phenomena.
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| 16. |
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| 17. |
- Martin, Colin, et al.
(författare)
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Eye dosimetry and protective eyewear for interventional clinicians
- 2015
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 165:1-4, s. 284-288
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Tidskriftsartikel (refereegranskat)abstract
- Doses to the eyes of interventional clinicians can exceed 20 mSv. Various protective devices can afford protection to the eyes with the final barrier being protective eyewear. The protection provided by lead glasses is difficult to quantify, and the majority of dosimeters are not designed to be worn under lead glasses. This study has measured dose reduction factors (DRFs) equal to the ratio of the dose with no protection, divided by that when lead glasses are worn. Glasses have been tested in X-ray fields using anthropomorphic phantoms to simulate the patient and clinician. DRFs for X-rays incident from the front vary from 5.2 to 7.6, while values for orientations reminiscent of clinical practice are between 1.4 and 5.2. Results suggest that a DRF of two is a conservative factor that could be applied to personal dosimeter measurements to account for the dose reduction provided by most types of lead glasses.
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| 18. |
- Nordén, Madeleine, 1979, et al.
(författare)
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Down-regulation of the sodium/iodide symporter explains 131I-induced thyroid stunning.
- 2007
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Ingår i: Cancer research. - 0008-5472. ; 67:15, s. 7512-7
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Tidskriftsartikel (refereegranskat)abstract
- (131)I radiation therapy of differentiated thyroid cancer may be compromised by thyroid stunning (i.e., a paradoxical inhibition of radioiodine uptake caused by radiation from a pretherapeutic diagnostic examination). The stunning mechanism is yet uncharacterized at the molecular level. We therefore investigated whether the expression of the sodium/iodide symporter (NIS) gene is changed by irradiation using (131)I. Confluent porcine thyroid cells on filter were stimulated with thyroid-stimulating hormone (TSH; 1 milliunit/mL) or insulin-like growth factor-I (IGF-I; 10 ng/mL) and simultaneously exposed to (131)I in the culture medium for 48 h, porcine NIS mRNA was quantified by real-time reverse transcription-PCR using 18S as reference, and transepithelial iodide transport was monitored using (125)I(-) as tracer. TSH increased the NIS expression >100-fold after 48 h and 5- to 20-fold after prolonged stimulation. IGF-I enhanced the NIS transcription at most 15-fold but not until 5 to 7 days. (131)I irradiation (7.5 Gy) decreased both TSH-stimulated and IGF-I-stimulated NIS transcription by 60% to 90% at all investigated time points. TSH and IGF-I stimulated NIS synergistically 15- to 60-fold after 5 days. NIS expression was reduced by (131)I also in costimulated cells, but the transcription level remained higher than in nonirradiated cells stimulated with TSH alone. Changes in NIS mRNA always correlated with altered (125)I(-) transport in cultures with corresponding treatments. It is concluded that down-regulation of NIS is the likely explanation of (131)I-induced thyroid stunning. Enhanced NIS expression by synergistically acting agents (TSH and IGF-I) partly prevents the loss of iodide transport expected from a given absorbed dose, suggesting that thyroid stunning might be pharmacologically treatable.
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| 19. |
- Sandblom, Viktor, 1987, et al.
(författare)
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Evaluation of eye lens doses received by medical staff working in interventional radiology at sahlgrenska university hospital
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Background: The International Commission on Radiological Protection (ICRP) recently lowered their recommended occupational eye lens dose limit from 150 mSv in a year to 20 mSv in a year, averaged over a defined period of 5 years. Aim: The main aim of the present study was to investigate the eye lens doses received by the interventional staff at Sahlgrenska University Hospital. Another aim was to evaluate whether the dose recorded by the PDM, a dosimeter worn at thorax height, could be used as an indicator of eye lens dose. Material and Methods: To prepare for the personnel eye lens dose assessments, phantom measurements were carried out. These preparations included deciding the optimal position of an eye lens dosimeter, evaluation of different models of lead glasses and estimation of a ratio between the eye lens dose and the dose recorded by the PDM. Personnel eye lens doses were assessed using TL-dosimeters held by individual headbands worn by staff members at the Catheterization Laboratory at the department of Cardiology and at the division of Peripheral Interventional Radiology at the department of Radiology at Sahlgrenska University Hospital for one month. Staff members also wore a PDM at thorax height outside their lead apron. Results and Discussion: Materials with an equivalent lead thickness of 0.75 mm block over 95% of incident radiation but the lead glasses evaluated (0.75 mm) reduced the eye lens dose by only 30-88% due to radiation back scattered in the head and oblique incident radiation. Many operators reported annual eye lens doses of over 10 mSv. The eye lens doses of nurses were generally much lower. The ratios between equivalent doses recorded by TLD and PDM were as expected higher for nurses than for operators but the ratios varied also between different operators. Conclusions: The estimations of annual doses have uncertainties and the lens doses of operators are high enough to cause concern. Based on the results of the present study, operators might be recommended to wear lead glasses in the future. Estimating eye lens dose from the dose recorded by the PDM is difficult. This method includes large uncertainties. The PDM should instead be used to indicate whether a more precise measurement is necessary.
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| 20. |
- Sandblom, Viktor, 1987, et al.
(författare)
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Evaluation of the impact of a system for real-time visualisation of occupational radiation dose rate during fluoroscopically guided procedures
- 2013
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Ingår i: Journal of Radiological Protection. - : IOP Publishing. - 0952-4746 .- 1361-6498. ; 33:3, s. 693-702
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Tidskriftsartikel (refereegranskat)abstract
- Optimisation of radiological protection for operators working with fluoroscopically guided procedures has to be performed during the procedure, under varying and difficult conditions. The aim of the present study was to evaluate the impact of a system for real-time visualisation of radiation dose rate on optimisation of occupational radiological protection in fluoroscopically guided procedures. Individual radiation dose measurements, using a system for real-time visualisation, were performed in a cardiology laboratory for three cardiologists and ten assisting nurses. Radiation doses collected when the radiation dose rates were not displayed to the staff were compared to radiation doses collected when the radiation dose rates were displayed. When the radiation dose rates were displayed to the staff, one cardiologist and the assisting nurses (as a group) significantly reduced their personal radiation doses. The median radiation dose (Hp(10)) per procedure decreased from 68 to 28 μSv (p = 0.003) for this cardiologist and from 4.3 to 2.5 μSv (p = 0.001) for the assisting nurses. The results of the present study indicate that a system for real-time visualisation of radiation dose rate may have a positive impact on optimisation of occupational radiological protection. In particular, this may affect the behaviour of staff members practising inadequate personal radiological protection.
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| 21. |
- Sandblom, Viktor, 1987, et al.
(författare)
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Evaluation of the impact of a system for real-time visualisation of occupational radiation dose rate during fluoroscopically guided procedures
- 2013
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Ingår i: Nationellt möte om sjukhusfysik 2013, 13-14 november 2013, Varberg.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Optimisation of radiological protection for operators working with fluoroscopically guided procedures has to be performed during the procedure, under varying and difficult conditions. The aim of this study was to evaluate the impact of a system for real-time visualisation of radiation dose rate on optimisation of occupational radiological protection during fluoroscopically guided procedures. Individual radiation dose measurements, using a system for real-time visualisation, were performed in a cardiology laboratory for three cardiologists and ten assisting nurses. Radiation doses collected when the radiation dose rates were not displayed to the staff (period 1) were compared to radiation doses collected when the radiation dose rates were displayed (period 2). The results showed that when the radiation dose rates were displayed to the staff, one cardiologist and the assisting nurses (as a group) significantly reduced their personal radiation doses. The median radiation dose ((Hp(10)) per procedure decreased from 68 to 28 μSv (p=0.003) for this cardiologist and from 4.3 to 2.5 μSv (p=0.001) for the assisting nurses. The results of the present study indicate that a system for real-time visualisation of radiation dose rate may have a positive impact on optimisation of occupational radiological protection. In particular, this may affect the behaviour of staff members practising inadequate personal radiological protection.
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| 22. |
- Sandblom, Viktor, 1987, et al.
(författare)
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Mätmetoder för bestämning av stråldoser till ögats lins
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I april 2011 sänkte International Commission on Radiological Protection (ICRP) sin rekommenderade dosgräns för ögats lins för arbetstagare vid verksamhet med joniserande strålning från 150 mSv/år till 20 mSv/år (ekvivalent dos). Under senare år har det i flera studier gjorts uppskattningar av ekvivalent dos till ögats lins för per-sonal som arbetar med röntgenvägledda procedurer. Resultaten från de flesta av dessa tyder på att det finns risk att personal överstiger 20 mSv/år till ögats lins. Hp(3) (persondosekvivalenten på 3 mm djup i mjuk vävnad) är den, av International Commission on Radiation Units and Measurements (ICRU), föreslagna storheten för att uppskatta ekvivalent dos till ögats lins. Konversionsfaktorer från luftkerma till Hp(3) finns i dag inte tillgängliga i någon internationell standard. För mätningar av persondosekvivalent till ögats lins används därför ofta Hp(0,07) istället. Aktiva dosimetrar (exempelvis EDD-30, NED-30, RaySafe i2, DMC 3000 eller EPD) kan användas för grov initial uppskattning av ekvivalent dos till extremiteter eller ögats lins. För att minska osäkerheter i samband med mätning bör passiva do-simetrar användas (exempelvis DIS-1, EYE-DTM, Inlight® nanoDotTM eller ett TLD-system). Om det tillgängliga mätinstrumentet inte är kalibrerat för relevant energi och djup samt med lämpligt fantom för den önskvärda tillämpningen bör det övervägas att utföra kalibreringen på annat sätt. Om lokal kalibrering av mätinstrument inte är möjligt kan de skickas in till SSM:s riksmätplats för joniserande strålning. SSM erbjuder spårbar kalibrering av mätinstrument i strålfält i ISO:s N-serie enligt ISO 4037. Operatörens position i förhållande till patient och röntgenrör ser olika ut för olika typer av röntgenvägledda procedurer. Vid vissa typer av procedurer inom kardiologi träffar dock den spridda strålningen nästan uteslutande operatörens ögon snett ner-ifrån vänster. Energiintervallet för den spridda strålningen som träffar operatören vid en röntgenvägledd procedur är ungefär 20–100 keV. Då primärstrålningen träffar patienten och sprids mot operatören vid röntgenvägledda procedurer förskjuts energispektrumet ungefär 10 keV mot lågenergiområdet. Felaktig positionering eller kalibrering av en dosimeter avsedd för uppskattning av ekvivalent dos till ögats lins leder till mätfel. För personal som arbetar med röntgen-vägledda procedurer bör dosimetern vara kalibrerad att mäta Hp(0,07) eller Hp(3). Att använda Hp(10) leder till större osäkerheter. Vad gäller positioneringen bör dosimetern placeras på tinningen bredvid ögat, så nära ögat som möjligt, på den sida röntgenröret befinner sig. Det är viktigt att vara medveten om vilka osäkerheter som förknippas med olika mätmetoder. Så länge man är medveten om osäkerheterna kan flera olika metoder användas för uppskattning av ekvivalent dos till ögats lins, det beror på vilket syfte mätningen har. Under arbetet med denna rapport har en del forskningsbehov identifierats, enligt följande. För att få en ökad kunskap om samband mellan exponering och hälsoeffekter behövs sannolikt en ökad kunskap om energideponering i ögat som organ för olika typer av strålningssituationer. De skyddsstorheter som beskrivs i denna rapport används ibland också i studier vars syfte är att kartlägga effekter av bestrålning, exempelvis i epidemiologiska studier. Skyddsstorheterna är en oexakt beskrivning av energideponering i olika delar av ögat. Rimligtvis kan en ökad kunskap om grundläggande dosimetri för olika energier och strålslag bidra till att osäkerheterna minskar i studier där effekter kartläggs. Även utredningsarbete om konsekvenser av en sänkt dosgränser behövs. Detta gäller såväl metoder för att kontrollera att dosimetrar uppfyller de krav som i dag ställs och att använda metoder i kliniken genererar tillräckligt noggranna värden för att säkerställa att dosgränser inte överskrids.
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| 23. |
- Sandblom, Viktor, 1987, et al.
(författare)
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Visualisering av osynliga risker: optimering av strålskydd för säkrare arbetsmiljö
- 2013
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Ingår i: Röntgenveckan 2013, 3-6 september 2013, Uppsala.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Joniserande strålning innebär en ökad risk för cancer och katarakt. Sänkning av gränsvärden och att fler grupper av personal exponeras för strålning, t ex i hybridsalar, kan leda till att fler hamnar i riskzonen. För att minska dessa risker har tekniker utvecklats som visar exponeringen av strålning i realtid, vilket ger helt nya möjligheter för optimering av strålskydd. Mot denna bakgrund initierades ett tvärvetenskapligt samarbete vid Göteborgs universitet, Det övergripande syftet med projektet är att bidra med kunskap om hur visualisering av joniserande strålning i realtid kan användas för att åstadkomma en säkrare arbetsmiljö. Vi undersöker a) om och i så fall för vilka procedurer visuell feedback kan minska personalens exponering för strålning, b) hur personalens agerande kan bidra till detta och c) hur personal förstår information om de registrerade stråldoserna och hur deras individuella erfarenheter kan tas tillvara för att förbättra arbetsmetoder. En pilotstudie av visualisering av doser i realtid under röntgenvägledda procedurer visade att en av tre kardiologer och de assisterande sjuksköterskorna som grupp uppvisade en statistiskt signifikant minskning av sina doser. En slutsats är att systemet för visualisering kan ha en positiv påverkan för optimering av strålskydd och bidra till minskade risker i arbete med joniserande strålning.
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| 24. |
- von Wrangel, Alexa, 1967, et al.
(författare)
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Video as a tool for optimization of radiological protection in image-guided interventions – possibilities and limitations
- 2015
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Ingår i: Optimisation in X-ray and Molecular Imaging 2015 - the Fourth Malmö Conference on Medical Imaging, Gothenburg, Sweden, 28-30 May 2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In healthcare, the highest patient and staff doses are received in image-guided intervention. This area includes a large variation of procedures with various prerequisites for performing radiological protection. Traditionally, radiation protection has mainly consisted of monitoring staff dose and providing personal radiation shielding in addition to education and training. New strategies have to be developed to achieve an optimized radiation protection in these changing environments. It could be anticipated that video could be a useful tool for optimization. The aim of this work was to develop video as a tool for optimization of radiological protection in image-guided interventions. Video recordings of the staff during image-guided abdominal interventions have been performed. Three cameras were used. Camera one was placed to get an overview of the room. The second camera was placed on the monitor facing the staff and camera three was recording the live monitor from the x-ray system. The video recordings were visually analyzed. Technical parameters were additionally collected from the x-ray system. Dose rate data was also collected during the procedures. So far, three procedures have been analysed in order to develop the optimization tool. The most important camera angle was the one over viewing the room. It was with the chosen angles, however, difficult to see what the staff members were looking at during the procedures. In developing the tool the following has been identified as important issues to consider; the number and position of cameras, the sound quality, editing of video material and safety issues. Furthermore, it is important to consider the competence of the evaluating team, which need to be multidisciplinary. Above all, ethical aspects of recording patients and staff have to be addressed. The present study combines video recordings of the interventional staff with information of the variation of dose rates during the procedure. This is a novel approach for education and training strategies.
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