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- Almén, Anja, 1964, et al.
(author)
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Optimisation of occupational radiological protection in image-guided interventions: potential impact of dose rate measurements.
- 2015
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In: 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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Journal article (peer-reviewed)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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| 2. |
- Martin, Colin, et al.
(author)
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Eye dosimetry and protective eyewear for interventional clinicians
- 2015
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In: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 165:1-4, s. 284-288
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Journal article (peer-reviewed)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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| 4. |
- Sandblom, Viktor, 1987, et al.
(author)
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Determination of 177Lu-octreotate activity concentration in vivo using intraoperative gamma probes - a comparative study
- 2015
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In: Cancerfondens planeringsgrupp för onkologisk radionuklidterapis vintermöte 2015, 22-23 januari, Umeå, Sverige..
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Conference paper (other academic/artistic)abstract
- INTRODUCTION Radionuclide therapy using 177Lu-octreotate has shown promising results for patients with metastasised neuroendocrine (NE) tumours. However, complete remission is achieved only in a few patients due to healthy limiting organs, e.g. kidneys and bone marrow. A new treatment method of NE liver metastases is under development at our facility, based on local administration of 177Lu-octreotate to the liver. However, this method requires the possibility to quantify activity concentration in vivo. Intraoperative gamma probes are routinely used for radio-guided surgery and localisation of diagnostic radionuclides. The aim of this study was to evaluate whether intraoperative gamma probes could be used to determine 177Lu activity concentration in vivo. METHODS Important performance parameters were acquired for two intraoperative gamma probes using different sources of 177Lu, in order to compare the characteristics of the probes. Point sources were used for determination of the range for linear response, and the spatial resolution (FWHM) was evaluated by measuring the line profile over a line source at different depths in a phantom of tissue equivalent plastic. To investigate the ability of the probes to distinguish between normal and tumour tissue, a clinical situation was simulated by creating an agarose gel phantom. This phantom contained a homogenous distribution of 177Lu of a low activity concentration, simulating normal tissue. To simulate metastases, hot gel spheres (5-20 mm), containing a higher activity concentration, were added to the phantom. RESULTS The point source measurements demonstrated great differences between the two probes; one probe showed saturation of the signal at much lower activities than the other. The spatial resolution (FWHM) increased from about 10 to 100 mm when the depth of the line source was increased from 0 to 80 mm. One probe showed lower values of FWHM than the other, for all depths. The measurements using the agarose gel phantom showed high ratios between count rates measured over the hot gel spheres and over the background, for both probes. These results indicated a good ability to distinguish between normal and tumour tissue. CONCLUSION The two evaluated gamma probes showed differences in technical performance. However, satisfying results were obtained for both probes, indicating that intraoperative gamma probe measurements are feasible for determination of 177Lu activity concentration in vivo.
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