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- Magee, Jill S, et al.
(författare)
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Derivation and application of dose reduction factors for protective eyewear worn in interventional radiology and cardiology.
- 2014
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Ingår i: Journal of radiological protection : official journal of the Society for Radiological Protection. - : IOP Publishing. - 1361-6498. ; 34:4, s. 811-823
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Tidskriftsartikel (refereegranskat)abstract
- Doses to the eyes of interventional radiologists and cardiologists could exceed the annual limit of 20mSv proposed by the International Commission on Radiological Protection. Lead glasses of various designs are available to provide protection, but standard eye dosemeters will not take account of the protection they provide. The aim of this study has been to derive dose reduction factors (DRFs) equal to the ratio of the dose with no eyewear, divided by that when lead glasses are worn. Thirty sets of protective eyewear have been tested in x-ray fields using anthropomorphic phantoms to simulate the patient and clinician in two centres. The experiments performed have determined DRFs from simulations of interventional procedures by measuring doses to the eyes of the phantom representing the clinician, using TLDs in Glasgow, Scotland and with an electronic dosemeter in Gothenburg, Sweden. During interventional procedures scattered x-rays arising from the patient will be incident on the head of the clinician from below and to the side. DRFs for x-rays incident on the front of lead glasses vary from 5.2 to 7.6, while values for orientations similar to those used in the majority of clinical practice are between 1.4 and 5.2. Specialised designs with lead glass side shields or of a wraparound style with angled lenses performed better than lead glasses based on the design of standard spectacles. Results suggest that application of a DRF of 2 would provide a conservative factor that could be applied to personal dosemeter measurements to account for the dose reduction provided by any type of lead glasses provided certain criteria relating to design and consistency of use are applied.
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- Sandblom, Viktor, 1987, et al.
(författare)
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Evaluation of the possibility of using intraoperative gamma probe measurements for determining 177Lu-octreotate activity concentration in vivo
- 2014
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Ingår i: 27th Annual Congress on European Association of Nuclear Medicine, Gothenburg, Sweden, October 18-22, 2014..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION Intraoperative gamma probes are routinely used for radio-guided surgery, primarily sentinel node mapping or localization of small tumors after injection of a diagnostic radiopharmaceutical, labelled with e.g. 99mTc or 111In. For therapy purposes, treatment of neuroendocrine (NE) tumors using the beta emitting radiopharmaceutical 177Lu-octreotate has shown promising results, with kidneys and red bone marrow as limiting organs. A new treatment method using 177Lu-octreotate for liver metastases is under development at our facility. For this development, a method to determine the activity concentration of 177Lu-octreotate in tumor and normal tissues in vivo during surgery is required. The aim of this study was therefore to evaluate whether an intraoperative gamma probe could be suitable for this purpose. METHODS Essential detector characteristics were acquired for two intraoperative gamma probes using different sources containing 177Lu. The range for linear response was determined using point sources of increasing activity. Spatial resolution (full width at half maximum, FWHM) and efficiency were determined, using a line source placed at different depths in a tissue equivalent plastic phantom, by moving each probe perpendicularly over the line source. To simulate a clinical situation, tumor phantoms were designed, consisting of agarose gel spheres (5–20 mm diameter) at the surface of a water background. The gel spheres, simulating tumors, contained a high activity concentration of 177Lu while the water, simulating normal tissue, contained a background activity concentration of 177Lu. Count rates were measured using the gamma probes in order to investigate the possibility to distinguish between normal and tumor tissue. RESULTS A linear response (within ±10 %) was seen for point source activities between 1–30 MBq, corresponding to count rates in the detectors of about 100–4,000 counts per second (cps). FWHM increased from about 10 to 70 mm when the depth of the line source increased from 0 to 80 mm. In the tumor phantom measurements, high ratios between count rates measured over the gel sphere and over the water background were acquired, indicating a good ability to distinguish between normal and tumor tissue. CONCLUSION An intraoperative gamma probe could be a useful tool for measurements of activity concentration of 177Lu-octreotate in tissues in vivo.
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- Sandblom, Viktor, 1987, et al.
(författare)
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Radiolabelled pharmaceuticals MIBG and octreotate for treatment of metastatic pheochromocytoma and paraganglioma
- 2014
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Ingår i: SweRays Workshop, Malmö, Sweden, Aug 20-22, 2014.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: The 5-year survival for patients with metastatic pheochromocytoma (PC) and paraganglioma (PGL) is less than 50%. There is a clear need for development of better diagnostic and therapeutic options for these patients. Radionuclide therapy offers the possibility to treat spread PC/PGL. The norepinephrine (NE) analogue metaiodobenzylguanidine (MIBG) and the somatostatin (SST) analogues octreotate or octreotide are possible molecules that could be used for this purpose. These analogues have different biodistribution and different organs at risk, when used for therapy. Thus, combined therapy, using both radiolabelled NE and SST analogues, might be beneficial for these patients. Aim: The aim of this study was to evaluate the possibility of using 177Lu-octreotate and/or 131I-MIBG for treatment of patients with metastatic PC/PGL. Materials and Methods: Three patients with metastatic PC/PGL were injected with 131I-MIBG and 111In-octreotide, and four patients with metastatic PC/PGL were injected with 111In-octreotide, before surgical removal of the primary tumour. During surgery, tissue samples of tumour, blood, fat and muscle were collected and weighed, and the radioactivity was measured in a gamma counter. The activity concentration in these tissue samples was then calculated for each radionuclide. Additionally, tumour-to-blood activity concentration ratios (T/B) were calculated. Results: The activity concentrations and T/B values showed large variations between patients. For 111In-octreotide, T/B values were 25-590 and for 131I-MIBG, the corresponding values were 0-1600. Conclusion: The sometimes high T/B values show a clear possibility of using 177Lu-octreotate and 131I-MIBG for treatment of some patients with metastatic PC/PGL. However, due to the large variation between patients, individual investigation of tumour uptake prior to treatment is required.
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- Ståhl, Ingun, 1984, et al.
(författare)
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Feasibility study of intraoperative gamma probes for determining 177Lu-octreotate activity concentration in vivo
- 2014
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Ingår i: SWE-RAYS (Swedish Radiation Research Association for Young Scientists) 3e årliga workshop, Malmö..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION 177Lu-octreotate is a good alternative for treatment of neuroendocrine tumors, with primarily kidneys as limiting organs. The development of a new treatment method using 177Lu-octreotate for liver metastases is under progress at our institute. This treatment method requires accurate activity concentrations of 177Lu-octreotate in tumor and normal tissues in vivo during surgery. Intraoperative gamma probes are mainly used for radio-guided surgery, where diagnostic radiopharmaceuticals including e.g. 99mTc or 111In are frequently used. The aim of this study was to investigate the possibility of using an intraoperative gamma probe for determining 177Lu-octreotate activity concentration in vivo. METHODS The performance of two intraoperative gamma probes was evaluated by determining the range for linear response and the spatial resolution (FWHM) at different depths using different sources containing 177Lu. To illustrate clinical conditions and further explore the ability of the gamma probes to distinguish tumor from normal tissues, measurements using various phantoms were performed. Tumor phantoms, made of agarose gel spheres (5-20 mm diameter) contained a high activity concentration of 177Lu, and were placed in a gel background containing a lower activity concentration of 177Lu, simulating tumors in a normal tissue. RESULTS A linear response (within ±10 %) was found for activities in the range of 1-30 MBq. The spatial resolution (FWHM) increased with depth (0 to 80 mm) from about 10 to 70 mm. The tumor phantom measurements showed high ratios between count rates measured over the gel spheres and the background gel, which indicates a good ability to distinguish between tumor and normal tissue. CONCLUSION The results in the present study imply that an intraoperative gamma probe could be used for measurements of activity concentration of 177Lu-octreotate in tissues in vivo.
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