| 1. |
- Ahlgren, L, et al.
(författare)
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Induced activity in a high-energy linear accelerator
- 1988
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 33:3, s. 4-351
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Tidskriftsartikel (refereegranskat)abstract
- Activation products which contribute significantly to the exposure of the staff operating the accelerator were found in the accelerator head in the transparent holder for the lead blocks and in the 60 degrees wedge filter made of lead. A proper choice of material in these parts of the accelerator could easily reduce this exposure without excessive changes in the construction. The absorbed dose-rate level should always be checked before maintenance is carried out inside the accelerator head.
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| 2. |
- Nilsson, Per, et al.
(författare)
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Computer controlled microwave system for clinical hyperthermia
- 1985
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 30:4, s. 283-292
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Tidskriftsartikel (refereegranskat)abstract
- A hyperthermia system which has been developed for clinical use is described. Different direct-contact applicators working at the ISM microwave frequency of 915 MHz are used for inducing heat in superficial tumours to a depth of about 3 cm. The system is a further development of an earlier prototype which worked at 2450 MHz. The microwave generator is controlled by a microcomputer governed by temperature measurements with thermistor probes inserted into the tissue. To minimise the influence of the interaction between the microwaves and the temperature probes, a pulsed irradiation technique is used. Up to July 1984, 80 superficial tumours had been treated with radiotherapy combined with local hyperthermia applied using this system.
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| 3. |
- Olsson, L E, et al.
(författare)
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Ferrous sulphate gels for determination of absorbed dose distributions using MRI technique : basic studies
- 1989
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 34:1, s. 43-52
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Tidskriftsartikel (refereegranskat)abstract
- Two gels have been found to be suitable to load with ferrous sulphate solution. In these soft tissue equivalent phantoms, the absorbed dose distribution can be measured after irradiation in clinically used MR imaging equipment. The present studies were carried out using a 0.25 T NMR analyser without imaging properties. A ferrous sulphate solution, 0.05 M with respect to sulphuric acid, can be gelled with 4% gelatin to give a dosemeter which has a response which is linearly correlated (r = 0.998) with the absorbed dose in the interval 0-40 Gy. Ferrous sulphate solution can also be gelled with 1% agarose, but this gel has to be purged with oxygen to obtain a linear relationship (r = 0.997) in the same absorbed dose interval. The ferrous sulphate loaded gels have a sensitivity which is a factor of 2.2 or 4.0 times higher for gelatin and agarose, respectively, than the ordinary dosemeter solution. Because the standard deviation of background measurements is higher for the gels than for the dosemeter solution, the minimum detectable absorbed dose is about the same, or 1.0 Gy, for the two gels and the dosemeter solution. The sensitivity of the ferrous sulphate loaded gels shows no dependence on dose rate if the mean dose rate and the absorbed dose per pulse are within the limits normally used by accelerators for radiotherapy.
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