| 1. |
- Kjellén, Elisabeth, et al.
(författare)
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Comparison of low dose nicotinamide versus benzamide, administered per os, as radiosensitizers in a C3H mammary carcinoma
- 1988
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 1879-0887 .- 0167-8140. ; 12:4, s. 327-331
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Tidskriftsartikel (refereegranskat)abstract
- We have evaluated if any differences in tumor radiosensitization exist between the two adenosine diphosphate ribosyl transferase (ADPRT) inhibitors nicotinamide and benzamide at fractionated low doses. A significant radiosensitizing effect with nicotinamide at a 10 mg/kg per day dose was found in the tumor model used. We found, however, no radiosensitizing effect with benzamide given according to this schedule.
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| 2. |
- Ekberg, Lars, et al.
(författare)
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What margins should be added to the clinical target volume in radiotherapy treatment planning for lung cancer?
- 1988
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Ingår i: Radiotherapy and Oncology. - 1879-0887. ; 48:1, s. 71-77
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The planning target volume in radiotherapy treatment planning takes into account both movements of the clinical target volume (CTV) and set-up deviations. MATERIALS AND METHODS: A group of patients who received radiotherapy for lung cancer were studied. In order to measure the CTV movements due to respiration and other internal organ motions, fluoroscopy was performed for 20 patients. To study the accuracy and reproducibility of patient and beam set-up, 553 electronic portal images from 20 patients were evaluated. Discrepancies between planned and actual field positions were measured and the systematic and random errors were identified. The combined effect of these geometrical variations was evaluated. RESULTS: The average CTV movement with quiet respiration was about 2.4 mm in the medio-lateral and dorso-ventral directions. Movement in the cranio-caudal direction was on average 3.9 mm with a range of 0-12 mm. The systematic set-up errors were on average 2.0 mm in the transversal plane and 3.0 mm in the cranio-caudal direction. The random errors can be described by their standard deviations of 3.2 and 2.6 mm. In this study, the combined effect of the two parameters (CTV movement and set-up deviations) varied between 7.5 and 10.3 mm in different anatomical directions. CONCLUSIONS: In our daily clinical routine, we use a margin of 11 mm in the transversal plane and 15 mm cranially and caudally, also taking into account other unquantified variations and uncertainties.
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| 3. |
- Knöös, Tommy, et al.
(författare)
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A method for conversion of hounsfield number to electron density and prediction of macroscopic pair production cross-sections
- 1986
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Ingår i: Radiotherapy and Oncology. - 1879-0887. ; 5:4, s. 337-345
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Tidskriftsartikel (refereegranskat)abstract
- A method for the determination of electron density using a narrow beam attenuation geometry is described. The method does not require that the elemental composition of the phantom materials is known. The Hounsfield numbers for the phantom materials used were determined using five different CT scanners. A relationship between Hounsfield number and electron density can thus be established, which is of considerable value in radiation therapy treatment planning procedures. Measurements of the ratio coherent/incoherent scattering of low energy photons in a certain geometry has proven valuable for determination of atomic number, which in its turn can be used for estimation of macroscopic pair production coefficients for high energy photons. The combination of knowledge of electron density with methods for determination of processes, dependent on atomic number, can form a base for adequate composition of phantom materials for purposes of testing dose calculation algorithms for photons and electrons.
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| 4. |
- Knöös, Tommy, et al.
(författare)
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Comparison of measured and calculated absorbed doses from tangential irradiation of the breast
- 1986
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Ingår i: Radiotherapy and Oncology. - 1879-0887. ; 7:1, s. 81-88
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Tidskriftsartikel (refereegranskat)abstract
- Calculated absorbed dose distributions from tangential irradiation of the breast have been compared with TLD measurements in a anthropomorfic body-shaped phantom which has gone through all phases of the radiation treatment planning cycle, including mapping of electron densities with a CT scanner, simulation of beam set-up and several treatments with an accelerator. The absorbed doses, measured in the breast are 2-6% lower than those calculated with the clinically used treatment planning system. The deviation is slightly higher when wedges are used. The main source for this deviation is shown to be the limitations in the loss-of-scatter correction in the dose calculation algorithm used. It has also been noted that the variation of the absorbed dose in the target volume is in general smaller than predicted by the calculations.
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