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- Gunnlaugsson, Adalsteinn, et al.
(författare)
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The effect on the small bowel of 5-FU and oxaliplatin in combination with radiation using a microcolony survival assay
- 2009
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Ingår i: Radiation Oncology. - London : BioMed Central. - 1748-717X. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Background: In locally advanced rectal cancer, 5-Fluorouracil (5-FU)-based chemoradiation is the standard treatment. The main acute toxicity of this treatment is enteritis. Due to its potential radiosensitizing properties, oxaliplatin has recently been incorporated in many clinical chemoradiation protocols. The aim of this study was to investigate to what extent 5-FU and oxaliplatin influence the radiation (RT) induced small bowel mucosal damage when given in conjunction with single or split dose RT.Methods: Immune competent balb-c mice were treated with varying doses of 5-FU, oxaliplatin (given intraperitoneally) and total body RT, alone or in different combinations in a series of experiments. The small bowel damage was studied by a microcolony survival assay. The treatment effect was evaluated using the inverse of the slope (D(0)) of the exponential part of the dose-response curve.Results: In two separate experiments the dose-response relations were determined for single doses of RT alone, yielding D(0) values of 2.79 Gy (95% CI: 2.65 - 2.95) and 2.98 Gy (2.66 - 3.39), for doses in the intervals of 5-17 Gy and 5-10 Gy, respectively. Equitoxic low doses (IC5) of the two drugs in combination with RT caused a decrease in jejunal crypt count with significantly lower D(0): 2.30 Gy (2.10 - 2.56) for RT+5-FU and 2.27 Gy (2.08 - 2.49) for RT+oxaliplatin. Adding both drugs to RT did not further decrease D(0):2.28 Gy (1.97 - 2.71) for RT+5-FU+oxaliplatin. A clearly higher crypt survival was noted for split course radiation (3 x 2.5 Gy) compared to a single fraction of 7.5 Gy. The same difference was seen when 5-FU and/or oxaliplatin were added.Conclusion: Combining 5-FU or oxaliplatin with RT lead to an increase in mucosal damage as compared to RT alone in our experimental setting. No additional reduction of jejunal crypt counts was noted when both drugs were combined with single dose RT. The higher crypt survival with split dose radiation indicates a substantial recovery between radiation fractions. This mucosalsparing effect achieved by fractionation was maintained also when chemotherapy was added.
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| 4. |
- Lindvall, Peter, et al.
(författare)
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Reproducibility and geometric accuracy of the Fixster system during hypofractionated stereotactic radiotherapy
- 2008
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Ingår i: Radiation Oncology. - 1748-717X. ; 3:16
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Hypofractionated radiotherapy has been used for the treatment of AVMs and brain metastases. Hypofractionation necessitates the use of a relocatable stereotactic frame that has to be applied on several occasions. The stereotactic frame needs to have a high degree of reproducibility, and patient positioning is crucial to achieve a high accuracy of the treatment.METHODS:In this study we have, by radiological means, evaluated the reproducibility of the isocenter in consecutive treatment sessions using the Fixster frame. Deviations in the X, Y and Z-axis were measured in 10 patients treated with hypofractionated radiotherapy.RESULTS:The mean deviation in the X-axis was 0.4 mm (range -2.1 - 2.1, median 0.7 mm) and in the Y-axis -0.3 mm (range -1.4 - 0.7, median -0.2 mm). The mean deviation in the Z-axis was -0.6 (range -1.4 - 1.4, median 0.0 mm).CONCLUSION:There is a high degree of reproducibility of the isocenter during successive treatment sessions with HCSRT using the Fixster frame for stereotactic targeting. The high reducibility enables a safe treatment using hypofractionated stereotactic radiotherapy.
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| 5. |
- Nyholm, Tufve, et al.
(författare)
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Systematisation of spatial uncertainties for comparison between a MR and a CT-based radiotherapy workflow for prostate treatments
- 2009
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Ingår i: Radiation Oncology. - 1748-717X. ; 4:54
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Tidskriftsartikel (refereegranskat)abstract
- Background: In the present work we compared the spatial uncertainties associated with a MR-based workflow for external radiotherapy of prostate cancer to a standard CT-based workflow. The MR-based workflow relies on target definition and patient positioning based on MR imaging. A solution for patient transport between the MR scanner and the treatment units has been developed. For the CT-based workflow, the target is defined on a MR series but then transferred to a CT study through image registration before treatment planning, and a patient positioning using portal imaging and fiducial markers. Methods: An "open bore" 1.5T MRI scanner, Siemens Espree, has been installed in the radiotherapy department in near proximity to a treatment unit to enable patient transport between the two installations, and hence use the MRI for patient positioning. The spatial uncertainty caused by the transport was added to the uncertainty originating from the target definition process, estimated through a review of the scientific literature. The uncertainty in the CT-based workflow was estimated through a literature review.Results: The systematic uncertainties, affecting all treatment fractions, are reduced from 3-4 mm (ISd) with a CT based workflow to 2-3 mm with a MR based workflow. The main contributing factor to this improvement is the exclusion of registration between MR and CT in the planning phase of the treatment.
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| 7. |
- Taheri-Kadkhoda, Zahra, 1969, et al.
(författare)
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Intensity-modulated radiotherapy of nasopharyngeal carcinoma: a comparative treatment planning study of photons and protons.
- 2008
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Ingår i: Radiation oncology (London, England). - 1748-717X. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this treatment planning study was to investigate the potential advantages of intensity-modulated (IM) proton therapy (IMPT) compared with IM photon therapy (IMRT) in nasopharyngeal carcinoma (NPC). METHODS: Eight NPC patients were chosen. The dose prescriptions in cobalt Gray equivalent (GyE) for gross tumor volumes of the primary tumor (GTV-T), planning target volumes of GTV-T and metastatic (PTV-TN) and elective (PTV-N) lymph node stations were 72.6 GyE, 66 GyE, and 52.8 GyE, respectively. For each patient, nine coplanar fields IMRT with step-and-shoot technique and 3D spot-scanned three coplanar fields IMPT plans were prepared. Both modalities were planned in 33 fractions to be delivered with a simultaneous integrated boost technique. All plans were prepared and optimized by using the research version of the inverse treatment planning system KonRad (DKFZ, Heidelberg). RESULTS: Both treatment techniques were equal in terms of averaged mean dose to target volumes. IMPT plans significantly improved the tumor coverage and conformation (P < 0.05) and they reduced the averaged mean dose to several organs at risk (OARs) by a factor of 2-3. The low-to-medium dose volumes (0.33-13.2 GyE) were more than doubled by IMRT plans. CONCLUSION: In radiotherapy of NPC patients, three-field IMPT has greater potential than nine-field IMRT with respect to tumor coverage and reduction of the integral dose to OARs and non-specific normal tissues. The practicality of IMPT in NPC deserves further exploration when this technique becomes available on wider clinical scale.
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