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- Fagerström Kristensen, Ingrid, et al.
(författare)
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Comparative Proton and Photon Treatment Planning in Pediatric Patients with Various Diagnoses
- 2015
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Ingår i: International Journal of Particle Therapy. - 2331-5180. ; 2:2, s. 367-375
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Radiation therapy with protons, owing to its physical properties, can beadvantageous for the treatment of children. This study was conducted in order to quantify the advantages of proton therapy from a treatment planning point of view in a consecutive, realistic, and mixed pediatric/adolescent population with varying diagnoses and target locations.Patients and Methods: Forty-five patients treated with conventional 3 dimensional conformal radiation therapy photon radiation therapy were retrospectively re-planned with scanned proton beams. Treatment sites represented were the central nervous system, head and neck, thorax, and abdomen. Median age was 8 years (range, 2-18 years). All plans were optimized with intensity-modulated proton therapy (multi-field optimization). We analyzed a number of dose-volume descriptors for planned targetvolumes (PTVs). Organ-specific mean doses and relevant DV -values were derived fororgans at risk. In addition, homogeneity index, conformity index, treated volume, and integral dose were calculated for each treatment plan. The Wilcoxon matched-pairs signed rank test was used for studying differences between these variables for the 2 treatment modalities.Results: Planned target volume coverage (V95%) was similar when comparing photons and protons. Conformity and homogeneity indices were similar or better for protons for most cases. In general, doses to organs at risk were lower with protons. In cases with organs at risk in close vicinity to the PTV, the gain with protons is less.Conclusions: The patient cohort benefits from reduced integral dose with protons compared with photons. Patients with tumors in the central nervous system, head and neck, upper mediastinum, and some abdominal locations will gain significantly if treated with protons compared with photons. For 7 of the 45 consecutive patients studied (whole brain, whole lung, whole abdomen, flank treatment), we found no gain with protons (difference in integral dose less than 8%).
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| 2. |
- Flejmer, Anna M., et al.
(författare)
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Potential benefit of scanned proton beam versus photons as adjuvant radiation therapy in breast cancer
- 2015
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Ingår i: International Journal of Particle Therapy. - 2331-5180. ; 1:4, s. 845-855
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate the feasibility of using scanned proton beams as adjuvant radiation therapy for breast cancer. Long-term cardiopulmonary complications may worsen the quality of life and reduce the positive contribution of radiation therapy, which has been known to improve long-term control of locoregional disease as well as the long-term survival for these patients.Materials and Methods: Ten patients with stage I-III cancer (either after mastectomy or lumpectomy, left- or right-sided) were included in the study. The patients were identified from a larger group where dose heterogeneity in the target and/or hotspots in the normal tissues qualified them for irregular surface compensator planning with photons. The patients underwent planning with 2 scanned proton beam planning techniques, single-field uniform dose and intensity-modulated proton therapy, and the results were compared with those from irregular surface compensator. All volumes of interest were delineated and reviewed by experienced radio-oncologists. The patients were prescribed 50 GyRBE in 25 fractions. Dosimetric parameters of interest were compared with a paired, 2-tailed Student t test.Results: The proton plans showed comparable or better target coverage than the original photon plans. There were also large reductions with protons in mean doses to the heart (0.2 versus 1.3 GyRBE), left anterior descending artery (1.4 versus 6.4 GyRBE), and the ipsilateral lung (6.3 versus 7.7 GyRBE). This reduction is important from the point of view of the quality of life of the patients after radiation therapy. No significant differences were found between single-field uniform dose and intensity-modulated proton therapy plans.Conclusion: Spot scanning technique with protons may improve target dose homogeneity and further reduce doses to the organs at risk compared with advanced photon techniques. The results from this study indicate a potential for protons as adjuvant radiation therapy in breast cancer and a further step toward the individualization of treatment based on anatomic and comorbidity characteristics.
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| 4. |
- Mondlane, Gracinda, 1987-, et al.
(författare)
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Dosimetric Comparison of Plans for Photon- or Proton-Beam Based Radiosurgery of Liver Metastases
- 2016
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Ingår i: International Journal of Particle Therapy. - 2331-5180. ; 3:2, s. 277-284
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Radiosurgery treatment of liver metastases with photon beams has been an established method for more than a decade. One method commonly used is the stereotactic body radiation therapy (SBRT) technique. The aim of this study was to investigate the potential sparing of the organs at risk (OARs) that the use of intensity-modulated proton therapy (IMPT), instead of SBRT, could enable.Patients and Methods: A comparative treatment-planning study of photon-beam and proton-beam based liver-cancer radiosurgery was performed. Ten patients diagnosed with liver metastasis and previously treated with SBRT at the Karolinska University Hospital were included in the study. New IMPT plans were prepared for all patients, while the original plans were set as reference plans. The IMPT planning was performed with the objective of achieving the same target dose coverage as with the SBRT plans. Pairwise dosimetric comparisons of the treatment plans were then performed for the OARs. A 2-sided Wilcoxon signed-rank test with significance level of 5% was carried out.Results: Improved sparing of the OARs was made possible with the IMPT plans. There was a significant decrease of the mean doses delivered to the following risk organs: the nontargeted part of the liver (P = .002), the esophagus (P = .002), the right kidney (P = .008), the spinal cord (P = .004), and the lungs (P = .002). The volume of the liver receiving less than 15 Gy was significantly increased with the IMPT plans (P = .004).Conclusion: The IMPT-based radiosurgery plans provided similar target coverage and significant dose reductions for the OARs compared with the photon-beam based SBRT plans. Further studies including detailed information about varying tissue heterogeneities in the beam path, due to organ motion, are required to evaluate more accurately whether IMPT is preferable for the radiosurgical treatment of liver metastases.
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