1. Sparing the hippocampus and the hypothalamic- pituitary region during whole brain radiotherapy: a volumetric modulated arc therapy planning study.
- Author
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Mehta P, Janssen S, Fahlbusch FB, Schmid SM, Gebauer J, Cremers F, Ziemann C, Tartz M, and Rades D
- Subjects
- Adult, Brain Neoplasms diagnosis, Brain Neoplasms secondary, Cranial Irradiation methods, Dose Fractionation, Radiation, Dose-Response Relationship, Radiation, Feasibility Studies, Female, Hippocampus diagnostic imaging, Hippocampus radiation effects, Humans, Hypothalamus diagnostic imaging, Hypothalamus radiation effects, Male, Organ Sparing Treatments adverse effects, Organs at Risk diagnostic imaging, Organs at Risk radiation effects, Pituitary Gland diagnostic imaging, Pituitary Gland radiation effects, Radiotherapy Dosage, Radiotherapy, Intensity-Modulated methods, Tomography, X-Ray Computed, Brain Neoplasms radiotherapy, Cranial Irradiation adverse effects, Organ Sparing Treatments methods, Radiotherapy Planning, Computer-Assisted, Radiotherapy, Intensity-Modulated adverse effects
- Abstract
Background: Feasibility testing of a simultaneous sparing approach of hippocampus, hypothalamus and pituitary gland in patients undergoing whole-brain radiotherapy (WBRT) with and without a concomitant boost to metastatic sites., Introduction: Cognitive impairment and hormonal dysfunction are common side effects of cranial radiotherapy. A reduced dose application to the patho-physiologically involved functional brain areas, i.e. hippocampus, hypothalamus and pituitary gland, could reduce these common side effects. While hippocampal sparing is already a common practice to improve cognitive outcome, technical experience of additional combined sparing of the hypothalamus/pituitary gland (HT-P) is insufficient., Methods: Twenty patients were included in the planning study. In 11 patients, a total dose of 36 Gy of WBRT (2 Gy per fraction) plus a simultaneous integrated boost (SIB) of 9 Gy (0.5 Gy per fraction, total dose: 45 Gy) to the brain metastases was applied. In 9 patients, prophylactic cranial irradiation (PCI) was simulated with a total dose of 30 Gy (2 Gy per fraction). In both patient cohorts, a sparing approach of the hippocampus and the HT-P area was simulated during WBRT. For all treatment plans, volumetric modulated arc therapy (VMAT) was used. Quality assurance included assessment of homogeneity, conformality and target coverage., Results: The mean dose to the hippocampus and HT-P region was limited to less than 50% of the prescribed dose to the planning target volume (PTV) in all treatment plans. Dose homogeneity (HI) of the target volume was satisfying (median HI = 0.16 for WBRT+SIB and 0.1 for PCI) and target coverage (conformation number, CN) was not compromised (median CN = 0.82 for SIB and 0.86 for PCI)., Conclusion: Simultaneous dose reduction to the hippocampus and the HT-P area did not compromise the PTV coverage in patients undergoing WBRT+SIB or PCI using VMAT. While the feasibility of the presented approach is promising, prospective neurologic, endocrine outcome and safety studies are required.
- Published
- 2020
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