Hippocampal-sparing and target volume coverage in treating 3 to 10 brain metastases: A comparison of Gamma Knife, single-isocenter VMAT, CyberKnife, and TomoTherapy stereotactic radiosurgery
| Autor: | Sussan Salas, Heather Zinkin, Isabella Zhang, Jeff Antone, Michael Schulder, Shyamali Saha, Adam C. Riegel, Lili Vijeh, Jonathan P.S. Knisely, Joe Lauritano, Anuj Goenka, M. Marrero, Jenny Li |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
medicine.medical_treatment
Planning target volume Gamma knife Hippocampal formation Radiosurgery Hippocampus Tomotherapy 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine Cyberknife Humans Medicine Radiology Nuclear Medicine and imaging Radiation treatment planning Brain Neoplasms business.industry Radiotherapy Planning Computer-Assisted Isocenter Radiotherapy Dosage Tumor Burden Treatment Outcome Oncology 030220 oncology & carcinogenesis Radiotherapy Intensity-Modulated business Nuclear medicine Organ Sparing Treatments |
| Zdroj: | Practical Radiation Oncology. 7:183-189 |
| ISSN: | 1879-8500 |
| Popis: | Our purpose was to evaluate hippocampal doses and target volume coverage with and without hippocampal sparing when treating multiple brain metastases using various stereotactic radiosurgery (SRS) platforms.We selected 10 consecutive patients with 14 separate treatments who had been treated in our department for 3 to 10 brain metastases and added hippocampal avoidance contours. All 14 treatments were planned with GammaPlan for Gamma Knife, Eclipse for single isocenter volumetric modulated arc therapy (VMAT), TomoTherapy Treatment Planning System (TPS) for TomoTherapy, and MultiPlan for CyberKnife. Initial planning was performed with the goal of planning target volume coverage of V100 ≥95% without hippocampal avoidance. If the maximum hippocampal point dose (Dmax) was6.6 Gy in a single fraction and40% of the hippocampi received ≤4.5 Gy, no second plan was performed. If either constraint was not met, replanning was performed with these constraints.There was a median of 6 metastases per plan, with an average total tumor volume of 7.32 mL per plan. The median hippocampal Dmax (in Gy) without sparing averaged 1.65, 9.81, 4.38, and 5.46, respectively (P.0001). Of 14 plans, 3 Gamma Knife and CyberKnife plans required replanning, whereas 13 VMAT and 8 TomoTherapy plans required replanning. The hippocampal constraints were not achievable in 1 plan on any platform when the tumor was bordering the hippocampus. The mean volume of brain receiving 12 Gy (in mL), which has been associated with symptomatic radionecrosis, was 23.57 with Gamma Knife, 76.77 with VMAT, 40.86 with CyberKnife, and 104.06 with TomoTherapy (P = .01). The overall average conformity indices for all plans ranged from 0.36 to 0.52.Even with SRS, the hippocampi can receive a considerable dose; however, if the hippocampi are outlined as organs of risk, sparing these structures is feasible in nearly all situations with all 4 platforms, without detriment to target coverage, and should be considered in all patients undergoing SRS for multiple brain metastases.Hippocampi play an important role in memory, and sparing of these structures in whole brain radiation can improve neurocognitive outcomes. The hippocampi are not routinely spared when using stereotactic radiosurgery. We evaluated the incidental dose to the hippocampi when treating multiple brain metastases and sought to examine if hippocampal sparing is feasible without detriment to target coverage. We found that hippocampal sparing is possible without affecting coverage or conformality in most cases across treatment platforms. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|