Room: AAPM ePoster Library
Purpose: We hypothesized that VMAT-TBI would be a safe and effective alternative to conventional TBI. Here we present the clinical outcomes from our five-year experience using VMAT-TBI.
Methods: Simulation is performed with the patient immobilized in a custom rotation frame in which head and feet first CT scans are acquired. A typical VMAT-TBI plan consists of 5-7 isocenters. The PTV consists of the body with a 5mm contraction and lungs subtracted. Planning objectives include V90%Rx of 100% and lung dose of 66-75%Rx. A single institution retrospective review was performed for all patients treated with VMAT-TBI. 44 patients were identified who were treated between 2014-20. The mean age was 27.1 years and median KPS was 90. 12 patients received 2-4Gy single-fraction TBI; the remaining received 12-13.2Gy multi-fraction TBI.
Results: Average PTV and lung coverage were 93.9% and 70.6% of the Rx dose, respectively. Typical treatment time ranges from 60-90 minutes. Median follow-up was 14 months. At last follow-up, 35/44 patients (80%) were alive. 2 deaths were due to recurrence. 4 other patients developed recurrence but underwent salvage treatment (total of 6 recurrences; recurrence free survival 85%). Mean overall and progression-free survival were 16.3 and 15.3 months, respectively, for the patients who received transplantation for malignant indications. Diarrhea (89%), mucositis (82%), and fatigue (77%) were the most common acute toxicities. The only grade 3 or higher acute toxicity was mucositis, observed in 71% of all patients and 25% of patients receiving single-fraction TBI. Late Grade 3+ pneumonitis was observed 4 patients (9%); of these cases, only one case (grade 3) was likely related to radiation and 3 cases were multifactorial with concomitant respiratory tract infections.
Conclusion: VMAT-TBI has replaced conventional TBI in our center and has shown to be as safe and effective with improved patient comfort, convenience, and dosimetric accuracy.
TBI, Treatment Techniques, Treatment Planning
TH- External Beam- Photons: Development (new technology and techniques)