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MA13 - Modern Technologies and Biological Factors in Radiotherapy (ID 395)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Radiotherapy
- Presentations: 1
MA13.02 - First-In-Human Clinical Experience with Real-Time Tumor Targeting via MLC Tracking for Stereotactic Radiotherapy of Lung Cancer (ID 5532)
16:00 - 17:30 | Author(s): V. Caillet
MLC tracking is an emerging technology to improve tumor targeting and reduce normal tissue irradiation during radiotherapy. The purpose of this work is to present the early clinical experience from the first-in-human trial of real-time tumor targeting via MLC tracking for stereotactic ablative body radiotherapy (SABR) of lung cancer.
Full ethics approval through an Australian ethics board has been received for recruitment of 20 patients with stage 1 lung cancer or lung metastases into the MLC tracking clinical trial (NCT02514512). To date, seven recruited patients have each had three electromagnetic beacons inserted near the tumor. An MLC tracking SABR plan was generated with planning target volume (PTV) expanded 5mm from end-exhale tumor volume (GTV). For comparison a conventional motion-encompassing SABR plan was generated with PTV expanded 5mm from a 4DCT-derived internal target volume. Treatment was delivered using a standard linear accelerator using in-house developed software to continuously adapt the MLC motion based on the Calypso beacons’ movement. Tumor motion, treated volume and reconstructed delivered dose were compared between MLC tracking and conventional motion-encompassing treatment planning.
All seven patients have been treated successfully with MLC tracking (29 successful fractions). The MLC tracking PTV for all patients has been smaller than with ITV based planning (range 12% to 41% reduction, or 2 to 18 cm with MLC tracking). Subsequent reductions in normal lung dose were observed. Tumor motion was seen to vary in motion range from the planning 4DCT during treatment; significantly, larger motion was observed during treatment that exceeded standard PTV boundaries. Reconstruction of delivered treatments confirmed the accurate delivery of MLC tracking, with 100% prescribed dose delivered to the GTV.Figure 1
The first treatments with MLC tracking have been successfully performed in seven lung cancer patients. Reductions in treated volumes were observed, which translated to reductions in delivered lung dose.
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