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P. Keall



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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
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      MA13.02 - First-In-Human Clinical Experience with Real-Time Tumor Targeting via MLC Tracking for Stereotactic Radiotherapy of Lung Cancer (ID 5532)

      16:06 - 16:12  |  Author(s): P. Keall

      • Abstract
      • Presentation
      • Slides

      Background:
      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.

      Methods:
      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.

      Results:
      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[3] 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



      Conclusion:
      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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    P2.05 - Poster Session with Presenters Present (ID 463)

    • Event: WCLC 2016
    • Type: Poster Presenters Present
    • Track: Radiotherapy
    • Presentations: 1
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      P2.05-043 - Lung Tumour Motion Kilovoltage Intrafraction Monitoring (KIM): First Clinical Results (ID 5538)

      14:30 - 14:30  |  Author(s): P. Keall

      • Abstract

      Background:
      Lung tumour positional uncertainty has been identified as a major issue that deteriorates the efficacy of radiotherapy. The recent development of the Kilovoltage intrafraction monitoring (KIM) which uses widely available gantry-mounted kilovoltage (kV) imager has been applied to prostate motion monitoring. This study reports the first clinical result of KIM for lung cancer radiotherapy with an Elekta machine.

      Methods:
      A locally advanced stage IIIlung cancer patient undergoing conventionally fractionated VMAT was enrolled in an ethics-approved study of KIM. A Gold Anchor fiducial marker (0.4 mm diameter x 20 mm length) was implanted in the tumour near the right hilum (Fig 1, left). kV images were acquired at 5.5 Hz during treatment. Post-treatment, markers were segmented and reconstructed to obtain 3D tumour trajectories. A Microsoft Kinect audio and depth sensing device was also mounted on the couch to get the external respiratory signal. Figure 1 Figure 1. kV image of the Gold Anchor marker (left) and the KIM measured lung tumour 3D motion and the external Kinect signal (right).



      Results:
      Our method was successfully applied for the first KIM lung patient. The fiducial marker was visible on 62.9% of the kV images. The average lung tumour motion (mean ± SD) in superior-inferior (SI), anterior-posterior (AP) left-right (LR), directions were 0.27±7.52, -0.09±3.37, and -0.64±4.55 mm respectively. Seven fractions of lung tumour 3D motion and Kinect external signal were acquired, with the representative result illustrated (Fig 1, right).

      Conclusion:
      This is the first time that KIM has been used for intrafractional tumour motion monitoring during lung cancer radiotherapy, and also the first implementation of KIM on an Elekta imaging platform. This clinical translational research milestone paves the way for the broad implementation of image guidance to facilitate the detection and correction of geometric error for lung radiotherapy, and resultant improved clinical outcomes.