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K. West



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    MINI 32 - Topics in Localized Lung Cancer (ID 166)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Treatment of Localized Disease - NSCLC
    • Presentations: 1
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      MINI32.07 - A Phase I Feasibility Study of Kilovoltage Intrafraction Monitoring for Lung Cancer (ID 1036)

      18:30 - 20:00  |  Author(s): K. West

      • Abstract
      • Presentation
      • Slides

      Background:
      New technologies in radiotherapy of lung tumours aim to reduce toxicity and increase tumour control by increasing the dose delivered, and reducing the size of radiotherapy margins. Kilovoltage intrafraction monitoring (KIM) is a novel image guidance technology, which permits visualisation of fiducials implanted into the tumour whilst the radiotherapy beam is on. KIM has been used in both prostate[1] and liver tumours[2], and has been shown to increase the accuracy of radiotherapy delivery. In this Phase I study we aim to establish whether it is feasible to use KIM to monitor the motion of lung tumours during radiotherapy delivery. 1. Ng J et al. IJROBP 2012:84(5):e656 2.Poulsen P et al. Radiotherapy and Oncology 2014:111(3):424

      Methods:
      Patients receiving curative radiotherapy for lung cancer will have between 3-5 fiducials inserted into their tumour during endobronchial ultrasound (EBUS). Radiotherapy will be planned and delivered as per standard departmental protocols for lung cancer patients. 4D-cone beam CT (CBCT) will be performed , in conjunction with acquisition of KIM images and respiratory motion signal acquisition on the 1[st], 6[th], 11[th], 16[th], 21[st], 26[th], and 30[th] fractions before treatment to assess the accuracy of patient and tumour position.

      Results:
      Initial studies in a respiratory motion phantom have indicated that 0.4mm diameter Gold Anchor fiducials are visible during radiotherapy treatment. Ethical approval has been obtained with patient recruitment to the study to commence shortly. The primary endpoint of this study is the successful visualisation by the KIM technique of fiducials inserted into the tumour. Each patient will have a minimum of 3 fiducials (markers) inserted. As the implanted fiducials may be migrated or lost, the definition of technical success will vary according to the number of fiducials present. In the case of 1 to 3 markers being present, segmentation of at least 1 marker will be required for the image acquisition to be deemed successful. In the case of 4 or more fiducials being present, segmentation by the KIM technique of at least 2 markers for each image will be required for the image acquisition to be deemed successful. Secondary endpoints include assessment of the stability of implanted markers, and the rate of marker migration, quantitative assessment of tumour motion, assessing the impact of tumour motion on dosimetry and an assessment of toxicity associated with marker insertion.

      Conclusion:
      Lung tumours move during radiotherapy treatment, both between radiotherapy fractions and whilst the radiotherapy dose is being delivered[3]. Establishing the feasibility of KIM will enable the visualization of tumour motion whilst the radiotherapy treatment is being delivered. This is currently impossible on a standard linac, limiting the ability of the clinician to implement changes in margin size, which could potentially reduce the severity of side-effects for patients. Assessing intra-fraction motion of lung tumours is a key step in this process – by identifying the uncertainty in treatment, we will in the future be able to implement gating and tracking of tumours, thus resulting in safer and more effective treatment. 3. Sonke J. et al. IJROBP 2008:70(2):590

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