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S.V. Beek

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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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      MA13.03 - Analysis of Intra-Thoracic Anatomical Changes Observed in Clinical Workflow of Cone-Beam CT Guided Radiotherapy for Lung Cancer (ID 4478)

      16:00 - 17:30  |  Author(s): S.V. Beek

      • Abstract
      • Presentation
      • Slides

      Objectives: In lung cancer patients treated with image-guided radiotherapy we use daily Cone-Beam CT (CBCT) guidance for setup verification and to check on intra-thoracic anatomical changes (ITACs). ITACs like tumor baseline shifts, the occurrence or dissolving of an atelectasis, tumor progression or regression, pleural fluid- and infiltrative changes have been reported in 72% of lung cancer patients (Kwint M R&O 2014) during the course of irradiation. A traffic light protocol has been in use by the radiation technologists since 2010 to classify anatomical changes seen on the CBCT with anticipated different influences on the dose distribution using 4 action levels. The purpose of this study was to quantify how often the ITACs occurred in daily clinical practice and for which action level.

      All lung cancer patients irradiated in 2015 (excluding stereotactic treatments) with a dose >44 Gy were included. All patients had a daily CBCT guided online correction protocol and the traffic light action level of each CBCT was recorded. The following action levels have been defined: code red for immediate consultation with the physician before beam-on, code orange for a decision on the notification of the physician before the next fraction, code yellow to inform the physician; no action is required- and green for no change so no intervention necessary. We also analyzed the percentage of patients that received a new planning-CTscan and/or a new treatment plan.

      In 2015 a total of 299 lung cancer patients were conventionally irradiated with radical intent and 5971 CBCT scans were made. Of these CBCTs 51% were scored as code green, 24% as code yellow, 24% as code orange and code red in less than 1% of the CBCTs. Forty patients (13%) had a new treatment plan, of which 34 patients (11%) had a new planning CT-scan and 6 patients (2%) had a new treatment plan on the original planning CT-scan.

      Image-guided irradiation for 299 conventionally fractionated lung cancer patients (>44 Gy) in 2015 revealed lTACs in 25% of the CBCT’s made and a physician’s decision on the notification was necessary. A total of 13% of the patients treated received an unscheduled adaptive treatment plan during the course of treatment. The traffic light protocol in daily clinical workflow worked well as a tool to prioritize a physician’s decision based on the ITACs seen on the CBCT images.

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