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  P3.08 - Oligometastatic NSCLC (Not CME Accredited Session) (ID 974)

  • Event: WCLC 2018
  • Type: Poster Viewing in the Exhibit Hall
  • Track:
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/26/2018, 12:00 - 13:30, Exhibit Hall

  • 27574

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    P3.08-17 - Paediatric Motion Management Solutions for Particle Therapy Based Thoracic Stereotactic Ablative Body Radiotherapy (SABR) (ID 12856)

    12:00 - 13:30  |  Author(s): Greg Wheeler
    • Abstract
    • Slides

    Background
    

    We have recently developed a paediatric protocol for the treatment of pulmonary metastases using Stereotactic Ablative Body Radiotherapy (SABR). In thoracic SABR the treatment is commonly planned to the internal target volume, which encompasses the gross tumour and excursion of the tumour in space.Particle therapy has been shown to be beneficial in paediatric patients, but unfortunately, most systems do not have respiratory motion management thereby limiting their utility in thoracic patients. We model the implementation of strategies such as ventilation using CPAP or deep inspiration breath hold (DIBH).The purpose of this study was to establish the benefit seen in a prospectively evaluated paediatric cohort to inform clinical trials.

    a9ded1e5ce5d75814730bb4caaf49419 Method
    

    Patients

    Two patients with a single lesion, and one patient with 3 lesions were volumed. Average age was 12 years (range 6 to 16), prescription dose was 24Gy in one fraction. Clinical volumes were based on the Maximum Intenstiy Projection (MIP) and this ITV covered all motion seen on 10 phases of respiratory binning. The test dataset was contoured on the maximum exhale dataset (ME), as this was felt to be the most stable respiratory phase. 5 mm was added to create the PTV. Dynamic conformal arc (DCAT) was used for planning using 6MV photons with 3 to 5 arcs.

    4c3880bb027f159e801041b1021e88e8 Result
    

    Reduction in radiotherapy target volumes:Exhale scans resulted in a reduction in the radiotherapy target volumes for all lesions with the average± standard deviation of the PTV being 3.85± 2.52 cc and 2.51± 1.35cc for MIP vs. ME scans respectively.

    Reduction in dose to lung and heart: V5Gy (%) was also reduced from a mean of 6.0±4.10 vs. 4.63 ±2.73 % for MIP vs. ME scans respectively. For the 2 patients with lesions near the heart the mean heart dose was also reduced from 2.35±0.78 Gy vs. 1.8± 0.28 Gy for the MIP vs. ME scans respectively.

    The maximum reduction was seen for patient 3, PTV was reduced from 8.2 to 4.9 cc, the V5Gy(%) was reduced from 10 to 4.9% and the mean heart dose dropped from 2.9 to 2.0 Gy.

    8eea62084ca7e541d918e823422bd82e Conclusion
    

    Respiratory motion management strategies such as DIBH and CPAP may be suitable for paediatric patients who are old enough to comply with these strategies, and who do not require general anaesthesia. As in adult patients, the implementation of these strategies reduces the radiotherapy target volume, and results in lower doses to critical normal organs such as the lung and heart.

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