Author of

• 15301

  +

  P3.02 - Poster Session/ Treatment of Localized Disease – NSCLC (ID 211)

  • Event: WCLC 2015
  • Type: Poster
  • Track: Treatment of Localized Disease - NSCLC
  • Presentations: 1
  • Moderators:
  • Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)

  • 15340

    +

    P3.02-039 - Is Volumetric Rapid Arc Irradiation Superior in the Treatment of Non Small Cell Lung Cancer? (ID 2986)

    09:30 - 09:30  |  Author(s): R. Reymen
    • Abstract

    Background:
    To make an irradiation plan for a patient with non small cell lung cancer without compromising myelum and healthy lung tissue, is often a challenging task. The purpose of this study was to investigate if Volumetric Rapid Arc irradiation would be superior in doing so.
    
    Methods:
    Patients were simulated with regular breathing on a lung support. The target alignation and definitions were standard. Dose optimalisation and calculation were performed in Eclipse using AAA version 10.0.28. 82 Different approaches in planning were made for different patients: conventional beams, and rapid arc plans with half arcs, full arcs, arcs with avoidance sectors and hybrid solutions. Calculations were made for a dose of 33 x 2Gy , with 98% coverage of PTV (planning target volume) with 95% of the dose , taking into account the mean lung dose, V20 and V5.
    
    Results:
    There is no class solution for the best treatment approach. The best technique depents on tumor size, lung size, tumor localisation and patient anatomy. Especially for small tumors, the conventional beams often give the best results in terms of lung dose, especially when myelum can be avoided without irradiating the contralateral lung. Half arcs were mostly not interesting, probably because both sides of oblique posterior fields are often needed for good PTV coverage. Using avoidance sectors was a better approach to spare more healthy lung tissue. Choosing the angles of the avoidance sectors is important, like choosing angles for conventional fields. Making a simple conventional plan first, gives a good idea of feasible lung and PTV dose and about angles for the avoidance sectors. The use of avoidance sectors generally gives a better solution in terms of lung dose, but if PTV is not fully covered and a lot of overdosage appears, one has to use smaller avoidance sectors or even work without. If the proposed constraints are not reached with these tools, it is possible to work with a hybrid solution. This is in practice more complicated, therefore we did not introduce this as a standard planning technique in our clinic.
    
    Conclusion:
    For small tumors, conventional beams are often better than rapid arc. If the tumorvolume is larger (> 300cc) and reaching different sides of the body (from left to right or from cranial to caudal), rapid arc gives better results. Avoidance sectors have to be chosen wisely to optain the constraints without turning to hybrid techniques.