Is there an advantage in designing adapted, patient-specific PTV margins in intensity modulated proton beam therapy for prostate cancer?

Joanna Góra*, Markus Stock, Carola Lütgendorf-Caucig, Dietmar Georg

*Korrespondierende:r Autor:in für diese Arbeit

Publikation: Beitrag in Fachzeitschrift (peer-reviewed)Artikel in Fachzeitschrift

12 Zitate (Scopus)

Abstract

Purpose: To investigate robust margin strategies in intensity modulated proton therapy to account for interfractional organ motion in prostate cancer. Methods and Materials: For 9 patients, one planning computed tomography (CT) scan and daily and weekly cone beam CTs (CBCTs) were acquired and coregistered. The following planning target volume (PTV) approaches were investigated: a clinical target volume (CTV) delineated on the planning CT (CTVct) plus 10-mm margin (PTV10mm); a reduced PTV (PTVRed): CTVct plus 5 mm in the left-right (LR) and anterior-posterior (AP) directions and 8 mm in the inferior-superior (IS) directions; and a PTV Hull method: the sum of CTVct and CTVs from 5 CBCTs from the first week plus 3 mm in the LR and IS directions and 5 mm in the AP direction. For each approach, separate plans were calculated using a spot-scanning technique with 2 lateral fields. Results: Each approach achieved excellent target coverage. Differences were observed in volume receiving 98% of the prescribed dose (V98%) where PTVHull and PTV Red results were superior to the PTV10mm concept. The PTVHull approach was more robust to organ motion. The V98% for CTVs was 99.7%, whereas for PTVRed and PTV10mm plans, V98% was 98% and 96.1%, respectively. Doses to organs at risk were higher for PTVHull and PTV10mm plans than for PTV Red, but only differences between PTV10mm and PTV Red were significant. Conclusions: In terms of organ sparing, the PTV10mm method was inferior but not significantly different from the PTVRed and PTVHull approaches. PTVHull was most insensitive to target motion.

OriginalspracheEnglisch
Seiten (von - bis)881-888
Seitenumfang8
FachzeitschriftInternational Journal of Radiation Oncology Biology Physics
Jahrgang85
Ausgabenummer3
DOIs
PublikationsstatusVeröffentlicht - 01 März 2013
Extern publiziertJa

ASJC Scopus Sachgebiete

  • Strahlung
  • Onkologie
  • Radiologie, Nuklearmedizin und Bildgebung
  • Krebsforschung

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