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Online-adaptive versus robust IMPT for prostate cancer: How much can we gain?
Jagt, Thyrza Z; Breedveld, Sebastiaan; van Haveren, Rens; Heijmen, Ben J M; Hoogeman, Mischa S.
Afiliación
  • Jagt TZ; Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. Electronic address: t.jagt@erasmusmc.nl.
  • Breedveld S; Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. Electronic address: s.breedveld@erasmusmc.nl.
  • van Haveren R; Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. Electronic address: r.vanhaveren@erasmusmc.nl.
  • Heijmen BJM; Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands. Electronic address: b.heijmen@erasmusmc.nl.
  • Hoogeman MS; Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, The Netherlands; Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands. Electronic address: m.hoogeman@erasmusmc.nl.
Radiother Oncol ; 151: 228-233, 2020 10.
Article en En | MEDLINE | ID: mdl-32777242
ABSTRACT
BACKGROUND/

PURPOSE:

Intensity-modulated proton therapy (IMPT) is highly sensitive to anatomical variations which can cause inadequate target coverage during treatment. Available mitigation techniques include robust treatment planning and online-adaptive IMPT. This study compares a robust planning strategy to two online-adaptive IMPT strategies to determine the benefit of online adaptation. MATERIALS/

METHODS:

We derived the robustness settings and safety margins needed to yield adequate target coverage (V95%≥98%) for >90% of 11 patients in a prostate cancer cohort (88 repeat CTs). For each patient, we also adapted a non-robust prior plan using a simple restoration and a full adaptation method. The restoration uses energy-adaptation followed by a fast spot-intensity re-optimization. The full adaptation uses energy-adaptation followed by the addition of new spots and a range-robust spot-intensity optimization. Dose was prescribed as 55 Gy(RBE) to the low-dose target (lymph nodes and seminal vesicles) with a boost to 74 Gy(RBE) to the high-dose target (prostate). Daily patient set-up was simulated using implanted intra-prostatic markers.

RESULTS:

Margins of 4 and 8 mm around the high- and low-dose target regions, a 6 mm setup error and a 3% range error were found to obtain adequate target coverage for all repeat CTs of 10/11 patients (94.3% of all 88 repeat CTs). Both online-adaptive strategies yielded V95%≥98% and better OAR sparing in 11/11 patients. Median OAR improvements up to 11%-point and 16%-point were observed when moving from robust planning to respectively restoration and full adaption.

CONCLUSION:

Both full plan adaptation and simple dose restoration can increase OAR sparing besides better conforming to the target criteria compared to robust treatment planning.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Neoplasias de la Próstata / Radioterapia de Intensidad Modulada / Terapia de Protones Tipo de estudio: Etiology_studies Límite: Humans / Male Idioma: En Revista: Radiother Oncol Año: 2020 Tipo del documento: Article

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Neoplasias de la Próstata / Radioterapia de Intensidad Modulada / Terapia de Protones Tipo de estudio: Etiology_studies Límite: Humans / Male Idioma: En Revista: Radiother Oncol Año: 2020 Tipo del documento: Article
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