Dosimetric evolution of the breast electron boost target using 3D ultrasound imaging

Danielle J. Fraser, Philip Wong, Khalil Sultanem, Frank Verhaegen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

10 Citations (Web of Science)

Abstract

Purpose To investigate the effect of treatment planning, patient setup, and interfraction motion errors on the delivered dose for external beam electron boosts for postoperative early stage breast cancer patients Methods and materials. For 5 patients, 10-15 Gy was prescribed and administered via a conventionally defined electron boost treatment field - no dose distribution was calculated. Two computed tomography (CT) data sets were acquired on an average of 47 days apart Using Monte Carlo techniques the clinically defined electron beams were reconstructed on CT1 and CT2, and a dosimetric comparison between the two data sets was made Additionally. 3D ultrasound (US) imaging was performed to mongol interfraction motion 3D US images were acquired concurrently with the CT images, as well as prior to each boost fraction in the treatment room Taking into account interfraction motion, the close to the clinical target volume (CTV) was calculated Results Based on conventionally determined treatment fields the CT1-based CTV D95 averaged 49% (range 12-89%) of the prescribed dose Representing setup errors, the CT2-based CTV D95 averaged 47% (range 16-91%) of the prescribed dose Considering interfraction motion, the average radial displacement was 11 mm, and the resulting CTV D95 was further reduced in 2/5 patients Conclusions Poor initial coverage at the time of planning is exacerbated by breast mobility and interfraction tumour bed motion, increasing the uncertainty in the delivered dose
Original languageEnglish
Pages (from-to)185-191
JournalRadiotherapy and Oncology
Volume96
Issue number2
DOIs
Publication statusPublished - Aug 2010

Keywords

  • Breast cancer
  • Electron boost
  • IGRT
  • 3D ultrasound
  • Monte Carlo dose calculation
  • Intramodality

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