title: On-line optimization of intraoperative electron beam radiotherapy of the breast.
abstract: OBJECTIVE
  To optimize the dose delivery to the breast lumpectomy target treated with intraoperative electron beam radiotherapy (IOERT).
  
  
  METHODS
  Two tools have been developed in our MU calculation software NEMO X to improve the dose homogeneity and the in-vivo dosimetry effectiveness for IOERT treatments. Given the target (tumor bed) thickness measured by the surgeon, NEMO X can provide auto dose normalization to cover 95% of the target volume with 95% of the prescription dose (PD) and a "best guess" of the expected dosimeter dose (EDD) for a deep seated in-vivo dosimeter. The tools have been validated with the data of 91 patients treated with IOERT on a LIAC mobile accelerator. In-vivo dosimetry has been performed with microMOSFETs positioned on the shielding disk inserted between the tumor bed and the chest wall.
  
  
  RESULTS
  On average the auto normalization showed to provide better results if compared to conventional normalization rules in terms of mean target dose (|MTD-PD|/PD ≤ 5% in 95% vs. 53% of pts) and V107 percentage (left angle bracket V107 right angle bracket =19% vs. 32%). In-vivo dosimetry MOSFET dose (MD) showed a better correlation with the EDD guessed by our tool than just by assuming that EDD=PD (|MD-EDD|/EDD ≤ 5% in 57 vs. 26% of pts).
  
  
  CONCLUSIONS
  NEMO X provides two useful tools for the on-line optimization of the dose delivery in IOERT. This optimization can help to reduce unnecessary large over-dosage regions and allows introducing reliable action levels for in-vivo dosimetry.
authors.affiliation: Department of Medical Physics, National Cancer Research Institute, Genova, Italy. stefano.agostinelli@istge.it
authors.forename: Stefano
authors.initials: S
authors.lastname: Agostinelli
authors.forename: Marco
authors.initials: M
authors.lastname: Gusinu
authors.forename: Francesca
authors.initials: F
authors.lastname: Cavagnetto
authors.forename: Stefania
authors.initials: S
authors.lastname: Garelli
authors.forename: Michele
authors.initials: M
authors.lastname: Zeverino
authors.forename: Marina
authors.initials: M
authors.lastname: Guenzi
authors.forename: Renzo
authors.initials: R
authors.lastname: Corvò
authors.forename: Gianni
authors.initials: G
authors.lastname: Taccini
mesh_terms: D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D004583:Electrons / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012984:Software