Breast electron boost planning: comparison of CT and US.
OBJECTIVE
To compare computed tomography (CT) with ultrasonography (US) for depiction of the biopsy cavity.


METHODS
Thirty-two consecutive patients who underwent radiation therapy following lumpectomy with a planned electron boost were examined. At the time of simulation for whole-breast radiation therapy, all patients underwent planning CT (CT 1) at 3-mm section intervals. At the time of electron boost simulation, US was performed to define the biopsy cavity. In 17 cases, a second CT examination (CT 2) was performed at the time of electron boost simulation. CT and US studies were reviewed jointly and assigned a cavity visualization score (CVS) of 1 (cavity not visualized) to 5 (all cavity margins clearly defined).


RESULTS
The median CVS at CT 1 was 5; at CT 2, 4; and at US, 4. For patients who underwent all three studies, the median CVS at CT 1 was 5; at CT 2, 4; and at US, 4. Factors related to CVS at CT 1 were homogeneous versus heterogeneous appearance (score, 5 vs 4), surgery-to-CT interval (< or =30 days, 5; 31-60 days, 4; >60 days, 4), and cavity size (>15 cm(3), 5; <15 cm(3), 4). In all cases, cavity volume decreased somewhat during the CT 1-to-CT 2 interval.


CONCLUSIONS
CT performed at the time of whole-breast simulation can be used to plan electron boost fields, with cavity visualization similar to that at US.
Department of Radiation Oncology, Stanford Hospital, Stanford University Medical Center, 300 Pasteur Dr, Stanford, CA 94305, USA. melanies@reyes.stanford.edu
M C
MC
Smitt
R L
RL
Birdwell
D R
DR
Goffinet
D000328:Adult; D000368:Aged; D001706:Biopsy; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000473:pathology / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D003198:Computer Simulation; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009367:Neoplasm Staging; D011880:Radiotherapy Planning, Computer-Assisted; D018714:Radiotherapy, Adjuvant; D014057:Tomography, X-Ray Computed; D016217:Ultrasonography, Mammary