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.
Smitt
M C
MC
Department of Radiation Oncology, Stanford Hospital, Stanford University Medical Center, 300 Pasteur Dr, Stanford, CA 94305, USA. melanies@reyes.stanford.edu
Birdwell
R L
RL
Goffinet
D R
DR
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