High definition three-dimensional ultrasound to localise the tumour bed: a breast radiotherapy planning study.
OBJECTIVE
Complex radiation techniques, such as conformal radiotherapy for partial breast irradiation, require accurate localisation of the tumour bed. This study investigated high definition 3D ultrasound for breast tumour bed localisation. Study aims were: firstly, to determine how easily a tumour cavity could be visualised with 3D ultrasound; secondly, to determine the accuracy of computed tomography (CT) and 3D ultrasound co-registration; thirdly, to compare 3D ultrasound with other methods of localisation.


METHODS
3D ultrasound examinations were carried out in 40 women attending for breast radiotherapy. 3D position data were co-registered with the radiotherapy planning CT. 2D ultrasound and CT, surgical clips and CT, and CT alone were also used to localise the tumour bed in 32/40, 14/40 and 5/40 patients, respectively. Tumour bed volume and centre of gravity measurements for all methods of localisation were compared.


RESULTS
Mean surgery to imaging interval was 44 days (range 23-86 days). The post-operative cavity was seen in all cases using the 3D ultrasound, and was graded as highly visible, visible and subtle in 21/40 (53%), 12/40 (30%) and 7/40 (17%) cases, respectively. There was a statistically significant improvement in the ability of 3D ultrasound to localise the tumour bed compared with 2D ultrasound. CT-ultrasound registration was achieved in all cases. Two-dimensional and 3D ultrasound showed smaller tumour bed volumes than clips.


CONCLUSIONS
Three-dimensional ultrasound localisation of the tumour bed appears superior to 2D ultrasound. It can also be co-registered with a planning CT, thus allowing additional information on the size and location of the tumour bed to be integrated into complex radiotherapy planning.
Coles
Charlotte E
CE
Department of Oncology, Cambridge University, UK. charlotte.coles@addenbrookes.nhs.uk
Cash
Charlotte J C
CJ
Treece
Graham M
GM
Miller
Fiona N A C
FN
Hoole
Andrew C F
AC
Gee
Andrew H
AH
Prager
Richard W
RW
Sinnatamby
Ruchi
R
Britton
Peter
P
Wilkinson
Jenny S
JS
Purushotham
Anand D
AD
Burnet
Neil G
NG
D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D019047:Phantoms, Imaging; D011880:Radiotherapy Planning, Computer-Assisted; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography