A comparison of CT- and ultrasound-based imaging to localize the prostate for external beam radiotherapy.
OBJECTIVE
This study assesses the accuracy of NOMOS B-mode acquisition and targeting system (BAT) compared with computed tomography (CT) in localizing the prostate.


METHODS
Twenty-six patients were CT scanned, and the prostate was localized by 3 observers using the BAT system. The BAT couch shift measurements were compared with the CT localization. Six of the patients had gold markers present in the prostate, and the prostate movement determined by BAT was compared with the movement determined by the gold markers.


RESULTS
Using the BAT system, the 3 observers determined the prostate position to be a mean of 1-5 mm over all directions with respect to the CT. The proportion of readings with a difference >3 mm between the observers was in the range of 25% to 44%. The prostate movement based on gold markers was an average of 3-5 mm different from that measured by BAT. The literature assessing the accuracy and reproducibility on BAT is summarized and compared with our findings.


CONCLUSIONS
We have found that there are systematic differences between the BAT-defined prostate position compared with that estimated on CT using gold grain marker seeds.
McNair
Helen A
HA
Department of Radiotherapy, Royal Marsden NHS Foundation Trust, Sutton, United Kingdom. Helen.McNair@rmh.nhs.uk
Mangar
Stephen A
SA
Coffey
Jerome
J
Shoulders
Beverley
B
Hansen
Vibeke N
VN
Norman
Andrew
A
Staffurth
John
J
Sohaib
S Aslam
SA
Warrington
Alan P
AP
Dearnaley
David P
DP
D006046:Gold; D006801:Humans; D008297:Male; D015588:Observer Variation; D019047:Phantoms, Imaging; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D019736:Prostheses and Implants; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
D006046:Gold