Independent verification of ultrasound based image-guided radiation treatment, using electronic portal imaging and implanted gold markers.
The aim of this paper is to study the correction of prostate motion and position during external beam therapy. The correction was performed using a commercially available ultrasound-based repositioning tool. Electronic portal imaging with the use of fiducial markers was used to assess efficacy and accuracy. Patients undergoing radiation treatment for adenocarcinoma of the prostate were enrolled in a positioning study. Fifteen patients had five to six gold fiducial markers implanted in their prostate. These patients were positioned daily in a standard manner and then were repositioned every other day using an ultrasound-based correction system. Every fraction of a patients' treatment was imaged. This yielded 156 image pairs with and 119 pairs without repositioning available for analysis. This group of patients with markers had the following residual positions measured after the use of ultrasound repositioning. A mean error of -0.4 mm (LL), -2.6 mm (CC), and +2.5 mm (AP) with a standard deviation of 4.3, 5.4, and 5.7 mm. In two directions the improvements of treatment using the ultrasound correction were smaller than the precision of this experiment. They were no larger than 0.81 mm (LAT), and 0.95 mm (CC). In the AP direction a significant improvement was found of 1.6 mm. A highly significant correlation (p < 0.001) was found between the residual errors in the cranio-caudal direction and the shifts performed on the basis of the ultrasound measurements (Spearman ranking R = 0.53). We presented a method to objectively estimate improvements by a correction scheme. This method applied to ultrasound-based adjustment showed significant improvement in one direction and no measurable improvement in two other directions.
Van den Heuvel
Frank
F
Department of Radiation Oncology, Barbara Ann Karmanos Cancer Institute, Wayne State University, Detroit, Michigan 48201, USA. vandenho@karmanos.org
Powell
Tanya
T
Seppi
Edward
E
Littrupp
Peter
P
Khan
Mubashra
M
Wang
Yue
Y
Forman
Jeffrey D
JD
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000532:radiotherapy; D000465:Algorithms; D003287:Contrast Media; D019544:Equipment Failure Analysis; D006046:Gold; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D008297:Male; D009068:Movement; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011859:Radiography; D011881:Radiotherapy, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods
D003287:Contrast Media; D006046:Gold