Three-dimensional intrafractional motion of breast during tangential breast irradiation monitored with high-sampling frequency using a real-time tumor-tracking radiotherapy system.
OBJECTIVE
To evaluate the three-dimensional intrafraction motion of the breast during tangential breast irradiation using a real-time tracking radiotherapy (RT) system with a high-sampling frequency.


METHODS
A total of 17 patients with breast cancer who had received breast conservation RT were included in this study. A 2.0-mm gold marker was placed on the skin near the nipple of the breast for RT. A fluoroscopic real-time tumor-tracking RT system was used to monitor the marker. The range of motion of each patient was calculated in three directions.


RESULTS
The mean +/- standard deviation of the range of respiratory motion was 1.0 +/- 0.6 mm (median, 0.9; 95% confidence interval [CI] of the marker position, 0.4-2.6), 1.3 +/- 0.5 mm (median, 1.1; 95% CI, 0.5-2.5), and 2.6 +/- 1.4 (median, 2.3; 95% CI, 1.0-6.9) for the right-left, craniocaudal, and anteroposterior direction, respectively. No correlation was found between the range of motion and the body mass index or respiratory function. The mean +/- standard deviation of the absolute value of the baseline shift in the right-left, craniocaudal, and anteroposterior direction was 0.2 +/- 0.2 mm (range, 0.0-0.8 mm), 0.3 +/- 0.2 mm (range, 0.0-0.7 mm), and 0.8 +/- 0.7 mm (range, 0.1-1.8 mm), respectively.


CONCLUSIONS
Both the range of motion and the baseline shift were within a few millimeters in each direction. As long as the conventional wedge-pair technique and the proper immobilization are used, the intrafraction three-dimensional change in the breast surface did not much influence the dose distribution.
Kinoshita
Rumiko
R
Department of Radiology, Hokkaido University School of Medicine, Sapporo, Japan.
Shimizu
Shinichi
S
Taguchi
Hiroshi
H
Katoh
Norio
N
Fujino
Masaharu
M
Onimaru
Rikiya
R
Aoyama
Hidefumi
H
Katoh
Fumi
F
Omatsu
Tokuhiko
T
Ishikawa
Masayori
M
Shirato
Hiroki
H
D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000532:radiotherapy*; D003199:Computer Systems; D005260:Female; D006046:Gold; D006801:Humans; D008875:Middle Aged; D009068:Movement; D019736:Prostheses and Implants; D011878:Radiotherapy / Q000295:instrumentation; D012044:Regression Analysis; D012119:Respiration
D006046:Gold