TY - JOUR
T1 - Modeling positioning uncertainties of prostate cancer external beam radiation therapy using pre-treatment data
AU - Munck Af Rosenschöld, Per
AU - Desai, Neil B.
AU - Oh, Jung Hun
AU - Apte, Aditya
AU - Hunt, Margie
AU - Kalikstein, Abraham
AU - Mechalakos, James
AU - Happersett, Laura
AU - Deasy, Joseph O.
AU - Zelefsky, Michael J.
PY - 2014/2
Y1 - 2014/2
N2 - Purpose To investigate the influence of treatment plan data and image guidance (IG) on positioning uncertainty during prostate cancer (PCa) radiotherapy (RT). Methods Body mass index (BMI), planning target volume (PTV), bladder volume (BV), and rectal cross section area (RCS) were collected for 267 consecutive PCa patients undergoing daily IGRT. Radiographic isocenter corrections to intra-prostatic fiducials for 12,490 treatment fractions were used to derive random (RE) and systematic (SE) inter-fraction uncertainties for the cardinal axes. These data were used to simulate RE and SE for weekly IG and Action Level (AL)-IG treatment protocols. Results SE and RE were 2-5 and 3-4 mm in the cardinal axes, respectively, during simulation of no IG. Without IG, positive correlations (p < 0.01) were noted for (1) anterior-posterior RE vs. RCS and BV and (2) cranio-caudal RE vs. RCS, BV and BMI. The RE increase was 3 mm for the highest quartile of RCS, BV and BMI. Daily IGRT eliminated this relationship. 3D IG corrections of 1 cm or more occured in 27% of treatment fractions and in 97% of patients. Conclusion PCa patients with elevated pre-treatment BV, RCS and BMI have increased inter-fractionation positioning uncertainty and appear the primary candidates for daily IGRT.
AB - Purpose To investigate the influence of treatment plan data and image guidance (IG) on positioning uncertainty during prostate cancer (PCa) radiotherapy (RT). Methods Body mass index (BMI), planning target volume (PTV), bladder volume (BV), and rectal cross section area (RCS) were collected for 267 consecutive PCa patients undergoing daily IGRT. Radiographic isocenter corrections to intra-prostatic fiducials for 12,490 treatment fractions were used to derive random (RE) and systematic (SE) inter-fraction uncertainties for the cardinal axes. These data were used to simulate RE and SE for weekly IG and Action Level (AL)-IG treatment protocols. Results SE and RE were 2-5 and 3-4 mm in the cardinal axes, respectively, during simulation of no IG. Without IG, positive correlations (p < 0.01) were noted for (1) anterior-posterior RE vs. RCS and BV and (2) cranio-caudal RE vs. RCS, BV and BMI. The RE increase was 3 mm for the highest quartile of RCS, BV and BMI. Daily IGRT eliminated this relationship. 3D IG corrections of 1 cm or more occured in 27% of treatment fractions and in 97% of patients. Conclusion PCa patients with elevated pre-treatment BV, RCS and BMI have increased inter-fractionation positioning uncertainty and appear the primary candidates for daily IGRT.
KW - IGRT
KW - Image guided radiotherapy
KW - Interfraction motion
KW - Prostate cancer
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U2 - 10.1016/j.radonc.2013.12.010
DO - 10.1016/j.radonc.2013.12.010
M3 - Article
C2 - 24560753
AN - SCOPUS:84896395902
SN - 0167-8140
VL - 110
SP - 251
EP - 255
JO - Radiotherapy and Oncology
JF - Radiotherapy and Oncology
IS - 2
ER -