TY - JOUR
T1 - Dosimetric Effect of Prostate Motion During Helical Tomotherapy
AU - Langen, Katja M.
AU - Lu, Weiguo
AU - Willoughby, Twyla R.
AU - Chauhan, Bhavin
AU - Meeks, Sanford L.
AU - Kupelian, Patrick A.
AU - Olivera, Gustavo
N1 - Funding Information:
Funding for this research was provided in part by TomoTherapy, Inc.
Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.
PY - 2009/7/15
Y1 - 2009/7/15
N2 - Purpose: To assess the dosimetric consequence of intrafraction prostate motion on helical tomotherapy plans. Methods and Materials: An electromagnetic tracking device was used to measure real-time prostate motion for 515 fractions (16 patients). Motion tracks were used to retrospectively recalculate dose distributions using a four-dimensional calculation engine. The minimum dose (Dmin), maximum dose (Dmax), and dose to 95% of the volume (D95%) were calculated for target volumes and compared with respective values from the treatment plan. The dosimetric effect was evaluated for each fraction. For each patient, the running cumulative effect was assessed throughout the course of treatment. Calculations were repeated assuming a time delay between initial patient setup and start of treatment. Results: Averaged over all fractions, the mean change in target D95% was <1% (SD, 3-4%). Reductions in target D95% of up to 20% were seen in individual fractions. Changes in prostate D95% were similar in frequency and magnitude to D95% changes in the planning target volume. The cumulative effect on target D95% was approximately 1% (SD, 1%). The average cumulative effect after five fractions was 1% (SD, 1.5%). Conclusions: In general, the dosimetric effect of observed prostate motion on target D95%was small. Infrequently severe D95% degradations were observed for individual fractions, but their effect on the cumulative dose distribution was quickly reduced with minimal fractionation.
AB - Purpose: To assess the dosimetric consequence of intrafraction prostate motion on helical tomotherapy plans. Methods and Materials: An electromagnetic tracking device was used to measure real-time prostate motion for 515 fractions (16 patients). Motion tracks were used to retrospectively recalculate dose distributions using a four-dimensional calculation engine. The minimum dose (Dmin), maximum dose (Dmax), and dose to 95% of the volume (D95%) were calculated for target volumes and compared with respective values from the treatment plan. The dosimetric effect was evaluated for each fraction. For each patient, the running cumulative effect was assessed throughout the course of treatment. Calculations were repeated assuming a time delay between initial patient setup and start of treatment. Results: Averaged over all fractions, the mean change in target D95% was <1% (SD, 3-4%). Reductions in target D95% of up to 20% were seen in individual fractions. Changes in prostate D95% were similar in frequency and magnitude to D95% changes in the planning target volume. The cumulative effect on target D95% was approximately 1% (SD, 1%). The average cumulative effect after five fractions was 1% (SD, 1.5%). Conclusions: In general, the dosimetric effect of observed prostate motion on target D95%was small. Infrequently severe D95% degradations were observed for individual fractions, but their effect on the cumulative dose distribution was quickly reduced with minimal fractionation.
KW - Dosimetry
KW - Prostate cancer
KW - Radiotherapy
KW - Real-time motion
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U2 - 10.1016/j.ijrobp.2008.09.035
DO - 10.1016/j.ijrobp.2008.09.035
M3 - Article
C2 - 19231105
AN - SCOPUS:67649553794
SN - 0360-3016
VL - 74
SP - 1134
EP - 1142
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 4
ER -