TY - JOUR
T1 - A method for increased dose conformity and segment reduction for sMLC delivered IMRT treatment of the prostate
AU - Price, Robert A.
AU - Murphy, Scott
AU - McNeeley, Shawn W.
AU - Ma, C. M.Charlie
AU - Horwitz, Eric
AU - Movsas, Benjamin
AU - Raben, Adam
AU - Pollack, Alan
PY - 2003/11/1
Y1 - 2003/11/1
N2 - Purpose: The focus of this work is to develop a practical planning method that results in increased dose conformity and reduced treatment time for segmental multileaf collimation (sMLC) based intensity-modulated radiation therapy (IMRT) delivery. Methods and Materials: Additional regions for dose constraint are introduced within the normal tissue during the planning process by designing a series of concentric ellipsoids around the target. A dose gradient is then defined by assigning dose constraints to each concentric region. The technique was tested at two centers and data for 26 and 10 patients, respectively, are presented allowing for differences in treatment technique, beam energy, ellipsoid definition, and prescription dose. At both centers, a series of patients previously treated for prostate cancer with IMRT were selected, and comparisons were made between the original and new plans. Results: While meeting target dose specifications and normal tissue constraints, the average number of beam directions decreased by 1.6 with a standard error (SE) of 0.1. The average time for delivery at center 1 decreased by 29.0% with an SE of 2.0%, decreasing from 17.5 min to 12.3 min. The average time for delivery at center 2 decreased by 29.9% with an SE of 3.8%, decreasing from 11 min to 7.7 min. The amount of nontarget tissue receiving D100 decreased by 15. 7% with an SE of 2.4%. Nontarget tissue receiving D95, D 90, and D50 decreased by 16.3, 15.1, and 19.5%, respectively, with SE values of approximately 2% at center 1. Corresponding values for D100, D95, D90, and D50 decreased by 13.5, 16.7, 17.1, and 5.1%, respectively, with SE values of less than 3% at center 2. Conclusions: By designating subsets of tissue as concentric regions around the target(s) and carefully defining each region's dose constraints, we have gained an increased measure of control over the region outside the target boundaries. This increased control manifests as two distinct endpoints that are beneficial to the IMRT process: increased dose conformity and decreased treatment time.
AB - Purpose: The focus of this work is to develop a practical planning method that results in increased dose conformity and reduced treatment time for segmental multileaf collimation (sMLC) based intensity-modulated radiation therapy (IMRT) delivery. Methods and Materials: Additional regions for dose constraint are introduced within the normal tissue during the planning process by designing a series of concentric ellipsoids around the target. A dose gradient is then defined by assigning dose constraints to each concentric region. The technique was tested at two centers and data for 26 and 10 patients, respectively, are presented allowing for differences in treatment technique, beam energy, ellipsoid definition, and prescription dose. At both centers, a series of patients previously treated for prostate cancer with IMRT were selected, and comparisons were made between the original and new plans. Results: While meeting target dose specifications and normal tissue constraints, the average number of beam directions decreased by 1.6 with a standard error (SE) of 0.1. The average time for delivery at center 1 decreased by 29.0% with an SE of 2.0%, decreasing from 17.5 min to 12.3 min. The average time for delivery at center 2 decreased by 29.9% with an SE of 3.8%, decreasing from 11 min to 7.7 min. The amount of nontarget tissue receiving D100 decreased by 15. 7% with an SE of 2.4%. Nontarget tissue receiving D95, D 90, and D50 decreased by 16.3, 15.1, and 19.5%, respectively, with SE values of approximately 2% at center 1. Corresponding values for D100, D95, D90, and D50 decreased by 13.5, 16.7, 17.1, and 5.1%, respectively, with SE values of less than 3% at center 2. Conclusions: By designating subsets of tissue as concentric regions around the target(s) and carefully defining each region's dose constraints, we have gained an increased measure of control over the region outside the target boundaries. This increased control manifests as two distinct endpoints that are beneficial to the IMRT process: increased dose conformity and decreased treatment time.
KW - Algorithms
KW - Humans
KW - Male
KW - Patient Selection
KW - Prostatic Neoplasms/diagnostic imaging
KW - Radiography
KW - Radiotherapy Dosage
KW - Radiotherapy Planning, Computer-Assisted/methods
KW - Radiotherapy, Conformal/methods
KW - Rectum
KW - Urinary Bladder
UR - http://www.scopus.com/inward/record.url?scp=0141838857&partnerID=8YFLogxK
U2 - 10.1016/S0360-3016(03)00711-9
DO - 10.1016/S0360-3016(03)00711-9
M3 - Article
C2 - 14529792
AN - SCOPUS:0141838857
SN - 0360-3016
VL - 57
SP - 843
EP - 852
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 3
ER -
