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Price RA , Murphy S , McNeeley SW , Charlie CM , Horwitz E , Movsas B , Raben A , Pollack A
A method for increased dose conformity and segment reduction for sMLC delivered IMRT treatment of the prostate
International Journal of Radiation Oncology Biology Physics. 2003 Nov;57(3) :843-852
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Abstract
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 I 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 D-100 decreased by 15.7% with an SE of 2.4%. Nontarget tissue receiving D-95, D-90, and D-50 decreased by 16.3,15.1, and 19.5%, respectively, with SE values of approximately 2% at center 1. Corresponding values for D-100, D-95, D-90, and D-50 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. (C) 2003 Elsevier Inc.
Notes
English Article Price, RA; *Fox* *Chase* Canc Ctr, Dept Radiat Oncol, 7701 Burholme Ave, Philadelphia, PA 19111 USA. Research Addresses: *Fox* *Chase* Canc Ctr, Dept Radiat Oncol, Philadelphia, PA 19111 USA. Monmouth Med Ctr, Dept Radiat Oncol, Long Branch, NJ USA. Cited References: *CRT ONC GROUP, 1996, 3DCRT *ICRU, 1993, 50 ICRU ADAMS EJ, 2001, INT J RADIAT ONCOL, V51, P579 BRAGG CM, 2002, INT J RADIAT ONCOL, V52, P729 CAROL MP, 1997, 12 INT C US COMP RAD, P317 CROOKS SM, 2001, INT J RAD ONCOL B S1, V51, P394 DAS IJ, 1998, MED PHYS, P25 DEMEERLEER GO, 2000, INT J RADIAT ONCOL, V47, P639 DOGAN N, 2002, RADIOLOGY, V223, P57 DONG YJ, 2001, BREEDING SCI, V51, P1 ESIK G, 1997, STRAHLENTHER ONKOL, V173, P193 HANKS GE, 2000, INT J RADIAT ONCOL, V46, P823 HANKS GE, 1999, 3D CONFORMAL RAD THE HUNT MA, 2001, INT J RADIAT ONCOL, V49, P623 KLEIN EE, 2000, INT J RADIAT ONCOL, V48, P1447 LATTANZI J, 1999, INT J RADIAT ONCOL, V43, P719 MOHAN DS, 2000, INT J RADIAT ONCOL, V46, P575 NUTTING CM, 2000, INT J RADIAT ONCOL, V48, P649 POLLACK A, 2002, INT J RADIAT ONCOL, V53, P1097 PRICE RA, 2002, INT J RADIAT ONCOL, V53, P236 THE BS, 2001, INT J RADIAT ONCOL, V49, P705 TRAN BN, 2001, INT J RAD ONCOL B S1, V51, P82 VINEBERG KA, 2002, INT J RADIAT ONCOL, V52, P1159 0360-3016