Jim P Tol1, Patricia Doornaert2, Birgit I Witte3, Max Dahele2, Ben J Slotman2, Wilko F A R Verbakel2. 1. Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: j.tol@vumc.nl. 2. Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands. 3. Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
Abstract
PURPOSE: To investigate changes in head-and-neck cancer (HNC) plan quality following the introduction of new technologies and planning techniques in the last decade. METHODS AND MATERIALS: Thirty plans were selected from each of four successive periods (P). P1: 7-field static intensity-modulated radiotherapy (IMRT) with parotid gland sparing; P2: dual-arc volumetric-modulated arc therapy (VMAT, similar to P3-P4), including submandibular gland sparing; P3: inclusion of individual swallowing muscles and attempts to further reduce parotid and oral cavity doses through manual interactive optimization; P4: containing the same organs-at-risk (OARs) as P3, but automatically interactively optimized. Plan benchmarking included mean salivary gland/swallowing muscle/oral cavity (Dsal/Dswal/Doc) doses. Differences in mean doses between the periods were analyzed by an ANCOVA, taking geometric differences across periods into account. RESULTS: Compared to P1, P2 plans improved Dsal by 3.4Gy on average. P3 improved Dsal/Dswal/Doc by 6.9/11.5/7.2Gy over P2, showing that Dswal and Dsal could be improved simultaneously. In P4, Doc/Dswal slightly improved over P3 by 1.7/3.8Gy. Improved OAR sparing in P3/P4 did not come at the cost of increased dose deposition elsewhere and planning target volume (PTV) dose homogeneity was similar. CONCLUSIONS: New technologies and planning techniques were successfully implemented into routine clinical care and resulting in improved HNC plan quality.
PURPOSE: To investigate changes in head-and-neck cancer (HNC) plan quality following the introduction of new technologies and planning techniques in the last decade. METHODS AND MATERIALS: Thirty plans were selected from each of four successive periods (P). P1: 7-field static intensity-modulated radiotherapy (IMRT) with parotid gland sparing; P2: dual-arc volumetric-modulated arc therapy (VMAT, similar to P3-P4), including submandibular gland sparing; P3: inclusion of individual swallowing muscles and attempts to further reduce parotid and oral cavity doses through manual interactive optimization; P4: containing the same organs-at-risk (OARs) as P3, but automatically interactively optimized. Plan benchmarking included mean salivary gland/swallowing muscle/oral cavity (Dsal/Dswal/Doc) doses. Differences in mean doses between the periods were analyzed by an ANCOVA, taking geometric differences across periods into account. RESULTS: Compared to P1, P2 plans improved Dsal by 3.4Gy on average. P3 improved Dsal/Dswal/Doc by 6.9/11.5/7.2Gy over P2, showing that Dswal and Dsal could be improved simultaneously. In P4, Doc/Dswal slightly improved over P3 by 1.7/3.8Gy. Improved OAR sparing in P3/P4 did not come at the cost of increased dose deposition elsewhere and planning target volume (PTV) dose homogeneity was similar. CONCLUSIONS: New technologies and planning techniques were successfully implemented into routine clinical care and resulting in improved HNC plan quality.
Authors: Alexander R Delaney; Lei Dong; Anthony Mascia; Wei Zou; Yongbin Zhang; Lingshu Yin; Sara Rosas; Jan Hrbacek; Antony J Lomax; Ben J Slotman; Max Dahele; Wilko F A R Verbakel Journal: Cancers (Basel) Date: 2018-11-02 Impact factor: 6.639