title: Conkiss: conformal kidneys sparing 3D noncoplanar radiotherapy treatment for pancreatic cancer as an alternative to IMRT.
abstract: When treating pancreatic cancer using standard (ST) 3D conformal radiotherapy (3D-CRT) beam arrangements, the kidneys often receive a higher dose than their probable tolerance limit. Our aim was to elaborate a new planning method that--similarly to IMRT--effectively spares the kidneys without compromising the target coverage. Conformal kidneys sparing (CONKISS) 5-field, noncoplanar plans were compared with ST plans for 23 consecutive patients retrospectively. Optimal beam arrangements were used consisting of a left- and right-wedged beam-pair and an anteroposterior beam inclined in the caudal direction. The wedge direction determination (WEDDE) algorithm was developed to adjust the adequate direction of wedges. The aimed organs at risk (OARs) mean dose limits were: kidney <12 Gy, liver <25 Gy, small bowels <30 Gy, and spinal cord maximum <45 Gy. Conformity and homogeneity indexes with z-test were used to evaluate and compare the different planning approaches. The mean dose to the kidneys decreased significantly (p < 0.05): left kidney 7.7 vs. 10.7 Gy, right kidney 9.1 vs. 11.7 Gy. Meanwhile the mean dose to the liver increased significantly (18.1 vs. 15.0 Gy). The changes in the conformity, homogeneity, and in the doses to other OARs were not significant. The CONKISS method balances the load among the OARs and significantly reduces the dose to the kidneys, without any significant change in the conformity and homogeneity. Using 3D-CRT the CONKISS method can be a smart alternative to IMRT to enhance the possibility of dose escalation.
authors.affiliation: University of Pécs, Institute of Oncotherapy, Pécs, Hungary. zsolt.sebestyen@aok.pte.hu
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Sebestyén
authors.forename: Péter
authors.initials: P
authors.lastname: Kovács
authors.forename: Ákos
authors.initials: Á
authors.lastname: Gulybán
authors.forename: Róbert
authors.initials: R
authors.lastname: Farkas
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Bellyei
authors.forename: Gábor
authors.initials: G
authors.lastname: Liposits
authors.forename: András
authors.initials: A
authors.lastname: Szigeti
authors.forename: Olga
authors.initials: O
authors.lastname: Esik
authors.forename: Katalin
authors.initials: K
authors.lastname: Dérczy
authors.forename: László
authors.initials: L
authors.lastname: Mangel
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D006801:Humans; D007668:Kidney / Q000528:radiation effects*; D008954:Models, Biological; D010190:Pancreatic Neoplasms / Q000532:radiotherapy*; D011835:Radiation Protection / Q000379:methods*; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*