A Radiotherapy Planning Study of RapidArc, Intensity Modulated Radiotherapy, Three-Dimensional Conformal Radiotherapy, and Parallel Opposed Beams in the Treatment of Pediatric Retroperitoneal Tumors

Background This planning study compared Rapid Arc fixed field IMRT (cIMRT) 3D conformal radiotherapy (3D CRT), and a parallel opposed pair (POP) for children with retroperitoneal tumors Procedure Plans were generated in eight patients to treat the PTV (dose range 19 8-45 Gy) while limiting kidney and liver doses In selected patients vertebral body (VB) dose heterogeneity was minimized Cumulative DVH parameters, monitor units (MU) and treatment times were compared for the four techniques using the Wilcoxon matched pairs test Results RapidArc and cIMRT covered target volumes more conformally than 3D CRT and POP (P=0 012) There was no difference in the ability to meet kidney dose constraints A significantly lower volume of the liver received 12 Gy with cIMRT or RapidArc compared with 3D CRT (P=0 028) Where VB was included in PTV VB dose homogeneity was generally within 94-104% of the prescription dose Time to deliver a single fraction with RapidArc POP, 3D CRT, and cIMRT was 1 25 +/- 0 01, 1 38 +/- 0 10 2 6 +/- 0 45, and 4 02 +/- 1 12 min, respectively (P = 0 012) Monitor units for a single fraction with POP 3D CRT RapidArc, and cIMRT were 203 +/- 26, 235 +/- 32 325 +/- 71 and 665 +/- 215, respectively (P < 0 05) Conclusions POP resulted in favorable MU, treatment time and dosimetry but had poor conformality 3D CRT was more conformal but had higher MU and treatment time RapidArc and cIMRT were generally no better dosimetrically than conformal techniques RapidArc was dosimetrically very similar to cIMRT, but resulted in a major reduction in time and MU used to deliver the radiation Pediatr Blood Cancer 2011 56 16-23 (C) 2010 Wiley Liss Inc