Portal de Periódicos da CAPES

Volumetric modulated arc therapy (VMAT) vs. serial tomotherapy, step-and-shoot IMRT and 3D-conformal RT for treatment of prostate cancer

2009; Elsevier BV; Volume: 93; Issue: 2 Linguagem: Inglês

10.1016/j.radonc.2009.08.011

1879-0887

Dirk Wolff, Florian Stieler, Grit Welzel, Friedlieb Lorenz, Yasser Abo‐Madyan, Sabine Mai, Carsten Herskind, Martin Poledník, Volker Steil, Frederik Wenz, Frank Lohr,

Radiation Therapy and Dosimetry

Introduction Volumetric modulated arc therapy (VMAT), a complex treatment strategy for intensity-modulated radiation therapy, may increase treatment efficiency and has recently been established clinically. This analysis compares VMAT against established IMRT and 3D-conformal radiation therapy (3D-CRT) delivery techniques. Methods Based on CT datasets of 9 patients treated for prostate cancer step-and-shoot IMRT, serial tomotherapy (MIMiC), 3D-CRT and VMAT were compared with regard to plan quality and treatment efficiency. Two VMAT approaches (one rotation (VMAT1x) and one rotation plus a second 200° rotation (VMAT2x)) were calculated for the plan comparison. Plan quality was assessed by calculating homogeneity and conformity index (HI and CI), dose to normal tissue (non-target) and D95% (dose encompassing 95% of the target volume). For plan efficiency evaluation, treatment time and number of monitor units (MU) were considered. Results For MIMiC/IMRTMLC/VMAT2x/VMAT1x/3D-CRT, mean CI was 1.5/1.23/1.45/1.51/1.46 and HI was 1.19/1.1/1.09/1.11/1.04. For a prescribed dose of 76 Gy, mean doses to organs-at-risk (OAR) were 50.69 Gy/53.99 Gy/60.29 Gy/61.59 Gy/66.33 Gy for the anterior half of the rectum and 31.85 Gy/34.89 Gy/38.75 Gy/38.57 Gy/55.43 Gy for the posterior rectum. Volumes of non-target normal tissue receiving ⩾70% of prescribed dose (53 Gy) were 337 ml/284 ml/482 ml/505 ml/414 ml, for ⩾ 50% (38 Gy) 869 ml/933 ml/1155 ml/1231 ml/1993 ml and for ⩾ 30% (23 Gy) 2819 ml/3414 ml/3340 ml/3438 ml /3061 ml. D95% was 69.79 Gy/70.51 Gy/71,7 Gy/71.59 Gy/73.42 Gy. Mean treatment time was 12 min/6 min/3.7 min/1.8 min/2.5 min. Conclusion All approaches yield treatment plans of improved quality when compared to 3D-conformal treatments, with serial tomotherapy providing best OAR sparing and VMAT being the most efficient treatment option in our comparison. Plans which were calculated with 3D-CRT provided good target coverage but resulted in higher dose to the rectum.