Volumetric modulation arc radiotherapy with flattening filter-free beams compared with static gantry IMRT and 3D conformal radiotherapy for advanced esophageal cancer: a feasibility study.

Abstract

PURPOSE:

A feasibility study was performed to evaluate RapidArc (RA), and the potential benefit of flattening filter-free beams, on advanced esophageal cancer against intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT).

METHODS AND MATERIALS:

The plans for 3D-CRT and IMRT with three to seven and five to seven fixed beams were compared against double-modulated arcs with avoidance sectors to spare the lungs for 10 patients. All plans were optimized for 6-MV photon beams. The RA plans were studied for conventional and flattening filter-free (FFF) beams. The objectives for the planning target volume were the volume receiving ≥ 95% or at most 107% of the prescribed dose of <1% with a dose prescription of 59.4 Gy. For the organs at risk, the lung volume (minus the planning target volume) receiving ≥ 5 Gy was <60%, that receiving 20 Gy was <20%-30%, and the mean lung dose was <15.0 Gy. The heart volume receiving 45 Gy was <20%, volume receiving 30 Gy was <50%. The spinal dose received by 1% was <45 Gy. The technical delivery parameters for RA were assessed to compare the normal and FFF beam characteristics.

RESULTS:

RA and IMRT provided equivalent coverage and homogeneity, slightly superior to 3D-CRT. The conformity index was 1.2 ± 0.1 for RA and IMRT and 1.5 ± 0.2 for 3D-CRT. The mean lung dose was 12.2 ± 4.5 for IMRT, 11.3 ± 4.6 for RA, and 10.8 ± 4.4 for RA with FFF beams, 18.2 ± 8.5 for 3D-CRT. The percentage of volume receiving ≥ 20 Gy ranged from 23.6% ± 9.1% to 21.1% ± 9.7% for IMRT and RA (FFF beams) and 39.2% ± 17.0% for 3D-CRT. The heart and spine objectives were met by all techniques. The monitor units for IMRT and RA were 457 ± 139, 322 ± 20, and 387 ± 40, respectively. RA with FFF beams showed, compared with RA with normal beams, a ∼20% increase in monitor units per Gray, a 90% increase in the average dose rate, and 20% reduction in beam on time (owing to different gantry speeds).

CONCLUSION:

RA demonstrated, compared with conventional IMRT, a similar target coverage and some better dose sparing to the organs at risk; the advantage against conventional 3D-CRT was more evident. RA with FFF beams resulted in minor improvements in plan quality but with the potential for additional useful reduction in the treatment time.

• Authors: Giorgia Nicolini, Sarbani Ghosh-Laskar, Shyam Kishore Shrivastava, Sushovan Banerjee, Suresh Chaudhary, Jai Prakash Agarwal, Anusheel Munshi, Alessandro Clivio, Antonella Fogliata, Pietro Mancosu, Eugenio Vanetti, Luca Cozzi
• Journal: International journal of radiation oncology, biology, physics (Int J Radiat Oncol Biol Phys) Vol. 84 Issue 2 Pg. 553-60 (Oct 01 2012) ISSN: 1879-355X [Electronic] United States
• PMID: 22386376 (Publication Type: Comparative Study, Journal Article)
• Copyright: Copyright © 2012 Elsevier Inc. All rights reserved.

Topics

• Esophageal Neoplasms (pathology, radiotherapy)
• Feasibility Studies
• Heart (diagnostic imaging, radiation effects)
• Humans
• Lung (diagnostic imaging, radiation effects)
• Matched-Pair Analysis
• Organs at Risk (diagnostic imaging, radiation effects)
• Radiation Injuries (prevention & control)
• Radiation Tolerance
• Radiography
• Radiotherapy Dosage
• Radiotherapy Planning, Computer-Assisted (methods)
• Radiotherapy, Conformal (methods)
• Radiotherapy, Intensity-Modulated (methods)
• Spinal Cord (diagnostic imaging, radiation effects)