Comparative dosimetric analysis of IMRT and VMAT (RapidArc) in brain, head and neck, breast and prostate malignancies
Purpose: Intensity modulated radiotherapy (IMRT) in the recent past has established itself as a gold standard for organs at risk (OAR) sparing, target coverage and dose conformity. With the advent of a rotational treatment technology such as volumetric modulated arc therapy (VMAT), an inter-comparison is warranted to address the advantages and disadvantages of each technique.
Methods: Twenty patients were selected retrospectively from our patient database. Sites included were brain, head and neck, chest wall, and prostate, with five patients for each site. For all the selected patients, both the IMRT and VMAT treatment plans were generated. Plan comparison was done in terms of OAR dose, dose homogeneity index (HI), dose conformity index (CI), target coverage, low isodose volumes, monitor units (MUs), and treatment time.
Results: The VMAT showed better sparing of “parotids minus planning target volume (PTV)”, spinal cord and head of femur as compared to the IMRT. The lung V40 for VMAT was lower, whereas the lung V10, contralateral lung mean dose, contralateral breast mean dose and mean body dose were lower with IMRT for chest wall cases. Both the VMAT and IMRT achieved comparable HI except for the brain site, where IMRT scored over VMAT. The CI achieved by the IMRT and VMAT were similar except for chest wall cases, whereas the VMAT achieved better dose conformity. The target coverage was comparable with both the plans. The VMAT clearly scored over IMRT in terms of average MUs (486 versus 812 respectively) and average treatment time (2.54 minutes versus 5.54 minutes) per treatment session.
Conclusion: The VMAT (RapidArc) has a potential to generate treatment plans for various anatomical sites which are comparable with the corresponding IMRT plans in terms of OAR sparing and plan quality parameters. The VMAT significantly reduces treatment time as compared to the IMRT, thus VMAT can increase the throughput of a busy radiotherapy department.
Gersem WD, Claus F, Wagter CD, et al. Leaf position optimization for step-and-shoot IMRT. Int J Radiat Oncol Biol Phys 2001; 51:1371-88.
Shepard DM, Earl MA, Li XA, et al. Direct aperture optimization: A turnkey solution for step-and-shoot IMRT. Med Phys 2002; 29:1007-18.
Cozzi L, Dinshaw KA, Shrivastava SK, et al. A treatment planning study comparing volumetric arc modulation with Rapid Arc and fixed field IMRT for cervix uteri radiotherapy. Radiother Oncol 2008; 89:180-91.
Fogliata A, Clivio A, Nicolini G, et al. Intensity modulation with photons for benign intracranial tumors: A planning comparison of volumetric single arc, helical arc and fixed gantry techniques. Radiother Oncol 2008; 89:254-62.
Shaffer R, Nichol AM, Vollans E, et al. A comparison of volumetric modulated arc therapy and conventional intensity modulated radiotherapy for frontal and temporal high-grade gliomas. Int J Radiat Oncol Biol Phys 2010; 76:1177-84.
Wagner D, Christiansen H, Wolff H, Vorwerk H. Radiotherapy of malignant gliomas: Comparison of volumetric single arc technique (RapidArc), dynamic intensity modulated technique and 3-D conformal technique. Radiat Oncol 2009; 93:593-6.
Rong Y, Tang G, Welsh JS, et al. Helical Tomotherapy versus Single Arc Intensity Modulated Arc Therapy: A collaborative dosimetric comparison between two institutions. Int J Radiat Oncol Biol Phys 2011; 81:284-96.
Wolff D, Stieler F, Welzel G, et al. VMAT versus serial tomotherapy, step-and-shoot IMRT and 3-D-conformal RT for treatment of prostate cancer. Radiother Oncol 2009; 93:226-33.
Wiezorek T, Brachwitz T, Georg D, et al. Rotational IMRT techniques compared to fixed gantry IMRT and Tomotherapy: multi-institutional planning study for head and neck cases. Radiat Oncol 2011; 6:20.
Alvarez MJ, Pohl F, Koelbl O, Dobler B. Evaluation of volumetric modulated arc therapy (VMAT) with Oncentra MasterPlan for the treatment of head and neck cancer. Radiat Oncol 2010; 5:110.
Holt A, Gestel DV, Arends MP, et al. Multi-institutional comparison of volumetric modulated arc therapy vs. intensity-modulated radiation therapy for head-and-neck cancer: a planning study. Radiat Oncol 2013; 8:26.
Stieler F, Wolff D, Schmid H, et al. Comparison of several modulated radiotherapy techniques for head and neck cancer and dosimetric radiation of VMAT. Radiother Oncol 2011; 101:388-93.
Johnston M, Clifford C, Bromley R, Back M, Oliver L, Eade T. Volumetric Modulated arc therapy in head and neck radiotherapy: A planning comparison using simultaneous integrated boost for his pharynx and oropharynx carcinoma. Clinical Oncol 2011; 23:503-11.
Palma D, Vollans E, James K, et al. Volumetric Modulated Arc Therapy for delivery of prostate radiotherapy: Comparison with Intensity-Modulated Radiotherapy and Three-Dimentional Conformal Radiotherapy. Int J Radiat Oncol Biol Phys 2008; 72:996-1001.
Quan EM, Li X, Li Y, et al. A comprehensive comparison of IMRT and VMAT plan quality for prostate cancer treatment. Int J Radiat Oncol Biol Phys 2012; 83:1169-76.
Zhang P, Happersett L, Hunt M, et al. Volumetric modulated arc therapy: Planning and evaluation for prostate cancer cases. Int J Radiat Oncol Biol Phys 2010; 76:1456-62.
Rao M, Yang W, Chen F, et al. Comparison of Elekta VMAT with helical tomotherapy and fixed field IMRT: Plan quality, delivery efficiency and accuracy. Med Phys 2010; 37:1350.
Ali AN, Dhabaan AH, Jarria CS, et al. Dosimetric comparison of volumetric modulated arc therapy and intensity modulated radiation therapy for pancreatic malignancies. Med Dosim 2012; 37:271-5.
Rana S, Pokharel S, Zheng Y, et al. Treatment planning study comparing proton therapy, Rapid Arc and intensity modulated radiation therapy for a synchronous bilateral lung cancer case. Int J Cancer Ther Oncol 2014; 2:020213.
Oliver M, Ansbacher W, Wayne A Beckham. Comparing planning time, delivery time and plan quality for IMRT, RapidArc and Tomotherapy. J Appl Clin Med Phys 2009; 10:4.
Vieillot S, Azria D, Lemanski C, et al. Plan comparison of volumetric-modulated arc therapy (RapidArc) and conventional intensity-modulated radiation therapy (IMRT) in anal canal cancer. Radiat Oncol 2010; 5:92.
Kumar SAS, Vivekanandan N, Sriram P. A study on conventional IMRT and RapidArc treatment planning techniques for head and neck cancers. Reports of Practical Oncology and Radiotherapy 2012; 17:168-75.
Marks LB, Yorke AD, Jackson A, et al. Use of normal tissue complication probability models in the clinic. Int J Radiat Oncol Biol Phys 2010; 76:S10-19.
RTOG Radiation Dose Constraints. http://en.wikibooks.org/wiki/Radiation_Oncology/Toxicity/RTOG.
Shaw E, Kline R, Gillin M, et al. Radiation therapy oncology group: Radiosurgery quality assurance guidelines. Int J Radiat Oncol Biol Phys 1993; 27:1231-9.
Yoon M, Park SY, Shin D, et al. A new homogeneity index based on statistical analysis of the dose-volume histogram. J Appl Clin Med Phys 2007; 8:2.
Monk JE, Perks JR, Doughty D, Plowman PN. Comparison of a micro-multileaf collimator with a 5 mm-leaf-width collimator for intracranial stereotactic radiotherapy. Int J Radiat Oncol Biol Phys 2003; 57:1443-9.
Ekambaram V, Velayudham R. Analysis of low-dose level volumes in intensity modulated radiotherapy and 3-D conformal radiotherapy. Int J Cancer Ther Oncol 2014; 2:02032.
Esch AV, Tillikainen L, Pyykkonen J, et al. Testing of analytical anisotropic algorithm for photon dose calculation. Med Phys 2006; 33:4130.
Bush K, Gange IM, Zavgorodni S, et al. Dosimetric validation of Acuros XB with Monte Carlo methods for photon dose calculations. Med Phys 2011; 38:2208.
Rana S. Clinical dosimetric impact of Acuros XB and analytical anisotropic algorithm (AAA) on real lung cancer treatment plans: review. Int J Cancer Ther Oncol 2014; 2:02019.
Ojala J. The accuracy of the Acuros XB algorithm in external beam radiotherapy - a comprehensive review. Int J Cancer Ther Oncol 2014; 2:020417.
This work is licensed under a Creative Commons Attribution 3.0 License.
International Journal of Cancer Therapy and Oncology (ISSN 2330-4049)
© International Journal of Cancer Therapy and Oncology (IJCTO)
To make sure that you can receive messages from us, please add the 'ijcto.org' domain to your e-mail 'safe list'. If you do not receive e-mail in your 'inbox', check your 'bulk mail' or 'junk mail' folders.