A comprehensive dosimetric evaluation of using RapidArc volumetric‐modulated arc therapy for the treatment of early‐stage nasopharyngeal carcinoma

Abstract

The purpose of this study was to investigate the potential benefits of using triple‐arc volumetric‐intensity modulated arc radiotherapy (RapidArc (RA)) for the treatment of early‐stage nasopharyngeal carcinoma (NPC). A comprehensive evaluation was performed including plan quality, integral doses, and peripheral doses. Twenty cases of stage I or II NPC were selected for this study. Nine‐field sliding window IMRT, double‐arc, and triple‐arc RA treatment plans were compared with respect to target coverage, dose conformity, critical organ sparing, and integral doses. Measurement of peripheral doses was performed using thermoluminescent dosimeters in an anthropomorphic phantom. While similar conformity and target coverage were achieved by the three types of plans, triple‐arc RA produced better sparing of parotid glands and spinal cord than double‐arc RA or IMRT. Double‐arc RA plans produced slightly inferior parotid sparing and dose homogeneity than the other two delivery methods. The monitor units (MU) required for triple‐arc were about 50% less than those of IMRT plans, while there was no significant difference in the required MUs between triple‐arc and double‐arc RA plans. The peripheral dose in triple‐arc RA was found to be 50% less compared to IMRT near abdominal and pelvic region. Triple‐arc RA improves both the plan quality and treatment efficiency compared with IMRT for the treatment of early stage NPC. It has become the preferred choice of treatment delivery method for early stage NPC at our center.PACS numbers: 87.53.Bn, 87.55.D, 87.55.de, 87.55.dk, 87.56.ng

The performance of the progressive resolution optimizer (PRO) for RapidArc planning in targets with low‐density media

“…Our previous study also reported better treatment efficiency and plan quality achieved using RapidArc (RA) compared to IMRT for early stage nasopharyngeal carcinoma (NPC) (2) . The study of Verbakel et al (4) showed that RA allowed much faster delivery of hypofractionated doses and generated more conformal plans than conventional stereotactic body radiotherapy (SBRT) for peripheral lung tumors.…”

“…Recently, RapidArc (Varian Medical Systems, Palo Alto, CA) has been found to produce comparable conformal dose distributions and faster treatment delivery compared to conventional static intensity‐modulated radiotherapy (IMRT) in various treatment sites, some of which involved low‐density medium such as lung, breast, and nasopharyngeal regions (1–5) …”

Improving target dose coverage and organ-at-risk sparing in intensity-modulated radiotherapy of advanced laryngeal cancer by a simple optimization technique

“…34 Reductions of the doses to the spinal cord or brainstem could be beneficial to patients with laryngeal cancer with recurrent or locally persistent diseases, especially when a second course of treatment is necessary. 35 The thyroid is a concern in IMRT because hypothyroidism has been reported to occur in between 6% and 48% of cases. [36][37][38][39] Akgun et al 40 and Cella et al 41 recommended the thyroid volume receiving $30 Gy (V 30Gy ) as a possible predictor of hypothyroidism.…”

Single arc volumetric-modulated arc therapy is sufficient for nasopharyngeal carcinoma: a dosimetric comparison with dual arc VMAT and dynamic MLC and step-and-shoot intensity-modulated radiotherapy

“…On the other hand, Kan et al [32] indicated that double-arc VMAT produced slightly inferior parotid sparing than nine-field “sliding-window” IMRT. A similar result was reported by Zhang et al [28], who showed that the dose distribution of single-arc VMAT plan for NPC was slightly worse than that of a nine-field IMRT plan.…”