Dynamic conformal arcs for lung stereotactic body radiation therapy: A comparison with volumetric‐modulated arc therapy

Abstract

This study constitutes a feasibility assessment of dynamic conformal arc (DCA) therapy as an alternative to volumetric-modulated arc therapy (VMAT) for stereotactic body radiation therapy (SBRT) of lung cancer. The rationale for DCA is lower geometric complexity and hence reduced risk for interplay errors induced by respiratory motion. Forward planned DCA and inverse planned DCA based on segment-weight optimization were compared to VMAT for single arc treatments of five lung patients. Analysis of dose-volume histograms and clinical goal fulfillment revealed that DCA can generate satisfactory and near equivalent dosimetric quality to VMAT, except for complex tumor geometries. Segment-weight optimized DCA provided spatial dose distributions qualitatively similar to those for VMAT. Our results show that DCA, and particularly segment-weight optimized DCA, may be an attractive alternative to VMAT for lung SBRT treatments if the patient anatomy is favorable. K E Y W O R D S conformal arcs, DCA, lung SBRT, VMAT This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT

“…Utilizing volumetric modulated arc therapy (VMAT) with FFF-beams 17,18 resulted in better tumor dose coverage and faster treatment delivery of complex lung SBRT treatments compared to historically used plans with 8-15 noncoplanar fixed fields or several coplanar DCA fields with flattened beams. [19][20][21][22] Similar results were observed when compared to linacbased intensity modulated radiation therapy (IMRT), VMAT plans, helical TomoTherapy, or optimized robotic CyberKnife plans (showing significant increases in SBRT treatment times). [23][24][25][26] However, for a single dose of lung SBRT treatments, highly modulated IMRT/ VMAT plans are susceptible to delivery uncertainties due to smallfield dosimetry error 27 and interplay effects 28 users can control the field aperture shape and create a 3D plan using dynamic conformal arc (DCA) therapy before VMAT optimization.…”

Novel Clinically Weight-Optimized Dynamic Conformal Arcs (WO-DCA) for Liver SBRT: A Comparison with Volumetric Modulated Arc Therapy (VMAT)

“…On the other hand, forward planning-based DCA delivery was shown to be efficient in lung SBRT by degrading the worries of the interplay effect. [21][22][23][24][25] The overall goal with DCA was to reduce treatment time with lower geometric complexity, which may diminish the risk of interplay errors induced by respiratory motion. As Pokhrel et al previously emphasized, flattening filter free (FFF) VMAT for SBRT of lung lesions would improve dose coverage at tumor-lung interface compared to flattened beams, 46 and additionally, there is growing evidence for FFF VMAT of various other tumor sites including the liver, brain, prostate, cervix cancers.…”

“…While lung SBRT studies have attested the necessity of using multiple arcs to obtain the average benefit for hypo-fractionated VMAT (Dynamic conformal arcs for lung stereotactic body radiation therapy: A comparison with volumetric-modulated arc therapy), an alternative technique such as dynamic conformal arcs (DCA) has been proposed to reduce or eliminate concerns of the interplay effect brought about by MLC movement in small areas. [20][21][22][23][24][25] In this respect, Pokhrel et al uncovered that hybrid 3Ddynamic conformal arc (h-DCA) therapy, a blend of the dynamic conformal arcs and static fields, in lung radiotherapy minimized the small-field dosimetry and MLC interplay effects with ensuant improved target coverage. 26 In the same way, Ross et al modified the dynamic conformal arc (MDCA) technique for lung SBRT and documented improved quality and PTV coverage with shortened treatment times in several clinical models.…”

Exactitud dosimétrica en tratamiento de radiocirugía mediante arcoterapia dinámica conformada y arcoterapia volumétrica modulada

“…El cálculo de la dosis es determinado de forma independiente para cada subarco, permitiendo a quien realiza el plan fijar los puntos de control en espaciamientos entre cada 5 • y 10 • . Comparaciones realizadas con técnicas de intensidad modulada de arco dinámico como también de estático han demostrado que DCA ofrece mejores resultados en la protección de los OAR, distribución de dosis óptima y tiempos de tratamiento menores la convierten en una opción de tratamiento a nivel intra como extracraneal [25] Figura 2.3: Posición del sistema MLC (a) en la técnica DCA y (b) técnica VMAT. Imagen tomada de referencia [25].…”

“…Desde de aplicación clínica en 2007, VMAT se ha convertido en una las técnicas ampliamente usadas en tratamiento de patologías en diferentes regiones (cabeza y cuello al igual que próstata) las cuales eran hasta la fecha tratadas con IMRT Step and Shoot y Sliding Window, obteniéndose reducciones en tiempo, lo que reduce la probabilidad que el volumen blanco se mueva, mayor conformidad especialmente en los tumores con forma cóncava. Los movimientos en arco mientras en haz se encuentran encendido permite aumentar la dosis entregada al volumen blanco sin que esta sobrepase lo tolerado por el tejido sano [25].…”