Comparison of semiautomated tangential VMAT with 3DCRT for breast or chest wall and regional nodes

Abstract

Radiotherapy to the breast after surgery sometimes requires adjoining nodes to be included in the treatment volume. In these cases, the traditional approach has been a complex 3‐Dimensional Conformal Radiotherapy (3DCRT) beam arrangement which can result in significant dose heterogeneity at the beam junctions. A Volumetric Modulated Arc Therapy (VMAT) beam arrangement has previously been proposed for breast cases, where the chest wall/breast is treated with a limited angle (partial arc) tangential VMAT technique (Virén et al. [2015] Radiat Oncol. 10:79). In our study, this approach is extended to breast and chest wall cases with adjoining nodes by adding a separate conventional VMAT arc field specifically limited to the superior nodes. This VMAT method was implemented using a semiautomated approach on 27 patients, and the resultant plan compared to a monoisocentric 3DCRT plan. Plan statistics, Dose‐Volume Histogram (DVH) analysis and Radiation Oncologist (RO) preference were assessed. When compared to the 3DCRT technique, the VMAT planning method was found to result in better target volume coverage, high doses to organs at risk (OAR) were reduced but greater OAR volumes received low doses. Having said that, the volume receiving low doses with this tangential VMAT technique was less than that of other VMAT planning methods described in the literature, and the integral dose was less than the 3DCRT method. The VMAT technique also resulted in more robust junction doses that the 3DCRT method. RO review found that the VMAT technique was preferred in 81% of cases. Specifically, the VMAT plans were preferred in all categories of patients except left chest wall cases where the intermammary nodes were also treated. The VMAT technique described here is a useful addition to the treatment options available for breast/chest wall and nodal patients.

In regards to Bogue J, Wan J, Lavey RS, Parsai EI. Dosimetric comparison of VMAT with integrated skin flash to 3D field‐in‐field tangents for left breast irradiation. Journal of applied clinical medical physics. 2019 Feb;20(2):24‐9

“…These articles are related to the use of volumetric modulated arc therapy (VMAT) technique for breast and chest wall radiotherapy. We hereby raise two concerns regarding the technique by Bogue J et al, and other authors [2][3][4][5][6] which have more to do with the planning systems and their optimization processes rather than about the authors or their methodologies.…”

“…We have read the article published by Bogue J et al 1 and in conjunction the few other articles [2][3][4] published in your esteemed journal in recent times. These articles are related to the use of volumetric modulated arc therapy (VMAT) technique for breast and chest wall radiotherapy.…”

“…However not all planning systems are capable of producing clinically acceptable dose distributions with shorter arcs. [1][2][3][4][5][6][7][8] Use of large arcs will make dose statistics for planning target volume better (dose coverage, heterogeneity index, hot spot) but will completely change the low dose characteristics of the treatment plan. Changes in low dose characteristics of the treatment plan is highly undesirable since it would make the clinicians uncomfortable with difficult choices for dose limits of critical organs (lung, heart) 9 and have its own demerits and implications.…”

“…10,11 The other point is the generation of the skin flash margin using a virtual bolus for Eclipse planning system. [1][2][3][4][6][7][8]…”

Breast boost vector: a new metric proposed to optimise isocentre location in an fIMRT–VMAT hybrid technique for a simultaneous integrated boost in breast radiotherapy

“…To overcome potential issues such as adjoining nodes irradiation or additional dose escalation of the tumour bed in a simultaneous integrated boost (SIB) scheme, volumetric-modulated arc therapy (VMAT) is being implemented to whole breast irradiation or for partial arcs in hybrid techniques. [5][6][7] Standard of care for boost breast radiotherapy is to administer radiation sequentially to the whole breast and then to the tumour bed. Nevertheless, SIB techniques are currently under study whether they are more or equally effective compared to conventional schemes.…”