Preplanning prediction of the left anterior descending artery maximum dose based on patient, dosimetric, and treatment planning parameters

Abstract

PurposeMaximum dose to the left anterior descending artery (LADmax) is an important physical constraint to reduce the risk of cardiovascular toxicity. We generated a simple algorithm to guide the positioning of the tangent fields to reliably maintain LADmax <10 Gy.Methods and materialsDosimetric plans from 146 consecutive women treated prone to the left breast enrolled in prospective protocols of accelerated whole breast radiation therapy, with a concomitant daily boost to the tumor bed (40.5 Gy/15 fraction to the whole breast and 48 Gy to the tumor bed), provided the training set for algorithm development. Scatter plots and correlation coefficients were used to describe the bivariate relationships between LADmax and several parameters: distance from the tumor cavity to the tangent field edge, cavity size, breast separation, field size, and distance from the tangent field. A logistic sigmoid curve was used to model the relationship of LADmax and the distance from the tangent field. Furthermore, we tested this prediction model on a validation data set of 53 consecutive similar patients.ResultsA lack of linear relationships between LADmax and distance from cavity to LAD (−0.47), cavity size (−0.18), breast separation (−0.02), or field size (−0.28) was observed. In contrast, distance from the tangent field was highly negatively correlated to LADmax (-0.84) and was used in the models to predict LADmax. From a logistic sigmoid model we selected a cut-point of 2.46 mm (95% confidence interval, 2.19-2.74 mm) greater than which LADmax is <10 Gy (95% confidence interval, 9.30-10.72 Gy) and LADmean is <3.3 Gy.ConclusionsPlacing the edge of the tangents at least 2.5 mm from the closest point of the contoured LAD is likely to assure LADmax is <10 Gy and LADmean is <3.3 Gy in patients treated with prone accelerated breast radiation therapy.

Knowledge‐based planning for intensity‐modulated radiation therapy: A review of data‐driven approaches

“…These methods aim to predict single or a small number of dose metrics to either guide plan optimization or a specific planning decision (e.g., the need for hydrogel injection) …”

“…One or more specific dose metrics (14 articles) These methods aim to predict single or a small number of dose metrics to either guide plan optimization or a specific planning decision (e.g., the need for hydrogel injection). 21,[43][44][45][46][47][48][49][50][51][52][53][54][55] 3. Voxel-level doses (13 articles) This group of methods predicts dose at each voxel in 3D space.…”

Safety Margins for the Delineation of the Left Anterior Descending Artery in Patients Treated for Breast Cancer

“…10 Cooper et al suggested only 2.5 mm. 19 These protocols have the advantage of being simple, but they cannot be applied when using volumetric modulated arc therapy techniques because the fields are not static and constantly change. It is interesting to note that the delineation method was not described in any of these articles.…”

Technical Challenges of Heart Avoidance for Synchronous Breast and Lung Cancers in a Postmenopausal Female: A Planning Case Report From a Safety-Net Hospital

“…Lind et al 25 studied single-photon emission tomography myocardial perfusion imaging in 69 patients who underwent RT for left-sided BC and found perfusion defects in the LAD distribution, pointing to a likely mechanism of cardiac damage. Copper et al 26 suggested the maximum LAD dose (LAD max ) may be more clinically relevant over the mean LAD dose, as occlusion of only 1 section of the LAD can result in symptomatic heart disease and proposed LAD max < 10 Gy. Our patient’s LAD max was very close at 10.9 Gy.…”