br Our mean whole heart doses are consistent with those
Our mean whole MDMB-CHMICA M2 doses are consistent with those of other published estimates for similar regimens (Table E7; available online at https://doi.org/10.1016/j. prro.2019.01.004). Dosimetric uncertainties are larger for cardiac segment doses than for mean whole heart doses because segment doses are more sensitive to interpatient anatomical variability than whole heart doses. Our estimated cardiac doses are subject to several other unavoidable sources of uncertainty that are common to all radiation therapy CT-planning studies, including errors in contouring,18,30 dose calculation algorithms,31 setup,32,33 and errors caused by cardiac and respiratory motion during treatment.34e36
Cardiac segment-specific doses may be used to rank segments by higher-versus-lower doses in epidemio-logical studies relating cardiac structure injury to radi-ation dose.17 However, the scope for developing quantitative dose-response relationships for cardiac segment injury based on information from the radiation therapy charts of patients treated before the era of 3-dimensional CT planning is limited because different segment doses are often highly correlated, and segment-specific dose uncertainties are not independent of each other.
The authors are grateful to Prof. Mike Partridge, University of Oxford, for his intellectual input.
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