Low dose exposure evaluation for hypofractionated breast intensity modulated radiation therapy – taking into account the fraction-size effect with the linear quadratic model


Klin Onkol 2020; 33(6): 474-476. DOI: 10.48095/ccko2020474.


Adjuvant radiation therapy after breast conserving surgery improves local control and reduces cancer mortality [1]. However, first generation breast irradiation techniques, based on wide irradiation fields, were associated with an increased cardiac mortality [2]. Fortunately, radiation therapy techniques evolved and current state-of-the-art breast irradiation techniques, such as rotational intensity modulated radiation therapy (rIMRT), improve cardiac sparing for breast cancer irradiation [3]while homogeneously covering target volumes for complex anatomic cases (such as pectus excavatum or breast implants). However, these recent techniques are associated with a greater low-dose radiation exposure to the lungs when compared with standard tridimensional techniques [4], which may lead to greater pulmonary toxicity such as fibrosis [5]. Hypofractionation for breast rIMRT is currently being evaluated [6] and since hypofractionation lowers total radiation dose, low-dose radiation exposure to the lung may be reduced accordingly. However, the fraction-size effect has to be taken into account when comparing hypo­fractionated regimens. In this perspective, we compared low-dose radiation exposure to the lungs and to the contralateral breast between hypofractionated and normofractionated breast rIMRT, taking into account the fraction-size effect with the linear-quadratic (LQ) model ...


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