Dosimetric comparison between volumetric-modulated arc radiotherapy and intensity-modulated proton therapy in patients with ventricular tachycardia using stereotactic ablative radiotherapy / 中华放射肿瘤学杂志

ABSTRACT

Objective:To evaluate the dosimetric properties of intensity-modulated proton therapy (IMPT) plans for simulated treatment planning in patients with ventricular tachycardia (VT) using stereotactic ablative body radiotherapy (SABR), in comparison with the volumetric-modulated arc therapy (VMAT).Methods:A total of 25 gross target volume (GTV) of the apical, anterior, septal, inferior and lateral wall of the left ventricle (LV) were delineated on the CT simulation images of 5 patients with complete data. An additional 5 mm GTV margin was added to the internal target volume (ITV), and an additional 3 mm ITV margin was added to the planning target volume (PTV). VMAT and IMPT plans were designed in each target area. Dose prescription was 25 Gy (RBE) in a single fraction. The dosimetric differences of ITV and organ at risk (OAR) were compared between VMAT and IMPT.Results:The median volume of ITV was 45.40 cm 3(26.72-67.59 cm 3). All plans had adequate target coverage(V 95%Rx≥99%). Compared with the VMAT plans, IMPT reduced the D mean of whole heart, pericardium and non-target cardiac tissues (relative difference) by 44.52%, 44.91% and 60.16%, respectively, which also reduced D 0.03 cm 3 of the left anterior descending artery by 17.58%( P<0.05). After stratified analysis according to the lesion sites, IMPT could still reduce the dose of most OAR. However, the D 0.03 cm 3 of LAD and LCX for the lesions in the anterior wall of LV, the D 0.03 cm 3 of LCX in the inferior wall and D 0.03 cm 3 of LAD in the apical wall did not significantly differ (both P>0.05). Conclusions:Both VMAT and IMPT plans can meet the clinical dosimetric requirements when SABR is simulated in patients with VT. However, IMPT can lower the dose of normal heart tissues, which has the potential benefit of reducing the risk of complications, such as ischemic heart disease, pericarditis/pericardial effusion, etc.