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.

This article presents a case of acute ST-segment elevation myocardial infarction (STEMI) in a pregnant woman caused by coronary artery dissection. The 41-year-old patient had undergone cardiac valve surgery at the age of 1 and had no risk factors such as hypertension, diabetes, smoking, alcohol use, or a family history of coronary artery disease. At 31 +1 weeks of gestation, she experienced sudden chest pain for 4 hours and was emergently referred to Peking University First Hospital on June 1, 2021. Electrocardiogram revealed ST-segment elevation in leads I, aVL, and V 2 to V 6. Biochemical assays showed elevated levels of high-sensitivity cardiac troponin I and creatine kinase-MB. Echocardiography indicated segmental ventricular wall motion abnormalities (apical) and reduced left ventricular function, confirming the diagnosis of acute anterior wall STEMI. The patient promptly underwent emergency coronary angiography and percutaneous coronary intervention and confirmed coronary artery dissection. Postoperative care included antiplatelet, anticoagulation, and supportive treatment. At 34 +3 weeks of gestation, with the condition of acute anterior wall STEMI being relatively stable, a cesarean section was successfully performed. Regular cardiology follow-ups were scheduled postpartum, and cardiac function was normal in two years after discharge.