Abstract: Radiation therapy is one of the important systematic treatment strategies for thoracic neoplasms, but it also can cause a definite cardiac toxicity. With the evolution of main radiotherapeutic technology, the characteristics of heart irradiation dose-volume distribution in patients with thoracic tumor receiving radiotherapy have been changed. The incidence of radiation-related heart diseases (RRHDs) has been significantly decreased. However, precise radiotherapy based on intensity modulated radiation therapy still can not guarantee the absolute cardiac safety currently. This article reviews the effect of heart irradiation dose-volume distribution on potential risks of RRHDs, and the parameters to evaluate heart doses and volume, as well as other techniques affecting the dose-volume distribution of heart irradiation and the detection of RRHDs.