The study had no comparison group, but researchers said the results compare well to historical data for similar patients who had radiation.

尽管这项研究没有设对照组，但研究人员表示，他们的研究结果相比之下不亚于接受放疗的类似患者的历史数据。

He noted that since the study did not have a comparison group getting regular ECG measurements, there is no way of knowing if the device missed heartbeat problems.

他指出，研究并未让对照组接受常规心电图测试，所以无法知道该设备是否有错过的心跳问题。