What is brachytherapy?

In this short video for our 100 Second Science series, Rachel Lea introduces the form of radiotherapy known as brachytherapy. Over a hundred years old, this treatment involves targeting cancer cells with radioactive sources no larger than a grain of rice. Lea, a principal clinical scientist at the Christie Hospital in Manchester, describes the medical situations in which brachytherapy is used and how the treatment has evolved over the decades.