Radha's full first name, Radha-Rani, was based on the name of the favourite consort of the Hindu god Krishna, followed by the Indian word Rani for queen. Her mother reportedly developed a love for India in the early 70's, inspiring her name. I'm not sure how popular it is in India, but it is not in the top 1000 in the US, or the top 100 baby names in Australia. For those of you familiar with the website www.names4real.wordpress.com (if you're not, it's well worth checking it out), it isn't even listed on their website, so must be rarely used in the western world indeed.
Radha is a Sanskrit name, pronounced RAA-daa, meaning 'success' or 'affluence'. I love the sound of Radha. Maybe it's due to the Rah sound, which reminds me of cheering and generally being happy. It also sounds kind of futuristic, like it wouldn't be out of place in 'The Hunger Games' or any post-apocalyptic tale (take note if you're a writer looking for these types of names!). Radha is a unisex name, and I think it could work well for either a boy or a girl.
Having a famous namesake has its benefits and its drawbacks. The benefit is that people are more likely to have heard of the name and therefore know how to pronounce it, despite it being a rarely used name. But the drawback is that it is more likely that people would be "Oh, like Radha Mitchell?". If you're a fan of Radha Mitchell, this isn't necessarily a problem though. With a happy sound and an aspirational meaning, this is one name that could potentially be a winner if it gets noticed by enough people.