Sir Chris Hoy has released never-before-seen images of him undergoing life-saving chemotherapy treatment for terminal prostate cancer. 

The images show the cycling legend, 48, in a treatment chair with a cumbersome cap secured to his head, as he grins at the camera. 

The father of-two explained that the hat is an ice cap, which is set to -27 degrees celcius and designed to minimise the risk of hair loss.

The images have been released as part of a clip posted to BBC Sport's social media, ahead of an exclusive interview with the sporting legend, to be aired tonight on BBC1. 

The clip also features segments of the interview, in which Sir Hoy explains he was initially not 'fussed' about losing his hair, but changed his view after hearing the concerns of his son Callum, nine.

'My son Callum was quite worried about what might happen,' said Sir Chris. 'Are you going to lose your hair? [he asked]. So for him, I thought, well this [wearing the cold cap] is something I want to do and it's important to do. '

However, Sir Chris admitted that wearing the freezing cold device was far from easy. 

'That was the biggest challenge,' he said. 'It was excruciating. It's like torture. 

 'The strategy was just one step at a time. Just watch that seconds hand go round the clock. If you can do one more minute, that's all you need to do.'

Cold caps are often used by patients undergoing cancer treatment to try and prevent hair loss.

 Its cooling effect reduces blood flow to the scalp, which also reduces the amount of chemotherapy medication that reaches this area, limiting hair loss.

It's usually worn for 15 minutes before each chemotherapy treatment and is thought to reduce the risk of chemo-induced baldness by around 50 per cent.

The new images come amid the six-time Olympic champion's first interview after revealing he could have just two years to live due to advanced prostate cancer. 

Sir Chris told the BBC: 'That was the first thought in my head. How on Earth are we going to tell the kids? It's just this absolute horror, it is a waking nightmare, living nightmare.

'We just tried to be positive and tried to say do you know what, this is what we're doing and you can help because when I'm not feeling well, you can come and give me cuddles, you can be supportive, you can be happy, you can be kind to each other.

 'I'm sure lots of families do it in different ways and I think there's no one right approach for anyone. There's no one-size-fits-all, but for us I think that was the best way to do it.'

While Sir Chris said chemotherapy 'was one of the biggest challenges I've ever faced and gone through', he is trying his best to stay positive and sees chemotherapy as 'a good thing, we're here to try and start punching back, this is going to be a positive fight against the cancer'.

 Sir Chris also took the opportunity to call for prostate cancer testing to be offered more widely.    

Recalling how he had suffered 'no symptoms, no warning, nothing' before his diagnosis, he said: 'It's logical to me - why wouldn't you get the test a little bit earlier?' 

'Catch it before you need to have any major treatment, to me it seems like a no brainer. 

'Why would you not reduce the age [and] allow more men to just go in and get a blood test.'

As a result of Sir Chris' extremely moving testimony, NHS chiefs announced the health service will consider whether to offer men over the age of 45 a screening test. 

Health Secretary West Streeting said he had ordered officials to 'look at whether we are in the right place when it comes to screening'.