The touching photo which shows a side of cancer treatment that's usually hidden.

Last week, a Californian teenager captured her father in a candid moment.

Mackenna Newman took a photo of her dad Jon sitting at a makeshift desk set up outside his bedroom door.

He was keeping her mother, Marci, company – from a safe distance.

As the 17-year-old explained when she shared the photo on Twitter, her mother was diagnosed with thyroid cancer in October and had to spend the week in isolation following her radiation treatment.

Hence, Jon’s bright idea.

The photo has already been retweeted more than 6,400 times, with many Twitter users wishing the family all the best during a difficult period.

LISTEN: Mia Freedman speaks to Emma Betts, who has now passed, about her early cancer diagnosis. Post continues after. 

“The amount of love I’ve received is crazy and I didn’t expect any of it, but I’m so grateful,” Mackenna told Buzzfeed, with her mum adding that the gesture was not unusual from her husband.

“Jon goes to every doctor’s appointment, every blood test, every surgery, every radiation. And as you can see, if he can’t be by my side he is as close as he can get,” Marci said.