Shannen Doherty is continuing to battle cancer with her first day of radiation treatment.

“I look like I’m about to make a run for it which is accurate. Radiation is frightening to me,” the 45-year-old actress wrote on Instagram on Monday, “Something about not being able to see the laser, see the treatment and having this machine moving around you just scares me.”

The 45-year-old continued, “I’m sure I’ll get used to it but right now…. I hate it.”

Doherty was diagnosed with breast cancer in early 2015. In August, she revealed that the cancer had spread to her lymph nodes and that she would undergo chemotherapy followed by radiation.

“I think what’s beautiful and hard and interesting about cancer is that it tears you down and builds you, and tears you down and builds you, and it remakes you so many different times,” she said in an emotional interview with Chelsea Handler last month. “The person I thought I was supposed to be, or was going to be, or who I thought I was six months ago is now somebody completely different.”

A photo posted by ShannenDoherty (@theshando) on

This article originally appeared in Page Six.