A junior doctor took intimate photos of patients and secretly filmed his colleagues getting changed at a major regional NSW hospital for sexual pleasure, court documents reveal.

A worried mother was the first person to raise suspicions about Nicholas Chia Wei Chu after he asked to take a photo of a 16-year-old patient's genitals during an assessment for appendicitis at Orange Health Service.

The woman reported the treatment of her child to hospital management in early 2023, leading police to Chu's devices filled with intimate photos of patients and covert recordings of co-workers.

Detectives also found hundreds of videos Chu had secretly filmed of friends naked in their bathrooms and bedrooms at houses in Orange, in central western NSW, and Sydney.

Chu, 27, last week pleaded guilty to a string of charges over covert images and videos of 11 patients, three friends and an "unknown" number of colleagues.

Among the admissions was one count of producing child abuse material, related to 21 intimate photographs of a 14-year-old patient.

On Thursday, Orange Local Court Magistrate David Day revoked Chu's bail and placed him in custody ahead of his sentencing.

According to an agreed statement of facts tendered in court, Chu admitted to police he took covert photos of patients.

"The offender explained he used these photographs later for his pleasure," the document said.

Chu took photos of several patients' genitals when they were in severe pain or unconscious, including a person who was undergoing bowel imaging in late 2022.

In early 2023, Chu told a patient experiencing chest pains about the possibility of deep vein thrombosis.

Chu asked the patient to strip down to their underwear so he could take photos to show his supervisor.

He took photos from a distance, which the victim "found odd" because they were supposed to be of their calves only.

Images of the patient in underwear were found on Chu's devices, along with a photo of their medical records.

In another incident, Chu examined a patient with leg injuries and ordered an ultrasound to look for tendon damage.

"While the victim was undergoing the ultrasound the offender took photographs of the victim's buttocks," the court document said.

Another patient questioned Chu's behaviour when he tried to move their underwear during an examination for a back injury.

"It's not sore down there, that's not my back," the patient told him.

A photograph of that patient's exposed buttocks was found on Chu's devices.

In several instances, Chu, who was a junior medical officer in the emergency department, asked patients whether he could take photos for medical purposes to show senior doctors.

But the head of emergency told police he never asked Chu to take photographs and was not shown any images.

The court document also revealed Chu secretly positioned his phone to film hospital staff in "various states of undress" between January 2022 and February 2023.

Chu, who has been suspended from practising, will face the NSW District Court in October.