X-ray

X-rays were a type of ray used in medical examinations.

In the 1970s, x-rays were used on the Doctor at Ashbridge Cottage Hospital, revealing binary vascular system and astounding Dr. Henderson. (DW: Spearhead from Space) In 1999, Dr. Grace Holloway was similarly astounded at the Doctor's x-ray results. (DW: Doctor Who)

the Doctor cured Liz Shaw and Captain Harvey of their possession by a sentient virus by using an x-ray machine on them. (DWA: Invaders Invisible)

In 2003, the Doctor used a singularity which generated x-ray pulses to sterilize Agent Yellow, saving humanity at the cost of killing millions. (NA: Eternity Weeps)

In 2007, the Doctor destroyed one of Florence Finnegan's Slabs by using his sonic screwdriver to increase the radiation of Royal Hope Hospital's x-ray machine by 5000%. (DW: Smith and Jones)

The Bekaran deep-tissue scanner used by Torchwood Three had greater accuracy and definition than a standard x-ray machine. (TWN: Another Life)

In the 21st century, Space Station W3 was armed with an x-ray laser. (DW: The Wheel in Space)

The Mantis leader, in his attempts to learn the nature of the Doctor's TARDIS, had it subjected to x-rays, discovering it was dimensionally transcendental nature and that the the Doctor was inside it. (TVC: Size Control)