Thulium is used in portable X-ray devices, particularly in medical and dental applications where compact and lightweight equipment is needed. It serves as a radiation source in certain types of X-ray machines due to its ability to emit X-rays when bombarded with electrons. These devices are useful in field medicine, remote clinics, and veterinary practices where traditional X-ray systems are impractical.

In addition, thulium is used as a dopant in solid-state lasers, especially in yttrium-aluminum-garnet (YAG) crystals, producing lasers that operate in the mid-infrared range. These lasers are employed in surgical procedures, dermatology, and lithotripsy due to their precision and minimal damage to surrounding tissues.

Thulium also finds use in high-temperature superconductors and in arc lighting for specialized illumination. Its unique luminescent properties make it valuable in certain types of optical sensors and in the development of fluorescent materials for display technologies.