A mouse-sized test phantom containing TL dosemeters was exposed to X-rays having a HVL value of 1.4-2.8 mm Cu. Dependence of the response of ⁷LiF dosemeters on the HVL of the incident beam resulted in an increase of TL response per rad in muscle for dosemeters positioned at the central axis of the phantom compared with the response of similar dosemeters exposed free-in-air. An increase of 7.3% in TL response per rad in muscle was found over the HVL range. The spread in effective energy inside the phantom was small and the dose distribution may be estimated directly from the TL response of ⁷LiF dosemeters at the entrance, central and exit position in the phantom.