As imaging technologies become increasingly advanced, it is possible to obtain detailed morphological information as well as functional imaging data. In some imaging technologies, the radiation dose increases with the ability to obtain better images or more detailed information. We encountered three cases of temporary bandage-shaped hair loss, which was caused by perfusion studies of the head by multi-detector row computed tomography (MDCT) for evaluation of cerebral blood flow in patients with vascular disorders. In all three patients with temporary hair loss, two angiographies of the head had been performed in the period of serial CT examinations. This suggested the possibility that radiation exposure from angiography performed in serial examinations, combined with the perfusion studies of the head with MDCT, played an important role in this temporary, bandage-shaped hair loss. Radiologists should be aware that a cumulative or multiplier effect of radiation exposure from multiple diagnostic techniques may result in hair loss and other types of radiation complications.