Tumoural hypoxia can influence response toradiotherapy and other treatments,andoxygenation status has proved to be a prognosticindicator of the outcome of radiotherapy.Therefore,it is important to assess tumoural hypoxiaand reoxygenation before selection of treatmentprotocols.During the last two decades,muchattention has been paid to noninvasive imagingtechniques using radiolabelled markers for thedetection of hypoxic cells in solid tumours.Technetium (~(99m)Tc) is a very convenient isotope foruse with such imaging because it is readily availableand suited to routine clinical use.~(99m)Tc labelledligands containing 2-nitroimidazole have been Tumoural hypoxia can influence response toradiotherapy and other treatments, andoxygenation status has proved to be a prognosticindicator of the outcome of radiotherapy.Therefore, it is important to assess tumoural hypoxiaand reoxygenation before selection of treatment protocols. During the last two decades, muchattention has been paid to noninvasive imagingtechniques using radiolabelled markers for the detection of hypoxic cells in solid tumors.Technetium (~ (99m) Tc) is a very convenient isotope foruse with such imaging because it is available and suited to routine clinical use. ~ (99m) Tc labeled ligands containing 2 -nitroimidazole have been