41 The EANM practice guideline for Bone Scintigraphy Preparation is done by addition of the required amount of sodium pertechnetate [99mTcO 4 -] diluted in sterile physiological saline to the vial in accordance with the manufacturer’s procedures. After labeling, the preparation should be kept at between 4 and 8 °C or either at room temperature, depending on brand used, and remains stable for eight hours. Because the radiopharmaceutical is susceptible to oxidation, care should be taken to avoid introducing air into the multidose vial during preparation or removal of doses. The radiopharmaceutical should be used within 6 hours after preparation unless otherwise mentioned by the manufacturer. 5. Administered activity The radiopharmaceutical has to be administered by the intravenous (IV) route, e.g. using direct IV injection, an indwelling catheter or butterfly needle. The activity of radiopharmaceutical to be administered should be determined after taking account the directive of the Council of the European Union (Directive 2013/59/ EURATOM), which guarantees health protection of individuals with respect to the dangers of ionising radiation in the context of medical exposure. According to this directive, member states are required to bring into force such regulations as may be necessary to comply with the directive. One of the criteria is the designation of Diagnostic Reference Levels (DRL) for radiopharmaceuticals; these are defined as levels of activity for groups of standard-sized patients and for broadly defined types of equipment. These levels are expected not to be exceeded for standard procedures when good and normal practice regarding diagnostic and technical performance is applied. For the above mentioned reasons the following activity for 99mTc-bisphosphonate should be considered only a general indication, based on the data of the literature and current experience. However, it should be noted that in each country nuclear medicine physicians should respect the DRLs and the rules set out by local law. For bone scintigraphy in adults, the average activity administered by a single intravenous injection should be 500 MBq (300-740 MBq, 8-20 mCi) (table 1). The administered activity usually ranges between 8 to 10 MBq/kg for adults. Lower activities may be used when equipment with higher detector sensitivity or resolution recovery resulting in similar image quality is available. For markedly obese adult patients, the administered activity may be increased to 11-13 MBq/kg. If the injected activity falls outside these recommended limits for clinical reasons, any deviation from this interval should be kept as small as possible. Practitioners could be required to justify administration of activities greater than local national DRLs. 2