[en] Background and Aim: Adult patients are generally, irrespective of size, given the same amount of activity for a certain type of nuclear medicine examination, a standard dosage. Identical image quality is essential when comparing different patient studies. The aim of this study is to evaluate different dosage methods for Tc-99m-MDP bone scintigraphy and to investigate whether individual dosage will decrease the variations in image quality between different patients. Material and Methods: 100 consecutive adult patients (aged between 40 and 89 years) undergoing whole body bone scintigraphy were studied. Eight patients were excluded from the study because of abnormal high uptake in the areas of interest. The patient weight and height were registered. The activity in the syringes was measured before and after the injection of about 600 MBq Tc-99m MDP. Scanning was performed, with a dual head gamma camera (Maxxus or Millennium VG, General Electric) equipped with a high-resolution collimator, at approximately 4 hours (mean 3.8 h) post-injection. Regions of interest (ROI) were drawn over the lumbar spine (posterior view), the right femur (anterior view) and also soft tissue background regions for each area. The total counts, maximum counts/pixel and number of pixels in the ROIs were registered. The maximum number of counts/pixel (background-subtracted), SPINEmax and FEMURmax were chosen as the image quality parameters. For each patient, SPINEmax and FEMURmax where recalculated to the number that would have been obtained with standard dosage (exactly 600 MBq), and dosage proportional to body weight, body surface area and body height. All values were corrected to a scanning time 3.8 h after injection. Results: Both with a standard activity dosage and a dosage proportional to body height, SPINEmax decreases with increasing body weight. Dosage proportional to body weight gives increasing values of SPINEmax with increasing body weight. Dosage proportional to body surface area gives no body weight dependence of SPINEmax. For all methods the variation in SPINEmax is large, with a coefficient of variation of approximately 25%. For the other image quality parameter, FEMURmax, it is the dosage method proportional to height which gives no dependence of patient size. Conclusion: It is possible to reduce the variations in count level (image quality) for bone scan patients using individual dosage based on body size. However, most variations remain because of other individual factors