Computational phantom libraries have been developed over the years to enhance the accuracy of Monte Carlo-based radiation dose calculations from radiological procedures. In this work, we report on the development of an adult computational anthropomorphic phantom library covering different body morphometries among the 20-80 years old population. The anatomical diversities of different populations are modeled based on anthropometric parameters extracted from the National Health and Nutrition Examination Survey (NHANES) database, including standing height, total weight and body mass index. Organ masses were modified to match the corresponding data. The ICRP reference male and female models were selected as anchor phantoms. A computer code was developed for adjusting standing height and percentage of fat free mass of anchor phantoms by 3D scaling. The waist circumference and total body mass were further adjusted. The diversity of organ masses due to anthropometric differences deviates from the mean values by about 3-21%, while this deviation exceeds 50% for genital organs. Thereafter, organ-level absorbed doses from both internal and external radiation exposure conditions were estimated. A total of 479 phantoms corresponding to seven age groups were constructed for both genders, thus fulfilling the criteria for representing a diverse adult population with different anthropomorphic and anatomical characteristics