Binding energy is equal to the amount of energy which is used to free electrons or disintegrate nuclides from their atomic bond.
The electron binding energy of a hydrogen atom is with 13.6 eV very low. The nuclear binding energy of an alpha-particle, energy equivalent of the sum of the individual masses of nuclides minus the mass of the whole nucleus, is 28.3 MeV.

See also Alpha Decay, Beta Decay and Gamma Quantum.

A bioassay is a medical test to measure, and quantify radionuclides in the body by direct (in vivo) or indirect (in vitro) analysis of tissues or excretions from the body.

See also Radioimmunoassay.

A bitewing radiograph is an intraoral device that demonstrates the crowns, necks and coronal thirds of the roots of both upper and lower teeth. The imaged person bites upon a tab or wing projecting from the center of the image-receptor packet.

See also Bisecting Angle Technique.

Bone densitometry measures the strength and density of bones. Changes in trabecular bone mineral density (BMD) is an early indicator of change in metabolic function. Bone densitometry measures the amount of calcium in regions of the bones. A bone densitometer is used to determine the risk of developing osteoporosis and can also be used to estimate a patient's risk of fracture.
Bone densitometry methods involve:
Dual energy x-rays (DEXA) or CT scans (Osteo CT or QCT) compare the numerical density of the bone (calculated from the image), with empirical data bases of bone density. DEXA is widely available and has an accuracy between those of QCT and ultrasound.

A bone scan or bone scintigraphy is used to in evaluate diseases of the skeletal system. Scintigraphic whole body bone imaging is a highly sensitive method to show changes in bone metabolism. Increased metabolic activity is seen as a hot spot.
The study requires the injection of a 99mTc-labeled radiopharmaceutical (most commonly methylene diphosphonate (MDP), hydroxymethylene diphosphonate (HMDP) or hydroxyethylene diphosphonate (HDP)). The activity administered for bone scanning is around 500 MBq (300-1100 MBq, 8-30 mCi), depending on age and weight of the patient. After 2-5 hours, the emitted gamma rays are detected by gamma cameras. The produced planar images include anterior and posterior views of the skeleton.
Multiphase bone scintigraphy is used to differentiate a bone process from tissue pathology. In some cases additional SPECT imaging is helpful to better characterize the presence, location and extent of disease.