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Bone scans

Technetium 99m labelled MDP (Mono - diphosphonate)

1. Pure gamma emitter

2. Half life only 6 hours

- limits radiation exposure

3. Localises in bone

- chemical interaction on the surface of the hydroxyapatite crystal of bone

- phosphorous component interacts with the endogenous calcium

- produces insoluble technetium calcium phosphate complexes.

Three 1° Ossification centres

- two lateral masses with posterior arch in between

- anterior arch which appears at 1 year

- posterior arch fuses at 4 years

- anterior & posterior fuses to body at 7 years

Five 1° Ossification centres

- two neural arches / lateral masses

- two 1/2 dens

- body

Five 2° Centres