Answers:

1. Dose depends on the imaging protocol acquisition settings (kVp, mA/mAs, Pitch etc) and attenuation of x-rays in tissues depends also on tissue density and x-rays energy. The lower the x-rays energy the higher the absorbed dose.

2. High Z number and highly dense tissues will have higher stopping power and hence higher attenuation of x-ray beams and shows-up as brighter pixels/areas generated images.

Hope this provide you a some elements of the answer you looking for.

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