Page 201 - Pharmaceutics IV (02-06-01305)

or tolerable damage to healthy, adjacent tissue ,this goal is
difficult R achieve .
Researches will continue to address problems as:
Efficient radiopharmaceutical delivery to the target site ,e.g. the
residence time of radioactivity at the target site, the in-vivo
catabolism & metabolism of the drug ,& the optimization of
relative rates of radiolabeled drug or drug metabolite clearance
from the target site .
Radioisotopes used for therapy can be applied to the target tissue
Either from an external source or administration to patient as a
drug.

1-External source application of radiation
Advantages:
a-The duration of dose titration ,with direct observation of the
target tissue.
b-The radiation source can be removed & terminate treatment
at any time.
e.g. of isotopes: Cobalt (60 Co) ,Cesium ( 137 Cs ),have been used for
the treatment of undesired lesions.
2-Internal application or administration of radiotherapy to
patient
Disadvantage : the source of radiation cannot be removed once
administered .The amount of radioisotope administered to the
patient must be carefully controlled.

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