- Dose area product
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Dose area product (DAP) is a quantity used in assessing the radiation risk from diagnostic X-rays examination and interventional procedures. It reflects not only the dose within the radiation field but also the area of tissue irradiated. Therefore, it may be a better indicator of the overall risk of inducing cancer than the dose within the field. It also has the advantages of being easily measured, with the permanent installation of a DAP meter on the X-ray set. DAP is expressed in Gray square centimetres (Gy*cm²)[1] (sometimes mGy*cm² or cGy*cm²). Manufacturers of DAP meters usually calibrate them in terms of absorbed dose to air.
Kerma area product (KAP)[1] is a related quantity which for all practical radiation protection purposes is equal to dose area product. However, strictly speaking DAP = KAP x (1-g) where g is the fraction of energy of liberated charged particles that is lost in radiative processes in the material[2], and the dose is expressed in absorbed dose to air. The value of g for diagnostic X-rays is only a fraction of a percent.
Coronary angiography and PCI produces expose patient to an average DAP in the range of 20 to 106 Gy*cm² and 44 to 143 Gy*cm² respectively.[3]
References
- ^ a b Kim S, Toncheva G, Anderson-Evans C, Huh BK, Gray L, Yoshizumi T (June 2009). "Kerma area product method for effective dose estimation during lumbar epidural steroid injection procedures: phantom study". AJR Am J Roentgenol 192 (6): 1726–30. doi:10.2214/AJR.08.1713. PMID 19457841.
- ^ ICRU Report 50, Fundamental Quantities and Units for Ionizing Radiation, International Commission on Radiation Units and Measurements 1998
- ^ priory.com RADIATION EXPOSURE IN THE CATH LAB – SAFETY AND PRECAUTIONS Dr S M S Raza, MB BS, MD. First Published October 2006
Categories:- Radiology
- Medical terms
- Nuclear medicine
- Medical physics
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