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Simple Approach to Determine Patient's Entrance Skin Exposure for Radiographic

S Maricle

S Maricle1*, L Jeutang1, G Prasad2, (1) Rosalind Franklin University of Medicine and Science, North Chicago, IL, (2) NorthShore University Hospital, Evanston, IL

SU-E-I-108 Sunday 3:00:00 PM - 6:00:00 PM Room: Exhibit Hall

To evaluate a model which can predict patient's Entrance Skin Exposure (ESE) from height and weight and a single kVp mR/mAs measurement for radiographic.

Patient height, weight and post exposure mAs are obtained to assess ESE based on IAEA model. Patient's thickness is obtained by assuming a cylindrical geometry. The validity of this assumption is tested against actual measurements. Source to Skin Distance (SSD) is computed from patient's thickness and the Source-Image receptor Distance (SID) used during exposure. Entrance Skin Exposure is calculated as a product of post exposure mAs and a single 80 kVp mR/mAs obtained at a reference distance corrected inversely for SSD. Values of mR/mAs at other kVp's are obtained by quadratic variation of output with kVp.

The validity of predicting patient thickness will be presented based on numerous measurements performed on test subjects. Deviation between the ESE values using of single kVp, mR/mAs measurement and the ones obtained by the conventional multiple kVp mR/mAs will be presented as well.

This work indicates a simple approach to determine the patient's ESE based on the patient's height and weight for radiographic units, which will be very useful for institutions that do not have a dedicated physicist.

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