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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

Purpose:
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.

Methods:
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.

Results:
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.

Conclusions:
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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