R Makkia*, M Fadhel, M Hoerner, D Vergara, Yale New Haven Hospital Department of Radiology and Biomedical Imaging and Yale University School of Medicine, New Haven, CT

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  R Makkia

SU-J-201-4 (Sunday, 7/10/2022) 4:00 PM - 5:00 PM [Eastern Time (GMT-4)]

Room 201

Purpose: The purpose of this study is to accurately estimate the radiation-induced skin injuries following a single or multiple FGIPs using the Radiation Dose-Structured Report (RDSR). To estimate the Peak Skin Dose (PSD) from the RDSR, a hybrid computational phantom that matches the patient's weight and height was created.

Methods: FGIP was performed on a male anthropomorphic phantom using calibrated nanoDot OSLDs (reference) arranged in a grid pattern on the posterior surface of the anthropomorphic phantom. The FGIP contained primary and secondary angulation, table shifts, square and rectangular fields. To construct a hybrid computational phantom, the patient's skin 3D surface was built using RhinocerosTM 6.0 (Rhinoceros, Seattle, WA) from the adult ICRP reference voxel-male-phantom. A second method used a computationally generated ellipsoidal phantom of the patient. Both phantoms’ sizes were based on the patient’s dimensions. The dose distribution was computed on both phantoms using Matlab software, in accordance with TG-357. The skin dose mapping on the hybrid computational phantom and the ellipsoidal phantom were compared with reference measurements.

Results: The estimated PSD using the hybrid computational and ellipsoidal phantoms are 225-mGy and 273-mGy, after using the appropriate BSF and table attenuation. Using the NanoDots, the measured PSD is 226-mGy. Applying the hybrid computational phantom method yields a difference of 1% compared to the reference, while the ellipsoidal phantom method yields a 21% difference to the reference. Both methods were lower than using the traditional dose conservative methods, which yields 41% difference to the reference.

Conclusion: The hybrid computational ICRP models accurately reflect the existing computational standards from the ICRP and can be useful in evaluating radiation PSD from FGIPs. The traditional “dose conservative” method yields a higher difference against our fluoroscopy PSD measurements while the hybrid computational phantom calculation method yielded a more accurate PSD estimate than using ellipsoidal phantom.

Keywords

Fluoroscopy, Phantoms, Dosimetry

Taxonomy

IM- Radiation Dose and Risk: General (Most Aspects)

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