David Borrego MS, Presenter: Nothing to Disclose

Daniel A. Siragusa MD, Abstract Co-Author: Nothing to Disclose

Wesley E. Bolch PhD, Abstract Co-Author: Nothing to Disclose

Knowledge of a patient’s organ doses from a fluoroscopically guided interventional (FGI) procedure is prudent for longitudinal dose tracking and assessing procedural risks. The authors of this work have focused on quantifying patient organ doses to compliment previous efforts of a rapid in-clinic peak skin dose algorithm. These methods allow for the computation of patient-specific organ doses per procedure without the limitations of dose conversion coefficients (DCCs).

Upon completion of a FGI procedure the RDSR is used to generate inputs for a Monte Carlo transport code. The software accounts for patient anthropometric variations with a library of hybrid computational phantoms. A one-time entry of geometry models, measured half-value layers, and KAP calibration factors is required. By clinician design, only five parameters are needed: patient sex, age, height, weight, and patient position on the table. The absorbed dose to organs is determined with energy deposition and volume-averaged fluence tallies. By default, these methods allow for dosimetry to 17 organ sites including breast, gonad, and the two radiosensitive skeletal tissues – active and shallow marrow. The list of organs amenable to dosimetry is extensive and dependent on physician input.

On average, the wall time for an entire RDSR is 38-min. In/out-of-field organ doses converged to within 1%. Neither the cumulative reference air kerma nor KAP correlated well with the excess lifetime risk of cancer incidence due to a FGI procedure (Pearson coefficients of r=0.07 and r=0.14 respectively). While not all irradiation events contribute equally to the aggregate organ dose, they do all contribute equally to computational time. In the interest of reducing computational time, limiting the model to only those irradiation events with a cumulative reference air kerma in the 50th percentile and above can provide reasonable estimates of the organ doses - within 10%.

One can achieve absolute organ dosimetry without the use of DCCs on a patient-dependent phantom. The results demonstrate clinical feasibility and require only minimal input parameters from clinicians.

This software may serve as a powerful training tool for physicians and clinical staff by providing high-specificity dosimetric reports for radiation safety protocols.

Borrego, D, Siragusa, D, Bolch, W, Computing Organ Doses from Fluoroscopically Guided Interventions Equipped with Radiation Dose Structured Reporting (RDSR).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009783.html