(Sunday, 7/29/2018) 3:00 PM - 6:00 PM
Room: Exhibit Hall
Purpose: It can be challenging to identify the type of fiducial markers used for the localization of prostate patients. Because markers of similar size and shape are difficult to distinguish with imaging alone, it can be difficult to independently verify which fiducials were placed during treatment planning or physics second check. By evaluating imaging parameters in the CT scan for simulation, scripting tools can help distinguish between fiducials related to their composition.
Methods: Two different fiducials were compared for 72 prostate patients treated at our institution. To better differentiate the marker placement and seed contours, our patients are scanned with 0.125 cm slice thickness. Imaging parameters of gold seeds and Calypso Beacons were compared. All fiducials were contoured during the treatment planning process and were evaluated both manually gathering mean contour values from Eclipse and with an API script to help identify the fiducial type.
Results: We found the difference between the HU values of the fiducials using the average of a profile using a script was 1818 HU (STDEV 251 HU) for Calypso beacons and 2645 HU (STDEV 321 HU) for gold seeds. By evaluating the mean contour value reported by Eclipse, we found 1023 HU (STDEV 376 HU) for Calypso beacons and 2645 HU (STDEV 321 HU) for gold seeds.
Conclusion: By evaluating imaging parameters in the CT scan for simulation, physicists can use scripting tools to help distinguish between fiducials to improve the quality of patient treatment and help alert the team if there are differences in documentation identifying the type of fiducial. A recommended clinical threshold of 2300 HU can be used as a flag during physics second check to verify if the fiducial is a Calypso beacon using the maximum average from a script evaluating the profile of the contour.
Keywords
Not Applicable / None Entered.
Taxonomy
Not Applicable / None Entered.
Contact Email
