Click here to


Are you sure ?

Yes, do it No, cancel

Scripting API-Based Frame Coordinate Calculator for Stereotactic Body Radiotherapy

Y Park1*, Z Iqbal1, A Pompos1 (1) UT Southwestern Medical Center, Dallas, TX


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: frame-based stereotactic body radiotherapy (SBRT), plan-specific frame coordinates are manually calculated to aid therapists with initial patient setup. This study aims to develop a semi-automatic frame coordinate calculator using scripting API technology to improve accuracy and efficiency in SBRT workflow.

Methods: CT image of an Elekta stereotactic body frame was acquired as a template for image registration. A C# application using Eclipse scripting API (ESAPI) and an open source image processing library (SimpleITK) was developed to: 1)Load patient CT data with plan isocenter position; 2)Overlay patient’s 2D images (axial, coronal and sagittal images) with the corresponding template images; 3)Provide a user-friendly interface for manual 2D/2D registrations; 4)Automatically calculate the absolute frame coordinates using the shift information from the registrations. A constant offset value which is added to the plan-specific registration shift was calibrated using a sample plan with the known shift value from a manual calculation. The software was validated for 10 clinical SBRT plans.

Results: mean absolute errors of the frame coordinates calculated from the software compared to those from the manual method were 1.3±0.9 mm, 1.2±0.9 mm and 1.6±1.1 mm, in lateral, anterior/posterior and superior/inferior directions, respectively. From the feedback of dosimetrist users, the calculation and printing time is <2 mins using the developed tool, compared to >5 mins using the manual calculation. After a year of use, it was demonstrated that the software successfully removes the relevant human errors.

Conclusion: semi-automated software tool empowered by scripting API technology was developed to quickly calculate and print frame coordinates for SBRT. The efficiency and the accuracy in calculating frame coordinates was notably improved by using the software. Future work includes implementing fully automated registration using advanced image processing methods.


Stereotactic Radiosurgery, Immobilization, Software


TH- RT Interfraction Motion Management: setup errors, immobilization, localization

Contact Email