A novel method of determining a body surface for collision detection using CT localization radiograph

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Imaging Science

Background:

• Identifying patient collision risk during radiation therapy often requires expensive equipment.
• Accurate localization of the patient's body surface is crucial for safe treatment delivery.

Purpose of the Study:

• To develop a cost-effective method for determining patient body surface coordinates using readily available planning CT localization radiographs.
• To assess the accuracy of this novel method in preventing collisions between the patient and the treatment machine gantry.

Main Methods:

• Metallic markers were placed on a mannequin's elbow.
• Localization radiographs were acquired at various tube angles.
• Three-dimensional coordinates were calculated from selected radiographs and compared to reference coordinates.

Main Results:

• The average difference between estimated and reference coordinates was within millimeters.
• Specific tube angle combinations showed greater deviations, highlighting optimal angle selection.
• The method demonstrated sufficient accuracy for preventing gantry collisions, with minor discrepancies compared to direct measurements.

Conclusions:

• Localization radiographs offer a viable, low-cost alternative for patient surface localization in radiotherapy.
• This method enhances patient safety by enabling accurate identification of potential collision points.
• Further optimization of tube angle selection can improve the precision of this technique.