Technical note: Short-time sequential high-energy gamma photon imaging using list-mode data acquisition system for...

Area of Science:

• Medical Physics
• Nuclear Medicine
• Radiation Oncology

Background:

• Precise dose delivery in high-dose-rate (HDR) brachytherapy relies on accurate measurement of iridium-192 (Ir-192) source dwell times and movement.
• Traditional methods may lack the temporal resolution to capture these dynamics accurately.

Purpose of the Study:

• To evaluate the feasibility of using a cerium-doped yttrium aluminum perovskite (YAP(Ce)) gamma camera system with list-mode acquisition for millisecond-order imaging of an Ir-192 source.
• To measure the dwell times and moving speeds of the Ir-192 source during HDR brachytherapy procedures.

Main Methods:

• Utilized a YAP(Ce) gamma camera system with a list-mode data acquisition system to capture short-time sequential images of the Ir-192 source.
• Sorted list-mode data into millisecond-interval images to assess dwell times at each position.
• Derived time count rate curves to calculate dwell times and source movement speeds.

Main Results:

• Successfully acquired millisecond-order time sequential images of the Ir-192 source.
• Measured dwell times closely matched preset values (e.g., 1.98-2.00 s for 2 s, 10.0 s for 10 s).
• Observed variations in dwell times at different positions and increasing source speed as it moved towards the afterloader.

Conclusions:

• Millisecond-order time sequential imaging of the Ir-192 source is achievable with a gamma camera system.
• This imaging technique is valuable for accurately evaluating dwell times and movement speeds, crucial for precise dose delivery in HDR brachytherapy.