Gadolinium concentration analysis in brain phantom by X-ray fluorescence.

Area of Science:

• Medical Physics
• Radiochemistry
• Oncology Imaging

Background:

• Gadolinium-based contrast agents are widely used in medical imaging.
• Accurate quantification of gadolinium concentration in tumors is crucial for effective diagnosis and treatment monitoring.
• Understanding gadolinium X-ray fluorescence properties is essential for developing novel imaging techniques.

Purpose of the Study:

• To measure X-ray fluorescence from gadolinium at various concentrations and positions within simulated tumors of different sizes and shapes.
• To evaluate the feasibility of using X-ray fluorescence for gadolinium concentration determination in oncological imaging.
• To investigate the impact of gadolinium concentration and tumor geometry on fluorescence signal.

Main Methods:

• Excitation of gadolinium fluorescence using an Americium-241 (Am-241) source.
• Detection of fluorescence signal with a Cadmium Telluride (CdTe) detector and multi-channel analyzer.
• Utilizing a head phantom with spherical and oblate spheroid tumors containing gadolinium concentrations ranging from 5.62 to 78.63 mg/ml.

Main Results:

• Clear separation of the gadolinium fluorescence peak from scattered X-rays was achieved.
• Observed trends of signal saturation at higher gadolinium concentrations, attributed to self-absorption within the tumor.
• Demonstrated the influence of tumor size, shape, and gadolinium concentration on fluorescence measurements.

Conclusions:

• X-ray fluorescence measurements of gadolinium in simulated tumors are feasible.
• Self-absorption of X-rays is a significant factor affecting gadolinium quantification at high concentrations.
• Further research is needed to optimize X-ray fluorescence techniques for accurate in-vivo gadolinium concentration determination in tumors.