Gadolinium-153 as a brachytherapy isotope.

Area of Science:

• Medical Physics
• Radiation Oncology
• Nuclear Medicine

Background:

• Brachytherapy is a cancer treatment utilizing localized radiation sources.
• Current brachytherapy often uses Iridium-192, necessitating significant shielding.
• Gadolinium-153 offers potential advantages in shielding and specialized delivery techniques.

Purpose of the Study:

• To determine the fundamental dosimetric characteristics of a hypothetical Gadolinium-153 ((153)Gd) brachytherapy source.
• To evaluate its suitability for low-dose-rate (LDR) and pulsed-dose-rate (PDR) brachytherapy.
• To explore its potential for interstitial rotating shield brachytherapy (I-RSBT) and reduced shielding requirements.

Main Methods:

• Simulation of a hypothetical (153)Gd brachytherapy source using Geant4.
• Calculation of radial dose function, anisotropy function, and photon spectrum in water.
• Application of the AAPM TG-43U1 dose-calculation formalism.

Main Results:

• The simulated (153)Gd source (242 GBq) exhibited a dose rate of 13.12 Gy/h at 1 cm.
• Beta particles are absorbed within the encapsulation; scattered photons dominate the dose at distance.
• The radial dose function increases due to low-energy photon scatter; anisotropy varies with polar angle and distance.

Conclusions:

• The (153)Gd source is suitable for LDR and PDR brachytherapy applications.
• It shows promise for I-RSBT, potentially enabling patient-specific and reduced personnel shielding.
• Further investigation into its clinical implementation is warranted.