Fig. 1. Diagram of detection model of the LaBr₃(Ce) detector and Marinelli beakers

Fig. 2. Design and physical drawing of 3D printing Marinelli beakers

Fig. 3. Variation curve of total energy peak efficiency of the LaBr₃(Ce) detector for ¹³¹I, ¹⁸F, and ^99mTc with depth h₂ at r = 53 mm

Fig. 4. Within the screening range of h₂, variation curves of the simulation efficiency for ¹³¹I, ¹⁸F, and ^99mTc with radius r at volumes of 0.5 L (a), 1.5 L (b), 1.0 L (c), 2.0 L (d),and the 3D distribution of the radius-depth direction at volumes of 0.5 L (e) and 1.0 L (f)

Fig. 5. Experimental verification results of 0.5 L and 1.0 L container sizes using ¹³¹I nuclide