Organ dose assessment in 15-year-old patients undergoing panoramic radiography: a Monte Carlo study using mesh-type...

This study evaluated organ-specific absorbed doses and sex-dependent dosimetric variations in 15-year-old patients undergoing panoramic radiography across different units technologies. ICRP 156 mesh-type reference computational phantoms (MRCPs) were coupled with the PHITS Monte Carlo code for this analysis. Three panoramic units with distinct kinematics and exposure protocols were simulated: Unit A (fixed isocentric rotation, constant parameters) and Units B and C (sliding rotation axis, dynamic kV/mA modulation). Absolute absorbed doses were estimated using experimentally derived air kerma-area product conversion factors. Salivary glands and oral mucosa received the highest absorbed doses, ranging from 270 to 640 µGy, depending mainly on the tube voltage protocols. Sex-specific dosimetric disparities appeared due to anatomical variations interacting with beam geometry. The female MRCP absorbed 26% to 28% higher doses in the head lymph nodes due to smaller craniofacial dimensions, increasing scattered radiation contribution. Male phantoms systematically received 12% to 13% higher doses to the extrathoracic lymph nodes across all systems, due to a larger cervical circumference intersecting the divergent primary beam. Patient anatomy dictated the relative dose distribution, but the unit's operational protocol, particularly dynamic modulation and beam energy, determined the absolute exposure magnitude. These findings emphasize that 15-year-old patients require age-specific protocol optimization. Using highly realistic MRCPs with dynamic exposure parameters shows that unit technology is the main determinant of patient risk, offering a framework for ALARA implementation in adolescent dental radiology.