Estimation of organ-absorbed doses in patients undergoing chest and abdominal X-ray examinations using Monte Carlo-based software

Background: Medical imaging is essential for diagnosis and treatment. However, it raises long-term radiation exposure concerns for patient safety. The measurements of entrance surface air kerma (ESAK), entrance surface dose (ESD), and dose area product (DAP) have been widely used to estimate patient doses. However, these parameters cannot represent the patient’s organ-absorbed doses. Objective: To establish a relationship between ESD and organ-absorbed doses, calculated using Monte Carlo-based software to estimate organ-absorbed doses in patients undergoing chest and abdominal X-ray examinations. Materials and methods: The SHIMADZU RADspeed Pro X-ray machine with VacuDAP meter, Radcal, and AGMS-D+ solid-state detector with Accu-Gold software was used to measure ESD. Tissue-equivalent slab phantoms with 9.8, 15.0, and 20.0 cm thickness were used at 60, 80, and 120 kVp and 3.2 mAs. Surface field sizes varied from 7×7 cm2 to 28×28 cm2. Organ-absorbed doses were calculated using PCXMC 2.0 from STUK (Finland) using the same X-ray exposure techniques as the experiment. Results: The X-ray tube voltage (kVp) is proportional to the ESD (µGy/mAs). This relationship can be described using a power equation. The ESD increased as the phantom thickness increased for each beam field size. A linear function was used to estimate the relationship between ESD and organ-absorbed doses. Due to their anatomical positions, which are most adjacent to the X-ray source, the breast, uterus, and heart have the highest organ-absorbed doses undergoing examinations of the chest (anteroposterior; AP), abdomen (AP), and chest (posteroanterior; PA), respectively. Conclusion: The relationships between ESD and kVp were established as power functions, but the relationships with DAP were linear functions. The relationship between ESD and organ-absorbed doses was described using linear equations that varied with beam field size and patient thickness. This study provides a helpful method for estimating organ-absorbed and effective patient doses. This is important in assessing the risk of radiation exposure from diagnostic radiography.