Assessment of the impact of chest radiography on the breast of female patients in a medical facility in Asaba, Delta State: An evaluation of the lifetime cancer risk

Abstract

Objectives: Posteroanterior (PA) Chest radiography is the most common medical investigation worldwide. This study is aimed at determining the mean and median entrance surface dose (ESD), 75th percentile ESD, dose to right (RT) and left (LT) breast, absorbed dose (DT) and organ dose from PA chest radiography for female patients between the ages of 20-79 years. It is also aimed at determining the effective dose (E) and estimating the lifetime cancer risk.
Methods: This prospective study was carried out with 121 female subjects who came for routine PA chest radiography. Digital radiography (DR) unit was used for all patients. Thermoluminescent dosimeters (TLDs) was positioned at the centre of the collimated beam of each patient and transparent nylon was attached to the skin. The TLDs were also attached to both breasts with the patient facing the erect bucky to estimate the exit dose (ED).
Results: The mean, median and 75th percentile ESD for the 6 age groups were 0.96 ±0.15 mGy, 0.95 (0.71-1.23) mGy and 1.07mGy respectively. The mean dose to the RT, LT breast and the DT were 0.35 ±0.12, 0.40 ±0.13 and 0.58 ±0.12 mGy respectively. The mean E for the age groups was 0.029 mSv, while the mean organ doses to the lungs, breast and thyroid were 0.290, 0.059 and 0.022 mGy respectively. The estimated lifetime cancer risk among the age groups ranged from 1.0-2.8 per million.
Conclusion: The mean ESD and E were above recommended guidelines. ESD and DT were primarily affected by focus film distance (FFD) and field size for all age groups. An evaluation of the lifetime cancer risk from this study shows that the risk was twice as high as the United Kingdom (UK) Health Protection Agency (HPA) report. Though the risk was minimal, there may
be need to review the current protocol to meet up with the reported values in the HPA published guidelines.