Chest X-rays of newborns in a medical facility: variation between the entrance skin dose measurements using the indirect and direct methods for clinical dose audit.

PURPOSE: This study aims to determine the mean and 75th percentile entrance skin dose (ESDcal) from anteroposterior (AP) chest X-rays using machine parameters (indirect method). Also, a comparison was made between the ESDcal and already determined thermoluminescent dosimeter (TLD) measurements (ESDTLD) from a previous study from the same patients' data. In addition, the results were compared to similar articles, where the direct and indirect methods were used in estimating ESD to newborns. MATERIALS AND METHODS: The study determined the digital radiography (DR) X-ray machine output using a calibrated XR Multidetector (silicon photodiode). X-ray machine milliampere-seconds (mAs), peak kilovoltage (kVp), focus to detector distance (FDD) and focus to skin distance (FSD) were used from a previous study. The mean kVp and mAs were 56.63 (52-60) and 5.7 (5-6.3) and the patient thickness was 9.5 (8-11.5) cm. RESULTS: The mean ESDs of the newborn between 0 and 28 days were 0.67 ± 0.09 mGy, and the 75th percentile was 0.75 mGy. The effective dose (E) for the 40 patients was 0.19 mSv and the estimated prenatal cancer risk ranged from (5-24.7) 10-6 Sv-1. The variation between the indirect and the direct methods for assessing ESD was 39.6 (33.7-45.1)%. CONCLUSION: The 75th percentile ESD was the highest compared to the American College of Radiology-American Association of Physicists in Medicine-Society for Pediatric Radiology (ACR-AAPM-SPR), European Commission (EC) and United Kingdom (UK) reports. Comparison of both methods for assessing ESD was within 40% as compared to other studies. Based on the above results, the indirect method can be implemented for clinical dose audit.

Evaluation of Three-Dimensional Conformal Radiotherapy and Intensity Modulated Radiotherapy Techniques for Left Breast Post-Mastectomy Patients: Our Experience in Nigerian Sovereign Investment Authority-Lagos University Teaching Hospital Cancer Center, South-West Nigeria.

OBJECTIVE: This study aimed to evaluate the dosimetric properties of treatment plans obtained from three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy techniques (IMRT) plans for left chest wall breast cancer patients. MATERIALS AND METHODS: A total of 20 patients with left-sided chest wall radiotherapy were randomly selected with the dose prescriptions: 42 Gy and 45 Gy in 15 and 18 fractions, respectively. Treatment plans were obtained using 3D-CRT and IMRT for each patient. Five to seven beams were used for IMRT, while tangential beams were used for 3D-CRT. Planning target volume, Dnear-max (D2 ), Dnear-min (D98 ), Dmean, Homogeneity and Conformity Indices (HI and CI) were obtained. Similarly, mean doses to organs at risk (OAR), V5, V10, V20, V25 were generated from the dose-volume histogram and compared. RESULTS: IMRT showed a significant improvement in HI compared to 3D-CRT (p<0.0001). Although there was no significant difference in sparing of the left lung between both plans for high-dose volumes (V20: 18.2 vs 30.55, p<0.0001), (V25: 11.17 vs 28.12, p<0.0001). IMRT however showed supremacy to 3D-CRT with high-dose volumes for the heart, including V20 (4.44 vs 10.29, p = 0.02), V25 (2.08 vs 8.94, p = 0.002). 3D-CRT was better than IMRT in low-dose volumes for left lung (V5: 92.23 vs 56.60, p<0.001; V10: 60.98 vs 47.20, p = 0.04) and heart (V5: 57.45 vs 30.39, p = 0.004). CONCLUSION: IMRT showed better homogeneity and sparing of high-dose volumes to OAR than 3D-CRT. On the other hand, 3D-CRT showed a reduction of low-dose volumes to OARs than IMRT.