Radiation dose to the thyroid, eyes and parotid glands of patients undergoing intra-oral radiographic procedures in a teaching hospital in Ibadan, Oyo state Nigeria

Background: Intraoral radiographs are believed to deliver low doses to patients, thus little work has been done in this regards. Considering the increment in the number of patients reporting for the examination and the probability of delayed somatic effects for accumulated low doses of X-irradiation, it is expedient to determine the doses to three critical organs eye, thyroid and parotid that are at risk during exposure

Materials and Methods: Thermoluminescent dosimeters was used to measure Entrance Surfaces Doses [ESDs] to the thyroid, eye and parotids salivary gland of 40 adult patients undergoing intra-oral radiographic examination at University College Hospital, [UCH] Ibadan, Oyo state

Results: Results indicated entrance surface doses [ESD] ranged between 0.0447 mGy to 0.3898 mGy to the thyroid, 0.0742 mGy to 0.3989 mGy to eye and 0.0467 mGy to 0.4164 mGy to the parotids for the period of study. The mean ESD +/- SD to the thyroid, parotids and eyes for male were 0.179810.081, 0.215510.109 and 0.219710.081 mGy with the female patients 0.195710.084, 0.209110.081 and 0.228010.113 mGy respectively. No statistically significant difference was found between these means

Conclusion: The doses obtained in this study were lower than the documented threshold that could cause significant damage in the various organs, not undermining stochastic effect of radiation. This study will assist in setting Diagnostic Reference Level [DRL] for intraoral radiographic imaging in Nigeria

Re-Irradiation of Hepatocellular Carcinoma: Clinical Applicability of Deformable Image Registration

PURPOSE: This study aimed to evaluate whether the deformable image registration (DIR) method is clinically applicable to the safe delivery of re-irradiation in hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Between August 2010 and March 2012, 12 eligible HCC patients received re-irradiation using helical tomotherapy. The median total prescribed radiation doses at first irradiation and re-irradiation were 50 Gy (range, 36-60 Gy) and 50 Gy (range, 36-58.42 Gy), respectively. Most re-irradiation therapies (11 of 12) were administered to previously irradiated or marginal areas. Dose summation results were reproduced using DIR by rigid and deformable registration methods, and doses of organs-at-risk (OARs) were evaluated. Treatment outcomes were also assessed. RESULTS: Thirty-six dose summation indices were obtained for three OARs (bowel, duodenum, and stomach doses in each patient). There was no statistical difference between the two different types of DIR methods (rigid and deformable) in terms of calculated summation operatorD (0.1 cc, 1 cc, 2 cc, and max) in each OAR. The median total mean remaining liver doses (M(RLD)) in rigid- and deformable-type registration were not statistically different for all cohorts (p=0.248), although a large difference in M(RLD) was observed when there was a significant difference in spatial liver volume change between radiation intervals. One duodenal ulcer perforation developed 20 months after re-irradiation. CONCLUSION: Although current dose summation algorithms and uncertainties do not warrant accurate dosimetric results, OARs-based DIR dose summation can be usefully utilized in the re-irradiation of HCC. Appropriate cohort selection, watchful interpretation, and selective use of DIR methods are crucial to enhance the radio-therapeutic ratio.