RAMANANDRAIBE

The most frequently used radiopharmaceutical for treatment of thyroid cancer is the radioactive iodine (RAI). Patients treated with RAI therapy cause risk of external radiation exposure to the public and family members. While the therapeutic use of iodine-131 for thyroid carcinoma patients offers enormous benefit to them, it contributes also significantly to the radiation exposure of individuals and population. Patients treated with radioiodine present a radiation hazard and precautions are necessary to limit radiation dose to the relatives and the members of the public. The study aims to develop guidelines for the release of thyroid cancer patients treated with I-131. For this purpose, simulations were performed for estimating suitable period of restriction during which close contact with the patient should be disallowed and limited. These simulations are based on the French working Group and the recommendations of the International Commission on Radiation Protection. The study was carried out at the Isotopes Laboratory (LRI), Department of Nuclear Medicine in Antananarivo, Madagascar. According to the current regulation in radiation protection in Madagascar, the dose limit for the members of the public is limited to 1 mSv. Guidelines for discharge from the hospital are as follows. Patients can travel using public transportation up to 15 minutes. Patients are suggested to sleep apart and restrict contact with partner for 4 days after leaving the hospital. Contact with children should be restricted according to their ages. Time to restrict contact with child ranging from 3 to 10 years is limited to 4 days, and up to 7 days for younger children. This guideline is based on the retained activity of 800 MBq or the external dose rate is less than 40 μSv/h at 1 m. For public transportation, the suggested travel times for thyroid cancer are similar to those recommended by the French group. The length of time for which patients are in contact with children in this study is widely less than recommendations by French Group.

To strengthen patient radiation protection and control of medical exposure, in the Haute Matsiatra region, Fianarantsoa District, Madagascar, we have carried out a study to develop a protocol for dose assessment in diagnostic radiology in order to ensure good radiological practice. In this region, no studies have ever been done in their radiology department. The patient entrance dose (De) is one of the basic dosimetric quantities for measuring the dose delivered to the patients. Therefore, to assess the patient entrance dose (De), we have chosen two hospitals such as the Andrainjato University Hospital Center (CHUA) and the Tambavao University Hospital Center (CHUT). We have chosen four most requested radilogicals examinations (Skull, Thorax, abdomen and pelvis) and we have evaluated the entrance doses of patient and we have compared the result found to the Diagnostic Reference Levels (DRL) recommended by the IAEA for each examination. We found that, the average doses delivered to the patients during their radiographic examinations, were below the reference doses recommended by the IAEA. For this comparison carried out in these two hospitals, we can be confirmed that the values obtained can be useful for the application of regulations on the patient radiation protection and the control of medical exposure in Fianarantsoa.

The medical use of ionizing radiation is the largest and a growing man-made source of radiation exposure. The aim of this study is to assess the doses received by patients during radiological examinations in order to standardize the examination procedures and optimize the patient dose. Four most frequented hospitals, located in the Vakinankaratra and Haute Matsiatra regions of Madagascar, were investigated. Patients dose undergoing chest posterior-anterior (PA) and lateral (LAT), skull (PA, LAT), lumbar spine (PA, LAT), spine cervical (PA, LAT), abdomen (AP, LAT) and members (AP, PA, LAT) X-ray examinations were involved in this study. Entrance Skin Dose (ESD) was calculated using the X-ray radiation output and the exposure parameters (high voltage, tube loading, focus-patient distance). Thermoluminescent dosimeters were used to measure the X-rays radiation output. Conversion coefficients were used to relate ESD to the effective dose (ED). A total of 302 radiographic examinations were collected from the four hospitals during two months of 2019. The highest ESD (mGy) was found for the lumbar spine lateral projection, with an average value of 2.66 mGy. The highest value of ED was observed for the abdomen lateral projection with an average of 0.174 mSv. The ESDs and EDs reported in this study are generally lower than reference dose values published by the IAEA. This trend is an indication that the patient radiation protection practices in these four hospitals are already acceptable. The results of this study showed that there is a need to improve the radiodiagnostic procedures for reducing patient radiation dose without affecting the quality of the radiography image. The data of this work will be useful in contributing to the formulation of regional guidance levels.

In radiation protection of patients and medical exposure control, the Radcal 3036 dosimeter is the standard device used for radiodiagnostic dosimetry in medical field. However, for various reasons, this device is not always available, resulting in service interruptions. This led us to assess the effectiveness of ThermoLuminescent Dosimeters (TLDs) for the same service. This study consists in setting an appropriate protocol, then comparing the surface doses measured by the dosimeter Radcal 3036 and those measured with TLDs. We selected three radiological departments in Antananarivo. For the four standard examinations selected (thorax, skull, abdomen and pelvis), the results show that the differences between the values measured by the two dosimeters remain below to 5%. These results confirm that TLDs offer a credible alternative for measuring the dose received by the patient during medical radiological examination. Dosimetric monitoring breakup can then be avoided, to the benefit of the safety of the public and patients.