Radioprotection 60-3 | Page 51

H. Khajmi et al.: Radioprotection 2025, 60( 3), 250 – 255 251

Table 1. Indications and number of scintigraphy exams collected. Scintigraphy Main Indications Number of Scintigraphy

radiopharmaceuticals, and advancements in imaging technology. In 2023, the International Atomic Energy Agency( IAEA) declared that this strategy is crucial to ensure the best possible use of radiation in nuclear medicine( AIEA, 2023).

In nuclear medicine, the DRLs were first defined as the average of the activities administered in all departments, responding to the national survey, for each exam; currently, medians are used as a replacement for averages to define DRLs. In fact, the arithmetic average is strongly affected by the lowest, repeated, or high values, which may be undetected bias in the data collection, whereas the median is less sensitive to these exceptions( Paul Newbold et al., 2012).

Numerous studies have been conducted in Europe to evaluate and update national DRL for administered activities in NM( France, 2018; Germany, 2012; Switzerland, 2014; Belgium, 2016; UK, 2017), in Africa( Ali et al., 2016; Dambele et al., 2021), in Asia( Watanabe et al., 2016; Song et al., 2019; Senthil Kumar et al., 2023), and in Australia( ARPANSA, 2017). The national DRLs proposed in these studies are all calculated on the basis of the average, or third quartile, of the administered activities.

Nuclear medicine applications are growing rapidly in Morocco, where the number of centres has increased by 25 % in the last five years. The increasing contribution of this speciality in patient diagnostic and therapeutic care is the reason for this rise. The number of patients undergoing nuclear medicine exams increased so much that the radiopharmaceutical demand increased up to 30 %. According to the latest statistics compiled in 2020 by the Moroccan Agency for Nuclear and Radiological Safety and Security( AMSSNuR), Morocco has 26 nuclear medicine centres with 14 PET-CT and 12 SPECT-CT cameras. Unfortunately, in Morocco, studies dealing with national DRL in NM are infrequent or non-existent because of the limited access to clinical data.

The main objective of our work is to present the results of data analyses for the period 2021 – 2023 and establish the local DRLs for routine SE for adult patients in the NM unit of OHH Med VI UHC-MM. We have also compared our results with the most recent guidelines of the ICRP( ICRP, 2023) and the French Institute of Radiation Protection and Nuclear Safety( IRSN, 2023). We hope that the findings of this investigation will be helpful to rapidly identify which SE needs activity revision and optimisation to reduce the radiation exposure for patients in our department. We hope also that Morocco will create in the near future a national DRL( NDRL) creating a central database for each NM department. Certainly, NDRLs will permit to optimize clinical practice and reduce patient’ s( and staff’ s) exposure in Nuclear Medicine in Morocco.

2 Methods

The examens studied were: bone( HMDP- 99m Tc), thyroid( 99m Tc), renal( DMSA- 99m Tc), octreoscan( Tectrotyd- 99m Tc), brain( HMPAO- 99m Tc), cardiac( Sestamibi- 99m Tc)( stress / rest), parathyroid( Sestamibi- 99m Tc / 99m Tc), and lungs( Pulmocis- 99m Tc)( Tab. 1) of adult patients(> 18 years) of the standard size( i. e., 70 ± 10 kg) of both sexes. Several indications were selected as shown in Table 1. For each scintigraphy exam, the information required was age, sex, and the administered activities. The activities delivered were measured using the dose calibrator LEMER PAX( REF: 00005194). The Siemens Symbia T6 SPECT / CT camera was used to acquire images, it has been installed in 2012 in our department and is routinely operative.

2.1 Data analysis

The statistics were performed with a Microsoft Excel 2019 spreadsheet. The minimum, maximum, mean, and median activity were calculated for each scintigraphy exam. For the first time, these local results are specific to oncology and haematology hospitals and have been brought together to calculate LDRLs for scintigraphy exams. The median values( MV) of the studied scintigraphy exams were compared with the DRLs of recently published studies in South Korea( Ho- Chun Song et al., 2019), France( IRSN, 2023), Croatia( Dundara et al., 2020), and Switzerland( OFSP, 2023).

3 Results and discussion

Activity data were collected for 1559 scintigraphy exams. The study involved adults aged between 18 and 93 years, with a mean of 52.7 years. The frequency distributions of scintigraphy exams are shown in Figure 1. Bone scintigraphy was the most common, representing 82.4 % of the exams. For 35 years, bone scintigraphy has been the most frequently performed examination in nuclear medicine( Paycha et al., 2007), due to its capability in assessing the extent of cancer before, during, and after treatment. Thyroid, renal, neuroendocrine( octreoscan),