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Home All issues Volume 60 / No 3 (Juillet-Septembre 2025) Radioprotection, 60 3 (2025) 250-255 Full HTML
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Issue
Radioprotection
Volume 60, Number 3, Juillet-Septembre 2025
Page(s) 250 - 255
DOI https://doi.org/10.1051/radiopro/2024061
Published online 15 September 2025

© H. Khajmi et al., Published by EDP Sciences 2025

Licence Creative CommonsThis is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

1 Introduction

Nuclear medicine (NM) is one of the medical specialties that involve exposure to ionizing radiation, as stated by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2017). Nuclear medicine has evolved significantly due to the growing diversity of radiopharmaceuticals used in healthcare. These radioactive compounds are crucial for obtaining functional images of the body, enabling early disease detection and accurate treatment assessment. However, its contribution to the radiation exposure of patients varies between countries, ranging from 0.4% to 14.5% of the total medical exposure (European Commission, 2014).

Given the growing importance of NM in the diagnosis and treatment of various pathologies, it is becoming crucial to optimize the activities administered to patients during scintigraphy examinations (SE). The optimization is achieved considering the balance between the patient’s irradiation and the image quality, ensuring the lowest amount required for diagnostic purposes. This is resumed by the ALARA principle (ICRP, 2007): « Optimizing radiation protection involves keeping doses as low as reasonably achievable, taking into account economic and social factors, and is best described as managing the radiation dose to the patient in a manner that is consistent with the medical goal». Indeed, a study carried out in 2012 (Roch and Aubert, 2012) showed significant variations in the activities delivered due to factors such as age, weight, and sex. In order to overcome these heterogeneities, DRLs are a type of reference for injected activities in nuclear medicine that were first introduced by the International Commission on Radiological Protection (ICRP) in 1996 (ICRP, 1996).

In 2022, research conducted in a university hospital in France showed that the application of an activity optimization system based on national DRLs decreased the average radiation exposure of patients by 15 % on average (Aubert et al., 2022). National DRLs must be updated regularly due to modifications in medical practice, the introduction of new 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-99mTc), thyroid (99mTc), renal (DMSA-99mTc), octreoscan (Tectrotyd-99mTc), brain (HMPAO-99mTc), cardiac (Sestamibi-99mTc) (stress/rest), parathyroid (Sestamibi- 99mTc/99mTc), and lungs (Pulmocis-99mTc) (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.

Table 1

Indications and number of scintigraphy exams collected.

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), pulmonary, cardiac, parathyroid and brain scans represented respectively 4.2%, 2.5%, 2.1%, 2.1%, 2.4%, 2.1% and 2.2% of all the exams studied.

The distribution of SE by gender is described in Table 2 and Figure 2: 28% (n = 451) of men, 72% (n = 1108) of women. The sex ratio was 39%, with a predominance of women.

Table 3 shows the activities injected to patients for each scintigraphy exam. The MV seen in Figure 3 for bone (HMDP-99mTc), thyroid (99mTc), parathyroid (Sestamibi-99mTc/99mTc), renal (DMSA-99mTc), neuroendocrine (octreoscan Tectrotyd-99mTc), lung scintigraphy (Pulmocis-99mTc), cardiac (Sestamibi-99mTc) (stress/rest), and brain (HMPAO-99mTc), were 666 MBq, 144.3 MBq, 85.8 MBq/666 MBq, 135.8 MBq, 555 MBq, 144.3 MBq, 333 MBq/ 1073 MBq, and 703 MBq, respectively. For the thyroid scan, the minimum injected activity value is 78 MBq, while the resting myocardium scan displays a maximum value of 1110 MBq.

thumbnail Fig. 1

Frequency distribution of scintigraphy examinations in OHH.
Table 2

Scintigraphy exams statistic by gender category.

thumbnail Fig. 2

Distribution of SE by gender.
Table 3

Distribution of minimum, maximum, mean and median values of injected activity for SE in our study.

thumbnail Fig. 3

Distribution of MV of injected activity.

3.1 International comparison

We determined LDRLs using the median activity administered of the survey results as specified in the latest recommendations of the ICRP and IRSN (2023). As shown in Table 4, for bone scintigraphy (99mTc-HMDP), thyroid scintigraphy (99mTc), DSMA renal scintigraphy and neuroendocrine (octreoscan) scintigraphy (Tectrotyd-99mTc) the median activities of the LDRL in this study were lower than the DRLs observed in South Korea in 2019 (Ho-Chun Song et al., 2019), in Croatia in 2020 (Dundara et al., 2020), in France in 2021 (IRSN, 2023), and in Switzerland in 2023 (OFSP, 2023).

Regarding parathyroid scintigraphy (Sestamibi- 99mTc/99mTc), South Korea (Ho-Chun Song et al., 2019) demonstrated the highest DRL value (185 MBq/740 MBq). The DRL of 144 MBq for lung scintigraphy (Pulmocis- 99mTc) was below the South Korea DRL of 185 MBq, the Croatian DRL of 200 MBq, and the Swiss DRL of 170 MBq and above the French DRL of 110 MBq.

Our LDRLs for cardiac scintigraphy stress/rest (333 MBq/1073 MBq) were higher than the French values reported in 2021 (285 MBq/785 MBq) and Swiss values reported in 2023 (300 MBq/900 MBq), but were lower than that of South Korea reported in 2019 (370 MBq/1110 MBq).

Finally, in this study, the LDRL of brain scintigraphy (HMPAO- 99mTc) was 703 MBq, which is in line with DRLs observed in South Korea (740 MBq), France (695 MBq), and Switzerland (700 MBq) and very much lower than the Croatian DRL (1110 MBq). These differences in clinical practice reflect the situation in each country where the cameras are of different technological generation and where the optimisation process (ALARA principal) is more or less applied.

The disparities in median scintigraphy activities between our nuclear medicine department and international departments may be due to changes in technology, techniques, and regulations in use. This suggests that, despite the fact that our LDRLs could differ from those in other nations, our department optimizes the injected activity to reduce exposure while ensuring enough image quality for a trustworthy diagnostic.

Table 4

Results of the median injected activity in SE found in this work compared to other countries.

4 Conclusion

This study realized at the OHH of Med VI UHC is the first one in Morocco to determine local DRLs for scintigraphy exams, which revealed some values higher than those observed in several other countries. By conducting this research, we hope to contribute to the achievement of national DRLs for NM in Morocco, promoting the development of a dose and activity registration national database, essential to optimize the practices and activities administered, and thus the patient radioprotection. Using national DRLs in future research protocols and clinical routine will significantly reduce patient exposure to medical radiation in Morocco.

Acknowledgments

We would like to thank Aboulhassane Nadia (NM chief technician), Hind Saykok (medical physicist) for their collaboration. We also like to thank the students of the Higher Institute of Nursing Professions and Health Technics, as well as the radiology technicians of the oncology and hematology hospital of the Mohammed VI University Hospital Center in Marrakech, Morocco, for their help in data collection.

Funding

The study’s authors did not receive any funding for it.

Conflicts of interest

There is no conflict of interest for this paper.

Data availability statement

The full results of this study are accessible from the corresponding author, H. KHAJMI.

Author contribution statement

Each author helped with the conception and execution of the study, the findings analysis, and the paper writing.

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Cite this article as: Khajmi H, Tounsi A, Oufni. L. 2025. Establishing diagnostic reference levels for scintigraphy exams at the Mohammed VI University Hospital Centre in Marrakech-Morocco. Radioprotection 60(3): 250–255. https://doi.org/10.1051/radiopro/2024061

All Tables

Table 1

Indications and number of scintigraphy exams collected.

In the text
Table 2

Scintigraphy exams statistic by gender category.

In the text
Table 3

Distribution of minimum, maximum, mean and median values of injected activity for SE in our study.

In the text
Table 4

Results of the median injected activity in SE found in this work compared to other countries.

In the text

All Figures

thumbnail Fig. 1

Frequency distribution of scintigraphy examinations in OHH.
In the text
thumbnail Fig. 2

Distribution of SE by gender.
In the text
thumbnail Fig. 3

Distribution of MV of injected activity.
In the text

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