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22-24 

22 

 

 

 

Perspective 

Evaluation of cumulative radiation exposure 

among dental workers at Usmanu Danfodiyo 

University Teaching Hospital, Sokoto, Nigeria 
Ahmadu Ibrahim* 

 Department of Physics, Usman Danfodiyo University, Sokoto, Sokoto state, Nigeria 

A R T I C L E   I N F O 
 

Article history: 
Received 30 June 2024  
Received in revised form 
08 August 2024 
Accepted 28 August 2024 
 
Keywords:  
Cumulative dose, Annual effective dose, Radiation, 
Ionization, Safety 
 
*Corresponding author 
Email address: 
ahmedmubi9133@gmail.com  
 
 
DOI: 10.55670/fpll.futech.3.4.3 
 

A B S T R A C T 
 

Continuous surveillance for radiation protection is imperative when employing 
ionizing radiation-emitting devices, such as those used at Usmanu Danfodiyo 
University Teaching Hospital (UDUTH) in Sokoto, Nigeria. In adherence to 
national regulations, it is mandatory for all personnel involved in activities with 
ionizing radiation to participate in a regular individual dosimetric monitoring 
program. This study evaluates the occupational radiation exposure of dental 
healthcare practitioners over the course of 2017, with assessments conducted 
on a quarterly basis. For this purpose, the HARSHAW 4500 Reader, in 
conjunction with Thermoluminescent Dosimeters (TLDs), was employed for 
individual radiation monitoring. This method ensures precise and reliable 
measurements of both skin and deep tissue doses, providing comprehensive 
data on the cumulative annual effective dose for each worker. The findings from 
this investigation reveal significant variations in the cumulative radiation doses 
among the dental staff. The practitioner identified as DN24b recorded the 
highest cumulative dose at 15.60 man Sieverts (manSv), highlighting a notable 
exposure level within the group. Conversely, the practitioner labeled DN13 
registered the lowest annual effective dose at 5.33 manSv, indicating effective 
adherence to radiation safety protocols. These results underscore the 
importance of rigorous and continuous radiation monitoring to ensure 
occupational safety. While the observed doses are within acceptable limits, the 
variation in exposure levels suggests the need for ongoing education and 
adherence to radiation protection principles. The study advocates for enhanced 
protective measures and continuous training to minimize radiation exposure 
and ensure the well-being of all dental healthcare workers at UDUTH. 

 

1. Introduction 

Utilizing ionizing radiation in dental practices is pivotal 
for diagnostic imaging and therapeutic interventions. 
However, this essential tool carries inherent risks of radiation 
exposure for healthcare workers, necessitating continuous 
monitoring and evaluation of their cumulative radiation 
exposure. This study focuses on assessing cumulative 
radiation exposure among dental workers at Usmanu 
Danfodiyo University Teaching Hospital (UDUTH) in Sokoto, 
Nigeria. Ionizing radiation, such as X-rays used in dental 
radiography, possesses the potential to ionize atoms and 
molecules within human tissue, thereby posing risks of 
cellular damage and increased cancer susceptibility [1]. 
Dental healthcare workers, due to their frequent exposure to 
low-dose radiation over prolonged periods, are particularly 
susceptible to these risks. Hence, regular monitoring of 

occupational exposure is crucial to ensuring radiation levels 
remain within safe limits and mitigating potential health 
hazards. Regulatory bodies like the International Commission 
on Radiological Protection (ICRP) and the Nigeria Nuclear 
Regulatory Authority (NNRA) provide guidelines and 
standards for radiation protection. The ICRP recommends an 
occupational exposure limit of 20 millisieverts (mSv) per 
year, averaged over five years, with no single year exceeding 
50 mSv [1]. Adherence to these guidelines is critical for 
minimizing risks associated with prolonged radiation 
exposure. Previous research underscores the significance of 
regular radiation monitoring in dental practices. Studies 
demonstrate that consistent use of dosimetry, such as 
Thermoluminescent Dosimeters (TLDs), effectively measures 
and manages radiation exposure among dental workers. 
Furthermore, implementing radiation protection principles, 

 

 

Future Technology 

Open Access Journal 

https://doi.org/10.55670/fpll.futech.3.4.3 

 

 

 

 

 

 

 

November 2024| Volume 03 | Issue 04 | Pages 22-24 

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Ahmadu Ibrahim /Future Technology                                                                                 November 2024| Volume 03 | Issue 04 | Pages 22-24 

23 

 

including maintaining appropriate distance, using protective 
barriers, and minimizing exposure time, is essential for 
reducing occupational exposure [2]. This study aims to 
evaluate the cumulative radiation exposure of dental workers 
at UDUTH over a one-year period. Utilizing the HARSHAW 
4500 Reader and TLDs for individual monitoring enables 
precise measurements of both skin and deep tissue doses. 
Analyzing quarterly dose records seeks to determine the 
annual effective dose for each dental worker and assess 
compliance with national and international radiation safety 
standards. Understanding cumulative radiation exposure 
among dental workers is crucial for several reasons. Firstly, it 
ensures the safety and health of workers by identifying 
potential overexposures and implementing corrective 
measures. Secondly, it contributes to the body of knowledge 
regarding occupational radiation exposure in dental settings, 
informing policy and improving safety protocols. Lastly, it 
underscores the importance of continuous education and 
training in radiation protection for healthcare workers. 

2. Methodology 

Information for this research was obtained from 
individuals employed in the Radiotherapy Departments of 
Usman Danfodiyo University Teaching Hospital in Sokoto, 
Nigeria. We obtained anonymous records containing 
quarterly dosage measurements from these departments for 
the period spanning 2014 to 2018. We secured documented 
information on the levels of medical radiation exposure. To 
adhere to Health Research Ethics Board (HREB) regulations, 
the collected documents were intentionally devoid of any 
information revealing the identities of the personnel. Instead, 
each participant was assigned a unique TLD code to ensure 
their anonymity. These depersonalized and coded records 
included details about quarterly whole-body and extremity 
doses for medical radiation workers in the department, and 
the cumulative annual dose was subsequently calculated 
using the formula from [3]. 

𝐷 =
𝐻𝑇

𝑊𝑅
             (1) 

Where D = Absorbed dose, 𝐻𝑇= Equivalent dose, 𝑊𝑅   = 
Radiation weighting factor.  

3. Results and discussion 

In this study, the statistical information is based on the 
dental personnel in the year 2017 at Usmanu Danfodiyo 
University Teaching Hospital in Sokoto. The presented Table 
1 indicates that throughout the entirety of 2017, the Dentist 
identified with the TLD code DN 24b recorded the highest 
annual effective and collective doses at 1.2 mSv and 15.6 man 
mSv, respectively. These findings (Figure 1) indicate that DN 
24b experienced higher radiation exposure compared to 
other Dentists. Conversely, DN13 registered the lowest 
annual and effective dose. The annual effective doses for 
Dentists ranged from 0.41 to 1.20 mSv, falling below the 
recommended limit of 5 mSv according to UNSCEAR (2008). 
Additionally, the collective doses varied from 5.33 to 15.60 
man mSv, remaining below the 240 man mSv threshold 
recommended by reference [4]. 

The data depicted reveal that in 2017, the Dentist 
identified by the TLD code DN24b had the highest exposure 
percentage at 13%. In contrast, DN11b, DN 01, DN 11, and DN 
05 recorded exposure percentages of 10%, while DN13 had 
the lowest percentage at 4%. These findings indicate that 
DN13 experienced comparatively lower radiation exposure. 
The findings indicate that the collective dose received by 
dental workers in 2017 followed an ascending order, as 

illustrated in Figure 2. DN13 received the smallest collective 
dose at 5.33 man mSv, whereas DN24b received the highest 
collective dose at 15.60 man mSv. 

Table 1. Descriptive statistics 

 

 

Figure 1. Pie chart for dentists' annual effective dose in mSv for 2017 

 

 

 
Figure 2. Dentists collective annual effective dose in man mSv 

 

 

Dentists AED CAED 

DN13 0.41 5.33 

DN19b 0.45 5.85 

DN06 0.48 6.24 

DN04 0.51 6.63 

DN24 0.67 8.71 

DN19 0.78 10.14 

DN05 0.88 11.44 

DN11 0.91 11.83 

DN01 0.93 12.09 

DN11b 0.95 12.35 

DN96 1.13 14.69 

DN24b 1.2 15.6 



Ahmadu Ibrahim /Future Technology                                                                                 November 2024| Volume 03 | Issue 04 | Pages 22-24 

24 

 

4. Conclusion and recommendations 

The results obtained for the entire year did not surpass 
the recommended threshold limits of 5 mSv for individual 
doses and 240 man mSv by UNSCEAR (2008). The collective 
dose results fell within the range of 5.33 to 15.6 man mSv. 
Assessing the level of radiation exposure across various 
medical departments at Usman Danfodiyo University 
Teaching Hospital is crucial, given the widespread use of 
ionizing radiation. Based on the findings, the following 
recommendations are suggested: 
• It is recommended to regularly calibrate the Harshaw 4500 

manual TLD reader, utilized in this study, using 137Cs 
beam exposure before its application. 

• A comparable investigation should be conducted using 
Harshaw automatic TLD reader models 8800/6600 due to 
their improved precision and accuracy. 

• Evaluation of radiation exposure among professionals 
other than dentists, such as radiotherapists, radiologists, 
and porters, should also be undertaken. 

• Measures to reduce workloads on radiation workers, which 
contribute to human errors, should be implemented 
through realistic scheduling. 

• Developing a model capable of detecting cancer in 
radiosensitive organs is recommended. 

• TLDs should be read after one month to prevent chip 
fading, considering Sokoto's temperature. 

• Increasing staffing levels to alleviate the workload within 
the departments is advisable. 

Ethical issue 
The author is aware of and complies with best practices in 
publication ethics, specifically with regard to authorship 
(avoidance of guest authorship), dual submission, 
manipulation of figures, competing interests, and compliance 
with policies on research ethics. The author adheres to 
publication requirements and states that the submitted work 
is original and has not been published elsewhere. 

Data availability statement 
The datasets analyzed during the current study are available 
and can be given upon reasonable request from the 
corresponding author. 

Conflict of interest 

The author declares no potential conflict of interest. 

References 

[1] International Commission on Radiological Protection 

(ICRP) (2005). Draft; recommendations of the 

International Commission on Radiological Protection, 

Sweden  

[2]  Abu-Jarad F. (2008). Application Radiation Sources in 

Oil and Gas Industry and Shortage in their Services 

International Symposium on the peaceful Application 

of Nuclear Technology in the GCC countries Jeddah 

2008. Radioisotopes Applications, session 10/No.3. 

[3]  Rahman, A., Khan, S., & Ali, M. (2019). Radiation dose 

measurement in CT procedures: A study in Pakistani 

hospitals. Radiation Protection Dosimetry, 168(4), 

559-564. doi:10.1093/rpd/ncv397 

[4]  United Nations Scientific Committee on the Effects of 

Atomic Radiation. Sources and effects of ionizing 

radiation. UNSCEAR, 2008, Vienna. 

 

 
This article is an open-access article distributed under the 

terms and conditions of the Creative Commons Attribution 

(CC BY) license 

(https://creativecommons.org/licenses/by/4.0/). 

https://creativecommons.org/licenses/by/4.0/

