Cumulative radiation exposure, effective and organ dose estimation from multiple head CT scans in stroke patients
Introduction
Computed tomography (CT) has changed the way doctors practice medicine since its emergence in 1971. Many patients benefit from it since it provides faster and more reliable diagnostic information less invasively than before (Liguori et al., 2015). CT is used for diagnostic purposes and therapeutic applications, including proton therapy and brachytherapy for precise treatment planning and optimization of radiotherapy using dual-energy CT (DECT) or spectral CT technology (Kruis, 2022; Van Elmpt et al., 2016). The growing number of exams done using this technology and the introduction of novel procedures performed under CT guidance in clinical practice have improved the role of CT in medicine and encouraged new clinical applications (Van Elmpt et al., 2016). However, ionizing radiation, which may trigger second malignancies, is a downside of CT. The number of CT scans performed increased significantly in recent years. Improvements in CT technology, the broad availability of CT, and patient and physician-generated demand. Importantly, some patients are subjected to multiple CT scans (Kwee et al., 2020). The repeated and multiple scans are considered problematic due to the cumulative dose and potential risk from ionizing radiation. Previous studies showed that CT radiation dosages vary significantly among patients, hospitals, and countries up to 17-folds (Smith-Bindman et al., 2019; Sulieman et al., 2020). Ionizing radiation is a proven carcinogen, and CT radiation has been linked to increased cancer risk. As a result, it's critical to decrease excessive variance in examination techniques and minimize exposure to medical imaging (Jaafar et al., 2021; Smith-Bindman et al., 2019).
Stroke is considered the major frequent cause of morbidity and mortality neurological disease and represents 11·6% of total deaths worldwide (Feigin, 2021). Stroke ranks first in frequency and important among all the neurological diseases of adult life. It is the third leading cause of death worldwide (Feigin, 2021). Neuroimaging is the foundation for guiding acute stroke patients by supplying the information needed to correctly triage patients, expedite clinical decision-making regarding treatment, and improve outcomes in patients presenting with acute stroke. It is critical to make an accurate and timely diagnosis. CT allows for time-critical decision-making in stroke patients, informing treatment and follow-up.
Multiple CT scan procedures are not unique for stroke patients. Patients with stroke receive multiple diagnostics scans during admission and are thus at risk from the cumulative radiation dose (CED). Previous studies reported in a multi-institutional study that 1.33%–2.72% of patients (20% ≤ 50 years old) received a cumulative effective dose of ≥100.0 mSv with an overall median and maximum value of 130.3 mSv and 1185 mSv, respectively (Rehani and Madan, 2020). The CED radiation exposure to young patients is high enough to cause serious side effects by increasing the probability of cancer incidence in the future (Rehani and Madan, 2020). Various studies reported that a high cumulative radiation dose could increase cancer risk (Griffey and Sodickson, 2009; Kim, 2004; Kritsaneepaiboon et al., 2018). Even though the minimum risk is expected, it should be weighted by the medical benefits. Proper procedural justification and dosage optimization are critical to quantifying the lifetime attributable risk of radiation-induced cancer. After the patient stabilized and during the rehabilitation phase, the debate between procedure rationale and patient life was decreased for stroke patients since non-ionizing radiation procedures could be requested. This study aimed to determine the effective dose and organ dose from several head scans in a short period. This study aimed to estimate cumulative radiation exposure, effective and organ dose of adult stroke patients undergoing multiple head CT scans.
Section snippets
Survey design and data collection
A retrospective study was conducted between March 2020 and May 2021 for adult patients diagnosed with acute stroke. The data collected included CT scanner information, patient protocol, and dose indices, including volume CT dose index (CTDIvol (mGy) and dose length product (DLP(mGy.cm)). A retrospective search of the picture archiving and communicating system (PACS) database for all stroke patients who had at least three head CT scans while in the hospital. The study conducted a retrospective
Patients' characteristics
A total of 152 patients' data was extracted from the (PACS). The patients conducted a range of three scans (32), four scans (56) and five scans (64). The patients were admitted to the hospital for 3 weeks to 3 months. The age ranged from 45 to 76 years old with a mean of 62 ± 6. Majority of the patients were male (n = 104, 68.4%) and (n = 48, 35.6%) were female. The scanning range was 20.9–28.8 cm, with a mean of 24.4 ± 1.5. The standard protocol used for all patients is shown in Table 1.
Patient dose indices
Table 2
Discussion
Radiologic procedures and diagnostic examinations are conducted to reveal injuries that can otherwise be sometimes fatal or compromise the quality of life. The effects of ionizing radiation are outweighed by the benefits from the information obtained in radiologic procedures when it comes to single or occasional examinations. However, a necessity emerges where patients will have to undergo multiple CT examinations, increasing the risks associated with exposure to ionizing radiation (Kwee et
Conclusion and recommendation
Although a small fraction of patients are subjected to multiple or repeat CT scans, this patient's subgroup may be at an increased risk of acquiring cancer due to cumulative CT radiation exposure. Therefore, there is a need to define referral guidelines and procedures justification. In addition, dose monitoring systems should be set up with alert levels for cumulative radiation exposures of patients.
Study limitation
This study has certain limitations. First, 152 patients were included in the study, which is not the most favourable sample size for organ dose and cumulative effective dose estimation. The ICRP dose limit recommendation is based on a single exposure, whereas our study is based on multiple exposures over a short period.
Funding
The authors received no financial support for the research, authorship and/or publication of this article.
Authors’ contributions
All authors participated in the project development, data collection, and manuscript writing. All authors read and approved the final manuscript.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
The author would like to acknowledge Canon Medical Middle East for supporting the author's participation in the conference.
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