Abstract Title
Patients Radiation Risks from Computed Tomography Lymphography

Authors

Abdullah Almujally
Abdelmoneim Sulieman
Fabrizio Calliada

Theme

Radiation Protection & Safety

INSTITUTION

Radiology Institute, University of Pavia
Prince Sattam bin Abdulaziz University, College of Applied Medical Sciences

Summary of Work

The usage of computed tomography (CT) for medical diagnostic imaging is increasing for differential diagnosis of lymphedema. Patients exposed to significant high radiation dose up to 400 times compared to conventional imaging.  The incidence of lymphedema is increasing due to increase of cancer incidence and survival rate due to advancement in cancer treatment.  The radiation induced cancer due to CT procedures may reach up to 2% of cancer incidence. Therefore, estimation of radiation risk from CT procedures is recommended. The aims of this study are, first, measure patient doses during CT chest , abdomen and extremities procedures, second, to estimate the radiation dose related risks during the procedures. Patient doses from two common CT examinations were obtained from three hospitals equipped with CT 128, 64 and 16 slices. The patient doses were estimated using measurements of CT dose indexes (CTDI), exposure-related parameters, and the ImPACT spreadsheet based on NRPB conversion factors. A large variation of mean organ doses among hospitals was observed for similar CT examinations. These variations largely originated from different CT scanning protocols used in different hospitals and scanner type. The largest range was found for CT of the chest, for which the dose varied from 2.3 to 46.9 (average 24.6) mSv and for abdomen CT, it was 3.3 to 26.9 (average 15.1) mSv. Radiation dose to the breast ranged from1.6 to 32.8 mSv for the chest and 2.3 to 18.8 mSv for the abdomen. The radiation risk per procedures was high and increase the risk of breast cancer for young females. These values were mostly higher than the values of organ doses reported from the other studies. It was concluded that current clinical chest and abdomen and extremities protocols result in variable radiation doses to the breast. Implementation of accurate referral criteria is recommended to avoid unnecessary breast radiation exposure.

Background

The lymphatic system plays an important role in human health. It composed of huge network of vessels, nodes and lymphatic organs. Diagnostic and therapeutic intervention with various imaging modalities is required to obtain accurate diagnosis. Lymphedema is a lymphatic system disorder caused by accumulation of lympha which diminishes lymphatic return. Subsequently there is inflammation, hypertrophy of adipose tissue and finally fibrosis. Imaging of lymphatic systems (lymphangiography) was first introduced to clinical practice in 1951 using an oil-based contrast medium (Gough 1964).Different imaging techniques are used to diagnose lymphatic disorders (lymphangiography, lymphoscintigraphy, computed tomography, MRL, PET/CT and ultrasound imaging) . However, all these techniques have different limitations (Xiong et al., 2014) .The frequency of  CT procedures has increased in recent years , resulting in 67% of the effective dose from diagnostic radiology (Mettler et al., 2009). The benefit of justified CT for accurate diagnosis is beyond doubt, but its use comes with risks. Patient radiation doses delivered by CT are 100–500 times higher compared to projection imaging.

 

Summary of Results

Patient doses from two common CT examinations were obtained from three hospitals equipped with CT 128, 64 and 16 slices. The patient doses were estimated using measurements of CT dose indexes (CTDI), exposure-related parameters, and the ImPACT spreadsheet based on NRPB conversion factors. A large variation of mean organ doses among hospitals was observed for similar CT examinations. These variations largely originated from different CT scanning protocols used in different hospitals and scanner type. The largest range was found for CT of the chest, for which the dose varied from 2.3 to 46.9 (average 24.6) mSv and for abdomen CT, it was 3.3 to 26.9 (average 15.1) mSv. Radiation dose to the breast ranged from1.6 to 32.8 mSv for the chest and 2.3 to 18.8 mSv for the abdomen. 

Conclusion

The radiation risk per procedures was high and increase the risk of breast cancer for young females. These values were mostly higher than the values of organ doses reported from the other studies. It was concluded that current clinical chest and abdomen and extremities protocols result in variable radiation doses to the breast. Implementation of accurate referral criteria is recommended to avoid unnecessary breast radiation exposure.

Acknowledgement

The authors would like to thank the staff of all hospitals for thier vital role in data collection

References

Alkhorayef M, Babikir E, Alrushoud A, Al-Mohammed H, Sulieman A. Patient radiation biological risk in computed tomography angiography procedure. Saudi J Biol Sci. 2017 24(2):235-240. 

Kim et al. Anatomic and Functional Evaluation of Central Lymphatics With Noninvasive Magnetic Resonance LymphangiographyMedicine _ Volume 95, Number 12, March 2016.

Mettler FA, Jr., Bhargavan M, Faulkner K, et al. Radiologic and nuclear medicine studies in the United States and worldwide: frequency, radiation dose, and comparison with other radiation sources--1950-2007. Radiology. 2009 Nov;253(2):520–531.

Arrivé L, Derhy SEl Mouhadi SMonnier-Cholley LMenu Y1, Becker C. Noncontrast Magnetic Resonance Lymphography. J Reconstr Microsurg. 2016 Jan;32(1):80-6.

Summary of Work
Background
Summary of Results
Conclusion
Acknowledgement
References
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