Background
Radiation therapy using external radiation beam is an established treatment for head and neck cancers. However, salivary glands are exposed leading to severe impairment of oral health. In order to devise patient care strategies, clinicians can measure the degree of salivary gland impairment using various imaging modalities.

Aims
The study aimed determining the best imaging modality for measuring salivary glands impairment post external radiation beam therapy of head and neck tumours.

Methods
A systematic literature review, performed using Google and Science Direct.com search engines. Publications in English on salivary gland imaging modalities post external radiation beam therapy of head and neck cancers were selected. Information on advantages and disadvantages of the imaging modalities was documented.

Results
The study established that the Magnetic Resonance Imaging (MRI), Computer Tomography (CT), Ultra Sound (US) depict structural changes while salivary gland scintigraphy provides functional information. It was also established that the obstruction of the salivary glands can be measured using Magnetic Resonance – Sialography.

Conclusion
The salivary gland scintigraphy technique is the most sensitive of all salivary gland imaging modalities with the ability to detect slight parenchymal injuries well before structural changes can be seen using the MRI, CT and US. However, when evaluating the obstruction of the salivary glands ducts, the Magnetic Resonance-Sialography modality offers the best option.