Analysis of salivary gland function by quantitative Scintigraphy in head and neck malignancies treated with Intensity Modulated Radiotherapy

Introduction:      

Incidence of head and neck cancers is 19.53% in India.Radiotherapy is an important modality in treatment of Head & neck cancers as  a definitive therapy or in adjuvant setting.  Radiotherapy to head and neck region has variety of complications inclding salivary gland dysfunction leading to Xerostomia, and it is one of the most common side effect.   Salivary scintigraphy using 99mTc- pertechnate is a simple, reproducible, and minimally invasive test for quantitative assessment of salivary gland functions. We will prospectively investigate functional alterations in major salivary glands using salivary scintigraphy in a group of patients treated with Intensity Modulated Radiotherapy for head and cancers.

Aims:

To correlate functional changes in major salivary glands using dynamic quantitative scintigraphy and estimate their dose–response relationship in a cohort of patients with Head and Neck cancers treated using gland sparing IMRT/IGRT techniques.

Objectives:

1. To estimate change in function of salivary glands irradiated during radiation treatment to head and neck cancers using salivary gland scintigraphy.

2. To asses dose-response relationship of salivary gland function and its recovery over that time.

Research Hypothesis:

Dose-response relationship of major salivary gland function which were irradiated while treating head and neck malignancies with radiotherapy.

Materials and Methods:

General workup includes general history taking, general physical examination, Complete systemic examination, local and regional lymph nodes examinaition, diagnostic work up and staging.

Patient will planned and treated with IMRT/IGRT technique.

Salivary Scintigraphy would be done as baseline before starting radiation therapy followed by three scans on followup after the treatement on six weeks, three months and six months.

Salivary gland scintigraphy will done with the protocol with 185 MBQ of pertechnatate administered iv and dynamic images of salivary glands acquired for 30mins. Oral lime stimulus administered at 10th minute.

Salivary excretion factor (SEF) will be quantified by determining the maximal excretion activity per gland as a function of maximal uptake

SEF = "Umax–Umin" /"Umax "

The relative change in saliva excretion rate (ΔF) compared with the baseline before the beginning of Radiation Therapy will be calculated using the pre-RT and post-RT excretion rate as follows-

∆F=(EpostRT-EpreRT)/EpreRT