Tomotherapy evaluation for head and neck cases using two types of phantoms

The use of rotational therapy as an important method of treatment delivery is expected to increase due in a large part to the development and utilisation of tomotherapy. Rotational therapy minimises the occurrence of hotspots and the irradiation of critical organs, providing more uniform dosing while sparing critical organs. Two important characteristics of rotational radiation are its dynamic nature and dosimetric variability in radiation delivery, both of which present a considerable challenge for clinical physicists seeking appropriate tools to meet the demands of quality assurance. In this paper 15 Delivery Quality Assurance (DQA) plans of head and neck patients were assessed for the Hi-Art tomotherapy system using Kodak X-Omat V film and an A1SL Ref F92722 ion chamber versus MapCheck. Absolute dose measurement showed average differences of 3.42 cGy and 98% Gamma (γ) factor for the Cheese phantom technique. For the MapCheck technique the average difference and Gamma factor were 0.74 cGy and 96%, respectively. Gamma (γ) matrix distribution was used to evaluate the difference between measured and calculated dose distribution. - Highlights: • Rotational therapy is an important for treatment delivery. • The important characteristic of rotational of radiation is its dynamic nature. • Challenge for clinical physicist is the dosimetric variability in radiation delivery. • Evaluating H and N cases using two type of phantoms, Cheese phantom and MapCheck. • Using the Cheese phantom gives us a good results