A109
Comparative analysis of Tomotherapy versus field in field complex forward planned conformal technique versus 2 phase conformal technique in the radical radiotherapy treatment of Squamous Cell Carcinoma of the Head and Neck
Hui Woon Loo, Nicolas Willis, Greg Smyth, Judith Mott, Werner Dobrowsky, Charles Kelly, Sanjoy Chatterjee
Northern Centre for Cancer Care, Newcastle-upon-Tyne, UK
Background
Intensity Modulated Radiotherapy (IMRT) is increasingly used in the treatment of Head and Neck Squamous Cell Carcinomas (HNSCC). Compared to 3-dimensional conformal radiotherapy (3D-CRT) IMRT can reduce radiation dose to organs at risk (OARs). The Tomotherapy Hi Art system delivers IMRT and Image Guided Radiotherapy (IGRT). IMRT and IGRT are resource intensive and many UK centres treat their HNSCC using a 2 phase matched photon and electron plan (2-Phase plan). A complex single phase plan using field-in-field techniques (1-Phase plan) has been used in Newcastle since 2002.
Method
Tomotherapy plans for 4 HN-SCC patients treated in Newcastle were selected. Each case was re-planned using a 2-Ph plan and 1-Ph plan to compare and analyse the doses given to PTV, CTV and OARs (Parotids, Larynx, Mandible, Cord). A dose of 65Gy in 30 fractions to the high risk PTV and 54Gy in 30 fractions to the elective PTV was prescribed. DVH data was analysed for CTV,PTV and individual OARs with respect to local IMRT protocol constraints.
Results
Tomotherapy plans offer the best conformity to the target volume and increased sparing of OARs. 1-Phase plans deliver treatment with optimal conformity to target volumes and allows more sparing of normal tissue when compared to 2-Phase plans. The 1-Phase plans eliminate some of the practical problems of treating in 2 phases, and removes the inherent uncertainties of using a matched photon and electron treatment plan.
Conclusion
Tomotherapy plans are superior but resource intensive. The 1-Phase plan we use is a superior alternative to a 2-Phase plan. Centres with limited capacity for inverse planned IMRT techniques could implement 1-Phase planning for routine patient care. (Full data on planning techniques and individual DVH will be presented).
