To implement total body irradiation (TBI) using volumetric modulated arc therapy (VMAT). We applied the Varian RapidArc™ software to calculate and optimize the dose distribution. Emphasis was placed on applying a homogenous dose to the PTV and on reducing the dose to the lungs and kidneys.

Two data- set of computed tomography (CT) (Head first supine and Feet first supine) were acquired. The planning target volumes included entire body trimmed to 3 mm below the skin. The organs at risk included the lungs and kidneys.Treatment planning was performed on the Eclipse 15.5 platform (Varian Medical Systems, Palo Alto, California, USA). A dose of 12 Gy in 6 fractions was prescribed to the target volume. Dose was normalized so that 95% of the prescribed dose covered 95% of the PTV. Planning objectives for PTV aimed to limit the minimum and maximum doses. 6 MV photon beam was used for the arc fields. A 120-leaf multi-leaf collimator (MLC) was used for beam modulation. Idependent plan was made on each data set of CT and then fuse them for final evaluation.
 

The total body volume in the study was 15469cm3 and the PTV volume was 11322cm3. The mean dose to PTV was 106%. The homogeneity index was 0.092. Sparing of normal tissues with adequate coverage of skeletal bones was shown to be feasible with Rapid Arc. Mean dose to lungs was 7.92 and both kidneys was 6.5 Gy .

This study has demonstrated the feasibility of achieving clinically acceptable RapidArc TBI plans with the Eclipse  treatment planning system and accurate delivery using Varian linac. The advantages of this technique include improved patient comfort and positioning reproducibility during treatment, accurate 3D dose information, and the ability to selectively spare organs at risk.TBI also provides the benefit of satisfactory dose distribution within the PTV, while slectively reducing the dose to the lungs and kidneys, if necessary, in the other organs too.

I whould like to acknowledge whole team of TBI including

Dr. Tabinda Sadaf  (Oncologist)

Mr. Abur Rafaye  (Physicist)

Mr. Umair Zafar  (Physicist)

Mr. Sajid Anees Minhas  (Physicist))

Zeshan Haider  (Therapist)

Ehsan Asif  (Therapist)

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2.  Teoh M, Clark CH, Wood K,et al . Volumetric modulated arc therapy: a review of current literature and clinical use in practice. Br J Radiol 2011; 84:967-96.

3. ChakrabortyS, CheruliyilS, BharthanR, MuttathG.Total body irradiation using VMAT (RapidArc): A planning study of a novel treatment delivery method. Int J Cancer Ther Oncol 2015;3(2):03028.