Abstract
Purpose: Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) has the capacity to optimize the dose distribution. We analyzed the dosimetric differences of plans in treatment planning system (TPS) between VMAT and IMRT in treating breast cancer. Methods : Fourteen patients were simulated, planned, and treated with VMAT using single, double or partial arcs. IMRT treatments were generated using 4 to 5 tangential IMRT fields for the same patients. All treatment plans were planned for 50 Gy in 25 fractions. The VMAT and IMRT plans were compared using the planning target volume (PTV) dose and doses to the other organs at risk (OARs). Results : For the PTV, comparable minimum, mean, maximum, median, and modal dose as well equivalent sphere diameter of the structure (Equis) were observed between VMAT and IMRT plans and found that these values were significantly equal in both techniques. The right lung mean and modal doses were considerably higher in VMAT plans while maximum value was considerably lower when compared with IMRT plans. The left lung mean and modal doses were higher with VMAT while maximum doses were higher in IMRT plans. The mean dose to the heart and maximum dose to the spinal cord was lower with IMRT. The mean dose to the body was higher in VMAT plans while the maximum dose was higher in IMRT plans. Conclusion : Four field tangential IMRT delivered comparable PTV dose with generally less dose to normal tissues in our breast cancer treatment study. The IMRT plans typically had more favourable dose characteristics to the lung, heart, and spinal cord and body dose when compared with VMAT. The only minor advantage of VMAT for breast cases was slightly better PTV coverage.
Highlights
The number of patients with breast cancer treated with radiation therapy has increased in the past few years
The mean dose to the body was higher in volumetric modulated arc therapy (VMAT) plans while the maximum dose was higher in intensity-modulated radiotherapy (IMRT) plans
The IMRT plans demonstrated significantly lower mean doses to organs at risk (OARs) and equivalent doses to the planning target volume (PTV) when compared with VMAT plans
Summary
The number of patients with breast cancer treated with radiation therapy has increased in the past few years. Normal tissue toxicities can limit the advantage of this treatment modality.[1,2] Standard tangential beams have resulted in excellent local control rates, low rates of cardiac and pulmonary complications, and excellent cosmetic results in the vast majority of patients.[3,4,5,6,7] Three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) techniques improve the treatment delivery by improving the target volume coverage and minimizing dose to other organs at risk (OARs).[8,9,10,11,12,13,14,15,16,17,18] With IMRT, it is possible to reduce the volume of the lung irradiated to full doses by tangential fields, and in left-sided cases, the heart can be partially spared. Several publications on this topic have discussed advantages and disadvantages of IMRT versus volumetric modulated arc therapy (VMAT).[19,20,21]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
