Comparison of intensity-modulated radiotherapy, adaptive radiotherapy, proton radiotherapy, and adaptive proton radiotherapy for treatment of locally advanced head and neck cancer

Abstract

Background and Purpose Various radiotherapy planning methods for locally advanced squamous cell carcinoma of the head and neck (SCCHN) have been proposed to decrease normal tissue toxicity. We compare IMRT, adaptive IMRT, proton therapy (IMPT), and adaptive IMPT for SCCHN. Materials and Methods Initial and re-simulation CT images from 10 consecutive patients with SCCHN were used to quantify dosimetric differences between photon and proton therapy. Contouring was performed on both CTs, and plans (n=40 plans) and dose volume histograms were generated. Results The mean GTV volume decreased 53.4% with re-simulation. All plans provided comparable PTV coverage. Compared with IMRT, adaptive IMRT significantly reduced the maximum dose to the mandible (p=0.020) and mean doses to the contralateral parotid gland (p=0.049) and larynx (p=0.049). Compared with IMRT and adaptive IMRT, IMPT significantly lower the maximum doses to the spinal cord (p<0.002 for both) and brainstem (p<0.002 for both) and mean doses to the larynx (p<0.002 for both) and ipsilateral (p=0.004 IMRT, p=0.050 adaptive) and contralateral (p<0.002 IMRT, p=0.010 adaptive) parotid glands. Adaptive IMPT significantly reduced doses to all critical structures compared with IMRT and adaptive IMRT and several critical structures compared with non-adaptive IMPT. Conclusions Although adaptive IMRT reduced dose to several normal structures compared with standard IMRT, non-adaptive proton therapy had a more favorable dosimetric profile than IMRT or adaptive IMRT and may obviate the need for adaptive planning. Protons allowed significant sparing of the spinal cord, parotid glands, larynx, and brainstem and should be considered for SCCHN to decrease normal tissue toxicity while still providing optimal tumor coverage.

Dose distribution resulting from changes in aeration of nasal cavity or paranasal sinus cancer in the proton therapy

“…Although dose distribution change for critical organs was not so large in the NCPS cancer patients as a whole, some patients in our study showed unexpected change which should not be overlooked. We propose that repeat imaging and dose recalculation is necessary, and that if adaptive treatment planning can be performed it should be positively adopted to avoid unexpected higher dose distribution to critical organs as suggested by previous studies [12,13].…”

“…However, as that increase had large variations, they suggested repeat imaging, dose recalculation, and, if required, adaptive planning to ensure sufficient target coverage and to avoid unwanted exposure of critical organs. Simone et al compared intensity-modulated proton radiotherapy (IMPT) and adaptive IMPT for head and neck cancers, and reported that although dose reduction of critical organs in adaptive IMPT was less clinically significant, care must be taken to account for these changes or to otherwise ensure accuracy of the beam range because proton plans are sensitive to interfractional changes in tumor volume and patient anatomy [13]. In recent years, adaptive treatment planning for head and neck cancers has increased, mostly in X-ray radiotherapy [14,15].…”

Investigating CT to CBCT image registration for head and neck proton therapy as a tool for daily dose recalculation

“…Intensity modulated proton therapy (IMPT) planning studies support this hypothesis by demonstrating improved sparing of OARs compared to IMRT. 2,3 The large anatomical changes which may be observed during fractionated H&N radiation therapy 4 suggest that the use of repeated computed tomography (CT) scanning may be essential during IMRT (Ref. 5) and IMPT (Ref.…”

Intensity Modulated Arc Therapy in Bilaterally Irradiated Head and Neck Cancer: A Comparative and Prospective Multicenter Planning Study

“…A future perspective for ensuring good target coverage while sparing OARs, would be adaptive radiotherapy and, farther away, adaptive proton radiotherapy (31,32).…”