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Dosimetry Comparison of IMRT, VMAT Versus Proton and Carbon Ion Pencil Beam Scanning Techniques for Tongue Cancer

X Ming1*, K Shahnazi1 , L Kong1 , W Wang1 , (1) Shanghai Proton and Heavy Ion Center, Shanghai


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: To evaluate the dosimetry advantage of particle radiotherapy for tongue cancer compared to photon therapy

Methods: Seven patients with tongue cancer were involved in this study. Intensity modulated proton therapy (IMPT), intensity modulated carbon therapy (IMCT), intensity modulated photon therapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were designed to give a similar dose distribution to the clinical target volume (CTV). The particle plans were optimized by local effect model (LEM) to calculate the relative biological dose calculation in Syngo(V13B, Siemens). The photon plans were by Eclipse(V11, Varian). Doses in the contralateral parotid, spinal cord, brainstem, oral cavity (mean dose) and the integral dose in the patients' body were evaluated in this study. T test was performed for statistical analyses.

Results: There was no significant difference (p>0.05) in the dose coverages (V95%) of CTV in the four modalities. The mean doses of the contralateral parotid could be significantly reduced from 24.30±17.02GyE (IMRT, p=0.008) and 25.05±15.90 GyE (VMAT, p=0.010) to 17.52±16.78 GyE (IMCT). V30GyE of the contralateral parotid could be also reduced by 27.61% (VMAT) and 25.08% (IMRT) in the carbon plans. The D1% of spinal cord (brain stem) in IMRT and VMAT were 22.88±9.06(8.68±9.14)GyE and 23.52±10.54(9.65±9.10)GyE, while D1% of spinal cord (brain stem) were 12.98±9.07(2.74±5.54)GyE and 14.13±11.03(2.49±3.86)GyE in IMCT and IMPT plans. The mean doses of the patients' oral cavity were 41.66±22.53GyE, 44.32±22.42GyE, 49.60±16.23GyE and 50.57±17.13GyE in IMCT, IMPT, IMRT and VMAT plans. No significant difference on the mean doses (p=0.11) and V30GyE (p=0.085) of the contralateral parotid was obtained between in IMPT and IMCT plans. The integral dose in patients' body could be significantly reduced from 7.68×〖10〗^3GyE×〖ccm〗^3(VMAT, p<0.001), 7.67×〖10〗^3GyE×〖ccm〗^3(IMRT, p=0.001) and 4.70×〖10〗^3GyE×〖ccm〗^3 (IMPT, p<0.001) to 3.77×〖10〗^3GyE×〖ccm〗^3(IMCT).

Conclusion: IMPT and IMCT are capable of reducing the doses in the OARs and normal tissues than photon techniques.


Protons, Radiation Dosimetry, Heavy Ions


TH- External Beam- Particle therapy: Proton therapy - treatment planning/virtual clinical studies

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