Abstract
PurposeThe aim of the present study was to compare the dose distribution generated from photon volumetric modulated arc therapy (VMAT), intensity modulated proton therapy (IMPT), and intensity modulated carbon ion therapy (IMCIT) in the delivery of hypo-fractionated thoracic radiotherapy.Methods and materialsTen selected patients who underwent thoracic particle therapy between 2015 and 2016 were re-planned to receive a relative biological effectiveness (RBE) weighted dose of 60 Gy (i.e., GyE) in 15 fractions delivered with VMAT, IMPT, or IMCIT with the same optimization criteria. Treatment plans were then compared.ResultsThere were no significant differences in target volume dose coverage or dose conformity, except improved D95 was found with IMCIT compared with VMAT (p = 0.01), and IMCIT was significantly better than IMPT in all target volume dose parameters. Particle therapy led to more prominent lung sparing at low doses, and this result was most prominent with IMCIT (p < 0.05). Improved sparing of other thoracic organs at risk (OARs) was observed with particle therapy, and IMCIT further lowered the D1cc and D5cc for major blood vessels, as compared with IMPT (p = 0.01).ConclusionAlthough it was comparable to VMAT, IMCIT led to significantly better tumor target dose coverage and conformity than did IMPT. Particle therapy, compared with VMAT, improved thoracic OAR sparing. IMCIT, compared with IMPT, may further improve normal lung and major blood vessel sparing under limited respiratory motion.
Highlights
Early-stage non-small cell lung cancer (NSCLC) and lung metastases have been treated with stereotactic body radiation therapy (SBRT) with excellent clinical outcome [1,2,3,4]
We explored the dosimetric characteristics of intensity-modulated proton therapy (IMPT) and carbon ion therapy (IMCIT) with raster scanning beams in the delivery of hypo-fractionated thoracic radiotherapy in comparison to volumetric modulated arc therapy (VMAT) under limited respiratory motion
No statistically significant differences in V95, D95, and D99 were observed between VMAT and fixed-beam IMPT, VMAT led to significantly lower Maximum dose (Dmax), conformity index (CI), homogeneity index (HI), and new Conformity Index (nCI) (p < 0.05)
Summary
Early-stage non-small cell lung cancer (NSCLC) and lung metastases have been treated with stereotactic body radiation therapy (SBRT) with excellent clinical outcome [1,2,3,4]. Particle therapy (PT), which includes proton and heavy ion therapies, may have an advantage over VMAT in OAR sparing This improvement is due to PT’s physical properties, which allow for better normal tissue protection, while heavy ions’ increased radiobiological effectiveness (RBE) increases the tumorcidal effect of radiotherapy over photons [13, 14]. PT’s dosimetric advantages have been shown in multiple studies [15,16,17,18,19,20,21,22] Given these advantages, PT is increasingly being considered for the delivery of hypo-fractionated thoracic radiotherapy [23, 24]. We explored the dosimetric characteristics of intensity-modulated proton therapy (IMPT) and carbon ion therapy (IMCIT) with raster scanning beams in the delivery of hypo-fractionated thoracic radiotherapy in comparison to VMAT under limited respiratory motion
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