Abstract
PurposeFor whole esophagus and T-shaped field radiotherapy using intensity modulated radiotherapy (IMRT) technique in advanced esophageal cancer, lower absorbed doses to lung and heart remains a challenge. The aim of this study was to investigate the dosimetric superiority in IMRT plans with jaw tracking technique for whole esophagus radiotherapy.Methods and materialsThirty-two patients with esophageal cancer were subjected to IMRT treatment plans using Eclipse treatment planning system. For every patient, four different plans were generated with six gantry angles: six large fields IMRT plans with fixed jaw (6F-IMRT), six large fields IMRT plans with jaw tracking technique (6F-IMRT-T), twelve small fields IMRT plans with fixed jaw (12F-IMRT), and twelve small fields IMRT plans with jaw tracking technique (12F-IMRT-T). Dosimetric evaluation was assessed for all plans.ResultsFor every technique, there were no differences in planning target volume (PTV) coverage and conformity. 6F-IMRT-T plans could significantly reduce lung irradiation with 7.9% (P<0.001) reduction in V5lung and 2.5% (P<0.001) reduction in V20 lung respectively compared to 6F-IMRT plans. 12F-IMRT-T plans resulted in superior plans compared to 12-IMRT plans with a reduction of 2.9% (P<0.001) in V5lung and 0.9% (P<0.001) in V20 lung, respectively. For heart irradiation, 6F-IMRT-T and 12F-IMRT-T plans were slightly superior to 6F-IMRT and 12-IMRT plans respectively with a reduction of 1.1 Gy and 0.5 Gy in the respective mean doses.ConclusionsBy the use of jaw tracking technique, the IMRT plans resulted in further lung and heart sparing compared to fixed jaw plans for radiotherapy in esophageal cancer.
Highlights
Esophageal cancer is cancer arising from the esophagus and is the eighth-most common cancer in the world [1]
There were no differences in planning target volume (PTV) coverage and conformity. 6F-intensity modulated radiotherapy (IMRT)-T plans could significantly reduce lung irradiation with 7.9% (P
By the use of jaw tracking technique, the IMRT plans resulted in further lung and heart sparing compared to fixed jaw plans for radiotherapy in esophageal cancer
Summary
Esophageal cancer is cancer arising from the esophagus and is the eighth-most common cancer in the world [1]. Radiation therapy is one of the main modalities for the treatment of esophageal cancer; the risk of radiationinduced toxicity (expecially radiation pneumonitis) may be increased due to the large target volume irradiation and combined- chemotherapy. Radiation pneumonitis is the most common complication of esophageal radiation, and the incidence is 10–20% in the clinic [5]. To reduce the radiation dose value of surrounding normal tissues and minimize the risk of radiationinduced toxicity, several investigators have studied various and sophisticated techniques. Louis Fenkell et al [7] have compared plan quality (e.g., target coverage, normal tissues sparing) of IMRT and 3D conformal radiotherapy (3D-CRT) for esophageal cancer irradiation, and showed that IMRT plans resulted in superior normal tissues sparing. The jaw tracking technique in IMRT or VMAT plans have been compared with static jaw technique by some investigators, and showed that jaw tracking technique can provide superior normal tissues sparing [13,14,15]
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