Evaluation of Dose Distributions Recalculated with Per-field Measurement Data under the Condition of Respiratory Motion during IMRT for Liver Cancer
Progress in Medical Physics 2014³â 25±Ç 2È£ p.79 ~ p.88
¼ÛÁÖ¿µ(Song Ju-Young) - Chonnam National University Medical School Department of Radiation Oncology
±è¿ëÇù(Kim Yong-Hyeob) - Chonnam National University Hwasun Hospital Department of Radiation Oncology
Á¤Àç¿í(Jeong Jae-Uk) - Chonnam National University Hwasun Hospital Department of Radiation Oncology
À±¹Ì¼±(Yoon Mee-Sun) - Chonnam National University Medical School Department of Radiation Oncology
¾È¼ºÀÚ(Ahn Sung-Ja) - Chonnam National University Medical School Department of Radiation Oncology
Á¤¿õ±â(Chung Woong-Ki) - Chonnam National University Medical School Department of Radiation Oncology
³²ÅñÙ(Nam Taek-Keun) - Chonnam National University Medical School Department of Radiation Oncology
Abstract
The dose distributions within the real volumes of tumor targets and critical organs during internal target volume-based intensity-modulated radiation therapy (ITV-IMRT) for liver cancer were recalculated by applying the effects of actual respiratory organ motion, and the dosimetric features were analyzed through comparison with gating IMRT (Gate-IMRT) plan results. The ITV was created using MIM software, and a moving phantom was used to simulate respiratory motion. The doses were recalculated with a 3 dose-volume histogram (3DVH) program based on the per-field data measured with a MapCHECK2 2-dimensional diode detector array. Although a sufficient prescription dose covered the PTV during ITV-IMRT delivery, the dose homogeneity in the PTV was inferior to that with the Gate-IMRT plan. We confirmed that there were higher doses to the organs-at-risk (OARs) with ITV-IMRT, as expected when using an enlarged field, but the increased dose to the spinal cord was not significant and the increased doses to the liver and kidney could be considered as minor when the reinforced constraints were applied during IMRT plan optimization. Because the Gate-IMRT method also has disadvantages such as unsuspected dosimetric variations when applying the gating system and an increased treatment time, it is better to perform a prior analysis of the patient¡¯s respiratory condition and the importance and fulfillment of the IMRT plan dose constraints in order to select an optimal IMRT method with which to correct the respiratory organ motional effect.
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Respiratory organ motion, IMRT, Internal target volume (ITV), Gating system, 3DVH
KMID :
1038720140250020079
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À¯È¿¼º°á°ú(Recomendation)
Dose distributions within the real volumes of the PTV and OARs during ITV-IMRT for liver cancer while under respiratory motional conditions could be acquired, and these data confirmed that higher irradiation doses were delivered to the OARs when compared to those calculated in the Gate-IMRT plan.