Impact of intensity-modulated radiation therapy as a boost treatment on the lung-dose distributions for non-small-cell lung cancer

Journal Article · Tue Nov 01 04:00:00 EST 2005 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2005.03.012· OSTI ID:20702179

Choi, Youngmin ^[1]; Kim, Jeung Kee ^[1]; Lee, Hyung Sik ^[1]; Hur, Won Joo ^[1]; Chai, Gyu Young ^[2]; Kang, Ki Mun ^[2]

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1. Department of Radiation Oncology, Dong-A University School of Medicine, Busan (Korea, Republic of)
2. Department of Radiation Oncology, Gyeongsang National University School of Medicine, Jinju (Korea, Republic of)

Purpose: To investigate the feasibility of intensity-modulated radiotherapy (IMRT) as a method of boost radiotherapy after the initial irradiation by the conventional anterior/posterior opposed beams for centrally located non-small-cell lung cancer through the evaluation of dose distributions according to the various boost methods. Methods and Materials: Seven patients with T3 or T4 lung cancer and mediastinal node enlargement who previously received radiotherapy were studied. All patients underwent virtual simulation retrospectively with the previous treatment planning computed tomograms. Initial radiotherapy plans were designed to deliver 40 Gy to the primary tumor and involved nodal regions with the conventional anterior/posterior opposed beams. Two radiation dose levels, 24 and 30 Gy, were used for the boost radiotherapy plans, and four different boost methods (a three-dimensional conformal radiotherapy [3DCRT], five-, seven-, and nine-beam IMRT) were applied to each dose level. The goals of the boost plans were to deliver the prescribed radiation dose to 95% of the planning target volume (PTV) and minimize the volumes of the normal lungs and spinal cord irradiated above their tolerance doses. Dose distributions in the PTVs and lungs, according to the four types of boost plans, were compared in the boost and sum plans, respectively. Results: The percentage of lung volumes irradiated >20 Gy (V20) was reduced significantly in the IMRT boost plans compared with the 3DCRT boost plans at the 24- and 30-Gy dose levels (p 0.007 and 0.0315 respectively). Mean lung doses according to the boost methods were not different in the 24- and 30-Gy boost plans. The conformity indexes (CI) of the IMRT boost plans were lower than those of the 3DCRT plans in the 24- and 30-Gy plans (p = 0.001 in both). For the sum plans, there was no difference of the dose distributions in the PTVs and lungs according to the boost methods. Conclusions: In the boost plans the V20s and CIs were reduced significantly by the IMRT plans, but in the sum plans the effects of IMRT on the dose distributions in the tumor and lungs, like CI and V20, were offset. Therefore, to keep the beneficial effect of IMRT in radiotherapy for lung cancer, it would be better to use IMRT as a whole treatment plan rather than as a boost treatment.

• OSTI ID: 20702179
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 63; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
CARCINOMAS
IRRADIATION
LUNGS
PATIENTS
PLANNING
RADIATION DOSE DISTRIBUTIONS
RADIATION DOSES
RADIOTHERAPY
SIMULATION
SPINAL CORD
TOLERANCE