Dosimetry of different techniques in postmastectomy radiation therapy on the ipsilateral lung
10.3760/cma.j.issn.0254-5098.2011.06.016
- VernacularTitle:乳腺癌改良根治术后放疗降低患侧肺受量的剂量学研究
- Author:
Wei HONG
;
Li RAN
;
Bing LU
;
Li YANG
;
Jianying CHANG
;
Jiaying GAN
;
Yinxiang HU
- Publication Type:Journal Article
- Keywords:
Postmastectomy;
Radiation therapy;
Ipsilateral lung dose;
Dosimetry
- From:
Chinese Journal of Radiological Medicine and Protection
2011;31(6):684-687
- CountryChina
- Language:Chinese
-
Abstract:
Objective To identify the best technique of postmastectomy radiation therapy (PMRT).Methods Twenty-eight patients with stage Ⅱ or Ⅲ invasive breast cancer were treated with modified radical mastectomy and radiotherapy sequaciously involving the supraclavicular region and the chest wall.Three different techniques were developed for each patient:two tangential conformal fields ( half field) in the chest wall plus supraclavicular intensity modulated radiotherapy (3D-CRT + IMRT),integrated chest wall and supraclavicular IMRT(IMRT),and two tangential conformal fields (half field) in the chest wall plus single field electron beam radiotherapy in the supraclavicular region( 3D-CRT + E).The dose distributions of the target areas and the irradiated volumes of the ipsilateral lung ( V5,V10,V20,and V45)were estimated with the dosage volume histogram (DVH).The dosage prescription was 50.4 Gy (1.8 Gy × 28 f).Results The conformity index (CI) of the 3D-CRT + IMRT group was (0.61 ± 0.03),not different from that of the IMRT [ (0.62 ±0.03),q =2.16,P ＞0.05],and the CI levels of these 2 groups were both higher than that of the 3D-CRT + E group [ (0.44 ± 0.02 ),q =20.50,22.66,P ＜0.01 ].The heterogeneity index (HI) of the 3D-CRT + IMRT group was ( 1.17 ±0.02),not different from that of the IMRT [ (1.15 ±0.02),q =1.66,P ＞0.05],and the HI levels of these 2 groups were both lower than that of the 3D-CRT + E group[ ( 1.24 ±0.04),q =3.91,5.58,P ＜0.01 ].The levels of V5 and V10 of the ipsilateral lungs of the 3D-CRT + E group(48.70％ ±3.24％,38％.56％ ±3.70％ ) and 3D-CRT + IMRT group (49.12％ ±3.03％,38.38％ ± 3.56％ ) were all significantly lower than those of the IMRTgroup [(77.18％ ±8.01％,53.07％ ±6.85％),V5,q =20.35,20.05,P＜0.01; V10,q=12.10,12.24,P ＜0.01 ] and there were not significant differences in the V5 and V10 levels between the 3D-CRT + E and 3D-CRT + IMRT groups ( q =0.30,0.14,P ＞ 0.05 ).The levels of V20 of the ipsilateral lungs of the 3D-CRT + IMRT group (26.57％ ±2.51％ )and IMRT group (25.22％ ±2.77％) were all significantly lower that those of the 3D-CRT + E group [ (31.79％ ± 3.00％ ),q =5.27,8.21,P ＜ 0.01 ]and there were not significant differences in the V20 level between the 3D-CRT + IMRT and IMRT groups (q=2.76,P ＞ 0.05 ).There were not significant differences in the V45 levels among these 3 groups (F =0.69,P ＞ 0.05).Conclusions The 3D-CRT + IMRT technique in PMRT effectively reduces the radiated dose on the ipsilateral lung.
