Majer Marija, Stolarczyk Liliana, De Saint-Hubert Marijke, Kabat Damian, Kneževic Željka, Miljanic Saveta, Mojzeszek Natalia, Harrison Roger
Ruder Boškovic Institute, Bijenicka cesta 54, 10000 Zagreb, Croatia.
Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342 Krakow, Poland.
Radiat Prot Dosimetry. 2017 Nov 1;176(3):331-340. doi: 10.1093/rpd/ncx015.
The purpose of this study was to measure out-of-field organ doses in clinical conditions in anthropomorphic paediatric phantoms which received a simulated treatment of a brain tumour with intensity modulated radiotherapy (IMRT) and 3D conformal radiotherapy (3D CRT). Organ doses measured with radiophotoluminescent and thermoluminescent dosemeters were on average 1.6 and 3.0 times higher for the 5 y-old than for the 10 y-old phantom for IMRT and 3D CRT, respectively. A larger 5-y to 10-y organ dose ratio for 3D CRT can be explained because the use of a mechanical wedge for the 5-y-old 3D CRT phantom treatment increased out-of-field doses. Due to different configurations of the radiation fields, for both phantoms, the IMRT technique resulted in a higher non-target brain dose and higher eye doses but lower thyroid doses compared to 3D CRT. For 3D CRT (which used a non-coplanar field configuration), eye doses were 3-6% and for IMRT (which used a coplanar field configuration) 27-30% of the treatment dose, respectively. For thyroid and more distant organs, doses were less than 1% of the treatment dose. Comparison of measured doses and doses calculated by the treatment planning system (TPS) showed that the TPS underestimated out-of-field doses both for IMRT and 3D CRT.
本研究的目的是在拟人化儿科体模的临床条件下测量野外器官剂量，这些体模接受了调强放射治疗（IMRT）和三维适形放射治疗（3D CRT）模拟的脑肿瘤治疗。对于IMRT和3D CRT，用放射性光致发光剂量计和热释光剂量计测量的5岁体模的器官剂量平均分别比10岁体模高1.6倍和3.0倍。3D CRT的5岁至10岁器官剂量比更大，这可以解释为在5岁3D CRT体模治疗中使用机械楔形物增加了野外剂量。由于辐射野的配置不同，对于两个体模，与3D CRT相比，IMRT技术导致更高的非靶区脑剂量和更高的眼部剂量，但甲状腺剂量更低。对于3D CRT（采用非共面野配置），眼部剂量分别为治疗剂量的3 - 6%，对于IMRT（采用共面野配置），眼部剂量为治疗剂量的27 - 30%。对于甲状腺和更远的器官，剂量小于治疗剂量的1%。测量剂量与治疗计划系统（TPS）计算剂量的比较表明，TPS低估了IMRT和3D CRT的野外剂量。
