Optimal Normal Tissue Sparing in Craniospinal Axis Irradiation Using IMRT With Daily Intrafractionally Modulated Junction(s)

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• 作者：Johannes M.A.M. Kusters Ph.D.^&lowast ; ; Rob J.W. Louwe Ph.D.^&lowast ; ; Peter G.M. van Kollenburg^&lowast ; ; Martina C. Kunze-Busch Ph.D.^&lowast ; ; Corrie E.M. Gidding Ph.D.^&dagger ; ; Erik J. van Lindert Ph.D.^&Dagger ; ; Johannes H.A.M. Kaanders Ph.D.^&lowast ; ; Geert O.R.J. Janssens M.D.^&lowast ; ;   ; ^{g.janssens@rther.umcn.nl}
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：2011
• 出版时间：1 December 2011
• 年：2011
• 卷：81
• 期：5
• 页码：1405-1414
• 全文大小：1655 K

文摘

Purpose

To develop a treatment technique for craniospinal irradiation using intensity-modulated radiotherapy (IMRT) with improved dose homogeneity at the field junction(s), increased target volume conformity, and minimized dose to the organs at risk (OARs).

Methods and Materials

Five patients with high-risk medulloblastoma underwent CT simulation in supine position. For each patient, an IMRT plan with daily intrafractionally modulated junction(s) was generated, as well as a treatment plan based on conventional three-dimensional planning (3DCRT). A dose of 39.6 Gy in 22 daily fractions of 1.8 Gy was prescribed. Dose¨Cvolume parameters for target volumes and OARs were compared for the two techniques.

Results

The maximum dose with IMRT was <107 % in all patients. V_<95 and V_>107 were <1 cm³ for IMRT compared with 3? cm³ for the craniospinal and 26?3 cm³ for the spinal¨Cspinal junction with 3DCRT. These observations corresponded with a lower homogeneity index and a higher conformity index for the spinal planning target volume with IMRT. IMRT provided considerable sparing of acute and late reacting tissues. V₇₅ for the esophagus, gastroesophageal junction, and intestine was 81 % , 81 % , and 22 % with 3DCRT versus 5 % , 0 % , and 1 % with IMRT, respectively. V₇₅ for the heart and thyroid was 42 % and 32 % vs. 0 % with IMRT.

Conclusion

IMRT with daily intrafractionally modulated junction results in a superior target coverage and junction homogeneity compared with 3DCRT. A significant dose reduction can be obtained for acute as well as late-reacting tissues.