Dosimetric comparison of three-field conformal spinal radiation and single posterior spinal field in craniospinal irradiation

Authors

  • Natcha Senawin Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society
  • Tassapong Raiyawa Division of Radiation Oncology, Department of Radiology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society

Keywords:

3D conformal radiotherapy, craniospinal irradiation, three-field conformal spinal radiation

Abstract

Background: Craniospinal irradiation (CSI) is technically challenging because of the need to cover complex clinical target volume. There are innovative techniques improving target volume coverage such as intensity-modulated radiotherapy (IMRT), tomotherapy, and proton therapy. However, 3D conformal radiotherapy (3D-CRT) is still used in limited-resource institutions.

Objectives: To compare the radiation dose to organs at risk (OARs), conformation number (CN), and homogeneity index (HI) between 3-field conformal spinal radiation (3F-SPINE) and single posterior spinal field (1F-SPINE).

Material and methods: From June 2011 to December 2012, 10 patients with high risk of craniospinal involvement  underwent CT simulation with supine position and replanned CSI with 3F-SPINE and 1F-SPINE. Prescription dose was 36 Gy to 95% of the PTV. The parameters were V25Gy of heart, V20Gy of lung, mean lung dose, V20Gy of kidneys, mean liver dose, CN, and HI.

Results: 3F-SPINE showed a significant reduction of V25Gy of heart within QUANTEC threshold compared to 1F-SPINE (3.03% vs 42.48%). However, doses to other OARs were within QUANTEC threshold in both techniques. 3F-SPINE showed better results in V20Gy of lung and CN than 1F-SPINE (V20Gy of lung of 9.83% vs 12.59%; and CN of 0.75 vs 0.70, respectively). In contrast, 1F-SPINE showed better results in mean lung dose, V20Gy of kidneys, and HI than 3F-SPINE (mean lung dose of 6.27 Gy vs 8.53 Gy, V20Gy kidneys of 11.24% vs 13.02%, and HI of 1.16 vs 1.17, respectively). There was no significant difference between 3F-SPINE versus 1F-SPINE for mean liver dose (9.03 Gy vs 9.16 Gy).

Conclusion: 3F-SPINE reduced V25Gy of heart to be within QUANTEC threshold. Doses to other OARs were within QUANTEC threshold in both techniques.

References

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Published

2020-07-30

How to Cite

1.
Senawin N, Raiyawa T. Dosimetric comparison of three-field conformal spinal radiation and single posterior spinal field in craniospinal irradiation. J Thai Assn of Radiat Oncol [Internet]. 2020 Jul. 30 [cited 2024 Dec. 21];26(2):R1-R13. Available from: https://he01.tci-thaijo.org/index.php/jtaro/article/view/240948

Issue

Vol. 26 No. 2 (2020): July - December

Section

Original articles

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