Spinal cord doses in palliative lung radiotherapy schedules
Joint Authors
Source
Journal of the Egyptian National Cancer Institute
Issue
Vol. 18, Issue 2 (30 Jun. 2006), pp.161-166, 6 p.
Publisher
Cairo University National Cancer Institute
Publication Date
2006-06-30
Country of Publication
Egypt
No. of Pages
6
Main Subjects
Topics
Abstract EN
Aim : We aim to check the safety of the standard palliative radiotherapy techniques by using the Linear quadratic model for a careful estimation of the doses received by the spinal cord, in all standard palliative lung radiotherapy fields and fractionation.
Material and Methods : All patients surveyed at this prospective audit were treated with palliative chest radiotherapy for lung cancer over a period from January to June 2005 by different clinical oncology specialists within the department.
Radiotherapy field criteria were recorded and compared with the recommended limits of the MRC trial protocols for the dose and fractionation prescribed.
Doses delivered to structures off the field central axis were estimated using a standard CT scan of the chest.
Dose estimates were made using an SLPLAN planning system.
As unexpected spinal cord toxicity has been reported after hypofractionated chest radiotherapy, a sagittal view was used to calculate the isodoses along the length of the spinal cord that could lie within the RT field.
Equivalent dose estimates are made using the Linear- Quadratic Equivalent Dose formula (LQED).
The relative radiation sensitivity of spinal cord for myelopathy (the a / b dose) cord has been estimated as a / b = 1Gy.
Results : 17Gy in 2 fraction and 39Gy in 13 fraction protocols have spinal cord equivalent doses (using the linear-quadratic model) that lie within the conventional safe limits of 50Gy in 25 fractions for the 100 % isodose.
However when the dosimetry is modelled for a 6MV 100cm isocentric linnac in 3 dimensions, and altered separations and air space inhomogeneity are considered, the D-Max doses consistently fall above this limit on our 3 model patients.
Conclusion : The 17Gy in 2 fraction and 39Gy in 13 fraction protocol would risk spinal cord damage if the radiotherapist was unaware of the potential spinal cord doses.
Alterative doses are suggested below 15.5 Gy / 2 fractions (7 days apart) would be most acceptable.
American Psychological Association (APA)
al-Booz, Huda& Parton, Carol. 2006. Spinal cord doses in palliative lung radiotherapy schedules. Journal of the Egyptian National Cancer Institute،Vol. 18, no. 2, pp.161-166.
https://search.emarefa.net/detail/BIM-29383
Modern Language Association (MLA)
al-Booz, Huda& Parton, Carol. Spinal cord doses in palliative lung radiotherapy schedules. Journal of the Egyptian National Cancer Institute Vol. 18, no. 2 (Jun. 2006), pp.161-166.
https://search.emarefa.net/detail/BIM-29383
American Medical Association (AMA)
al-Booz, Huda& Parton, Carol. Spinal cord doses in palliative lung radiotherapy schedules. Journal of the Egyptian National Cancer Institute. 2006. Vol. 18, no. 2, pp.161-166.
https://search.emarefa.net/detail/BIM-29383
Data Type
Journal Articles
Language
English
Notes
Includes bibliographical references : p. 165-166
Record ID
BIM-29383