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Calculation and measurements of absorbed dose in total body irradiation

Svahn-Tapper, Gudrun LU ; Nilsson, Per LU ; Jönsson, Christel LU and Alvegård, Thor LU (1990) In Acta Oncologica 29(5). p.627-633
Abstract
A method which is simple, reliable, and rapid to use in clinical routine for basic dose calculation in total body irradiation (TBI) has been tested with 8 MV x-rays. The dosimetry follows, as far as possible, national and international recommendations for conventional radiotherapy. The dose rate at different locations and depths is calculated from the absorbed dose rate at dose maximum for a phantom size of 30 x 30 x 30 cm in the TBI field (Dc), an inverse square law factor (SAD2/SPD2), the tissue-maximum ratio (TMR), an equivalent phantom and patient size correction factor (A), a factor for lack of back-scattering material (B), an off-axis output correction factor (O), and a factor that corrects for off-axis variations in effective photon... (More)
A method which is simple, reliable, and rapid to use in clinical routine for basic dose calculation in total body irradiation (TBI) has been tested with 8 MV x-rays. The dosimetry follows, as far as possible, national and international recommendations for conventional radiotherapy. The dose rate at different locations and depths is calculated from the absorbed dose rate at dose maximum for a phantom size of 30 x 30 x 30 cm in the TBI field (Dc), an inverse square law factor (SAD2/SPD2), the tissue-maximum ratio (TMR), an equivalent phantom and patient size correction factor (A), a factor for lack of back-scattering material (B), an off-axis output correction factor (O), and a factor that corrects for off-axis variations in effective photon beam energy and for oblique beam penetration of the patient (R). The collimator opening is constant for all patient sizes. It is shown that TMR, A, B and R can be measured in conventional geometry in ordinary phantoms but at an extended distance, while Dc, O and SAD2/SPD2 must be measured in TBI geometry. Tests in Humanoid phantoms showed an agreement in measured and planned AP/2 doses of 2% or better. If the calculation method is used for lower photon energies or in other TBI geometries it may be necessary to correct for the elliptical shape of the patient and for back-scattered radiation from the walls or floor. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
leukaemia, 8 MV x-rays, radiotherapy, Total body irradiation, dosimetry, bone marrow transplantation
in
Acta Oncologica
volume
29
issue
5
pages
627 - 633
publisher
Taylor & Francis
external identifiers
  • pmid:2206578
  • scopus:0024989394
ISSN
1651-226X
DOI
10.3109/02841869009090064
language
English
LU publication?
yes
id
b4284d66-b1a2-4ab0-bd61-c7d1865ff235 (old id 1105059)
date added to LUP
2008-08-04 16:02:47
date last changed
2017-01-01 07:10:09
@article{b4284d66-b1a2-4ab0-bd61-c7d1865ff235,
  abstract     = {A method which is simple, reliable, and rapid to use in clinical routine for basic dose calculation in total body irradiation (TBI) has been tested with 8 MV x-rays. The dosimetry follows, as far as possible, national and international recommendations for conventional radiotherapy. The dose rate at different locations and depths is calculated from the absorbed dose rate at dose maximum for a phantom size of 30 x 30 x 30 cm in the TBI field (Dc), an inverse square law factor (SAD2/SPD2), the tissue-maximum ratio (TMR), an equivalent phantom and patient size correction factor (A), a factor for lack of back-scattering material (B), an off-axis output correction factor (O), and a factor that corrects for off-axis variations in effective photon beam energy and for oblique beam penetration of the patient (R). The collimator opening is constant for all patient sizes. It is shown that TMR, A, B and R can be measured in conventional geometry in ordinary phantoms but at an extended distance, while Dc, O and SAD2/SPD2 must be measured in TBI geometry. Tests in Humanoid phantoms showed an agreement in measured and planned AP/2 doses of 2% or better. If the calculation method is used for lower photon energies or in other TBI geometries it may be necessary to correct for the elliptical shape of the patient and for back-scattered radiation from the walls or floor.},
  author       = {Svahn-Tapper, Gudrun and Nilsson, Per and Jönsson, Christel and Alvegård, Thor},
  issn         = {1651-226X},
  keyword      = {leukaemia,8 MV x-rays,radiotherapy,Total body irradiation,dosimetry,bone marrow transplantation},
  language     = {eng},
  number       = {5},
  pages        = {627--633},
  publisher    = {Taylor & Francis},
  series       = {Acta Oncologica},
  title        = {Calculation and measurements of absorbed dose in total body irradiation},
  url          = {http://dx.doi.org/10.3109/02841869009090064},
  volume       = {29},
  year         = {1990},
}