ASSESSMENT OF NORMAL TISSUE COMPLICATION PROBABILITY FOR PATIENTS UNDERGOING EXTERNAL BEAM RADIOTHERAPY OF CANCER OF THE CERVIX
ASSESSMENT OF NORMAL TISSUE COMPLICATION PROBABILITY FOR PATIENTS UNDERGOING EXTERNAL BEAM RADIOTHERAPY OF CANCER OF THE CERVIX
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Date
2014-08
Authors
ONUH, ECHECHE
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Abstract
The effect of cervical cancer treatment on women was re-examined in the northern
Nigeria with a view to observe the resulting effect of the available diagnosis and
treatment procedures. Although, modern radiation therapy techniques which includes
External Beam Radiotherapy (EBRT), have the ability to conform the dose distribution of
ionizing radiation tightly around the volume to be treated, unwanted irradiation to
surrounding organs remains a problem. Three basic methods were followed during the
radiotherapy planning of these patients which included the pre-planning stage, planning
radiotherapy treatment stage and treatment delivery. Various tests were carried out on
these patients which helped to confirm the diagnosis after which they were treated using
the linear accelerator, computed tomography simulator and the treatment planning
system. The probability of a side effect arising in the normal tissue of a patient after
radiation therapy was modelled by sigmoid mathematical functions known as normal
tissue complication probability (N.T.C.P) models. Hence, to compute N.T.C.P in this
research work, the linear equation used in the work developed by Emami et al (1991) was
used. This equation has three tissue specific parameters, aG, k & N0, and three variables
(NTCP, dose and volume of the organ). The equation has been applied to compute the
above said three parameters of the NTCP model using the doses of normal tissues /
organs around the cervix extracted from cervical cancer patients under study at the
Usman Danfodio University Teaching Hospital. The graphs obtained from this work
show that all the organs (bladder, rectum, gastro-intestine, left femur, right femur and
skin) are dose and volume dependent and also exhibit a threshold dose for the whole
volume (plotted data) above which a complication arises. The threshold doses for
bladder, rectum, gastro-intestine, left femur, right femur and skin are at 5Gy, 6Gy, 21Gy,
5Gy, 2Gy and 7Gy respectively. Fitting equations were also obtained for each curve and
a line of best fit was obtained using the method of least square fit. A C++ program code
was written to help in the plotting computation and the Gnuplot plotting software was
used for both the plots and fitting. This retrospective study was carried out on a total
number of 50 non-pregnant cervical cancer patients.
Description
A thesis submitted to the school of postgraduate studies, Ahmadu Bello University, Zaria.
In Partial fulfillment of the requirements for the Award of Masters Degree of science in
radiation biophysics, Department of Physics, Faculty of Science Ahmadu Bello University,
Zaria Nigeria.
DEPARTMENT OF PHYSICS,
FACULTY OF SCIENCES,
AHMADU BELLO UNIVERSITY, ZARIA.
NIGERIA
AUGUST, 2014
Keywords
NORMAL TISSUE,, COMPLICATION,, PROBABILITY,, BEAM RADIOTHERAPY,, CANCER, CERVIX