Biomedical Engineering Reference
In-Depth Information
Fig. 24.3
Linear accelerator for clinical radiotherapy use. A positioning and immobilization
device can be seen on the treatment couch. Below the couch, a system for obtaining the beam's
eye view (see Sect.
24.2.3
) of the treatment in course. At the right (background of the room), an
alternative verification system using radiographic films can be seen
•
Prescription of tumour dose and fractionation schedules.
•
Prescription of dose limits for organs at risk. Organs at risk are normal tissues
whose radiation sensitivity may significantly influence treatment planning and/or
dose prescription. The dose limits for normal tissues have been tabulated [
17
]and
organs at risk can be divided into three different classes according to the severity
of the radio-induced lesions.
•
Dosimetric procedures with designation of the treatment portals, dose calcula-
tion, beam selection and computation and isodose curve generation.
•
Definitive dose prescription: selection of the treatment plan to be used for the
patient.
Treatment delivery During treatment delivery, some verification procedures such
as image-view or verification films (Fig.
24.3
)and
in vitro
and/or
in vivo
dosimeters
must be carried out. The patient's status must be evaluated periodically during the
course of therapy in order to assess tumour response and the patient's tolerance of
the treatment.
Follow-up after treatment After finishing treatment, periodic follow-up examina-
tions of the patient are critical for evaluating the general condition of the patient and
the tumour response and for a timely detection of recurrences or secondary effects
on normal tissues.
