Page 207 - 00. Complete Version - Progress Report IPEN 2014-2016

Nuclear Science and Technology | Progress Report 207

by movement using the Magnetic Resonance body, the angles of electron incidence that are
Image - MRI and compared qualitatively and varied and the orientation of the bundles. In
quantitatively with other systems. The con- this study, LiF:Mg,Ti and CaSO4:Dy dosime-
gruence of the isodose curves, with the signal ters were used to evaluate the entrance dose
intensity of the MRI image and the large dif- distribution to the skin. The LiF:Mg,Ti showed
ference in signal intensity of the MRI image uncertainty of ± 0,1% and CaSO4:Dy, ± 0,2%.
with the isodoses, shows that the movement In the TSI irradiation procedure, the real con-
generates a blurring are shown in figure 7. ditions for the patient’s treatment were im-
plemented. An anthropomorphic phantom
(Figure 8) was positioned on a turntable and
the TL dosimeters were positioned in sever-
al anatomical regions such as abdomen, tho-
rax center, thorax right, thorax left, posterior,
right side, right thigh, perineum and front.
The doses were acquired on alternate days,
allowing a better study of the skin. Other fac-
tors were analyzed in this study, such as the
homogeneity of the field and the dose at the
calibration point (ZRef). Considering the char-
Figure 7- Fricke Gel Phantom VMAT Irradiation and con- acteristics of the irradiation field(,) the maxi-
gruence between dose distribution and MRI signal.
mum dose deposition should be delivered in
a few millimeters of the skin surface (5 - 15
Comparative study of the TL response in mm). Comparing the dose at the calibration
clinical electron beams dosimetry applied to point, a small variation was observed in re-
Total Skin Irradiation – TSI Treatments lation to the other points studied such as the

posterior region and the right side of the an-
Total Skin Irradiation - TSI is a radiothera- thropomorphic phantom. The TL dosimeters
py technique applied in the treatment of cer- presented good results for dose evaluation in
tain generalized malignant diseases of the TSI treatment.
skin. This treatment aims to irradiate the pa-
tient’s entire skin evenly with large electron
fields. The radiation penetrates a few milli- Figure 8 -
meters into the skin and reaches the affect- Phantom
AldersonRando®
ed part completely without penetrating the used in clinical
internal organs. The application of electrons electron beams
dosimetry applied
in therapy requires great accuracy in the dose to Total Skin
absorbed by the tumor since a variation of ± Irradiation – TSI
Treatments.
5% is determinant in the risk of relapse or se-
quelae. In the TSI Stanford technique, the pa-
tient is treated by a two-day cycle with three
dual fields per day. When the patient is placed
in the six positions with a double field irradia-
tion at each position, the dose is considered less
uniform due to the curvature of the patient’s