3. Radiotherapy in bone marrow transplantation conditioning regimens was
introduced in the late fifties by Nobel Prize Laureate E.D. Thomas (Ferrebee
and Thomas, 1958).
Since that time, total body irradiation (TBI) has been widely used in bone
marrow transplantation.
TBI aims to eradicate malignant cells in the same area that chemotherapy
does (Bortin et al., 1992; Vriesendorp et al., 1991) and in sanctuary organs
that are not reached by chemotherapy drugs, which are mainly the brain
and testes.
4. DEFINITION
It consists of irradiating with photon fields the
whole body and is associated with intensive
chemotherapy as a conditioning regimen for
transplant parents hematopoietic.
11. PATIENT POSITIONING
TBI is mostly performed with standard linear accelerators.
The primary limitation of standard linear accelerators is the maximum field
size of 40 × 40 cm at a standard source-surface distance (SSD).
12. P. ANTERO-POSTERIOR
Directed fields are the simple technique.
The patient is treated in alternative dorsal and
ventral decubitus, and gantry remains at the 0°
position.
Patients are treated lying down in a couch or on
the floor.
This position is convenient for children or for those
patients with a height that allows for it. It is also
the position of choice for children who need
anesthesia.
13. P. LATERAL DECUBITUS
Is an alternative set up, in which
the gantry is turned at 90° with a
collimator rotation of 45°.
15. QUALITY ACCURACY
According to the ACPSEM, the TBI working group and American College of
Radiology (ACR) and American Society for Radiation Oncology (ASTRO)
guidelines:
The simulation of treatment, including shield placement, should be done in
the treatment position.
Reference points for the patient and shield positioning should be marked on
the patient’s body for setup accuracy.
16. QUALITY ACCURACY
Data from whole body computed tomography are useful for dose calculation
and for taking into account the shape of the lungs.
In accordance with the ICRU 50 and 62 reports, the dose prescription is
delivered to a relevant point, which is often at the umbilicus or pelvic region.
17. INTENSITY MODULATED RADIOTHERAPY IN BONE MARROW
TRANSPLANTATION
The primary limitation of TBI is its toxicity
to organs at risk, especially to the lungs,
heart, liver and kidneys.
19. TOTAL MARROW IRRADIATION (TMI) AND TOTAL MARROW AND
LYMPHOID IRRADIATION (TMLI)
TMI
CTV: includes the entire bony skeleton.
To take into account chest mobility, three CT scans are performed with
different breathing patterns: shallow breathing, inspiration and expiration.
Inspiration and expiration CT scans are used to determine a contouring
margin for the ribs and sternum.
20. TOTAL MARROW IRRADIATION (TMI) AND TOTAL MARROW AND
LYMPHOID IRRADIATION (TMLI)
TMLI
CTV: includes the CTV from the TMI and every major lymph node,
the spleen, the liver and sanctuary sites such as the brain or testes.
23. Computed tomography (CT) images were obtained in the head-first supine
(HFS) orientation from the top of the skull to mid-thigh, with a 5 mm slice
thickness.
The patients were simulated with:
A thermoplastic mask over the head and neck region
A full body vacuum bag for immobilization
Arms at their sides
The planning aims were to deliver a uniform dose of 12 Gy to the PTV while
limiting the mean lung dose to less than 8 Gy, and the mean kidney and liver
doses to below 9 Gy
24. The PTV was split into subsections for the head, chest,
abdomen, and pelvis.
A combination of nine 6 MV photon beams were arranged
along the patient's longitudinal axis using an isocenter at
the middle of each sub-PTV.
25. All isocenters had the same coordinates lateral and anterior–
posterior.
The head, abdomen, and pelvis subsections each had two VMAT
arcs rotating through 356o.
An additional arc was required to achieve the planning aims in the
chest PTV.
26.
27. The planning aims for the PTV were to deliver 12 Gy to at least 90% of the PTV
(i.e., V100% ≥ 90%) and 11.4 Gy to at least 95% of the PTV (i.e., V95% ≥ 95%).
The mean dose to the lungs was able to be restricted to less than 8 Gy.
A 30% dose reduction to the liver and a 40% dose reduction to the kidneys
proved to be feasible, while the maximum dose and dose homogeneity were
kept to acceptable ranges.
34. The primary aim of this study was to determine the impact of the
intensity and quality of the conditioning regimen on the risk of
developing SMNs after allogeneic HCT.
Overall results confirmed data from earlier reports, showing an
incidence of malignancies 2.8-fold higher than expected.
35. TBI given as a single exposure (dose range, 600-1000 cGy) carried the highest risk for SMNs,
nearly eightfold higher than seen in the general population.
Administration of TBI in smaller fractions (120-200 cGy) reduced the risk of SMNs.
The risk of SMNs was significantly reduced at very low TBI doses (200-450 cGy), it was
comparable to the risk associated with chemotherapy-only conditioning.
36. Younger age (≤20 years) at the time of HCT was associated
with a more than twofold higher risk of SMNs.
Risk of SMNs was higher among patients of white race than
among other racial groups.
39. THE CUMULATIVE INCIDENCE OF FOR
SECOND SOLID NEOPLASMS
0.7% at
5 years
2.2% at
10 years
6.7% at
15 years
40. TSI (TOTAL SKIN IRRADIATION)
One of the main therapeutic indications in cutaneous lymphomas.
A disease that has an effective control with this irradiation
technique.
The white volume is defined in this technique over the entire skin
surface from the epidermis to the dermis (approximately 5 mm).
Lutsyk M, Ben-Yosef R, Bergman R, et al: Total Skin Electron Irradiation and Sequential Malignancies in Mycosis Fungoides
Patients: Longitudinal Study. Clin Oncol (R Coll Radiol) 30:618-624, 2018
