oral and maxillofacial surgery

1. RADIATION THERAPY
• DR DAVIS NADAKKAVUKARAN
• M.D.S oral and
Maxillofacial surgery
• Malabar dental college manoor

2. CONTENTS
introduction
Radiation effects
Radaition treatment plan
Radiation protection
Radiation dose
External beam radiation therapy
Intensity modulated radiotherapy
fractionation
brachytherapy
Effects of radiation therapy

3. INTRODUCTION
• Roengten discovered X-rays ,their clinical
usefulness as a mean of treatment of cancer
• Since that time ,radiation therapy has
developed into a recognized medical speciality
• Alexander Graham bell suggested the use of
radium in brachytherapy for direct
implantation in malignant tumors
• Limiting factor-skin tolerance

4. • Sensitive radiation –given as a single bolus
dose for the patient
• This is was overcomed by the incorporation of
the use hyperfractionation concept –by
Coutard’s

5. Radiation therapy (also radiotherapy or
radiation oncology, sometimes abbreviated to
XRT) is the medical use of ionizing radiation as
part of cancer treatment to control malignant cells.
Radiotherapy may be used for curative or
adjuvant cancer treatment.
It is used as palliative treatment (where cure is not
possible and the aim is for local disease control or
symptomatic relief) or as therapeutic treatment
(where the therapy has survival benefit and it can
be curative).

6. Radiation effects
Direct effect indirect effect
Interact with water molecules hydrolysis of
water

7. • Produces charged molecules
• Interact with biochemical process in cells
• Direct damage to the DNA

10. Affected cells may
die or remain
incapable of division
Central hypoxic
cells-less susceptible
to radiotherapy
If the tumour is
more differentiated-
less rapid will be
response to
radiotherapy
Exophytic,well
oxygenated tumors-
radiosensitive

11. Radiation treatment plan
Tumour site and size
Volume to be irradiated
Number of treatment fractions
Total number of day of treatment
Tolerance of the patient

12. Radiation protection
• Dose to the eyes ,optic chiasma,spinal
cord,salivary glands,alveolar bone and soft
tissues-limited through the selection of
radiation source,field set up,shielding and by
moving the un involved tissue out of the field
• Immobilised by:
• Head holders

13. • Bandages
• Laser positioning
• Head and neck land marks or tattos
• Custom acrylic shells

14. Radiation dose
• Based on the location and type of malignancy
and whether or not radiotherapy will be used
solely or in combination with other modalities
• Recommended dose-50-70 Gy-period of 5-7
week period,once a day, 5 days a week 2Gy
per fraction

15. External beam radiation therapy
Source of radiation –either low energy(50-300kvp)
Or
High energy (cobalt 60 or linear accelerators of 4
million electron volts)
Low energy beams –useful for small sized intra oral
tumours,lips and skin cancers
High energy radiation-provides variable penetration
due to its ability to vary the energy of the photons
as it spares the bone an d skin

17. Intensity modulated radiotherapy
• Most applicable in the treatment of head and
neck cancer
• It employs a computer directed radiation
source that target the cancer more accurately
than conventional radiation therapy
• This is accomplished with computer
algorithms to design treatment plans

18. Advantage
Limit dose depletion to the
vital structures such as
parotid gland
Disadvantage
As there is multiple fields of
radiation which rotates
around the patient-increased
normal tissue exposure

19. Fractionation
 The total dose is fractionated (spread out over time) for several
important reasons.
 Fractionation allows normal cells time to recover, while tumor
cells are generally less efficient in repair between fractions.
 Fractionation also allows tumor cells that were in a relatively
radio-resistant phase of the cell cycle during one treatment to
cycle into a sensitive phase of the cycle before the next fraction is
given.
 Similarly, tumor cells that were chronically or acutely hypoxic
(and therefore more radioresistant) may reoxygenate between
fractions, improving the tumor cell kill.

20. Fractionation –based on the 4 R’s
of radiobiology
• After initial application of dose-
• Repair of the damaged DNA
Repair
Reoxygenation
• Multiple fractions-the chance of
irradiating a given cell in a sensitive
phase of the cell cycle -increased
Redistribution
HYPOXIC CELLS-more resistant to radaition than
well oxygenated cells
During fractionation-the oxygen status of the
hypoxic cells-may improve before the subsequent
doser

21. • The cells that divide during
the cycle-also irradiated
Repopulation

22. Fractionation
Altered
Accelerated
Overall time-
reduced by giving 2
or more daily doses
Hyperfractionation
Overall time-same as
conventional
But increase in total dose-by
giving 2 or more smaller
dose fractions on each
treatment day
Conventional
1.8-2Gy per day
each week for 5-7
weeks

23. Brachytherapy
Interstitial and intracavitary
implants may be used to
treat cancers in the head
and neck region
Primary treatment
modality for localized
tumours in the anterior
two-thirds of the oral cavity
For the boosted dose of
radiation to a specific site
And
For reccurence cases
Isotopes include
Cesium,Iridium and gold
Radiation source-placed by
using previously inserted
catheters or guide tubes

25. Forms of brachytherapy
• Mold brachy therapy-strontitium-90 blocks
• Intracavitary brachytherapy
• Intravascular brachytherapy
• Photodynamic therapy

26. Effect of radiation therapy
Effects
Hyperpigme
ntation of th
skin surface
Transien
t loss of
hair
Loss of
taste
Salivary
dysfuncti
on
Radiation
caries
mucositis
Fungal
infections
pain
osteoradi
onecrosis
Difficulty in
speech and
mastication

27. Mucocutaneous lesions
• Following 2 weeks after
radiation
• Erythematous and
hyperpigmentation along with
mucositis
• Dose-180-220cGy-sufficient to
produce mucositis
• Intense erytghema,pain and
associated with sloughing

29. Treatment
• Viscous xylocaine
Topical
anesthetics
• Benzydamine
hydrochloride
Topical
analgesics

30. Loss of taste sensation
Taste buds-in
radiation field
• Complete loss of
taste buds
• Regenerate within 4
months duration
Significant change
in the perception
of all types of
taste
Treatment
• Change the diet to
facilitate better taste
perception
• Zinc sulfate
capsules(220mg
twice daily with food)

31. Salivary function
xerostomia
Fatty
degeneration
Acinar
atrophy
Cellular
necrosis

32. • Patient present with-reduced thick and ropy saliva
• Reversible condition within 12 months
• Irreversible changes-seen with a total dose of 6000cGy
for 5 weeks
• Treatment –patients advised to sip water frequently
and chew on sugarless gum to stimulate salivation
• In severe cases-salivary substitutes like carboxymethyl
cellulose can be used
• Salivary stimulants-pilocarpine hydrochloride 5mg 4
times daily and bethanechol 25-200mg daily

33. Radiation caries
• Always secondary to xerostomia
• Common sites –cerviacl areas followed by
cuspal or incisal tips
‘
Types
• Type 1-dark pigmentation og the crown
• Type 2-circumferential caries or
amputation caries
• Type 3-widespread superficial caries
involving the smooth surface of the crown

34. Treatment
• Maintain good oral hygiene
• 3% hydrogen peroxide
• Topical fluoride application

35. Effect on developing tooth
• Delayed tooth eruption
• Malformation of the teeth with stunted roots
• Occasionally the tooth may not be formed

36. Osteoradionecrosis
• Radiation therapy causes endarteritis
obliterans,which in turn results in
hypovascularity,hypocellularity and finally
hypoxic tissue
Predisposing factors
Trauma
Periodontal disease
Ill fitting dentures
Periodontally weak or pulpally affected teeth
in the lline of radiation

37. Clinical features
Pain,foul taste,paresthesia
Intra oral or extra oral discharging
sinus
Lymph adenopathy
Pathologic fracture
Radiographic features
Ill defined patchy patchy
destruction (sclerossis)

38. Treatment
• As preventive measures,if extractions are
planned,it is desirable to allow as much as
healing time as posible
• 7-14-21 days of healing time recommended
• Avoid mucosal irritants
• Discontinue the use of dental appliances if
they contact with the area of the lesion
• Maintain nutritional status

39. • Best managed with topical antibiotic TTR or
antiseptic (chlorhexidine) rinses
• Hyperbaric oxygen therapy increases the
oxygenation of the tissue,increases
angiogenesis and promotes osteoblast and
fibroblast function
• HBO therapy-60 dives of O2 at 100 % at 2.4
atm

40. Referance …
• Textbook of oral medicine and diagnosis-
Ravikiran Ongole
• Burkkit’s Text book of oral medicine
• Text book of oral and maxillofacial surgery-
Peterson