Rx planning and post rx care of radiation therapy patient

Vinay Pavan Kumar K
2nd year PG student
AECS Maaruti College of Dental Sciences

Radiation
therapy
Introduction
History
General
factors
Treatment
modalities
Dose
Dental
management
Implants in
irradiated
bone

 Early dental intervention is most important factor
to prevent possibility of infection during Rx
 Frequently, the patients are elderly, have poor oral
hygiene, low economic status, receive limited
dental care
 Patient should be explained about the short term
and long term side effects of the treatment

The use of high energy radiations from X-rays,
gamma rays, neutrons and other sources to kill
cancer cells and shrink the tumor

Era of discovery (1895 - 1920s)
 Roots of RT were established
 Atom and various electromagnetic particles, their
therapeutic use
 Lack of knowledge of the biological effects
 As the era progressed, biologists began to
understand the relationship between time and dose
Slater J.M, From X-rays to Ion beams: A short history of radiation therapy, Biological and
Medical Physics, pp:3-18

 Regaud demonstrated that fractionated therapy;
Coutard – External beam radiation therapy
 Coolidge developed a practical X-ray tube, to
deliver higher-energy X-rays (180–200 KV) to
deeper tumors
 Rutherford, 1919, the structure of atom
 Two major divisions of radiation medicine –
diagnosis and therapy
Slater J.M, From X-rays to Ion beams:A short history of radiation therapy, Biological and

Orthovoltage era (1920 – 1950s)
 Treatment of deep tumors - Radium-based
intracavitary and interstitial irradiation
 A transitional period : Physical developments that
led to supervoltage (approx. 500 KV–2MV) RT
were being made

 The first supervoltage X-ray tubes, built by
Coolidge were the basis of the linear accelerator
 Electron beam therapy became a practical and
useful therapeutic option in 1940, when Kerst
developed the betatron. The first machine
produced 2 MeV electrons; later devices yielded
up to 300 MeV

Megavoltage era (1950 – 1985)
 Tumors located in deep tissues - the development
of cobalt teletherapy machines and megavoltage
linear electron accelerators
 Cobalt teletherapy was capable of producing
beams equivalent to approximately 1.3 MeV X-rays
 During this era, radiation medicine advanced as a
discipline
Slater J.M, From X-rays to Ion beams:A short history of radiation therapy,
Biological and Medical Physics, pp:3-18

Era of intensity modulated X-ray
therapy ( 1970s)
 Background started in 1946, with Wilson claiming
the use of protons in medical treatments
 Wilson reasoned that protons, among the charged
particles, offered the longest range for a given
energy and were the simplest and most practical
for medical use

Kelly J A, Beumer J, Dental management of irradiated patients, ppt

 Physical principles
 Absorption of radiation by tissues
 Biologic effects
 Dosimetry
 Radiation curves
GENERAL FACTORS

Electromagnetic
waves
Photons
Particulate
Radiations
Electron, proton,
neutrons

Electromagnetic waves
 Photoelectric effect
 Compton effect
 Pair production
Particulate radiations

 DNA – Confined to
intranuclear damage –
most cell deaths
 Water – Abundant
compared to DNA

 Anoxia – 3x resistant to radiation
 Cell cycle – Asynchronous
 Radiation – Series v/s fractioned dose
Reoxygenation
Redistribution
Repopulate
Repair

Amount of energy absorbed by the tissues
subjected to radiation
(rads = 100ergs/gm)

 Isodose curves – Electromagnetic waves
Particulate radiations
Single beam
Multiple beam

Single beam curve (photons) –
 Dose decreases from surface to depth
 Low energy X-rays – Surface receives highest dose
 High energy X-rays – ‘Skin-sparing’ effect

Single beam curves (particulate radiations)
 Homogeneous from surface to depth depending
on the energy of beam

 Simulation
 Maintain same position
 Body molds, face masks, tattoos
www.cancer.gov, National Cancer Institute, Radiation therapy for cancer

 After simulation, the exact area that will be
treated, the total radiation dose, dose allowed for
the normal tissues, and the safest angles (paths)
for radiation delivery
 150-200 cGy / fraction

 The type of cancer
 The size of the cancer
 The cancer’s location in the body
 Approximity to normal tissues

 How far into the body the radiation needs to travel
 The patient’s general health and medical history
 Whether the patient will have other types of
cancer treatment
 Other factors, such as the patient’s age and other
medical conditions

 External beam radiation therapy
 Internal beam radiation therapy
 Systemic radiation therapy

 Coutard
 3D conformal RT (3D-CRT)
 Delivered using Linear Accelerator (LINAC)
 Sophisticated computer software and advanced
treatment machines to deliver radiation precisely

 Numerous tiny radiations – Collimators
 Allows change in intensity – Modulation
 Inverse treatment planning
 Greater dose in areas required

 Repeated imaging scans
 Current condition of the patient
 Accurate radiation treatment, allows reductions in
the planned volume of tissue to be treated

 Cyberknife
 Radiation in fewer sessions
 Small radiation fields and higher doses

 Type of IMRT
 CT imaging scanner + external beam RT
 Both imaging and treatment

 Brachytherapy
 Radiation source placed in or on the body
 Interstitial – Within the tumor
 Intracavitatory – Within surgical or body cavity
 Episcleral – Melanoma (eye)
 Permanent – Low dose treatment
 Temporary – Low or high dose treatment

 Swallows or receives an injection of radioactive
substance
 Radioactive I, samarium, strontium, ibritumomab
tiuxetan

 External beam radiation therapy – One dose
 Minimizes damages to the normal tissues
 Exposing cancer cells at right stage of cell cycle

Regaud – Fractionated therapy
 Accelerated fractionation – Large daily or weekly
dose
 Hyperfractionation – Smaller fraction more than
once a day
 Hypofractionation – larger dose once a day or less
often

o Dental examination before radiation therapy and
treatment plan
o Dental management during radiation therapy
o Dental management following radiation therapy

 Dental extractions
 Minor surgical procedures
 Pre – radiation prosthodontic care

 Dental awareness of the patient
 Condition of the residual dentition
 Urgency of treatment
 Mode of therapy

 Radiation fields
 Mandible vs Maxilla
 Prognosis for tumour control

To ensure best results following extraction prior to
radiation therapy -
 Radical alveolectomy to ensure primary closure
 Teeth should be removed in segments
 Antibiotics should be administered during the
healing period
 Risk of bone necrosis due to dental extractions
prior to radiation therapy was 12.7%

 Dentures
 Avoid relining ill fitting dentures
 Avoid soft temporary reline
 Advised not to wear denture
 Metallic crowns or fixed partial denture
 Custom made soft plastic stent

o Mucositis
o Xerostomia
o Change in oral microflora
o Loss of taste
o Increased sensitivity to spicy food
RADIATION EFFECTS OF ORAL CAVITY
Short term effects

Long-term effects
o Reduced bone healing – Osteoradionecrosis
o Permanent loss of salivary function
o Increased potential for dental caries
o Increased susceptibility to infections – Candidiasis
o Trismus

Mucositis
 Earliest
 2-3 week and subsides within 8-10 week
 Slight erythema-desquamation-frank
ulceration, pain and dsyphagia, weight loss
 Severe cases may require stopping the
therapy

 Maintaining good oral hygiene, frequent brushing
 Oral mouth rinses - Combination of salt and sodium
bicarbonates in water or dilute hydrogen peroxide

Loss of taste
 Radiation to tongue and palate (5000 cGy)
 1-2 week and returns to normal once treatment is
completed
 Damage to taste buds and microvili, disrupted
innervation, lack of saliva
Xerostomia and dental caries
 60 rads
 Decrease in salivary flow rates, increase in
acidogenic bacteria
 Prevention by daily use of topical fluoride
Stannous and Sodium fluoride

Saliva substitutes and sialogogues
 Most persistent morbidity is dry mouth
 1 week and worsens with time
 Sialogogues are used to stimulate salivary flow
 Salivary substitutes
Trismus and fibrosis
 Shortly after radiation begins
 May worsen by surgery prior to radiation
 Primary treatment - excercising by using tongue
blades, or bite openers

 Maintaining position of structures to be treated

 Removing structures from the radiation field
 Positioning peroral cones

 Positioning dosimetric devices
 Recontouring tissues to simplify dosimetry

 Positioning radioactive source

Only used with electron beam therapy

Mucositis and loss of taste
 Subsides gradually
 Heavy smokers or drinkers may experience longer
delay in healing
 Continue mouth rinses
Xerostomia and dental caries
 Salivary loss is permanent
 Long term salivary substitutes and sailogogues
 Fluoride application for tooth
 Maintainence of oral hygiene

Candidiasis
 Mainly because of xerostomia
Trismus and fibrosis
 Increase in severity with time
 Only way to benefit is by regular exercising

Post radiation extractions
 Greater risks of bone necrosis as high as 100%
has been reported
 Periodontally compromised and mobile tooth can
be extracted with minimal risk
 Localized periapical infection can be managed
conservatively with anbibiotics avoiding the need
for removal

 Regaud,1922
 “when bone in the radiation field was exposed for
atleast 2 months in the absence of local neoplastic
disease” - Beumer
 “an area greater than 1 cm of exposed bone in a
field of irradiation that had failed to show any
evidence of healing for atleast 6 months” - Marx

 The reported incidence of ORN of the mandible
varies widely, ranging from 2-39 per cent
 Trauma, exposure of radiated bone, infection
 Hypovascular, hypocellular and hypoxic
conditions of the bone
 Type of radiation treatment, dosage, tissue
volume

ORN
Stage I
30 Dive of
HBO
Healing
Non
responder
10 Dive of
HBO
Stage II
Non
responder
Stage III
Local surgical
debridement
Wound
dehiscence
Nonresponder
to stage II
Healing
10 Dive of
HBO
Total of 30
Dive of HBO
Surgical
resection
10 Dive of
HBO
Patient pain
free
Reconstruction
surgery
Stage IIIR

 Three types of ORN –
Type 1 –
 Radiation therapy within 21 days of tooth extraction
Type 2 –
 Induced by trauma
 It generally occurs 3-6 months after radiation therapy
Type 3 –
 Spontaneously 6 months to 2 years after radiation therapy
 Associated with higher radiation doses, brachytherapy
(Cronje, 1998)
Hyperbaric oxygen therapy for prophylactic treatment after head and neck radiation to
prevent osteoradionecrosis of the mandible, Group health - A clinical review

Radiation
Irreversible cell
damage
Tissue
breakdown
Hypocellularity
Osteoblasts
death – direct
RT damage
ORN
Vascular
damage
Endarteritis
obliterans
Thrombosis of
vessels
Gradual
ischemia
Damage to bone
tissue
Loss of
reparative
and
synthetic
function
Lyons A, Ghazali N, Osteoradionecrosis of the jaws:Current understanding of its
pathophysiology and treatment, Brit J Oral Maxillofac Surg, 2008;46:653-660

 Conservative measures
 Hyperbaric oxygen (HBO)
 PENTO or PENTOCLO
 Surgical

The HBO treatment –
 20 sessions each at 2.4 ATA for 90 minutes,
followed by a 30 minute ascent back to one ATA.
This is known technically as a 14/90/30 cycle
 Followed by surgery and then 10 further 14/90/30
sessions
Vudiniabola S et al, Hyperbaric oxygen in the prevention of osteoradionecrosis of the jaw,
Aust Dent J, 1999;44(4):243-247

 Increases diffusion distance of oxygen in tissue of
the compromised vascular beds
 Improves the wound environment, resists infection,
and enhances wound repair
Lin YC et al, Scientific rationale of hyperbaric oxygen therapy for osteoradionecrosis of the
jaw, Clin Dent J, 2005;24(1):1-14

Lin YC et al, Scientific rationale of hyperbaric oxygen therapy for osteoradionecrosis of the
jaw, Clin Dent J, 2005;24(1):1-14

 Enhance the killing ability of leucocytes to
stimulate fibroblast growth
 Increase collagen formation - promotes
growth of capillaries
 Toxic to aerobic and anaerobic bacteria, and
inhibits bacterial toxin formation

Vudiniabola S et al, Hyperbaric oxygen in the prevention of osteoradionecrosis of the jaw,
Aust Dent J, 1999;44(4):243-247

 PENtoxifylline – Improves peripheral vasculature
 400 mg b.i.d
 TOchopherol (Vit.E) – Anticoagulant,
scavangers
 1000 IU (600 and 400 IU)

 Often candidates for new dentures
 To prevent trauma due to dentures – 6 months
 Social status
 Conventional techniques to be followed
 Border extension should be carefully evaluated

 Systematic review and meta-analysis was done to
evaluate the failure rate of dental implants placed in
irradiated bone between 6 and 12 months and after
12 months from the cessation of radiotherapy
 Placement of dental implants between 6 and 12
months post radiotherapy was associated with a
34% higher risk of failure
 Placing implants in bone within a period shorter
than 12 months after radiotherapy may result in a
higher risk of failure
Claudy M P et al, Time interval after radiotherapy and dental implant failure:Systematic review
of observational studies and meta analysis, Clin Imp Dent Rel Res, 2013:1-10

References
o Taylor T D , Clinical Maxillofacial Prosthetics, 1st
edition, 2000, Quintessence publications, Illionis,
pp 37 – 52
o Beumer J, Curtis TA, Firtell D N, Maxillofacial
Rehabilitation : Prosthodontic and Surgical
Considerations, 3rd edition, 1996, Mosby, St. Louis,
pp 23-78
o Slater J.M, From X-rays to Ion beams:A short
history of radiation therapy, Biological and

o www.cancer.gov, National Cancer Institute, Radiation
therapy for cancer
o Marx R E, A New Concept in the Treatment of
Osteoradionecrosis, J Oral Maxillofac Surg, 1983;
41:351-35
o Lyons A, Ghazali N, Osteoradionecrosis of the
jaws:Current understanding of its pathophysiology and
treatment, Brit J Oral Maxillofac Surg, 2008;46:653-
660
o Kelly J A, Beumer J, Dental management of irradiated
patients, ppt

 Hyperbaric oxygen therapy for prophylactic
treatment after head and neck radiation to prevent
osteoradionecrosis of the mandible, Group health -
A clinical review
 Vudiniabola S et al, Hyperbaric oxygen in the
prevention of osteoradionecrosis of the jaw, Aust
Dent J, 1999;44(4):243-247
 Lin YC et al, Scientific rationale of hyperbaric
oxygen therapy for osteoradionecrosis of the jaw,
Clin Dent J, 2005;24(1):1-14

Rx planning and post rx care of radiation therapy patient

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to Rx planning and post rx care of radiation therapy patient

Similar to Rx planning and post rx care of radiation therapy patient (20)

Recently uploaded

Recently uploaded (20)

Rx planning and post rx care of radiation therapy patient