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سـم ماللهب ــ الرحمـن الرحي
What is Radiotherapy?
an introduction for Oncologists
Ashraf Hamed Hassouna
Professor of Radiation Oncology
NCI, Cairo University
• Mode of action
• Treatment Policy
• Combined modalities
• Patient care before and during RT
• Techniques
• Planning
• Dose & fractionation
• QA
• Side effects
Contents
Mode of Action
RT effects
▪Cell death
• Tumour cell death
• Normal tissue side effects
▪ Cell transformation
• Mutations
• Carcinogenesis
▪ Radiosensitive
• Leukemia
• Lymphoma
• Myeloma
• Ewing
• SCLC
▪ Radioresponsive
• HNSCC
• Breast
• GIT
• Bladder
• NSCLC
▪ Radioresistent
• Melanoma
• Osteosarcoma
• STS
• GBM
• RCC
Therapeutic ratio
Treatment PolicyRadical, Adjuvant, Palliative
Brain mets
Combined Modality Treatment
Pre-operative Radiotherapy
Cons
• Treatment based on clinical
stage, may overtreat patients.
• Potential increase in intra-
operative and post-operative
surgical complications.
• Delay primary treatment.
• Disrupt surgical staging of the
tumor and/or the expression of
histologic or
immunohistochemical
prognostic factors.
Pros
• Smaller RT volumes and doses and potential decreased RT side
effects.
• Sterilization of tumour bed in preparation for surgery.
• Avoidance of surgery in those who progress with systemic disease.
• Tumour down-staging, improved resectability.
• Unaltered blood supply leading to decreased proportion of radio-
resistent hypoxic cells.
• Potential for short-duration hypo-fractionation for patient
convenience and improved resource allocation.
Post-operative Radiotherapy
Cons
• Larger RT volumes and difficulty of RT planning.
• Usually higher RT doses due to altered blood
supply and decreased oxygenation to the tumour
bed.
• Protracted treatment schedule.
• Reduced functional status or delayed patient
recovery after surgery may preclude the use of
postoperative RT.
• Delay in initiation of RT until wound healing is
completed.
Pros
• Treatment decision based on true
pathologic stage, avoids RT in
patients who may not require it.
• More accurate assessment of disease
extent to allow for delineation of
disease involvement.
• Less concern about increase in
perioperative morbidity and mortality
after preoperative induction.
Chemo-Radiotherapy
Types
• Sequential C-RT
• Concurrent C-RT
• Radiosensetizer
Pros
• Lower dose
• Synergistic effect
• Overcome resistance
Cons
• Higher toxicity
• Tolerability
Examples
• HNSCC
• GIT
RT techniques2D, 3DCRT, IMRT, SRS, Brachytherapy
Cobalt Machine
Linear Accelerators (LINACs)
IMRT2D
Novalis System
Cyberknife
Treatment session
Patient care
before and during RT
Oral Hygiene
Naso-Gastric tube
Percutaneous Endoscopic Gastrostomy
PEG
RT Planning
Immobilization
Simulation
LN Contouring
RT
Dose & Fractionation
Altered Fractionation
• Hyperfractionation
• Hypofractionation
• Accelerated fractionation
5Rs of Radiobiology
• Repair
• Repopulation
• Redistribution
• Reoxygenation
• Radiosensitivity
Conventional Fractionation
• 2Gy / Fraction
• 1 Fraction / Day
• 5 Days / Week
Doses
• Radical: 70Gy/35F/7W
• Adjuvant: 50Gy/25F/5W
• Palliative: 30Gy/10F/2W
RT QA
EPID
DRR EPID
CBCT
RT Side Effects
Site
• H&N
• CNS
• Chest
• Abdomen
• Pelvis
Grade
• 0-4
Time
• Early (acute)
• Late (chronic)
Management
• Before RT
• During RT
• After RT
Factors
• Total dose
• Fractionation
• Tissue type
• Volume
Xerostomia
Mucositis
Skin Reaction
Osteoradionecrosis
Thank You
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