![LINAC MACHINE[ Linear accelerator]
High, Medium , Low energy X-rays, Electrons
Beam is much superior.
Expensive
No decaying source
Good penetration](https://image.slidesharecdn.com/radiotherapy-241101180033-d3f65ea5/85/Radiotherapy-indications-and-complications-13-320.jpg)
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Radiotherapy indications and complications
- 2. DEFINITION The application of radiation for the purpose of therapeutic gain. Radiation is the process of emitting radiant energy in the form of waves or particle. Aim of Radiotherapy Delivering tumoricidal dose to a defined target volume Respecting the normal tissue tolerance Trying to achieve an optimum therapeutic ratio Improvement of quality of life
- 3. MECHANISM OF RADIOTHERAPY Radiations act on biological cells by ionization which can be direct or indirect. Direct ionization(Electron, Heavy Ion radiations) photons hit matter produce secondary electrons damage DNA directly
- 4. Indirect ionization( X-ray, Neutrons ) photons hit matter produce secondary electrons with water and oxygen free radicals damage DNA Indirect ionization is more common ( > 2/3rd ) Radiations also causes cell reproduction failure by inhibiting mitosis.
- 5. BIOLOGICAL EFFECTS OF RADIATIONS Affects cell by breaking strands of DNA Single strand breaks - repairable than double strand breaks which are lethal. Sub-lethal damage refers to DNA damage that can be repaired if given the right cellular conditions and sufficient time. Sub-lethal damage is less efficient in tumor cells, hypoxia or low pH. DNA damage is repairable with low radiation dose and the relation is proportional. (Absorbable dose )
- 6. TUMOR CELL KINETICS AND RESPONSE TO RT CELL PROLIFERATION AND LOSS radiosensitive in the G(2)-M phase, less sensitive in the G(1) phase least sensitive during the latter part of the S phase INTRINSIC RADIOSENSITIVITY Lesser the SF2 better the radiosensitivity/prognosis. X-rays are more effective on cells which have a greater reproductive activity HYPOXIA - radioresistant
- 7. The response of a tumour to radiotherapy is dependent upon Inherent Radiosensitivity Tumour cell Repopulation Redistribution through the cell cycle (G2/M is the most sensitive phase of the cell cycle, late-S phase is the most radioresistant) Repair of radiation induced damage- atleast 6hrs to complete. Reoxygenation of tumour tissues between fractions i.e. Hypoxic cells re-oxygenate and become radiosensitive.
- 8. FACTORS INFLUENCING THE EFFECTIVENESS OF RT FACTOR CHANGE IN LOCAL CONTROL CONCURRENT CHEMOTHERAPY OR BIOLOGICAL AGENTS 10% INCREASE 70Gy rather than 66Gy 5% INCREASE DELAYS IN STARTING RADIOTHERAPY 15% DECREASE PER MONTH TREATMENT INTERRUPTIONS 1.4% DECREASE PER EXTRA DAY ANEMIA 10-15% DECREASE SMOKING 10-15% DECREASE
- 9. TYPES OF RADIOTHERAPY External Beam Radiotherapy or Teletherapy Brachytherapy or Sealed Source Radiotherapy Systemic Radioisotope therapy or Unsealed Source Radiotherapy
- 10. EXTERNAL BEAM RADIOTHERAPY Radiation beam is directed from a machine placed outside the patient to a treatment volume located within. SOURCE OF RADIATIONS X-Ray Machines Particle accelerators Gamma rays i) LINAC (Cobalt 60) ii) Betatron iii)Cyclotron iv) Nuclear Reactors v) Radionuclides
- 11. COBALT 60 MACHINE Gamma rays Beam is weak Cheap Disadvantage : Decaying source causing reduced output & requires change of source every 5-7 years Does not give ideal depth dose and require complicated plans to deliver the effective tumor dose
- 13. LINAC MACHINE[ Linear accelerator] High, Medium , Low energy X-rays, Electrons Beam is much superior. Expensive No decaying source Good penetration
- 14. BRACHYTHERAPY Radioactive material is introduced directly to within the tumor or tumor bearing area. Radium needles were first to be used. Iridium (Ir-192) wire is the source of choice for modern head and neck brachytherapy. Brachytherapy can be temporary or permanent.
- 15. INDICATIONS OF BRACHYTHERAPY Site oral cavity , base of tongue Localized disease Small (T1) lesion Accessible site Substantial local recurrence rate Lesions away from bone
- 16. The temporary sources are usually placed by a technique called Afterloading. In afterloading a hollow tube or applicator is placed surgically in the organ to be treated, and the sources are loaded into the applicator after the applicator is implanted.
- 17. This minimizes radiation exposure to health care personnel. Advantage - high dose in small area Limitation - need for adequate radiation protection and cant be done in cases where wider field irradiation is required.
- 18. Doses in Brachytherapy Low dose rate = <2 Gy/hr ( used in oral, lip, tongue CA ) High dose rate = >12 Gy/hr Pulsed dose rate (uncommon) = 2-12 Gy/hr
- 19. SYSTEMIC RADIOISOTOPE THERAPY Systemic radioisotope therapy (RIT) is a form of targeted therapy. The radioisotopes are delivered through infusion (into the bloodstream) or ingestion. Examples : Infusion of meta- iodobenzylguanidine (MIBG) to treat neuroblastoma, Oral iodine-131 to treat thyroid cancer or thyrotoxicosis.
- 20. RADIOTHERAPY IN HEAD AND NECK CANCER More than 70% of oncological cases receive RT Modalities of RT used in head and neck cases are Definitive/Curative/Radical RT- Stage I-IV A Palliative RT Stage IV B- IV C, unresectable / metastatic disease with good general condition Neo-Adjuvant RT- adjuvant treatment given prior to definitive treatment Concurrent treatment : Chemoradiation
- 21. PRE-RT ASSESSMENT Examination under anesthesia Tumor biopsy Imaging CT/MRI of head and neck CXR/ CT thorax Full Blood count Urea and electrolytes LFT Dietician assessment Dental assessment Speech Therapist
- 22. CONTRA-INDICATIONS OF RT Cachexia Anemia Leukopenia Acute septic states Decompensated states of heart, liver, kidneys Active tuberculosis Extension of tumors to adjacent hollow organs Growth into great blood vessels. An inflammatory process
- 23. DOSIMETRY It is the measurement, calculation and assessment of the ionizing radiation dose absorbed by the human body. It can be internal or external dosimetry. Medical dosimetry is the calculation of absorbed dose and optimization of dose delivery in radiation therapy. Grays (Gy) is the S.I unit of absorbed dose Sieverts is the S.I unit of dose equivalence. 1 Gy = 100 rads = 1J/kg
- 24. Dose required for disease control Subclinical disease : 45-50Gy Microscopic disease : 60-65Gy Gross disease : 65-80Gy
- 25. Selection total radiation dose in head and neck cancer depends on Primary tumor Neck node size Fractionation Clinical circumstances Concurrent systemic therapy used or not
- 26. To ensure accurate radiation therapy, the following measures are taken Positioning and immobilization of patient ( moulded thermoplastic shield, custom made cabulite)
- 27. Target definition and delineation by imaging (Gross tumor volume(GTV) , Clinical target volume(CTV), Planning target volume(PTV) Coverage of Organ at risk Field arrangement ( Lateral parallel opposed fields and a wedged pair field are the most common used) Beam Modification ( wedges and shielding )
- 28. RADIOTHERAPY FRACTIONATION CONVENTIONAL FRACTIONATION 1.8-2Gy/day for 5 days/week. Curative doses 66-70Gy in 33-35 Fractions over 6.5-7weeks HYPERFRACTIONATION <1.8Gy/day Increases time Reduces risk for late damage Reduce effectiveness
- 29. HYPOFRACTIONATION > 2Gy/day Shorter duration Limits tumor repopulation Increases risk for late damage ACCELERATED FRACTIONATION Treatment time reduced Hyperfractionation treating two-three times each day Time between fractions should be minimum 6 hours Reduced risk of normal tissue damage
- 30. CHART( Continuous hyperfractionated accelerated radiotherapy) 1.5Gy three times/daily for 12 days = 54 Gy ( total dose) No weekend break
- 31. DEFINITIVE /CURATIVE RADIOTHERAPY Dose of curative radiotherapy by EBRT is dependent on the sites The maximum dose limits are 70 Gy (2Gy/day) for the following sites Lip, oral cavity, oropharynx, hypopharynx, glottic larynx, supraglottic larynx, occult primary, salivary gland tumors
- 32. Cancer pharynx with high subclinical risk should be given 2.12Gy/day radiations for total dose of 69.96 Gy for 6-7 weeks ( Mon-Fri ). 3D-Conformal RT and sequential planned IMRT 44- 50 Gy. For IMRT, some suggest 54-63 Gy.
- 33. PALLIATIVE RADIOTHERAPY Palliative RT considered in advanced cancer when curative intent is not appropriate. Basic principle of palliative RT is to avoid any regimen that causes severe toxicities. Hypofractionated regimen should be preferred in end stage diseases.
- 34. Recommended RT regimens 50 Gy in 20 fractions 37.5 Gy in 5 fractions 30 Gy in 10 fractions 44.4 Gy in 12 fractions, in 3 cycles
- 35. POST-OPERATIVE RT Post-operative RT is recommended based on T-stage T3/T4 disease Close or positive margins of excision Depth of invasion Multiple positive nodes ( without extracapsular nodal spread) Perineural/lymphatic/vascular invasion.
- 36. Higher doses of post-operative RT alone (60-66 Gy) or with systemic therapy are recommended for the high- risk features of extracapsular disease and/ or positive margins. The preferred interval is 6 weeks or less, between resection and commencement of postoperative RT
- 37. FOLLOW-UPAFTER RT Assessment of thyroid function (i.e. TSH test ever 6- 12 months) Clinical assessment at 4-8 weeks or CT-evaluation with or without contrast at 8 weeks after completion of RT alone or chemoradiation. Follow up 3-6 monthly
- 38. REIRRADIATION Repeating course of RT carries greater risk of damage to normal tissue. Reirradiation has to be weighed against other treatment options and against the risk and consequences of normal tissue damage. General rule- Minimize dose to critical normal tissues esp. spinal cord and optic tracts. ( IMRT, IGRT etc ) 6 months gap between previous RT and reirradiation. Addition of chemotherapy increases the effectiveness of reirradiation without increasing late morbidity.
- 39. Field cancerization biological process in which large areas of cells at a tissue surface or within an organ affected by carcinogenic alterations. Commonly seen in head and neck carcinoma , oral carcinoma , lung carcinoma
- 40. ORAL CAVITY Buccal mucosa , floor of mouth , retromolar trigone 皰 T1 and small T2 tumours- Radical implantation 皰 Larger lesions- EBRT and implantation 皰 In case of bone invasion surgery followed by EBRT 皰 In case of retromolar trigone surgery followed by postoperative EBRT or EBRT alone
- 41. LIP T1, T2 surgery (wide excision) RT (radical radiotherapy/ brachytherapy) T3, T4 surgery + postoperative radiotherapy N0 observe or Supraomohyoid neck dissection N+ - Modified neck dissection
- 42. Tongue 皰 SmallLarger T2 and T3 lesion EBRT followed by interstitial implantation 皰 Early tumors with mobile lymph nodes Surgery/ interstitial implant for primary and neck dissection for lymph nodes 皰 superficial tumors - Surgery 皰 T1 and small T2 tumors- Interstitial implants
- 43. Brachytherapy Tumour < 1 cm: Hairpin technique Tumour upto 2 cm: Plastic loop technique
- 44. DOSE IN ORAL CAVITY Brachytherapy Radical treatment-65-70 Gy to the 85% reference iso doseusing Paris system Boost treatment:25-30 Gy to the 85% reference iso doseusing Paris system EBRT Radical treatment:66-70 Gy in 33-35 fractions over 6.5-7 weeks Preimplantation:40-50 Gy in 20-25 fractions given 4- 5 weeks
- 45. OROPHARYNX Early T1-T2 tumours: Radiotherapy alone T3-T4 tumours:Concomitant chemotherapy + Radiotherapy T1-T2,N2-N3:Concomitant chemotherapy + Radiotherapy followed by neck salvage if residual nodes are present
- 46. In node negative patients- Elective neck irradiation is done Mobile unilateral nodes: block dissection followed by radiotherapy Fixed bilateral nodes:Radical radiotherapy if residual nodes- Surgery
- 47. Dose for Oropharynx: 66 Gy in 33 fractions over 6.5 weeks for T1-T2 nonbulky 70 Gy in 35 fraction over 7 weeks for T2(bulky)-T4
- 48. LARYNX Choice of treatment depends upon Voice preservation Local control rate Fitness for surgery Reliability of follow up
- 49. Supraglottic tumours T1-T2- radiotherapy or partial laryngectomy T3-T4-laryngectomy and post op radiotherapy N0 disease target volume includes primary tumor, upper deep cervical and midjugular lymphnodes.
- 50. Glottic tumour T1 and T2 radical radiotherapy; 5yr survival rate being 80-95% T3 radiotherapy and surgery; 5 yr survival rate being 50% Target volume T1 T2 5x5 field size , center lies below the promontory of thyroid cartilage
- 51. If T2 disease with supraglottic or subglottic extension; volume larger to include the extension and margins T3 and T4 radiotherapy n postoperative setting and target volume is to cover the potential sites of recurrence.
- 52. Subglottic tumour T1 and T2- radiotherapy or partial laryngectomy T3 and T4 laryngectomy and postoperative radiotherapy Target volume primay tumour , pre and paratracheal lymph nodes, lower jugular lymph nodes and superior mediastinum Dose 66Gy in 33 fractions over 6.5 weeks In postoperative , 58-60Gy is required
- 53. Hypopharynx Pyriform fossa radiotherapy in postoperative to reduce the local recurrence Postcricoid tumors without lymphadenopathy or with mobile lymph node laryngopharyngectomy . Radical RT is given in palliative settings for advanced cases Posterior pharyngeal wall tumors radical radiotherapy is treatment o choice
- 54. Ear Given in postoperative settings Palliative settings Inoperable cases Assessment of disease Clinical examination- parotid region, ear, facial nerve , mastoid region, regional lymphatics Otoscopy Ct scan
- 55. Indications for radiotherapy in Glomus tumor Larger tumors Inoperable sites: glomus jugulare , glomus tympanicum Extensive bone destruction Intracranial involvement Jugular foramen syndrome Dose : 45-55 Gy in 5 weeks
- 56. Nasal cavity and Ethmoid sinuses Limited disease : target volume includes medial maxillary sinus , ethmoid sinus , medial portion of orbit , nasopharynx , sphenoid sinus and base of skull
- 57. Nasopharynx For all stages radiotherapy is treatment of choice and intent is radical Bilateral neck irradiation mandatory even it is unilateral involvement T3 , T4 with any N status- concurrent chemotherapy and radiotherapy
- 58. Dose Patients without lymphadenopathy Nasopharyngeal and neck fields 56Gy in 28 fractions given in 5.5 weeks Nasopharynx alone 10-14 Gy in 5-8 fractions in 1-1.5 weeks
- 59. Patients with lymphadenopathy Large lateral fields 40Gy in 20 fractions over 4 weeks Nasopharyngeal field 26 Gy in 13 fractions over 2.5 weeks Neck field boost 26Gy in 13 fractions over 2.5 weeks
- 60. TREATMENT MORBIDITY OF RT IN HEAD AND NECK CA ACUTE TOXICITY Dose-response relationship Starts from 3rd week onwards
- 61. TOXICITIES MANAGEMENT Xerostomia ( damage to the plasma membrane of secretory granules both in Parotid & Submandible gland) Non alcoholic Anti-septic mouth wash, narcotic analgesic, anti-fungals for oral candidiasis, saliva replacement gel Ageusia ( Increased by Xerostomia ) Mucositis ( erythemapatchy mucositisconfluent mucositis) Analgesics, Zinc supplementation, Amifostine Odynophagia/dysphagia AnalgesicNG tubePEG Skin erythemaMoist desquamation Aqueous creamHydrocolloid dressing Lethargy Resolves itself in 6months
- 62. CHRONIC TOXICITY Toxicity is based on dose and latency of tissues at risk.
- 63. Late effect latency Osteoradionecrosis (mandible/ maxilla) Mostly 1-3 yrs Loss of teeth 1-5yrs trismus 6-12 months Larynx necrosis 6-18months Cartilage necrosis 6-18 months Spinal cord damage 6 months 5 yrs Optic nerve damage 6months 5 yrs
- 64. OSTEORADIONECROSIS Inflammatory condition of bone(osteomyelitis) due to high doses of radiation given for malignancy of head and neck region. Mandible is particularly susceptible( microanatomy and less vasculature) Dose above 50Gy cause irreversible damage Hallmark : Loss of mucosal covering and exposed bone
- 65. Pain +/- Swelling present and drainage extraorally Necrosis of bone- result of loss of vasularity from periosteum and sequestra Radiologically Early changes : well defined area of bone resorption Later changes : lytic or sclerotic or mixture
- 66. Management Administration of antibiotics , rinsing Use of narcotic analgesics, hydration , nutrition Ultrasound therapy RADICAL METHOD Hyerbaric O2 therapy reduces hypoxia and increases healing Sequestrectomy , local debridement
- 67. NEWER TECHNIQUES OF RT 3D conformal Radiotherapy Intensity Modulated Radiotherapy ( IMRT ) Volumetric Modulated Arc Radiotherapy ( VMAT ) TomoTherapy Image Guided Radiotherapy (IGRT) Proton Beam Therapy (PBT) Stereotactic Body Radiation Therapy (SBRT) Advanced radiation technologies mostly offer the advantage of sparing of important organs at risk and tight conformal doses to cancer targets
- 68. INTENSITY MODULATED RADIOTHERAPY The intensity of radiation beam can be modulated to decrease doses to normal tissue without compromising the doses to the cancer targets Advanced form of 3D-conformal RT IMRT dose painting refers to the medthod of assigning different dose levels to different structures within the same treatment fraction resulting in different total doses to different targets. Useful in oropharyngeal, paranasal sinus and nasopharyngeal cancers Xerostomia decreased greatly
- 69. Volumetric modulated arc radiotherapy (VMAT) VMAT is a new type of IMRT technique. The radiotherapy machine rotates around the patient during treatment. The machine continuously reshapes and changes the intensity of the radiation beam as it moves around the body
- 70. IMAGE GUIDED RADIOTHERAPY Images of each beam are obtained, stored and reviewed electronically Used to confirm that set up is within tolerance i.e. 3mm for head and neck cancer and no unacceptable deviation from the original treatment plan.
- 71. IGRT involves both fitting the linear accelerator with CT capability so that patient position may be confirmed prior to treatment and programming the linear accelerator to carry out any necessary shifts in treatment position. Helical Tomotherapy is advanced technique of IGRT
- 72. PET- BASED RT PLANNING Potential to improve accuracy of target definition. PET images obtained using hypoxia marker offers possibility of delivering a greater does to hypoxic areas in order to overcome their relative radioresistance.
- 73. PROTON BEAM THERAPY Uses Proton particle as radiation Highly Conformal RT Lower mean doses. Typically used in patients with most challenging disease for which other RT options were not safe or of any benefit.
- 74. PBT for treatment of sinonasal cancer is associated with good locoregional control, freedom from distant metastasis and acceptable toxicity. Serious toxicities encountered in trials but in less rate.
- 75. STEREOTACTIC BODY RADIATION THERAPY (SBRT) Advanced technique of EBRT. Delivers large ablative doses of radiation. Shorter treatment time, promising local control rates and acceptable toxicities. Less evidence for treatment of Head and neck cancers. Beneficial for palliation or older adults.
- 76. PRINCIPLE Uses 3D imaging to target high dose of radiation Minimal impact to the surrounding tissue Works by damaging the DNA of the targeted cells Delivery of radiation is accurate to within 1-2mm Radiation is delivered only when the outer and inner collimators are aligned.
- 77. USES Brain tumours pituitary adenomas , craniopharyngiomas, meningiomas etc Vestibular schwannoma Glomus jugulare Arteriovenous malformations Trigeminal neuralgia
- 78. RADIOSURGERY/CYBERKNIFE THERAPY Radiosurgery is a form of radiation therapy that uses precisely targeted radiation to destroy tumors. Radiosurgery is non-invasive there is no cutting involved. The CyberKnife System is a unique, robotic system designed to deliver high- precision radiosurgical and SBRT procedures.
- 79. Patient lies comfortably on a treatment table while the machine's robotic arm moves around him/her, aiming and firing targeted radiation beams from numerous angles. The cumulative dose of radiation kills tumor cells while minimizing exposure to the surrounding healthy tissue. Single high dose radiation fraction. Used in acoustic neuroma, skull base tumors.
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