Radiotherapy /certified fixed orthodontic courses by Indian dental academy


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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

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Radiotherapy /certified fixed orthodontic courses by Indian dental academy

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. INTRODUCTION With discovery of X-rays in 1895 by Wilhelm Rontgen, much advancement has taken place in the field of radiology. Radiation oncology is a medical specialty that utilizes ionizing radiation to treat many different types of malignancies. Oral cancer – 3.5% of all malignancies.
  3. 3. For more early stage of oral cancer radiation therapy and surgery are effective. For intermediate stage radiation therapy used as an adjuvant role to surgery. For advanced tumors radiation therapy is extensively used. The success of radiation therapy as a treatment modality depends on differences in repair capabilities between normal & malignant cells.
  4. 4. OBJECTIVE OF TREATMENT The choice of treatment depends on Cell type Degree of differentiation Location of primary lesion Site and size General condition of patient
  5. 5. Patients age Lymph node status Bone involvement Preservation of functions Physical and mental status of patients Complications
  6. 6. MECHANISM OF RADIOTHERAPY Radiation kills cells by interaction with water molecules in cells, producing charged molecules that interact with bio-chemical process in the cells • DNA is damaged • Chromosomal damage • Incapable of cell division
  7. 7. Radiotherapy deals with use of ionizing radiation in treatment of malignant neoplasm. Ionizing radiation Photons (X-rays and Gamma-rays) Particulate Radiation (Electron, Protons, Neutrons, Alpha and Beta)
  8. 8. BIOLOGICAL EFFECT OF RADIATION Depends On dose per fraction The number of fractions per day Total treatment time Total dose of radiation
  9. 9. ROLE OF RADIOTHERAPY IN CANCER Combined Adjuvant Alone Pallative
  10. 10. INDICATIONS OF RADIOTHERAPY Posterior 1/3 of tongue Oropharynx Tonsillar pillar Exophytic lesions Well differentiated carcinomas
  11. 11. ADVANTAGES Extensive lesions. Treating the disease in-situ. Avoid the surgical removal of tissue. To operate in accessible site. Choice of treatment for T1 and T2 tumors. Lymph node metastases. To eradicate well oxygenated tumor cells at the periphery.
  12. 12. DISADVANTAGE Radio resistant tumors Treatment of hypoxic cells Complications of radiotherapy
  13. 13. PRINCIPAL OF RADIATION To deliver a precise dose of radiation to a definite tumor volume with minimal damage. The goal of radiotherapy is sterilized is tumor and avoid causing un-acceptable degree of toxicity to the surrounding normal tissue.
  14. 14. The first dose of radiation kills cells that are well oxygenated and in sensitive phases of cell cycle. Palliation and prevention of symptoms of disease. Absorption of x-ray in the medium is an important factor for radiation therapy Gy). (Dose :
  15. 15. Before the delivery of next dos of radiation sublethal damage repair can occur in both the tumor and normal tissues. Because a substantial number of cells within the tumor have been killed by the first dose of radiation, there is less competition for the available oxygen, and some of the hypoxic tumor cells can re-oxygenate and become more radiosensitive.
  16. 16. Radiotherapy works in most cases not because the tumors are more radiosensitive than the normal tissues, but rather because normal tissues are better at repair and repopulation within the context of clinically utilized fractionation schemes. Cells tend to be more radiosensitive in mitosis and late G1 - early S phase than in early G1 and G2 phases. So, radiation perferentially kills cells in the more sensitive phase of cell cycle.
  17. 17. FRACTIONATION SCHEMES Early or acute responding tissues - skin and pharyngeal mucosa. Late responding tissue - spinal cord. The early responding tissues limit both the size of dose fraction and the degree to which time course of radiation can be compressed.
  18. 18. The late responding tissues limits total radiation dose, so giving smaller dose per fraction allows higher total dose to be given. This is the basic rationale for giving multiple smaller fractions of radiation per day instead of single daily dose. The require of minimum time is approximately 6 hours for normal tissue to repair.
  19. 19. HYPER FRACTIONATION Reduce the size of individual radiation fractions in an attempt to reduce normal tissues late effect and to allow a higher total dose of radiation. ACCELERATED FRACTIONATION Same dose delivered rapidly to treat the rapidly proliferating tumors.
  20. 20. CONTINUOUS HYPER FRACTIONATION RADIOTHERAPY (CHART) Extreme accelerated schedules Consists of giving three daily radiation treatments of 1.5Gy each to a total dose of 54Gy without giving any weekend breaks.
  21. 21. CANCER STAGING • Commonly used staging UICC-TNM • T – Size of tumor • N – Lymph node spread • M – Metastasized to other organs of body • T1 - <2cms N1 – Ipsilateral single <3cms • T2 - >2 to 4cms N2 – a. Ipsilateral single >3 to 6cms • T3 - >4cms b. Ipsilateral multiple <6cms • T4 – Adjacent structures. c. Bilateral, Contralateral <6cms N3 - >6cms
  22. 22. TOLERANCE LIMITS Tongue / Lips : High tolerance (70 to 80 Gy) Floor of the mouth : Intermediate Tolerance Alveolar ridges / Mandible: Lowest Tolerance T1 & T2 tumors : 65 to 70 Gy in 7 Weeks T3 & T4 tumors : 75 to 80 Gy Tongue alveolus : 45 to 50 Gy. N2 & N3 nodes : Radiation followed by surgery
  23. 23. TREATMENT PLANNING The radiation treatment plan is determined by tumor site and size, the total volume to be radiated, the number of treatment fractions, total number of days of treatment, tolerance of patient and the sparing of uninvolved tissues or organs. Type of treatment includes external therapy • External therapy (Teletherapy) • Internal therapy (Branchytherapy)
  24. 24. EXTERNAL THERAPY (Teletherapy) X-rays Source / Point of Origin is at a distance away from patients body. In external therapy two principal field arrangements are parallel opposed fields and wedged pair fields. The wedged pair fields allow a therapeutic dose to unilateral disease while sparing high dose to the opposite side.
  25. 25. When a large tumor are midline lesion is present a parallel opposed field setup may be needed, which produced a uniform exposure for midline disease. Fields of modified by placing a wedges in the beam to accommodate variation in tissue contour. Radiation
  26. 26. Epithelial malignancy 1.8 to 2 Gy per fraction for 5 weeks (6000 to 6500cGy). Lymphomas 180 to 200cGy per day (3500 to 5000cGy). Superficial tumors : Low penetration Lip and Skin : Low Kilovolt Parotid : Electron beam therapy Deep seated lesions : Neutrons
  27. 27. INTERNAL THERAPY (Branchy Therapy) X-rays source is placed in contact with the tumor. One way of concentrating the radiation dose in the tumor tissue and the limiting the dose to the surrounding normal tissues. Branchy therapy is used as a boosted dose of radiation to specific site or for treatment for recurrence.
  28. 28. The isotopes used include cesium, irridium, iodine, radium and gold. Directly implanted source may be used to deliver the radiation by covering the unexposed areas with bandages, holders, wax and shields. THREE CATEGORIES Molds / Plaques Interstitial implants Intra cavitary / intra luminal
  29. 29. MOLDS / PLAQUES Radioactive source is loaded into a surface mould and placed within the tumor. INTERSTITIAL IMPLANTS Radioactive source is past through and through the tumor. INTRA CAVITARY / INTRA LUMINAL Radioactive source placed in natural body cavities.
  30. 30. PRE AND POSTOPERATIVE THERAPY Preoperative radiation are used for destruction of peripheral tumor cells, the potential control of sub-clinical disease. Postoperative therapy can be used to treat cells that remain the margin of resection and to control sub-clinical disease. Example (Carcinoma, extracapsular extension of tumor).
  31. 31. COMPLICATION OF RADIOTHERAPY Acute reactions - During the course of radiotherapy due to tissue toxicity and resolve over several weeks. Chronic reactions - develops slowly over months to years.
  32. 32. Mucositis Xerostomia Candidiasis Caries Tissue necrosis Speech and mastication problem Nutritional deficiency Mandibular dysfunction Dentofacial abnormalities Pain
  33. 33. MUCOSITIS Epithelial thinning, altered vascular supply, fibrosis in connective tissue, friable mucosa and hyalinization of collagen (1 to 2 weeks). TREATMENT Diluting agents/saline, hydrogen peroxide rinse Coating agents – Kaolin-pectin and hydroxy popylcellulose.
  34. 34. MUCOSITIS LIP LUBRICANTS Topical anesthetics – Xylocaine HCl. Analgesic agents.
  35. 35. XEROSTOMIA Acinar cell atrophy, hypo-vascularity, altered neurologic function, decrease buffering capacity, altered oral microbial flora treatment. Sialagogues – sugar free gum or candies Pilocaropine – 15mg per day Saliva substitute (Carboxymethylcellulose)
  36. 36. CANDIDIASIS / CARIES Opportunistic infection due therapy. TREATMENT Tropical anti-fungal agents to radiation
  37. 37. Loss of remineralization, loss of buffering capacity, gingival third and the incisal cusp tips – caries. TREATMENT Fluorides, occlusive splints, chlorhexidine gel 2%.
  38. 38. TISSUE NECROSIS Hypo vascular, hypo cellular and hypoxic tissue unable to repair – tissue necrosis. Clinical features – discomfort, bad taste, parasthesia, fistula, infection and fracture. TREATMENT Hyper baric oxygen therapy, IV fluids, nutritional supplement, removing of underlying tropical antibiotic and antiseptic. etiology,
  39. 39. SPEECH AND MASTICATION PROBLEM Abnormal speech after radiation affects tongue mobility mandibular movement, soft palate function and palatal defect. TREATMENT Speech therapy and prosthesis.
  40. 40. NUTRITIONAL AND MANDIBULAR DYSFUNCTION Radiation therapy produces changes in taste, smell and secondary infection (>3000 Gy). TREATMENT Nutritional counseling and ↑caloric intake.
  41. 41. Due to fibrosis stress of muscles. TREATMENT Physiotherapy, excises, muscle relaxants and analgesics injection.
  42. 42. DENTOFACIAL ABNORMALITIES / PAIN Affects the facial skeleton, growth and development agenesis of teeth, abnormal micrognathia. root, trismus,
  43. 43. Pain due to tumor or recurrence or progression of tumor. TREATMENT Tropical anesthetics, inflammatory muscle analgesic, relaxants depressants. and antianti-
  44. 44. CONCLUSION Radiation therapy place an integral role in management of most head and neck malignancies. Hence proper use requires basic understanding of how it affects both tumors and normal tissues. Research will continue and investigations of radiation fractionation, radiosensitizers therapy. may include source, radiation and combined
  45. 45. Advances in radiation 3-Dimensional treatment planning and delivery – paranasal sinus. High LET Radiotherapy – Neutrons. Laser guided radiation.
  46. 46.