Basics in radiation oncology

basics in radiation oncology

slides are in short
please do refer radiation reference books, Eg Parez

1. BASICS IN RADIATION ONCOLOGY

2. RADIATION ONCOLOGY Radiation oncology is that discipline of human medicine concerned with the generation, conservation, and dissemination of knowledge concerning the causes, prevention, and treatment of cancer and other diseases involving special expertise in the therapeutic application of ionizing radiation.

3. Medical Oncology is that discipline of human medicine specializes in diagnosing and treating cancer using chemotherapy, hormonal therapy, biological therapy, and targeted therapy. Surgical Oncology branch of  surgery  applied to  oncology ; it focuses on surgical management of tumours mainly cancerous tumour.

4. RADIATION THERAPY Radiation therapy is the clinical modality dealing with the use of ionizing radiations in the treatment of patients’ with malignant neoplasias (and occasionally benign diseases). The aim of radiation therapy is to deliver precisely measured dose of radiation to a defined tumour volume with as minimal damage as possible to the healthy surrounding tissue, resulting in eradication of the tumour, high quality of survival and prolongation of survival at competitive cost.

5. CELL CYCLE

6. G0 – Cell rests and does normal work in the body G1 – RNA and proteins are made for dividing S – Synthesis ( DNA is made for new cell ) G2 – Apparatus for mitosis is built M – Mitosis ( The cell divides into 2 cells )

7. Radiation kills cells that are actively dividing. It also causes damage to the surrounding tissue. Radiation doesn’t kill cells instantly, it may take day to weeks depending on the cell Skin, bone marrow, lining of intestines affects quickly. Nerve, breast, brain, and bone tissue show affects later

8. TYPE OF RADIATION IONIZING PHOTON THERAPY ( X- RAYS AND GAMMA RAYS ) PARTICLE THERAPY ( ELECTRONS, PROTONS, NEUTRONS, CARBON IONS, ALPHA PARTICLES AND BETA PARTICLES ) NON – IONIZING RADIO WAVES, MICROWAVES, VISIBLE LIGHT

9. RADIOCURABILITY – It refers to the eradication of tumour at the primary or regional site and reflects a direct effect of the irradiation ; but this does not equate with patients cure from cancer. RADIOSENSITIVITY – is the measure of tumour radiation response, thus describing the degree and speed of regression during and immediately after radiotherapy

10. Factors affecting Radiosensitivity Histologic type High sensitivity: Malignant lymphoma, Seminoma, etc. Moderate sensitivity: Epithelial tumour (Carcinoma) Low sensitivity: Osteosarcoma, Malignant melanoma, etc. Oxygen concentration in tumour tissue: Radiosensitivity is low in the hypoxic state. Cell cycle: Radiosensitivity is high in M phase and low in S phase. Cancer-related genes: p53, Bel-2, Fas, VEGF, etc.

11. 4 R’s of Radiotherapy Repair (few hours ) Lethal damage Sublethal damage Potentially lethal damage Reassortment (few hours) Repopulation (5 – 7 weeks) Reoxygenation (hours to few days)

12. RADIOTHERAPY PRIMARY ADJUVANT NEO-ADJUVANT CONCURRENT PALLIATIVE

13. Planning and conduct of course of Radiation Therapy Indication for radiotherapy Goal of radiation therapy Planned treatment volume Planned treatment technique Planned treatment dose

14. EXTERNAL BEAM RADIATION 2D RADIOTHERAPY 3D CONFORMAL RADIOTHERAPY INTENSITY MODULATED RADIOTHERAPY IMAGE GUIDED RADIOTHERAPY STEREOTACTIC RADIOTHERAPY / SURGERY INTRAOPERATIVE RADIOTHERAPY ELECTROMAGNETIC GUIDED RADIATION THERAPY

15. BRACHYTHERAPY CESIUM, GOLD, IODINE, IRIDIUM, PALLADIUM MAIN TYPES OF INTERNAL RADIATION INTERSTITIAL PERMANENT BRACHYTHERAPY TEMPORARY BRACHYTHERAPY HIGH DOSE RATE BRACHYTHERAPY LOW DOSE RATE BRACHYTHERAPY INTRACAVITARY INTRALUMINAL SURFACE

16. Radiation Oncologist - Plans treatment. Radiation Physicist – Working o f radiation equipment & delivering the radiation dose. Dosimetrist – Helps the doctor plan and calculate the needed number of treatment. Radiation therapist – operates the equipment. Radiation therapy nurse – cares the patient and advice them on radiation treatment & dealing with radiation side efftects .

17. PLANNING IMMOBILIZATION CT Simulation Treatment Planning System Target delineation Dose prescription Beam placement Dose calculation Plan evaluation & Approval Quality assurance RADIATION DELIVERY

18. IMMOBILIZATION GOALS DEVICES PLASTIC HEADHOLDERS AND SPONGES THERMOPLASTS PLASTER OF PARIS VACUM MOULDED THERMOPLASTS POLYURETHANE FOAMS

19. THERMOPLAST IMMOBILIZATION

20. Video

21. TARGET DELINEATION & DOSE PRESCRIPTION Gross tumour volume – 60 – 70 Grays Clinical target volume High risk – 45 – 54 Grays Low risk – 45 Grays Planning target volume.

22. COMBINATION THERAPY CONCURRENT CHEMOTHERAPY CISPLATIN 40mg/m² in 1pint NS IV over 20mins ( Cover bottle with black paper) after premedication CARBOPLATIN , TAXOL MONOCLONAL ANTIBODIES BioMap

23. TARGETED THERAPY Targeted therapy blocks the growth and spread of cancer by preventing cancer cells from dividing or destroying them directly . EGFR monoclonal antibodies cetuximab , panitumumab , zalutumumab , nimotuzumab EGFR tyrosine kinase inhibitors gefitinib , erlotinib , lapatinib , afatanib , dacomitinib V ascular endothelial growth factor receptor (VEGFR) inhibitors bevacizumab , sorafenib , sunitinib , vandetanib

24. SIDE EFFECTS

25. ORAL MUCOSITIS

26. Symptoms include pain, Dysphagia, Odynophagia, Nausea, Vomiting, Diarrhoea – GI Toxicity. Prevention Midline mucosa sparing blocks 3D treatment planning and conformational dose delivery Topical benzydamine – anti inflammatory, analgesic and anti microbial effect

27. Treatment Lidocaine , milk of magnesia, chlorhexidine and diphendhydramine Antibiotic lozenges or sucralfate

28. DERMATITIS

29. Erythema, desquamation, oedema, necrosis or ulceration (dose and duration ) Sweat glands and hair follicles – damaged Alopecia permanent – Follicular fibrosis . Treatment Gentle cleansing with mild agent, washing with water. Petrolatum based, castor oil, trolamine . Steroids ameliorate the symptoms, but do not prevent. Ulcers – Gention violet, Hydrogel dressings If infected – Ionic silver powder, topical antibiotics Recent years – Topical granulocyte-macrophage-colony stimulating factor, tacrolimus , platemet derived growth factor

30. Chronic skin changes Oral pentoxifylline (800mg/day) Vitamin E (1000IU/day) For 6 months Prophylactic use of Pentoxifylline reduces late skin changes, fibrosis and soft tissue necrosis

31. XEROSTOMIA Subjective experience of dry mouth. 50 – 60% decrease – 1 st week Continues in dose dependent fraction Symptoms Systemic problems – loss of apetite , chronic oesophagitis , gastroesophageal reflux Local problems include dental caries, periodeontal disease, atrophy and ulceration

32. Prevention Surgical transplantaion of salivary gland. Submandibular gland to submental space. Intensity modulated RT. Amifostine therapy. 200mg/m² 15 – 20mins prior irradiation Treatment Dietary and oral hygiene Saliva substitution Medications ( carboxymethylcellulose , porcine, bovine mucin ) Increase flow – Chewing gums, Lozenges, Vitamin C Oral pilocarpine 5 -10mg TID

33. SPINAL CORD Transient myelopathy ( 2 – 4 months later ). LHERMITTE SIGN or LHERMITTE SYNDROME. Rarely, Permanent paralysis, presumed to be from acute infarction of cord. HEARING Cochlear damage – SNHL ( ˃60grays ). Concurrent Chemotherapy with Cisplatin increases risk.

34. THANKYOU