Radiotherapy One of the main treatment Siemens Oncology

Radiotherapy • One of the main treatment Siemens Oncology modalities for cancer (often in combination with chemotherapy and surgery) • It is generally assumed that 50 to 60% of cancer patients will benefit from radiotherapy • Minor role in other diseases 2/20/2021 Clinical Radiation Generator 2

External Beam Radiotherapy Beam 2 Beam 3 Beam 1 tumor 2/20/2021 patient Clinical Radiation Generator 3

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External Beam Radiotherapy • More than 90% of all radiotherapy patients are treated using EBT • Most of these are treated using X-rays ranging from 20 ke. V to 20 Me. V in peak-energy • Other EBT treatment options include telecurie units (60 -Co and 137 -Cs), electrons from linear accelerators and accelerators for heavy charged particles such as protons 2/20/2021 Clinical Radiation Generator 5

Cancer incidence (WHO) 2/20/2021 Clinical Radiation Generator 6

Major indications for radiotherapy • • Head and neck cancers Gynaecological cancers (eg. Cervix) Prostate cancer Other pelvic malignancies (rectum, bladder) Adjuvant breast treatment Brain cancers Palliation 2/20/2021 Clinical Radiation Generator 7

Approaches • Palliative radiotherapy to reduce pain and address acute symptoms - eg bone metastasis, spinal cord compression, . . . • Radical radiotherapy as primary modality for cure - eg head and neck • Adjuvant treatment in conjunction with surgery - eg breast cancer 2/20/2021 Clinical Radiation Generator 8

Patient Aim • To kill ALL viable Critical organs cancer cells Beam • To deliver as much directions target dose as possible to the target while minimising the dose to surrounding healthy tissues 2/20/2021 Clinical Radiation Generator 9

Prognostic Factors • • Cancer type and stage Patient performance Radiation dose. . . survival Bad prognosis 2/20/2021 Clinical Radiation Generator Good prognosis time 10

Prognostic Factors • • Cancer type and stage Patient performance Radiation dose. . . Accurate dose delivery matters! 2/20/2021 Clinical Radiation Generator 11

Dose should be accurate • To target: • 5% too low - may result in clinically detectable reduction in tumour control (eg. Head and neck cancer: 15%) • To normal tissues: • 5% too high - significant increase in normal tissue complication probability = morbidity = unacceptable side effects 2/20/2021 Clinical Radiation Generator 12

External beam radiotherapy (EBT) treatment approaches • • Superficial X-rays Orthovoltage X-rays Telecurie units Megavoltage X-rays Electrons Heavy charged particles Others 2/20/2021 Clinical Radiation Generator 13

External beam radiotherapy (EBT) treatment approaches • • • Superficial X-rays Orthovoltage X-rays Telecurie units Megavoltage X-rays Electrons Heavy charged particles • Others 2/20/2021 +40 to 120 k. Vp +150 to 400 k. Vp +137 -Cs and 60 -Co +Linear accelerators +Protons from cyclotron, C, Ar, . . . +Neutrons, pions Clinical Radiation Generator 14

Superficial radiotherapy • • • 50 to 120 k. Vp - similar to diagnostic X-ray qualities Low penetration Limited to skin lesions treated with single beam Typically small field sizes Applicators required to collimate beam on patient’s skin • Short distance between X-ray focus and skin 2/20/2021 Clinical Radiation Generator 15

Superficial radiotherapy Philips RT 100 2/20/2021 Clinical Radiation Generator 16

Superficial radiotherapy issues • Due to short FSD high output and large • • • influence of inverse square law Calibration difficult (strong dose gradient, electron contamination) Dose determined by a timer - on/off effects must be considered Photon beams may be contaminated with electrons from the applicator 2/20/2021 Clinical Radiation Generator 17

Orthovoltage radiotherapy • 150 - 400 k. Vp • Penetration sufficient for palliative treatment of bone lesions relatively close to the surface (ribs, spinal cord) • Largely replaced by other treatment modalities 2/20/2021 Clinical Radiation Generator 18

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Kilovoltage Equipment (150 - 400 k. Vp) l. Depth dose dramatically affected by the FSD 6 cm, HVL 6. 8 mm Cu 2/20/2021 Clinical Radiation Generator FSD 30 cm, HVL 4. 4 mm Cu 21

Orthovoltage patient set-up l Like for superficial irradiation units the beam is set-up with cones directly on the patient’s skin 2/20/2021 Clinical Radiation Generator 22

Megavoltage radiotherapy • 60 -Cobalt (energy 1. 25 Me. V) • Linear accelerators (4 to • • • 25 MVp) Skin sparing in photon beams Typical focus to skin distance 80 to 100 cm Isocentrically mounted 2/20/2021 Clinical Radiation Generator 23

ﻣﻊ ﺃﻄﻴﺐ ﺍﻷﻤﻨﻴﺎﺕ 2/20/2021 Clinical Radiation Generator 24