Radiotherapy plays an important role in the treatment of cancer. It can be used with curative or palliative intent. New techniques allow for more precise delivery of radiation doses to tumors while minimizing exposure of surrounding normal tissues. This improves treatment outcomes and reduces side effects. Adaptive radiotherapy using real-time tracking may further enhance precision and enable dose escalation for better tumor control.

1. Radiotherapy in the Treatment
of Cancer
Darin Gopaul MD FRCPC
Grand River Regional Cancer Centre

2. Introduction

5. POISONED! -- as They Chatted Merrily at Their Work
Painting the Luminous
Numbers on Watches, the
Radium Accumulated in Their
Bodies, and Without Warning
Began to Bombard and
Destroy Teeth, Jaws and
Finger Bones. Marking
Fifty Young Factory Girls for
Painful, Lingering,
But Inevitable Death"

6. Marie Curie (1867 – 1934)
Born in Poland
University of Paris age 24
Discovered Radium 1898
t1/2 = 1602 years

7. Fletcher-Suit applicator
Intracavitary
Brachytherapy

8. Interstitial
Brachytherapy
Radium Needles

9. Prostate Brachytherapy

10. Prostate Brachytherapy
Iodine 125
t ½ = 60 days
Gamma emitter
Energy 35 kV

11. Free-hand implant technique

12. Prostate Brachytherapy

14. Prostate Brachytherapy
Adverse effects
• Urinary symptoms common
• Dysuria, frequency, urgency, nocturia
• Acute urinary retention 1-14%
• Urinary incontinence 5- 6%
• Proctitis 1-3%
But…
• Sexual potency preserved 86 -96%
• At 2 – 3 years

15. Prostate Brachytherapy
Results:
Gleason 2-4 86%
Gleason 5-6 63%
PSA < 4 93-100%
PSA 4 -10 70-86%
T1c 90-94%
T2a 70-74%
5 year actuarial biochemical freedom from failure

16. Prostate Brachytherapy
Patient Selection
• PSA < 10
• Gleason score 2 – 6
• T1c – T2a

17. Prostate Brachytherapy
• Advantages over standard EBRT:Advantages over standard EBRT:
– Does not require 6 - 7 weeks of daily fractionated treatmentsDoes not require 6 - 7 weeks of daily fractionated treatments
– Less long-term toxicity due to radiation of adjacent organsLess long-term toxicity due to radiation of adjacent organs
– Lower incidence of erectile dysfunctionLower incidence of erectile dysfunction
– Day surgery procedure requiring only a single visitDay surgery procedure requiring only a single visit
• Disadvantages compared to EBRT:Disadvantages compared to EBRT:
– More susceptible to dosimetry errors in delivery of radiationMore susceptible to dosimetry errors in delivery of radiation
– Requires a general / spinal anesthetic for implantRequires a general / spinal anesthetic for implant
– Higher incidence of voiding dysfunction at time and afterHigher incidence of voiding dysfunction at time and after
treatmenttreatment
– Requires precautions regarding radiation exposure to familyRequires precautions regarding radiation exposure to family
and friendsand friends
– Only proven for low-stage and low-grade diseaseOnly proven for low-stage and low-grade disease

18. External Beam Radiotherapy

19. 1951 – First Cobalt machine
• Saskatoon, Saskatchewan
• London, Ontario
• Co 60
– t ½ = 5.26 years
– Gamma emitter
– Energy 1.25 MV

20. Cobalt- 60

21. Definition
Gray:
A unit of absorbed radiation equal to the
dose of one joule of energy absorbed per
kilogram of matter, or 100 rads.

22. Typical doses
Palliative therapy 8 Gy in 1 fraction
20 Gy in 5 fractions
Adjuvant therapy 42.5 Gy in 16
50 Gy in 25
Radical Doses 60 Gy in 30
78 Gy in 39

23. Palliative Radiotherapy

24. Palliative radiotherapy
• Relief of symptoms (bone met)
• Prevention of symptoms or morbidity
• Improve survival duration (brain mets)

25. Case 1 – Palliative Radiotherapy
58 yo female with a history of metastatic breast ca.
Has had increasing back pain for 6 months. Bone
scan showed uptake (metastasis) at T5. No evidence
of visceral mets. Pain not well controlled with
narcotics (limited by side effects)
Pain reproduced on palpation of T5

26. Case 1 – Palliative Radiotherapy
Treated with palliative radiotherapy from T3 – T7
inclusive with 30Gy in 10 fractions over 2 weeks.
Possible side effects:
- skin dryness
- skin erythema
- odynophagia (radiation esophagitis)

27. Case 1 – Palliative Radiotherapy
Treated with palliative radiotherapy from T3 – T7
inclusive with 30Gy in 10 fractions over 2 weeks.
Possible side effects:
- skin dryness
- skin erythema
- odynophagia (radiation esophagitis)
Pain relief within 3-4 weeks
Prevention of spinal cord compression?

28. Skin Care Recommendations
Prevention
- Wash daily with mild, non-scented pH balanced soap
- Use of hand for washing the area, pat dry
- No new creams or oils in the treatment area
Treatment
- Asymptomatic erythema : no treatment
- Dry / itchy skin: aqueous cream (glaxal base, biafine)
- Red/ burning skin: 1% hydrocotisone cream
- Moist desquamation : Flamazine Cream +/- dressing

29. Case 2 – Palliative Radiotherapy
59 yo male smoker presenting with SOB, cough
and chest discomfort. No hemoptysis.
Anorexia, fatigue and a 30 lb weight loss.
CT Chest/abdomen, CT Brain, Bone scan
demonstrate 14cm lung mass invading into the
mediastinum (unresectable) but no mets.
PFTs demonstrate FEV1 0.8L and DLCO 36%

30. Palliative Radiotherapy – Lung Ca
• Stage III : Not a candidate for radical radiotherapy
– Poor PS
– Significant weight loss
– Large tumor > 7cm
– Inadequate pulmonary reserve for radical
radiotherapy
• Stage IV : metastatic

31. Palliative Radiotherapy – Lung Ca
Goals
• Symptom Control
– Cough
– Hemoptysis
– Chest Pain
• Delay intrathoracic progression
– Prevent lung collapse
– Prevent SVC
Aim is Quality of life not Quantity of life

32. Case 3 – Palliative Radiotherapy
• 42 yo female T2N1 NSCLCa, treated with
surgery. 8 months later presented with a
seziure, CT scan demonstrates multiple (4
brain mets)
• Treated with Whole Brain Radiotherapy
with clinical/radiologic response

33. Case 3 – Palliative Radiotherapy
• 8 months post Whole Brain XRT, presents
with clinical/ radiologic progression.
Options?
- Steroids (no response)
- Surgery (not for multiple lesions)
- Radiotherapy (already treated)
- Radiosurgery

34. Co 60 Radiosurgery – “Gamma Knife”

35. “Co 60 Radiosurgery – “Gamma Knife”
• Invented 1950’s
• 201 Cobalt sources
• Precision mounted
• 4mm – 4cm target
• Rigid Immobilization

36. Gamma Knife

38. Linear Accelerator

39. Linear Accelerator
• X-rays
• Higher energy (4 - 18Mv)
– compared to Gamma rays (1.25 Mv)
• Higher energy means
–More penetrating beam
–Treat deeper tumors
–Enhanced skin sparing

40. Linac Radiosurgery – “X Knife”
• High energy beam
• 1 moving source
• 5mm – 4cm target

41. Linac Radiosurgery – “X Knife”
Advantages
• Allows multiple fractions
• More widely available
• Linac has other uses

42. Cranial Radiosurgery
Indications
• Solitary Brain Met on MRI
• < 4 cm maximal dimension
• 1- 3 Recurrent post Whole Brain Rads
• Good Performance Status (KPS > 70%)
• Limited or Controlled Extracranial Disease

43. Adjuvant Radiotherapy

44. Definition
Adjuvant Therapy:
Post-operative treatment in the absence of
demonstrable residual disease, to reduce
the possibility of recurrence.

45. Adjuvant radiotherapy – Breast cancer
• Breast conservation
• Post mastectomy (loco-regional)

46. Breast Conservation
• No difference in OS
• LR uncommon post adjuvant XRT
• LR can be salvaged with further surgery
BCS + Radiotherapy = Mastectomy

47. Breast Tangents
Computer assisted radiation planning

48. Adjuvant radiotherapy – Breast cancer
Reducing treatment duration (OCOG study)
• 42.5 Gy in 16 vs 50 Gy in 25
• No difference in LR control
• No difference in cosmesis

49. Adjuvant radiotherapy – Breast cancer
42.5 Gy in 16 fractions now standard
• Not for very large Breast volumes
• 3-5 “boost” treatments to the tumor bed
• Close or focal positive margins
• Premenopausal status

50. Postmastectomy Radiotherapy
Standard for High Risk disease
• Tumor > 5cm (T3)
• Tumor involves skin or chest wall (T4)
• 4 or more lymph nodes
– LRR 25-30% postmastectomy
– LRR 5- 10% post Locoregional radiotherapy
– OS improves 5%

51. Postmastectomy Radiotherapy
Intermediate Risk disease
– T2 tumor with multiple adverse features
– High grade, LVI+, ER-
– 1-3 lymph nodes
– Age < 45 years
– LRR 10 -18% postmastectomy
– LRR 5% post Locoregional radiotherapy

52. 3D Conformal Radiotherapy

53. 3D Conformal Radiotherapy
• Acquire 3D spacial data
• Radiation Planning in 3D
• Deliver Radiation in 3D

54. Couch
CT Simulator

55. MRI-CT Fusion (Co-Registration)
 MRI
 Excellent soft tissue
contrast allows
better differentiation
between normal
tissues and many
tumors
 Disadvantages:
 Susceptible to spatial
distortions

56. Treatment Planning
Beam
Placement

57. Multileaf Collimator (MLC)
No more
lead blocks!

58. Prostate Radiotherapy

59. Prostate 3D Planning

60. Shaping the beam with MLC - prostate
Beam’s Eye View (BEV)Beam’s Eye View (BEV)
AP View Lateral View

61. Verification - EPID images

62. Increasing Conformality

63. Advantages
• Enhanced Normal Tissue Sparing
• Reduces side effects
• Dose Escalation Improves Cure Rate
• Higher Dose per Fraction
• Reduce Number of fractions
• Reduce Treatment Duration

64. The Future

65. Synchrony™
camera
Linear
accelerator
Manipulator
Image
detectors
X-ray sources
Targeting System
Robotic Delivery System

66. Thank-you!