1) The study developed an intensity-modulated radiotherapy (IMRT) technique for post-operative prostate bed irradiation and compared it to the standard 4-field box technique. 2) IMRT achieved better sparing of the rectal wall and bladder wall from radiation while still providing adequate target coverage. 3) Acute gastrointestinal and genitourinary toxicity rates were lower with IMRT compared to the standard technique.

1. Acute Toxicity for
Prostatectomy Patients receiving
y g
Intensity Modulated Radiotherapy
V. Kong, T. Craig, A. Bayley, R. Bristow, C. Catton,
P. Chung, M. Gospodarowicz, M. Milosevic, P. Warde, C. Ménard

2. Introduction
Radical Prostatectomy
y
Effective treatment for patients with favorable
prognostic factors
Intent of Post-Operative Radiotherapy
Reduces local recurrence rate for high risk patients
Used as either adjuvant or salvage therapy
V. Kong, PMH Conference

3. Post-
Post-Operative Radiotherapy
Treatment Volume & Technique
q
Defined using bony landmark
4 Field Box
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4. Side effects from Radiotherapy
Gastrointestinal (GI)
Proctitis
Loose bowel movement
or diarrhea
Genitourinary ( )
y (GU)
Urinary incontinence
Increased frequency
Pain/Burning senation
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5. Advancement of Technology
New consensus guideline for prostate bed
g p
Clinical Target Volume (CTV) definition
Increase volume? -> Increase toxicity?
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6. The need to change
Treatment technique
q
Conformal 4 field box
62.7 Gy
55.0 Gy
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7. Objectives
To describe the development of an Intensity
p y
Modulated Radiotherapy (IMRT) technique for
the Prostate Bed
To
T report th clinical dosimetric characteristics of
t the li i l d i t i h t i ti f
the new technique
To report acute GI and GU toxicity outcomes
To compare results with a historical cohort
treated by 4 field box technique (4FB)
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8. Method
50 patients accrued to prospective trial
p p p
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9. Process Flowchart
Patient Education Sess o
at e t ducat o Session
CT Simulation
Delineation of Regions of Interest (ROI)
Generation of IMRT Distribution
Treatment
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10. Process Flowchart
Patient Education Sess o
at e t ducat o Session
CT Simulation
Delineation of Regions of Interest (ROI)
Generation of IMRT Distribution
Treatment
V. Kong, PMH Conference

11. CT Simulation
Full bladder and empty rectum
py
Pelvic vacuum immobilization device
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12. Process Flowchart
Patient Education Sess o
at e t ducat o Session
CT Simulation
Delineation of Regions of Interest (ROI)
Generation of IMRT Distribution
Treatment
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13. Clinical Target Volume
Inferior CTV (ICTV) Superior CTV (SCTV)
Wiltshire et al. IJROBP 2007 69(4); 1090-1099
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14. Planning Target Volume
Planning Target Volume (PTV) Margin (mm)
g g ( ) g ( )
Online guidance using soft tissue/surgical clip
Chu, 2007
AP SI RL
SCTV 14 13 7
ICTV 10 11 5
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15. Organ at Risk (OAR)
Rectal Wall (RW)
( )
Bladder Wall (BW)
Penile Bulb (PB)
Femur
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16. Process Flowchart
Patient Education Sess o
at e t ducat o Session
CT Simulation
Delineation of Regions of Interest (ROI)
Generation of IMRT Distribution
Treatment
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17. IMRT
7 field step-and-shoot distribution
p
Dose fractionation
66Gy in 33 fractions
y
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18. IMRT
Treatment planning objectives
p g j
1. Avoid irradiating rectum circumferentially to
55 Gy
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19. IMRT
Posterior Rectal Wall (pRW)
(p )
62.7
62 7 Gy
55.0 Gy
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20. IMRT
Treatment planning objectives
p g j
1. Avoid irradiating rectum circumferentially to
55 Gy
2. PTV D99 ≥ 54 Gy
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21. IMRT
Treatment planning objectives
p g j
1. Avoid irradiating rectum circumferentially to
55 Gy
2. PTV D99 ≥ 54 Gy
3. Maximize % of PTV receiving 95% of
prescription dose – V95
i ti d
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22. Dose Constraints
Organs at Risk Metric Dose (Gy)
Rectal Wall 1 cm3 ≤ 66 0
66.0
Bladder Wall 2 cm3 ≤ 67.3
Penile Bulb 0.5 cm3 ≤ 66.0
Femur 1 cm3 ≤ 55.0
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23. Monitoring Side Effect
Acute Toxicity Scoring
y g
Common Terminology Criteria Adverse Events
(CTCAE) v3.0
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24. V. Kong, PMH Conference

25. Monitoring Side Effect
Acute Toxicity Scoring
y g
Common Terminology Criteria Adverse Events
(CTCAE) v3.0
GI GU
Diarrhea Frequency
Proctitis Haematuria
Cystitis
Spasm
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26. Is IMRT better?
Comparison with 4FB technique
p q
23 patients with acute toxicity scored using
CTCAE v3.0
Dose to Rectal Wall and Bladder Wall
Acute GI/GU toxicity
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27. Result
Mean PTV V95 = 95.2% (SD = 2.1)
( )
20
18
16
14
Number 12
of 10
Patients 8
6
4
2
0
90 92 94 96 98 100
PTV V95 (%)
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28. Result
64.0
Patient A
62.0
60.0
PTV D99
58.0
(Gy)
56.0
54.0
2
R = 0.8514
Patient B 52.0
90.0 92.0 94.0 96.0 98.0 100.0
PTV V95 (%)
Mean PTV D99 = 57.8 Gy (
y (Range: 53.4 – 62.9 Gy)
g y)
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29. Result
Patient A Patient B
62.7 Gy
55.0 Gy
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30. Result
Acute GI Toxicity
y
Score Diarrhea Proctitis GI
0 19 (38%) 17 (34%) 10 (20%)
1 25 (50%) 23 (46%) 27 (54%)
2 6 (12%) 13 (20%) 13 (26%)
3 0 0 0
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31. Result
Acute GI Toxicity
y
Score Diarrhea Proctitis GI
0 19 (38%) 17 (34%) 10 (20%)
1 25 (50%) 23 (46%) 27 (54%)
2 6 (12%) 13 (20%) 13 (26%)
3 0 0 0
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32. Result
Acute GU Toxicity
y
Score Frequency Haematuria Cystitis Spasms GU
0 19 (38%) 45 (90%) 39 (78%) 27 (54%) 14 (28%)
1 24 (48%) 5 (10%) 10 (20%) 20 (40%) 28 (56%)
2 5 (10%) 0 1 (2%) 3 (6%) 6 (12%)
3 2 (4%) 0 0 0 2 (4%)
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33. Result
Acute GU Toxicity
y
Score Frequency Haematuria Cystitis Spasms GU
0 19 (38%) 45 (90%) 39 (78%) 27 (54%) 14 (28%)
1 24 (48%) 5 (10%) 10 (20%) 20 (40%) 28 (56%)
2 5 (10%) 0 1 (2%) 3 (6%) 6 (12%)
3 2 (4%) 0 0 0 2 (4%)
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34. Result
Comparison of Dose to Rectal Wall
p
100
4FB
IMRT
80
Normalized 60
Volume
(%) 40
20
0
0 1000 2000 3000 4000 5000 6000 7000
Dose (cGy)
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35. Result
Comparison of Dose to Bladder Wall
p
100
4FB
IMRT
80
Normalized 60
Volume
(%) 40
20
0
0 1000 2000 3000 4000 5000 6000 7000
Dose (Gy)
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36. Result
Comparison of Acute GI/GU Toxicity Score ≥ 2
p y
50 IMRT
4FB
40
Number 30
of
Patient
20
(%)
10
0
GI GU
G and
GI a d GU C Square value = 5
Chi Squa e a ue 5.21 & 9 , d = 1, p < 0 05
9.77, df , 0.05
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37. Conclusion
Avoidance of circumferential irradiation of rectum
to 55Gy with minimal compromise of PTV coverage
is achievable with IMRT
The use of IMRT reduces acute GI/GU toxicity rate
when compared with the 4FB technique
Ongoing investigation to determine if improved
dosimetry to OARs translates to improved late
toxicity and biochemical control
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38. Acknowledgment
Dr. Kirsty Wiltshire
y
Dr. William Chu
Clinical Trial Co ordinators
Co-ordinators
Debbie Tsuji
Bernadeth Lao
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