the real time image guided hdr brachytherapy for prostate
TRANSCRIPT
The Real Time Image Guided HDR Brachytherapy for Prostate Cancer.
Treatment Planning
Bashar Al-Qaisieh
Treatment Planning Objectives:
Delivery of prescription dose to target volume and minimise dose to nearby
normal tissues
Prostate HDR Treatment Planning Involves:
• Pre-treatment QA:- equipment functionality and connectivity
• Patient setup:- measurement of US probe and template position with respect to patient
• Needle Insertion:- optimal position
• Contouring:- position of applicators with respect to PTV and OAR
• Dosimetry Planning:- needle reconstruction- source activation- optimisation
Patient Setup
• Position of the US probe in the stepper unit
• Position of template with respect to the US probe
• Position of anatomy with respect to the template and US probe
“Virtual” Contouring
• Option 1:- Contour Prostate, Urethra, Rectum
- Utilise to produce a “virtual” plan- Utilise at later stages after needle insertion
• Option 2:- Calculate volume estimate from H,W,L measurement (SJIO)
“Virtual” Contouring- Option 2HWL Volume Estimate
0
10
20
30
40
50
15 20 25 30 35 40 45
Virtual height (mm)
Live
hei
ght (
mm
)
0
10
20
30
40
50
60
70
25 30 35 40 45 50 55
Virtual width (mm)Li
ve w
idth
(m
m)
Regression line
Recorded live width
95%
90%
85%
80%
0
10
20
30
40
50
60
70
80
20 25 30 35 40 45 50 55 60
Virtual length (mm)
Live
len
gth
(mm
)
Regression line
Recorded live length
95%
90%
85%
80%
“Virtual” Needle Insertion
• Option 1:- Forward
- Manual and Geometric- SJIO
• Option 2:- Inverse
- HIPO
“Virtual” Needle Insertion-Option 1:Forward SJIO
• Reference transverse plane for peripheral needles
• Base and Apex for middle needles
“Virtual” Needle Insertion-Option 1:Forward SJIO
• All needles inserted to same depth of at least 1.0cm beyond the base to account for needle dead end for metal needle 1 cm
“Live” Image Capture
• All needles pushed to at least 1.0 cm deep from the base.
• Needles Locked to the template.
• Take final base measurement
“Live” Needle Tip Tracking
• All needle tips are updated at the same depth (base). Convert needles from “V” to “L”
“Live” Contouring Guidance
• Update “Virtual”contours to match “Live” image set
• Prostate dimension pre needle insertion
• Record of needle position with respect to the prostate as a surrogate
Planning Aims and Optimisation Options
• Prostate:– 15Gy=100% isodose– V100%>95%– V150%<45%– V200%<15%– D90>100%
• PTV:– V100%>95%
• Rectum:– D2cc<11.8Gy– V100%=0.0cc
• Urethra:– D10%<17.5Gy– D0.1cc<17.5Gy
Morton et al 2009, GEC-ESTRO 2013
TG 43 Dose Calculation
0.5 1.0 1.5 2.0 2.5 3.00123456789
10
r
Dep
th D
ose
Distance (cm)
Good Job…well done!!!
• Oncologist check• Approve plan• Print and transfer to treatment machine• Handover to physics to independent check• Handover to radiographers• Have a cup of coffee!!
Timing According to Individual Planners
Planner (no cases) Time from probe in to patient
treated Needle
insertion Needle
reconstruction Planning
A (4) 02:22 00:24 00:14 00:10
B (4) 02:54 00:28 00:29 00:13
C (2) 02:54 00:38 00:16 00:24
D (7) 02:53 00:25 00:16 00:15
E (3) 02:52 00:36 00:21 00:14
Data from 20 implants- 2012
