A project of mine.
HDR motion study
• Background– Hollow plastic catheters implanted through the skin into the prostate
– Implant locked together and stitched to the patient’s skin
– A tiny radioactive source moved through the catheters in the prostate and treats it from the inside
– Very tightly defined dose distribution
– Called brachytherapy and is a very successful treatment
– Patients lie in hospital and get 2 treatments over 2 days
Next slide not for the squeamish!
HDR Motion study • Collection of catheters into prostate• The template is being stitched to the skin
HDR Motion study
• Problem– The catheters tend to move out of the patient
• Question– Is this due to movement of the patient while in bed in hospital, or is it
due to swelling?
The Project
• To get a measure of patient movement while in bed
• Uses electronic inclinometers to measure angles of legs and torso
• Based on solid state accelerometer
• Now cheaply available since used in laptops to detect motion
• If acceleration detected HDD suspends operation
Inclinometer
• Device measures ‘static acceleration’ due to gravity
• Can easily calculate angle to vertical
z
yaTan
g
z
y
Analysis
• Angle of leg to vertical can be calculated
• Use with sensor on abdomen to find hip flexion
Leg Angle (rel horizontal)
0
20
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60
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120
0 5 10 15 20 25 30 35 40 45
Time (s)
An
gle
(d
egre
es)
•Search for correlation between hip flexion/extension angles and implant movement.
Results
• No relationship between patient movement and implant displacement.
• In publication
Spares
• Following slides just junk for recycling
• An opportunity to review restrictions on patient movement
• May reinforce/reduce need to for patients to lie still
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Prevalence Vs Incidence
• Autopsy results
• Patients did not die from the cancer.
Waveguide cont
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