Radiation Treatment Planning
Ali Fatemi PhD, MCCPM, ABMP (MRI)
Chief Physicist, Department of Radiology Director of MR guided Radiotherapy Lab
Assistant Professor, Departments of Radiation oncology and Radiology
February 26, 2017 Nuclear Medicine conference
Radiation can kill cells
“ Tumor control depends on preventing continued proliferation of clonogenic cells “ ICRP 103
Q) What is the relationship between the fraction of cells retaining their reproductive integrity and absorbed dose
a/Ɓ indication of Early and Late effects
Early effects: radiation response days to weeks after irradiation. (Tumor cells)
- Erythema, desquamation, dry skin, mucositis, hair loss, pneumonitis, diarrhoea, proctitis.
Late effects: response months to years after irradiation.
– Necrosis, fibrosis, stenosis, inflammation, telangiectasia,
blindness, myelopathy, sterility, cataracts, atrophy. (Most of Normal tissues)
LET and RBE
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Hyper and Hypofractionation
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[Text Box: Radiation Treatment Planning ]
Introduction: Dose Calculation
Factors (f;) that modify the dose rate
General components depend on machine & patient e g
coll1ma:or scatter 1ROF
al1aS s_ phOtOn 0Utp;.;:I
Pat,er: or phantom scaer RDF a:1as S phc<:ofl outpu! 1
Linked wrth emp1rrcal systems of calculation
Phantom Ra: o
fax 1mum Ra:10
Treatment distance (ISL)
Off Axis Distance
Pat1M t CMtOur Air Gai:i Tissue heterogeneities
[Text Box: Y90 Brachytherapy Radiation Treatment Planning ]
Decay product of strontium-90 or prod neutron bombardment of Yttrium-89
Tissue penetration range mean 2.5, max 11mm
67 day half life (==64 hours)
Shelf life of the device is 24 hours
How Do We Do It?
• Calculate therapy dose
Volumes of liver and tumor
Which lobe or segment and if spl t dose
Dictate NM planning note
Emailinformation to attendings of day
Written directive signed by AU
MAA Shunt Study
We prefer using more "objective" approach. Deconstruct to understand what we need.
action of enti
I s used would just thenmultiply by that lobar
f er (e.g. rightlobe,60%).
Actually employ a more advanced variant which requires right and left lobe tumor
and liver volumes to be known
[Text Box: Lobar dose in GBq =]
[(BSA - 0.2) + (% tumorinvolvement of lobe
to be treated/100)] X [percent of total liver
that treated lobe comprises]
Then apply various .