NUCLEAR MEDICINE

MISSISSIPPI


SOCIETY of

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

 

 

 

 

 

Radiobiology

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

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)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 


 

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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

T1ssue·A

 

T1ssue -

Tissue -

 

Phantom Ra: o

 

 

1r Ratio

fax 1mum Ra:10


 

Treatment distance (ISL)

Treatment Depth

Fre

id srze

 

Off Axis Distance

Fr

 

lters

 

blocks.·MLC

 

\'edges

Compensa o

Trays

 

 

 

'•

rs

 

Pat1M t CMtOur   Air Gai:i Tissue heterogeneities


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Text Box: Y90 Brachytherapy Radiation Treatment Planning ]


 

 

 

 

 

 

Yttrium-90

Decay product of strontium-90 or prod neutron bombardment of Yttrium-89

 

ced by

 

 

 

u

 

 

 

Tissue penetration range mean 2.5, max 11mm

 

67 day half life (==64 hours)

 

 

Shelf life of the device is 24 hours

 

 

 

2.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

How Do We Do It?

 

• Calculate therapy dose

Volumes of liver and tumor

Which lobe or segment and if spl t dose

Lung shunt

Labs (LFTs)

 

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.

 

SIR-Spheres calculation:

 

                                                                                   

 

oba

r th

erap

yI

 

action of enti

re liv

 

 

f l

r

 

 

 

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]

 

 

corr

ecti

on fact

ors

 

 

Then apply various                            .