Treatment Verification with Cherenkov Imaging

Brian W Pogue PhD MacLean Professor of Engineering, Dartmouth

Editor-in-Chief, Journal of Biomedical Optics

Dose imaging?Beam Tracking Cherenkov emission from eye

Disclosures

DoseOptics LLC: President and co-founder

Developing Cherenkov imaging cameras software and systems.

LINAC Radiation Dose produces pulses with Cherenkov light

Characteristic spectrum

Cherenkov in tissue

oxygenated De-oxygenated

Cherenkovemission

Tissue phantom 1% blood +

1% Intralipid

Axelsson et al, Med. Phys. 2010Zhang et al, Med. Phys. 2012

Cherenkov spectroscopy

Linac

(Cherenkov)

pulses

Cherenkov frame

Background frame

TimeC

am

era

ga

tin

g

Ambient room light

Time-gated Intensified Camera System

Time-gatedImage

Intensifier

CMOSCamera

FPGABoard

USB3 in/out

DISCLOSURE: B. Pogue is founder & president of DoseOptics.

Single photon imagingwith room lights on!

Petr Bruza Mike JermynVenkat Krishnaswamy Bill Ware Cedar Farwell

Linac

(Cherenkov)

pulses

Cherenkov frameBackground frame

Time

Ca

me

ra

ga

tin

g

Relay lens

FarzeenChristie

Cameras installed in all Dartmouth Linac Rooms

AdditionalUser sites:DartmouthU PennWash UEmoryHarvard/MGH

Verification of

beam positionon the

patient

Cherenkov is a direct display of surface dose

Miao et al, Med. Phys. 2019

Light Field Cherenkov FILM

CherenkovFILM

Cherenkov

Confidential DoseOptics LLC

Live Cherenkov Cumulative Cherenkov

Planned Treatment Area Planned Cumulative Surface Dose

Whole breast radiotherapy verification

Incidents observed with Cherenkov images

Day 1

1050

‘arm down’ treatments on different days

Jarvis et al, IJROBP (in review 2020)

Day 2

Day 3 Day 4

R Hachadorian, et al,

Session:Multi-Disciplinary ePoster

Poster #: PO-GeP-M-194

Contralateralbreast

Contralateralbreast

shoulder

Incidents observed with Cherenkov images

Day 1

104 105

Day 2

Neck involvementBolus placement differences

Jarvis et al, IJROBP (in review 2020)

R Hachadorian, et al,

Session:Multi-Disciplinary ePoster

Poster #: PO-GeP-M-194

11/10

Match line views from Cherenkov on skin

Hachadorian et al, submitted 2020

R Hachadorian, et al

Session Title: Multi-Disciplinary ePoster

Poster #: PO-GeP-M-75

Supraclavicular field Tangent field

Match region

Head and Neck Tumor Treatments

Planned dose

Imaged signal

Real time view of treatment

Treatment Plan

Dan Alexander

Cherenkov ≈ Surface Dose ?

X-ray dose builds up & Cherenkov is emitted

(b) (c)

Build up is always linear over the first 8 mm!!

𝜑𝑅 𝑧 = 𝑆(𝑧)3𝜇𝑠

/

𝜇𝑎𝑒−𝜇𝑒𝑓𝑓𝑧 S(z) = S0 (k1 + k2z)

𝜑𝐶ℎ 𝑧 =𝑆0 𝑘1

𝐷𝜇𝑒𝑓𝑓𝑒−𝜇𝑒𝑓𝑓𝑧 −

𝑆0 𝑘2

2𝐷𝜇𝑒𝑓𝑓2 (𝑒

−𝜇𝑒𝑓𝑓𝑧 − 𝑒𝜇𝑒𝑓𝑓𝑧)

Pogue et al, Proc SPIE BiOS 2020

Signal is dependent upon:• Build up rate with depth• Absorption coefficient (≈blood volume)

Cherenkov emission is decreases with CT number!

Higher CT number ≈ higher blood vol(blood attenuates light)

IC(E) = c(CT,E) ∙ IR(E)

Blue Ribbon ePoster

Poster Number: BReP-SNAP-M-87

I. Tendler et al, IJROBP 2020YOUNG INVESTIGATOR SYMPOSIUM

Session: MO-CD-TRACK 1-2

AutomatedNon-contact

Dose readout

back delivery

Stanford Technique

front delivery

T Miao & T. Zhu

Blue Ribbon ePoster

BReP-SNAP-M-141

Prof Tim Zhu UPenn

Cumulative Dose-Rate Histogram

XY

Z

Scre

en

Spot Scanning

Radioluminescence Imaging of Proton Beam DoseDose Rate Dynamics Volumetric LET and Dose Patient Plan Imaging

Op

tic

al

Relative Dose

70 MeV 150 MeV100 MeV

M Rahman: Therapy General

ePoster PO-GeP-T-388

Summary of observations:

• Cherenkov imaging allows real time view of delivery & incidentsneck, shoulder, contralateral, bolus, plan incidents

• Quantitative dose imaging with CT and optical corrections

• Match lines can be visualized at adjacent fields

• Absolute dose point values obtained with scintillator imaging

• Total skin electron therapy mapping is possible

• Small beam dosimetry

• Proton beam dosimetry via scintillation