Radiation Therapy Treatment System

Overview: From Source to Patient

Jacob (Jake) Van DykProfessor Emeritus

Western University, London, Ontario, Canadaand

Past-President, MPWB

Accelerating the Future:Designing a Robust and Affordable Radiation Therapy Treatment System for Challenging Environments

Linac with IMRT & IGRT

kV x-ray source forCone-Beam CT (CBCT)Flat panel kV

x-ray detectorfor CBCT

Flat panel MV x-ray detectorElectronic Portal Imaging

Device (EPID)

MLC

AcceleratorTomoTherapyHelical “slice”

delivery & helical CT

2003

Varian HalcyonCone-beam delivery

(VMAT) &cone-beam CT

2017

Schematic: From Source to PatientElectron Beams

ConventionalPhoton Beams

Flattening Filter Free (FFF) Machine

Ma et al, Med. Phys. 46 (1), January 2019

x2

FFF

Monitor Ionization Chamber

http://www.uthgsbsmedphys.org/GS02-0113/Section1/Accelerator%202.pdf

IAEA slides

Controls:- Total dose- Flatness

- Symmetry

Multileaf Collimator

Huq et al, PMB 47: N159–N170; 2002

Varian

Elekta

TomoTherapy

Shielding Blocks

X XShielding tray _________

Courtesy TR Mackie

Accelerator

MagnetronCT Detectors

Binary MLC

PFN

HV PS

Control computer

Beam stop

ImageGuidanceTomoTherapy

Tomotherapy MV CT Image Guidance

9

Patient/

Beam

Shifts

MVCT

kVCT

Manual alignment or grey scale alignment with mutual information

algorithm

Nasopharynx … TomoTherapy

Dose Rate Cumulative Dose

… results similar to VMAT

Summary• Treatment system: source to patient

• Multiple designs

• Conventional … photons & electrons• IMRT, VMAT with photons

• Rotational slice imaging & treatment• Tomotherapy

• Rotational cone beam imaging, VMAT delivery• Halcyon