IROC Houston QA Center end-to-end

QA phantom program key findings over

the past 15 years

David Followill, Ph.D.

AAPM 2017 Summer Meeting

Denver, CO

July 30, 2017

Extent of Activities

• 1,837 RT facilities

participate in NCTN and

monitored by IROC

Houston

• 329 other sites (primarily

international also audited

• 56 countries monitoring a

total of 2166 sites

• Largest QA audit program

• Shipping >700 phantoms/yr

Imaging, Planning and Delivery - QA required at each step

Positioning

and

Immobilization

Image

Acquisition

(CT, MR)

Structure

Segmentation

treatment

planning

File

transfer and

management

Plan

validation

Position

verification

treatment

delivery

Black Box

Thus the need for an end-to-end

QA audit tool to verify the

intended treatment goal.

Deliver the correct dose

to correct location

as planned

Phantom Family

2 prostate phantoms

19 SRS phantoms

33 lung phantoms

8 Spine

phantoms 10 liver inserts24 H&N

phantoms

• Anthropomorphic shape with targets and OARs

• Independent “end to end” audit

• Imaging• Planning/dose calculation• Setup• delivery

• Uniform phantoms and dosimeters

• Standardized analysis

• Uniform pass/fail criteria

• Allows inst. to inst. comparison

• Established infrastructure

Benefits of IROC-H PhantomsPhantom Patient

PhantomPatient

Photon Phantom Results

Phantom H&NLiver

insertLung Prostate Spine

Irradiations 2052 165 1109 566 336

Pass 1755 (86%) 120 (73%) 921 (83%) 484 (86%) 261 (78%)

Fail 297 45 188 82 75

Criteria 7%/4mm 7%/4mm 5%/5mm 7%/4mm 5%/3mm

Comparison between institution’s plan and delivered dose.

Problems that have been

detected

0 10 20 30 40 50 60 70 80 90520

540

560

580

600

620

640

660

680

700

Distance along line

Do

se V

alu

e

Calc

Meas

Criteria: 3%/2 mm

Varian 6 MV IMRT H&N

PAxial

9

0 10 20 30 40 50 60 70 80 90520

540

560

580

600

620

640

660

680

700

Distance along line

Do

se V

alu

e

Calc

Meas

Measurement vs. Monte Carlo

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2.0

LATERAL

L

R L

Lung Phantom TLD results

TLD results

Irradiation Lung Phantom

0.90

0.92

0.94

0.96

0.98

1.00

1.02

1.04

1.06

1.08

1.10

0 50 100 150 200 250

Irradiation

RP

C/I

nst

Average = 0.967 +/- 2.9%

274 irradiations

Algorithms included:

AAA/Superposition/MonteCarlo

Lung Phantom TLD resultsTLD results

Irradiation Lung Phantom

0.90

0.92

0.94

0.96

0.98

1.00

1.02

1.04

1.06

1.08

1.10

0 50 100 150 200 250

Irradiation

RP

C/I

nst

Average = 0.967 +/- 2.9%

274 irradiations

Algorithms included:

AAA/Superposition/MonteCarloAverage = 0.994 +/- 3.3%

30 irradiations

Algorithms included: MonteCarlo

Lung Phantom ResultsPercent of pixels passing 5%/3mm gamma criteria

9690

50

86

52

85

94

31

61

0

20

40

60

80

100

Pin

nac

le S

C

Ecl

ipse

AAA

Ecl

ipse

PB

XiO

SC

XiO

Cla

rkso

n

TomoThera

py SC

Multi

Pla

n MC

Multi

Pla

n PB

Corv

us PB

Pe

rce

nt

of

pix

els

pa

ss

ing

±5

%/3

mm

cri

teri

a

Proton Phantom Audits

• 136 proton phantoms irradiated, analyzed

Brain Liver Lung Prostate Spine TOTAL

Total Irradiations 25 14 38 38 21 136

# Passed 24 7 24 30 17 102

Pass Rate [%] 96% 50% 63% 79% 81% 75%

Lung Phantom Results

Lung Phantom Results

Lung Phantom Results

Summary

• Introduction of new technologies present challenges that need to be verified prior to treating patients

• End-to-end QA phantoms detect errors, improve dose delivery accuracy and provide confidence

• Improved compliance with protocol prescription specifications and reduced deviation rate

Questions?