Initial Results from Multiple Irradiations of an Anthropomorphic Spine Phantom

Andrea Molineu, Nadia Hernandez, Paola Alvarez, David Followill, Geoffrey Ibbott

lung

lung

heart

Spine phantom

PTV

bonespinal cord

esophagus

Treatment Plan• 6 Gy to at least 90% of PTV

• Min PTV dose at least 5.25 Gy

2.781000 ccWhole Lung

9.758.63<10 ccSkin

6.004.46<5 ccEsophagus

8.256.00<15 ccHeart

5.253.752.63

<0.35 cc<1.2 ccSpinal Cord

Max Point Dose (Gy)

Volume Max (Gy)

VolumeNormal structure

Representative Treatment Plan

Criteria

• TLD±7%

• Film (axial and sagittal planes)85% meet 5%/3mm

• Plan DVHmust comply with protocol

Good Agreement

PlanMeasurement

PTV

Cord/boneOAR

Good Agreement

Gamma

Measurement100%

passing

Poor AgreementPTV

Cord/boneOAR

Measurement Plan

Poor Agreement

Gamma

Measurement100%

passing26%

passing

Overall results

• 41 irradiations at 35 institutions

• 17 irradiations failed

• 1 failed TLD criteria only

• 8 failed gamma criteria only

• 8 failed both TLD and gamma

All Results

42 - 9922 - 1000.67 - 1.510.88 - 1.15range

14.616.40.170.05std dev

86851.020.99mean

Sagittal Gamma

Axial GammaHeartPTV

Passing Results

85 - 9985 - 1000.67 - 1.180.93 - 1.03range

5.14.60.120.03std dev

94941.020.99mean

Sagittal Gamma

Axial GammaHeartPTV

Results by Machine

8812441total

230813Varian

01012TomoTherapy

01012Siemens

2101013Novalis

22026Elekta

20125CyberKnife

Dose and GammaGammaTLD Dose

Criteria FailedPassesIrradiationsMachine Manufacturer

Results by TPS

8812441total

11013superpositionXiO

11035convolutionPinnacle

10078pencil beam

11024Monte CarloiPlan

01012superpositionHi-Art

10012pencil beam

140712AAAEclipse

20114raytracing

00011Monte CarloCyberKnife

Dose and GammaGammaTLD

Dose

Criteria FailedPassesIrradiationsAlgorithmTPS

Results by Algorithm

8812441total

20114raytracing

200810pencil beam

11035Monte Carlo

230510superposition/convolution

140712AAA

Dose and GammaGammaDose

Criteria FailedPassesIrradiationsAlgorithm

Conclusions

•Challenging credentialing process

•Treatment couch should be considered in these treatments

•Cannot make generalizations with regard to machine, TPS, or algorithm

Thank you.

The investigation was supported by PHS grants CA10953 and CA81647

awarded by the NCI, DHHS.