Application of 3D printed surface mould

for skin cancer brachytherapy

Adam Yeo (PhD), Kurian George and Tomas Kron (PhD)

Senior Medical Physicist

Peter MacCallum Centre Centre

• No conflict of interest

(I’ll show a couple of commercial slices as examples)

Disclaimer

• Additive manufacturing, often referred to as 3D printing, has become an important tool for RT

• What can we do with this tech?

Background – 3D printing

• PeterMac uses it routinely as bolus for breast and HnN cases

better fitted & little airgap

• Clinically driven need for brachytherapy application

e.g. skin cancer with largely curved or circumferential lesions,

Background – 3D printing

• It’s listed in Cancer Council Australia guidelines as a tx option for NMSC

Review of surface mould BT: not new!

Summary of article Articles Study in Canada looking at patterns of practice, which showed that not many centres do it. Only 7 out of the 39 centres. Large variation on dose and fractionation.

“Surface mould brachytherapy for nonmelanoma skin cancer: Canadian patterns of practice.”

Rose JN, McLaughlin PY, Hanna TP, D'Souza D, Sur R, Falkson CB.

Pract Radiat Oncol. 2014 Nov-Dec;4(6):398-403. doi: 10.1016/j.prro.2013.12.003. Epub2014 Jan 30.

• It’s listed in Cancer Council Australia guidelines as a tx option for NMSC

Review of surface mould BT: not new!

Summary of article Articles There are a lot of studies looking at using surface mould brachy for NMSC (ie intra-oral & skin in H&N; ear nose)

“Clinical outcomes with high-dose-rate surface mould brachytherapy for intra-oral and skin malignancies involving head and neck region.”Budrukkar A, et al. J Contemp Brachytherapy. 2017 Jun;9(3):242-250.

“Highly conformal CT based surface mould brachytherapy for non-melanoma skin cancers of earlobe and nose.”Kuncman Ł, et al . Contemp Brachytherapy. 2016 Jun;8(3):195-200.

• Surface mould brachytherapy for melanoma

Review of surface mould BT: not new!

Summary of article Articles Small study from NZ (n=6 ) showing good response rates for patients with cutaneous melanoma mets using SMBT. All had CMR. No infield recurrence at 23 months

“Treatment of regional cutaneous nodular metastases from melanoma using high-dose rate mould brachytherapy.”

Chaudhuri A, et al. J Med Imaging RadiatOncol. 2011 Apr;55(2):206-12.

• Feasibility and clinical application of 3D printing for SMBT

Review of surface mould BT: not new!

Summary of article Articles A study looking at the use of 3D printed superficial applicators for HDR skin brachy at Guy's and St Thomas.

“Introduction of novel 3D-printed superficial applicators for high-dose-rate skin brachytherapy.”Jones et al. Brachytherapy, March-April 2017, Vol.16(2), pp.409-414

*No other article detailing the clinical use of 3D printing in this setting

• Feasibility and clinical application of 3D printing for SMBT

Review of surface mould BT: not new!

Summary of article Articles Physics study from Brisbane showing that it is feasible

“A feasibility study for using ABS plastic and a low-cost 3D printer for patient-specific brachytherapy mould design.”

Harris BD, Nilsson S, Poole CM.Australas Phys Eng Sci Med. 2015 Sep;38(3):399-412.

• Financial incentive for 3D printing the surface moulds

Review of surface mould BT: not new!

Summary of article Articles Study suggests its cheaper and quicker to use 3D printer

“Individualized 3D scanning and printing for non-melanoma skin cancer brachytherapy: a financial study for its integration into clinical workflow.”

Arenas M, et al J Contemp Brachytherapy. 2017 Jun;9(3):270-276.

• Is the 3D-ink water-equivalent? e.g. PLA: (C3H4O2)n

• Is it accurately printed? Can we 3D-print catheter channels?

• Shielding requirement?

• Need to fine-tune printing parameters: Filling, temperature, smoothing, nozzle size, shell thickness

• Need 3D-contouring tool (2D brush vs. 3D brush) Contour-3Dprint conversion ratio (at least 1.5)

What to consider?

3D ink

3D ink (too many options!)

Can we trust 3D-printed mould?

• Is 3D-printed mould fit into the original contour?

• Can we print catheter channels? (equidistant from skin along curvature)

Software:

MIM3Dslicer

MeshimixerSimlify3D

CreateBox Dx

Test plan for measurements

• Need to be homogeneous

Film measurements:

i) Calib depth points

ii) PDD (3Dprint vs water)

10 Gy7 Gy5 Gy3 Gy

Px 10 Gy to 1cm depth

• Need Soft-beam equivalent PW

From IORT plan

EBT3 Film calibration

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60

Dose

(Gy)

Depth (mm)

Calib pointsWater

PDD with line source plan(error bar ± 1mm in lateral direction) Calib points Dose in Gy

Depth in mm (+1)

Calibdose

Dose±1mm %diff

2 52.9 46 6.93 34.9 33.3 1.65 21 20.5 0.5

10 10 10.7 -0.720 4.5 4.52 -0.0230 2.64 2.64 040 1.74 1.74 050 1.22 1.22 0

3D print0.5 cm

0.5 cm

1.0 cm

1.0 cm

PLA plastic (C3H4O2)n attenuation

3Dprint vs Water

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60

Dose

(Gy)

Depth (mm)

Calib points

Water

3Dprint_5mm

3Dprint_15mm

PDD with line source plan(error bar ± 1mm in lateral direction)

1

10

100

0 10 20 30

Proposed workflow

CT sim CT 3D-mould

Data convertin 3Dslicer

Contouring in MIMVol marking

Setup(Position?)Plan Pre-tx QA TreatmentHU/densityRegistrationCatheter

check

QA

Non-invasive No cath insertion No patient transfer butNeed to consider shielding requirement

3D print

• Coming next meeting… Planning study VMAT vs SMBT

• And more to come!

More exciting slices; still work in progress…

Thank you

Any questions (discussion)?