ESTRO38

Poster

presented at:

Comparison of pancreatic respiratory motion using three abdominal corsets for particle therapy

S. Schneider1,2,†, K. Dolde3,4,5,†, M. Alimusaj6, B. Fluegel6, N. Saito7, A. Hoffmann1,2,8, A. Pfaffenberger3,4

†Both authors contributed equally:

Sergej Schneider, MSc

OncoRay – National Center for Radiation Research

in Oncology

MRI-based Radiation Therapy Planning Group

sergej.schneider@oncoray.de | +49 (0)351 458-6538

1Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology - OncoRay, Dresden, Germany. 2OncoRay - National Center for Radiation Research in Oncology, Dresden, Germany. 3German Cancer

Research Center (DKFZ), Medical Physics in Radiation Oncology, Heidelberg, Germany. 4National Center for Radiation Research in Oncology, Heidelberg Institute for Radiooncology, Heidelberg, Germany. 5Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany. 6Center for Orthopedic and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany. 7Department of

Radiation Oncology, University Clinic Heidelberg, Heidelberg University, Heidelberg, Germany. 8Department of Radiation Oncology, University Hospital Carl Gustav Carus at the TU Dresden, Dresden, Germany

Motivation Results

Conclusion

Kai Dolde, MSc

German Cancer Research Center (DKFZ)

Medical Physics in Radiation Oncology

k.dolde@dkfz-heidelberg.de | +49 6221 423486

Material & Methods

Abdominal compression (AC) is commonly applied in

radiotherapy (RT) of abdominal tumours to reduce

respiratory tumour motion. In proton therapy (PT) of

pancreatic cancer AC is often impeded by interference of

the beam with the AC equipment, causing uncertainty in

dose application. The aim of this study was to evaluate the

effectiveness of three different abdominal corsets

regarding their reduction of respiratory induced organ

motion and to test their applicability in PT.

• 4D MRI (1.5T) of volunteer in free breathing and in three corsets

on two consecutive days for pancreas motion assessment

• CT scans of corsets for material homogeneity (standard

deviation of CT values) and thickness constancy analysis

• Water equivalent ratio (WER) of corset samples for

assessment of impact on proton therapy

Figure 2: Healthy volunteer with three tested abdominal corsets (patient specific

polyurethane (PU) corset, semi-specific polyethylene (PE) corset, patient specific 3D

surface scan based polyethylene (3DPE) corset) in treatment position at a 1.5T MR

scanner.

• Three abdominal corsets tested for potential use in PT

Patient specific

polyurethane

(PU) corset

moulded on patient

where material

hardens after mixing

its two components

Semi-specific

polyethylene (PE)

corset available in

different generic sizes

of breast, hip, waist

and lordosis angle

Patient specific 3D

surface scan based

polyethylene

(3DPE) corset

thermo-formed on

a wooden replicate

of the body

• PE & 3DPE have a WER similar to water, PU has a reduced WER

• PE & 3DPE corsets show a constant thickness and

homogenous material composition

• PU corset shows large thickness variance and air inclusions

of different sizes with mean size of 12.9 mm³

Figure 4: (left) Exhale phase of 4D MRI with 3D segmented pancreas (yellow) in

end-expiration. (right) Measured pancreas center-of-mass motion in inferior-

posterior- (IS), anterior-posterior- (AP), and left-tight (LR) direction in free

breathing and wearing the respective corset.

Material properties

Figure 5: (left) Coronal reconstruction of CT showing posterior part of PU

corset with inhomogeneous distribution of air inclusions of different sizes.

(right) Histogram showing amount and sizes of air inclusions in PU corset.

All three abdominal corsets reduced the respiratory pancreas

motion to a similar amount, mainly in inferior-superior (IS)

direction from 12.5 mm to 3.5 ‒ 5.6 mm and in anterior-posterior

(AP) direction from 1.6 mm to 0.2 ‒ 0.4 mm

Corset WER Thickness [mm] Homogeneity [HU]

PU 0.298 ± 0.001 [4.2 ─ 27.7] -677 ± 113

PE 0.956 ± 0.002 [2.8 ± 0.2] -130 ± 31

3DPE 0.990 ± 0.003 [3.8 ± 0.2] -107 ± 32

Pancreas motion

Respiratory motion is reduced by all three abdominal

corsets to a comparable amount, primarily in IS direction.

Material analysis revealed a possible implementation for

proton therapy only for the tested PE corsets.

3DPE corset is currently been tested in a clinical study

for proton therapy of pancreatic and liver patients.

Figure 1: Coronal cine MRI of upper abdomen in end exhale and end inhale

showing a substantial amount of respiratory organ motion (diaphragm motion

of 2.2 cm in inferior-superior (IS) direction).

2.2 cm

EP-1971Sergej Schneider DOI: 10.3252/pso.eu.ESTRO38.2019

Physics track: Intra-fraction motion management