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The dose accumulation and the impact of deformable image registration on dose reporting parameters in a moving patient undergoing proton radiotherapy

Gasper Razdevsek
Gasper Razdevsek
, 
Urban Simoncic
Urban Simoncic
, 
Luka Snoj
Luka Snoj
 et 
Andrej Studen
Andrej Studen
   | 17 mai 2022
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Article Category: Research Article
Publié en ligne: 17 mai 2022
Pages: 248 - 258
Reçu: 11 avr. 2021
Accepté: 18 févr. 2022
DOI: https://doi.org/10.2478/raon-2022-0016
© 2022 Gasper Razdevsek, Urban Simoncic, Luka Snoj, Andrej Studen, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

A coronal view of the deformable image transformation deformation field of moving exhale phase with respect to the reference deep inspiration breath-hold (DIBH) phase. Size and direction of the local motion is indicated by the arrows with the colour/whiteness of the arrow indicating the size of the translation.
A coronal view of the deformable image transformation deformation field of moving exhale phase with respect to the reference deep inspiration breath-hold (DIBH) phase. Size and direction of the local motion is indicated by the arrows with the colour/whiteness of the arrow indicating the size of the translation.

Figure 2

Scatter plots of the annotated landmarks with respect to the residual shift between expiration and inspiration positions on y-axis and location of landmark along the inferior-superior direction on the x-axis. A total of twelve panes indicate residual extent in the left-right direction (first column), anterior-posterior direction (second column) and inferior-superior direction (third column). The top row shows differences in landmark locations without registration, following rows correspond to (S) Staring deformable image registration (DIR), (G) Guy DIR and (M) Mattes DIR algorithms. Indicated numbers correspond to Pearson’s r coefficient calculated for the shown distribution.
Scatter plots of the annotated landmarks with respect to the residual shift between expiration and inspiration positions on y-axis and location of landmark along the inferior-superior direction on the x-axis. A total of twelve panes indicate residual extent in the left-right direction (first column), anterior-posterior direction (second column) and inferior-superior direction (third column). The top row shows differences in landmark locations without registration, following rows correspond to (S) Staring deformable image registration (DIR), (G) Guy DIR and (M) Mattes DIR algorithms. Indicated numbers correspond to Pearson’s r coefficient calculated for the shown distribution.

Figure 3

A sagittal view of the pair of the 4D CT image corresponding to the extreme breathing frames, left: deep inspiration breath-hold (DIBH) reference geometry, T00, right: exhale off-reference geometry, T50. A tumour delineated in Non-Small Cell Lung Cancer (NSCLC) Radiomics study, case R005, was artificially added into the lung. Dose delivered according to beamlet set that was optimized for irradiation in the reference frame is superimposed with colour scale/grey scale corresponding to the accumulated dose where bright colours/white corresponds to a higher accumulated dose. A slight relative upward motion of tumour in T50 geometry causes the right pane dose distribution to deviate from the planned distribution illustrated in the left pane.
A sagittal view of the pair of the 4D CT image corresponding to the extreme breathing frames, left: deep inspiration breath-hold (DIBH) reference geometry, T00, right: exhale off-reference geometry, T50. A tumour delineated in Non-Small Cell Lung Cancer (NSCLC) Radiomics study, case R005, was artificially added into the lung. Dose delivered according to beamlet set that was optimized for irradiation in the reference frame is superimposed with colour scale/grey scale corresponding to the accumulated dose where bright colours/white corresponds to a higher accumulated dose. A slight relative upward motion of tumour in T50 geometry causes the right pane dose distribution to deviate from the planned distribution illustrated in the left pane.

Figure 4

Colormap/grayscale image of dose distributions superimposed on lung mask for two views (axial and sagittal) and two irradiation conditions - irradiation geometry identical to planned geometry, T00, top panes and irradiation geometry non equal to the planned geometry, with dose registered back to the reference geometry T50, below. Red/dark arrows indicate areas of under-treatment for the off-geometry case. Blue/light arrows indicate areas of over-treatment in organs at risk.
Colormap/grayscale image of dose distributions superimposed on lung mask for two views (axial and sagittal) and two irradiation conditions - irradiation geometry identical to planned geometry, T00, top panes and irradiation geometry non equal to the planned geometry, with dose registered back to the reference geometry T50, below. Red/dark arrows indicate areas of under-treatment for the off-geometry case. Blue/light arrows indicate areas of over-treatment in organs at risk.

Figure 5

Dose-volume histogram (DVH) for planning tumour volume (PTV) under different irradiation conditions and volume representations. Comparison of DT00(T00), thick solid line DVH for irradiation geometry identical to planned geometry, and DT00/S(T50) DT00/M(T50) and DT00/G(T50), solid, dashed and dotted lines for DVH in off-geometry but evaluated in the reference geometry using Staring (S), Mattes (M) or Guy (G) deformable image registration (DIR) method, respectively. Curves for Mattes and Guy registration methods nearly overlap.
Dose-volume histogram (DVH) for planning tumour volume (PTV) under different irradiation conditions and volume representations. Comparison of DT00(T00), thick solid line DVH for irradiation geometry identical to planned geometry, and DT00/S(T50) DT00/M(T50) and DT00/G(T50), solid, dashed and dotted lines for DVH in off-geometry but evaluated in the reference geometry using Staring (S), Mattes (M) or Guy (G) deformable image registration (DIR) method, respectively. Curves for Mattes and Guy registration methods nearly overlap.

Figure 6

Dose-volume histogram (DVH) for planned organ at risk volume of organ at risk (OAR), left lung, under different irradiation conditions and volume representations. Comparison of DT00(T00), thick solid line DVH for irradiation geometry identical to planned geometry, and DT00/S(T50), DT00/M(T50) and DT00/G(T50), solid, dashed and dotted lines for DVH in off-geometry but evaluated in the reference geometry using Staring (S), Mattes (M) or Guy (G) deformable image registration (DIR) method, respectively.
Dose-volume histogram (DVH) for planned organ at risk volume of organ at risk (OAR), left lung, under different irradiation conditions and volume representations. Comparison of DT00(T00), thick solid line DVH for irradiation geometry identical to planned geometry, and DT00/S(T50), DT00/M(T50) and DT00/G(T50), solid, dashed and dotted lines for DVH in off-geometry but evaluated in the reference geometry using Staring (S), Mattes (M) or Guy (G) deformable image registration (DIR) method, respectively.

Figure 7

Gamma analysis for 3 mm/3% distance to agreement / dose difference tolerance criteria. All panes show sagittal projection of the CT image overlaid with planning tumour volume (PTV), indicated by arrow, and superimposed gamma function, where yellow/bright colour corresponds to a gamma value of approximately 2. Top left and bottom right pane show dose comparison of statistically independent realizations of the same dose plan, top left for reference geometry, bottom-right for off-reference geometry registered with Guy’s deformable image registration (DIR). Top right is a comparison of T50 dose registered to T00 using Guy’s method and T00 dose. Bottom left is a comparison of T50 dose registered to T00 using two registration methods, S for Staring and G for Guy.
Gamma analysis for 3 mm/3% distance to agreement / dose difference tolerance criteria. All panes show sagittal projection of the CT image overlaid with planning tumour volume (PTV), indicated by arrow, and superimposed gamma function, where yellow/bright colour corresponds to a gamma value of approximately 2. Top left and bottom right pane show dose comparison of statistically independent realizations of the same dose plan, top left for reference geometry, bottom-right for off-reference geometry registered with Guy’s deformable image registration (DIR). Top right is a comparison of T50 dose registered to T00 using Guy’s method and T00 dose. Bottom left is a comparison of T50 dose registered to T00 using two registration methods, S for Staring and G for Guy.

Dose-volume histogram parameters for planning tumour volume (PTV) and (CTV) and dose distributions delivered in reference, T00, geometry corresponding to reference deep inspiration breath-hold (DIBH) and off-reference T50, geometry, corresponding to exhale phase. Subscripts indicate coordinate system where the doses were evaluated with the letter following the slash indicating the deformable image registration (DIR) method used: S for Staring, M for Mattes and G for Guy. Relative doses are reported. The number of decimal places indicates statistical accuracy evaluated by repeated simulation

Dose PTV CTV
distribution D2% (%) D50% (%) D98% (%) HI D2% (%) D50%(%) D98% (%) HI
DT00(T00) 106.4 102.9 89.5 0.2 106.7 103.4 100.8 0.05
DT00/S(T50) 107.1 103.0 87.2 0.24 107.3 103.4 98.2 0.09
DT00/M(T50) 107.1 102.9 80 0.39 107.4 103.4 97 0.10
DT00/G(T50) 107.2 102.9 79 0.38 107.4 103.4 96 0.11

Gamma analysis pass rate for comparing the dose distributions in reference coordinate system achieved under different irradiation conditions and with different registration methods. For identical anatomies, the gamma passing rate between doses achieved for subsequent realizations was performed. For mismatching irradiation anatomies, the average pass rate over multiple realizations is reported. The number of decimal places indicates statistical uncertainty tested by repeated simulation

Pass rate (%)
Dose pairs PTV Lung
3 mm/20 % 3 mm/3 % 3 mm/20 % 3 mm/3 %
T00 with T00 100 97 97 90
T50/S with T00 99 85 91 79
T50/M with T00 98 77 87 67
T50/G with T00 98 83 89 77
T50/G with T50/G 100 96 98 92

Dose-volume histograms (DVH) parameters for OAR (left lung) and dose distributions delivered in deep inspiration breath-hold (DIBH), reference, T00 geometry and exhale, off-reference, T50 geometry. Subscripts indicate coordinate system where the dose was evaluated, with the letter following the slash indicating the deformable image registration (DIR) method used: S for Staring, M for Mattes and G for Guy. V20Gy and V35Gy are derived for a prescribed dose of 70 Gy. The uncertainty σD is the standard deviation of VD for repeated simulation

Dose distribution V20Gy (%) σ20Gy (%) V35Gy (%) σ35Gy (%)
DT00(T00) 26.2 0.2 18.3 0.1
DT00/S 26.8 0.1 18.7 0.1
DT00/G(T50) 27.4 0.1 19.1 0.1
DT00/M(T50) 27.3 0.1 19.0 0.1
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Medicine, Clinical Medicine, Internal Medicine, Haematology, Oncology, Radiology
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