Limits...
Comparing voxel-based absorbed dosimetry methods in tumors, liver, lung, and at the liver-lung interface for (90)Y microsphere selective internal radiation therapy.

Mikell JK, Mahvash A, Siman W, Mourtada F, Kappadath SC - EJNMMI Phys (2015)

Bottom Line: Excluding 1, 2, and 3 cm of RL near the interface changed the resulting RL [Formula: see text] by -22, -38, and -48 %, respectively, for all VBDM.SK underestimates RL [Formula: see text] relative to MC whereas LD and SKD overestimate.RL [Formula: see text] is strongly influenced by the liver-lung interface.

View Article: PubMed Central - PubMed

Affiliation: Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1155 Pressler St, Unit 1352, Houston, TX, 77030, USA.

ABSTRACT

Background: To assess differences between four different voxel-based dosimetry methods (VBDM) for tumor, liver, and lung absorbed doses following (90)Y microsphere selective internal radiation therapy (SIRT) based on (90)Y bremsstrahlung SPECT/CT, a secondary objective was to estimate the sensitivity of liver and lung absorbed doses due to differences in organ segmentation near the liver-lung interface.

Methods: Investigated VBDM were Monte Carlo (MC), soft-tissue kernel with density correction (SKD), soft-tissue kernel (SK), and local deposition (LD). Seventeen SIRT cases were analyzed. Mean absorbed doses ([Formula: see text]) were calculated for tumor, non-tumoral liver (NL), and right lung (RL). Simulations with various SPECT spatial resolutions (FHWMs) and multiple lung shunt fractions (LSs) estimated the accuracy of VBDM at the liver-lung interface. Sensitivity of patient RL and NL [Formula: see text] on segmentation near the interface was assessed by excluding portions near the interface.

Results: SKD, SK, and LD were within 5 % of MC for tumor and NL [Formula: see text]. LD and SKD overestimated RL [Formula: see text] compared to MC on average by 17 and 20 %, respectively; SK underestimated RL [Formula: see text] on average by -60 %. Simulations (20 mm FWHM, 20 % LS) showed that SKD, LD, and MC were within 10 % of the truth deep (>39 mm) in the lung; SK significantly underestimated the absorbed dose deep in the lung by approximately -70 %. All VBDM were within 10 % of truth deep (>12 mm) in the liver. Excluding 1, 2, and 3 cm of RL near the interface changed the resulting RL [Formula: see text] by -22, -38, and -48 %, respectively, for all VBDM. An average change of -7 % in the NL [Formula: see text] was realized when excluding 3 cm of NL from the interface. [Formula: see text] was realized when excluding 3 cm of NL from the interface.

Conclusions: SKD, SK, and LD are equivalent to MC for tumor and NL [Formula: see text]. SK underestimates RL [Formula: see text] relative to MC whereas LD and SKD overestimate. RL [Formula: see text] is strongly influenced by the liver-lung interface.

No MeSH data available.


Related in: MedlinePlus

1D dose distributions at the liver-lung interface to compare the four VBDM for different spatial resolution and LS. LS is 1 % in 0 mm FWHM (a), 10 mm FWHM (b), and 20 mm FWHM (c) while LS is 20 % in 0 mm FWHM (d), 10 mm FWHM (e), and 20 mm FWHM (f). A.U. arbitrary units
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4538912&req=5

Fig7: 1D dose distributions at the liver-lung interface to compare the four VBDM for different spatial resolution and LS. LS is 1 % in 0 mm FWHM (a), 10 mm FWHM (b), and 20 mm FWHM (c) while LS is 20 % in 0 mm FWHM (d), 10 mm FWHM (e), and 20 mm FWHM (f). A.U. arbitrary units

Mentions: Figure 7 provides context of the relative differences in Fig. 6 by showing line profiles of absorbed dose in arbitrary units for the VBDM with different lung shunt fractions and spatial resolutions. Figure 7 can be used to estimate absolute errors in the absorbed dose near the interface. For example, if one assumes the absorbed dose within the liver far from the interface is 80 Gy, then the SKD absorbed dose in the lung at 7 mm from the interface for LS = 1 % and FWHM = 20 mm would be ≈9.4E-15/1.1E-14 × 80 Gy ≈ 68 Gy whereas the true value would be ≈1.9E-15/1.1E-14 × 80 Gy = 14 Gy.Fig. 7


Comparing voxel-based absorbed dosimetry methods in tumors, liver, lung, and at the liver-lung interface for (90)Y microsphere selective internal radiation therapy.

Mikell JK, Mahvash A, Siman W, Mourtada F, Kappadath SC - EJNMMI Phys (2015)

1D dose distributions at the liver-lung interface to compare the four VBDM for different spatial resolution and LS. LS is 1 % in 0 mm FWHM (a), 10 mm FWHM (b), and 20 mm FWHM (c) while LS is 20 % in 0 mm FWHM (d), 10 mm FWHM (e), and 20 mm FWHM (f). A.U. arbitrary units
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4538912&req=5

Fig7: 1D dose distributions at the liver-lung interface to compare the four VBDM for different spatial resolution and LS. LS is 1 % in 0 mm FWHM (a), 10 mm FWHM (b), and 20 mm FWHM (c) while LS is 20 % in 0 mm FWHM (d), 10 mm FWHM (e), and 20 mm FWHM (f). A.U. arbitrary units
Mentions: Figure 7 provides context of the relative differences in Fig. 6 by showing line profiles of absorbed dose in arbitrary units for the VBDM with different lung shunt fractions and spatial resolutions. Figure 7 can be used to estimate absolute errors in the absorbed dose near the interface. For example, if one assumes the absorbed dose within the liver far from the interface is 80 Gy, then the SKD absorbed dose in the lung at 7 mm from the interface for LS = 1 % and FWHM = 20 mm would be ≈9.4E-15/1.1E-14 × 80 Gy ≈ 68 Gy whereas the true value would be ≈1.9E-15/1.1E-14 × 80 Gy = 14 Gy.Fig. 7

Bottom Line: Excluding 1, 2, and 3 cm of RL near the interface changed the resulting RL [Formula: see text] by -22, -38, and -48 %, respectively, for all VBDM.SK underestimates RL [Formula: see text] relative to MC whereas LD and SKD overestimate.RL [Formula: see text] is strongly influenced by the liver-lung interface.

View Article: PubMed Central - PubMed

Affiliation: Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1155 Pressler St, Unit 1352, Houston, TX, 77030, USA.

ABSTRACT

Background: To assess differences between four different voxel-based dosimetry methods (VBDM) for tumor, liver, and lung absorbed doses following (90)Y microsphere selective internal radiation therapy (SIRT) based on (90)Y bremsstrahlung SPECT/CT, a secondary objective was to estimate the sensitivity of liver and lung absorbed doses due to differences in organ segmentation near the liver-lung interface.

Methods: Investigated VBDM were Monte Carlo (MC), soft-tissue kernel with density correction (SKD), soft-tissue kernel (SK), and local deposition (LD). Seventeen SIRT cases were analyzed. Mean absorbed doses ([Formula: see text]) were calculated for tumor, non-tumoral liver (NL), and right lung (RL). Simulations with various SPECT spatial resolutions (FHWMs) and multiple lung shunt fractions (LSs) estimated the accuracy of VBDM at the liver-lung interface. Sensitivity of patient RL and NL [Formula: see text] on segmentation near the interface was assessed by excluding portions near the interface.

Results: SKD, SK, and LD were within 5 % of MC for tumor and NL [Formula: see text]. LD and SKD overestimated RL [Formula: see text] compared to MC on average by 17 and 20 %, respectively; SK underestimated RL [Formula: see text] on average by -60 %. Simulations (20 mm FWHM, 20 % LS) showed that SKD, LD, and MC were within 10 % of the truth deep (>39 mm) in the lung; SK significantly underestimated the absorbed dose deep in the lung by approximately -70 %. All VBDM were within 10 % of truth deep (>12 mm) in the liver. Excluding 1, 2, and 3 cm of RL near the interface changed the resulting RL [Formula: see text] by -22, -38, and -48 %, respectively, for all VBDM. An average change of -7 % in the NL [Formula: see text] was realized when excluding 3 cm of NL from the interface. [Formula: see text] was realized when excluding 3 cm of NL from the interface.

Conclusions: SKD, SK, and LD are equivalent to MC for tumor and NL [Formula: see text]. SK underestimates RL [Formula: see text] relative to MC whereas LD and SKD overestimate. RL [Formula: see text] is strongly influenced by the liver-lung interface.

No MeSH data available.


Related in: MedlinePlus