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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 profiles from VBDM simulations with different spatial resolution (20 mm FWHM (blue), 10 mm FWHM (red), 0 mm FWHM (orange)) at the liver-lung interface showing percentage differences from MC without blurring. LD is omitted since it is similar to SKD. LS is 1 % in MC (a), SKD (b), and SK (c). LS is 20 % in MC (d), SKD (e), and SK (f).
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Fig6: 1D profiles from VBDM simulations with different spatial resolution (20 mm FWHM (blue), 10 mm FWHM (red), 0 mm FWHM (orange)) at the liver-lung interface showing percentage differences from MC without blurring. LD is omitted since it is similar to SKD. LS is 1 % in MC (a), SKD (b), and SK (c). LS is 20 % in MC (d), SKD (e), and SK (f).

Mentions: Figure 6 shows the percent differences of the different absorbed dose calculations relative to the truth (MC of true activity distributions) for different LS and different FWHM. LD is not displayed since the differences are similar to SKD. Errors on the liver side of the interface were generally within 30 % and approached 0 as the blurring decreased to 0 and moved away from the interface deeper into the liver. Near the lung interface, errors for 20 mm FWHM blurring and 1 % LS were within 20 % when using SK compared to errors over 200 % for MC and SKD. Table 3 lists the distance intervals where agreement with MC was within 10 %; on the liver side, agreement to within 10 % for all methods was found beyond 4, 6, and 12 mm from the interface for 0, 10, and 20 mm FWHM blurring, respectively, with a LS from 1 to 20 %. For MC, LD, and SKD in the lung, agreement was found beyond 26, 31, and 39 mm for 0, 10, and 20 mm FWHM blurring, respectively.Fig. 6


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 profiles from VBDM simulations with different spatial resolution (20 mm FWHM (blue), 10 mm FWHM (red), 0 mm FWHM (orange)) at the liver-lung interface showing percentage differences from MC without blurring. LD is omitted since it is similar to SKD. LS is 1 % in MC (a), SKD (b), and SK (c). LS is 20 % in MC (d), SKD (e), and SK (f).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig6: 1D profiles from VBDM simulations with different spatial resolution (20 mm FWHM (blue), 10 mm FWHM (red), 0 mm FWHM (orange)) at the liver-lung interface showing percentage differences from MC without blurring. LD is omitted since it is similar to SKD. LS is 1 % in MC (a), SKD (b), and SK (c). LS is 20 % in MC (d), SKD (e), and SK (f).
Mentions: Figure 6 shows the percent differences of the different absorbed dose calculations relative to the truth (MC of true activity distributions) for different LS and different FWHM. LD is not displayed since the differences are similar to SKD. Errors on the liver side of the interface were generally within 30 % and approached 0 as the blurring decreased to 0 and moved away from the interface deeper into the liver. Near the lung interface, errors for 20 mm FWHM blurring and 1 % LS were within 20 % when using SK compared to errors over 200 % for MC and SKD. Table 3 lists the distance intervals where agreement with MC was within 10 %; on the liver side, agreement to within 10 % for all methods was found beyond 4, 6, and 12 mm from the interface for 0, 10, and 20 mm FWHM blurring, respectively, with a LS from 1 to 20 %. For MC, LD, and SKD in the lung, agreement was found beyond 26, 31, and 39 mm for 0, 10, and 20 mm FWHM blurring, respectively.Fig. 6

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