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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

The MC  to the patients’ RL (N = 17) when regions extending 1 (blue circle), 2 (red x), or 3 cm (green pentagon) from the liver-lung interface were excluded from the original RL VOI shown together with the linear fit. The gray dashed line represents the line of equivalence
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Fig5: The MC to the patients’ RL (N = 17) when regions extending 1 (blue circle), 2 (red x), or 3 cm (green pentagon) from the liver-lung interface were excluded from the original RL VOI shown together with the linear fit. The gray dashed line represents the line of equivalence

Mentions: Figure 5 shows the MC to the RL when regions extending 1, 2, or 3 cm from the liver-lung interface were excluded from both the liver and lung VOIs. The sensitivity was similar for all VBDM. For total liver, the slopes were 0.94, 0.87, and 0.74 when excluding 1, 2, and 3 cm from the interface, respectively; NL was less sensitive with slopes of 0.97, 0.94, and 0.92, respectively, and RL was the most sensitive with slopes of 1.43, 1.89, and 2.14, respectively. The RL sensitivity to the liver-lung interface was seen as a strong departure from the line of equivalence (Fig. 5). Excluding up to 3 cm of the liver-lung interface for the total liver and NL resulted in average differences of 4.1 and 6.9 %, respectively, from the original to VOIs (without excluded regions), suggesting relative insensitivity to the interface region. On the contrary, excluding up to 3 cm of the interface for the RL led to an average difference of −48.4 % from the original , suggesting that RL is very sensitive to the interface region.Fig. 5


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)

The MC  to the patients’ RL (N = 17) when regions extending 1 (blue circle), 2 (red x), or 3 cm (green pentagon) from the liver-lung interface were excluded from the original RL VOI shown together with the linear fit. The gray dashed line represents the line of equivalence
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig5: The MC to the patients’ RL (N = 17) when regions extending 1 (blue circle), 2 (red x), or 3 cm (green pentagon) from the liver-lung interface were excluded from the original RL VOI shown together with the linear fit. The gray dashed line represents the line of equivalence
Mentions: Figure 5 shows the MC to the RL when regions extending 1, 2, or 3 cm from the liver-lung interface were excluded from both the liver and lung VOIs. The sensitivity was similar for all VBDM. For total liver, the slopes were 0.94, 0.87, and 0.74 when excluding 1, 2, and 3 cm from the interface, respectively; NL was less sensitive with slopes of 0.97, 0.94, and 0.92, respectively, and RL was the most sensitive with slopes of 1.43, 1.89, and 2.14, respectively. The RL sensitivity to the liver-lung interface was seen as a strong departure from the line of equivalence (Fig. 5). Excluding up to 3 cm of the liver-lung interface for the total liver and NL resulted in average differences of 4.1 and 6.9 %, respectively, from the original to VOIs (without excluded regions), suggesting relative insensitivity to the interface region. On the contrary, excluding up to 3 cm of the interface for the RL led to an average difference of −48.4 % from the original , suggesting that RL is very sensitive to the interface region.Fig. 5

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