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Table 2 The comparison of dose values (in Gy) at organs at risk points (fovea, optic disc center, lens center and lacrimal glad center) for four different plaque positions (#1-#4) [15] of the 16 mm COMS plaque loaded with 125I seeds (model 6711) calculated in our in-house program with average off-axis dose values calculated from treatment planning systems used in Rivard et al.’s study

From: A practical approach to estimating optic disc dose and macula dose without treatment planning in ocular brachytherapy using 125I COMS plaques

Plaque position

Off-axis location

Current Study

Data from Table III in Rivard et al. [15]

\( \left|{\mathrm{D}}_{\mathrm{diff}}^{\mathrm{Rel}}\left(\%\right)\right| \)

#1

Fovea

16.50

16.3

1.25

Optic disc

11.29

11.2

0.79

Lens

21.59

21.5

0.40

Lacrimal gland

40.92

39.2

4.39

#2

Fovea

16.50

16.3

1.25

Optic disc

28.02

27.6

1.52

Lens

21.59

21.5

0.40

Lacrimal gland

7.19

7.1

1.22

#3

Fovea

16.50

16.3

1.25

Optic disc

16.48

16.3

1.08

Lens

21.59

21.5

0.40

Lacrimal gland

40.92

39.2

4.40

#4

Fovea

16.50

16.3

1.25

Optic disc

16.48

16.3

1.08

Lens

21.59

21.5

0.40

Lacrimal gland

7.19

7.1

1.22

  1. Dose values were calculated for a prescribed dose of approximately 85 Gy to a central-axis depth of 5 mm (Sk = 4.752 U and irradiation time = 100 h) using a line source approximation of the AAPM TG-43 formalism and homogeneous water phantoms. \( \left|{\mathrm{D}}_{\mathrm{diff}}^{\mathrm{Rel}}\left(\%\right)\right| \) is a modulus of a relative percent difference in dose between the two studies