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Determination of dosimetric parameters for shielded 153Gd source in prostate cancer brachytherapy Cover

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Determination of dosimetric parameters for shielded 153Gd source in prostate cancer brachytherapy

Radiology and Oncology

Volume 51 (2017): Issue 1 (March 2017)

By: Mahdi Ghorbani, Benyamin Khajetash, Najmeh Ghatei, Mohammad Mehrpouyan, Ali S. Meigooni and Ramin Shahraini

Open Access

|Feb 2017

Figures & tables

Figures & Tables

A schematic view of the simulated ¹⁵³Gd source, Nitinol needle including Pt shields and Al windows. (A) transverse view, (B) longitudinal view. This figure is not in to a real scale. Polar angles that were used to calculate the anisotropy function.

Table 1

The energy spectrum of ¹⁵³Gd radionuclide.¹⁸ In these data, the energy values were rounded to two decimal places

Energy (keV)	Prevalence (%)
5.18	0.374
5.82	0.976
5.82	0.1341
5.85	8.86
6.44	0.559
6.46	5.64
6.57	0.9214
6.62	0.0845
6.84	1.8512
7.48	0.947
7.77	0.173
7.79	0.244
14.06	0.0183
21.20	0.0224
40.47	0.00953
40.90	35.29
41.54	63.516
46.90	6.2516
47.04	12.13
47.37	0.1848
48.25	4.001
48.39	1.597
54.19	40.01622
69.67	2.41923
75.42	0.078323
83.37	0.1964
89.49	0.0694
96.88	0.0022
97.43	29
103.18	21.1123
118.11	0.000121
166.56	0.00033
172.30	0.00022
172.85	0.036017

Polar distribution of angles in calculation of anisotropy function in the shielded mode.

Table 2

Radial dose function values for the non-shield and shield modes. The shield mode is related to the Pt and Al window sides

g(r)

r(cm)	Without shield	With shield

		Pt shield side	Al window side
0.5	0.90	0.52	0.93
1	1.00	1.00	1.00
1.5	1.06	1.39	1.04
2	1.11	1.73 1.04
2.5	1.13	2.03	1.07
3	1.18	2.22	1.07
3.5	1.14	2.44	1.07
4	1.19	2.72	1.05
5	1.17	2.65	1.02
8	1.01	3.01	0.91
10	0.89	2.63	0.80
12	0.77	2.44	0.71

(A) Radial dose function for the ¹⁵³Gd source without the shield and with the shield on Al window side (B) radial dose function for the shielded source at Pt shield side.

Relative dose in non-shielded mode, Pt shield side and aluminum window side in the shielded mode of the source. The normalization point is at 1 cm for the non-shielded case.

Table 3

Anisotropy function values for the ¹⁵³Gd source at different distances for the non-shielded mode

θ(degrees)	r(cm)

	0.5	1	2	3	5	10
0	0.71	0.59	0.48	0.41	0.29	-
10	0.75	0.63	0.58	0.51	0.44	0.75
20	0.82	0.76	0.69	0.64	0.63	0.81
30	0.86	0.83	0.77	0.75	0.76	0.86
40	0.90	0.85	0.85	0.84	0.87	0.91
50	0.95	0.91	0.90	0.90	0.93	0.94
60	0.95	0.98	0.94	0.94	0.96	0.96
70	1.00	0.96	0.97	0.98	0.98	0.97
80	0.99	0.99	0.97	0.98	1.01	1.00
90	1.00	1.00	1.00	1.00	1.00	1.00
100	0.97	0.97	0.99	1.00	1.01	1.00
110	1.01	0.95	0.97	0.97	0.96	0.97
120	0.97	0.95	0.92	0.94	0.96	0.97
130	0.95	0.93	0.89	0.90	0.93	0.94
140	0.92	0.87	0.85	0.84	0.87	0.90
150	0.88	0.80	0.78	0.76	0.79	0.87
160	0.83	0.74	0.68	0.65	0.63	0.81
170	0.76	0.65	0.56	0.50	0.45	0.75
180	0.69	-	-	-	-	-

Anisotropy function for the ¹⁵³Gd source: (A) non-shielded mode, (B) shielded mode, Pt shield side, (C) shielded mode, Al window side.

Table 4

Anisotropy function values for the ¹⁵³Gd source at different distances for the shielded mode at the Pt and Al windows sides

r(cm)

θ(degree)	Pt shield side							Al window side

	0.5	1	2	3	5	10	12	0.5	1	2	3	5	10	12
	0	0.42	0.39	0.30	-	-	-	-	1.80	1.78	1.56	-	-	-	-
10	0.51	0.52	0.42	0.35	0.31	0.29	0.76	1.54	1.57	1.38	1.32	1.22	0.35	-
20	0.62	0.61	0.58	0.51	0.50	0.55	0.81	1.41	1.36	1.23	1.21	1.12	0.88	0.38
30	0.72	0.71	0.72	0.66	0.66	0.70	0.85	1.24	1.31	1.18	1.17	1.10	0.87	0.56
40	0.81	0.81	0.79	0.77	0.78	0.81	0.90	1.15	1.23	1.14	1.07	1.07	1.05	0.77
50	0.88	0.88	0.87	0.86	0.87	0.90	0.93	1.09	1.14	1.07	1.08	0.98	0.86	0.84
60	0.93	0.91	0.95	0.92	0.94	0.97	0.96	1.05	1.07	0.98	1.06	1.05	0.91	0.94
70	0.98	0.96	0.99	0.97	0.98	1.01	0.98	1.02	1.07	0.91	1.04	0.99	1.03	1.00
80	0.99	0.99	1.00	1.00	1.00	1.06	0.99	1.02	1.01	0.98	0.99	0.96	1.00	1.00
90	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00
100	0.98	0.99	1.00	0.98	1.00	1.02	1.00	0.96	1.01	1.01	1.04	0.99	1.03	1.00
110	0.96	0.97	0.98	0.97	0.99	0.97	0.98	0.96	1.07	0.96	1.01	1.04	0.99	0.95
120	0.93	0.93	0.95	0.92	0.94	0.96	0.97	1.08	1.09	1.02	1.07	1.01	1.08	0.82
130	0.88	0.89	0.90	0.88	0.88	0.93	0.93	1.13	1.24	1.03	1.07	1.09	0.95	0.84
140	0.82	0.83	0.81	0.77	0.78	0.84	0.89	1.18	1.21	1.14	1.12	1.07	1.04	0.74
150	0.73	0.70	0.69	0.67	0.66	0.71	0.86	1.27	1.29	1.16	1.15	1.13	0.87	0.63
160	0.63	0.62	0.56	0.52	0.50	0.54	0.81	1.45	1.53	1.23	1.33	1.21	0.89	0.37
170	0.53	0.49	0.43	0.36	0.33	0.30	0.75	1.59	1.57	1.47	1.51	1.38	1.06	-
180	0.43	0.41	-	-	-	-	-	1.83	1.89	-	-	-	-	-

Table 5

Mass attenuation coefficient (rμ/ρ) of Pt, Al and Ti in the 40 keV-100 keV energy range²¹

Energy (keV)	Pt	Al	Ti
40	12.45	0.57	2.21
50	6.95	0.37	1.21
60	4.34	0.28	0.77
80	8.73	0.20	0.41
100	4.99	0.17	0.27

Comparison of anisotropy function for non-shielded mode, Pt shielded mode, Al window mode. All modes are presented for distances: (A) 0.5 cm, (B) 2 cm, (C) 5 cm, (D) 12 cm.

Isodose curves (%): (A) non shielded source, (B) shielded source. The dose distributions were normalized to the dose at 1 cm distance from the source at transverse plane. The Z axis is on the longitudinal axis of the source.

Articles in this issue

DOI: https://doi.org/10.1515/raon-2017-0009 | Journal eISSN: 1581-3207 | Journal ISSN: 1318-2099

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Language: English

Page range: 101 - 112

Submitted on: Jun 22, 2016

|

Accepted on: Dec 27, 2016

|

Published on: Feb 22, 2017

Published by: Association of Radiology and Oncology

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

interstitial rotating shield brachytherapy,

¹⁵³Gd,

TG-43 dosimetric parameters,

Monte Carlo simulation

Related subjects:

Clinical medicine,

© 2017 Mahdi Ghorbani, Benyamin Khajetash, Najmeh Ghatei, Mohammad Mehrpouyan, Ali S. Meigooni, Ramin Shahraini, published by Association of Radiology and Oncology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 51 (2017): Issue 1 (March 2017)

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