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Effect of edema associated with<br />
131 Cs prostate permanent seed implants on<br />
dosimetric quality indices<br />
Than S. Kehwar, Heather A. Jones, M. Saiful Huq,<br />
Sushil Beriwal, Ronald M. Benoit, and Ryan P. Smith<br />
Med. Phys. 36(8), August 2009, pp 3536-3542<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Conclusion<br />
• Edema adversely effects dose delivery<br />
• Short half life of 131 Cs exacerbates effect w.r.t. other<br />
radionuclides<br />
• Recommend: Use post-needle prostate volume to<br />
plan seed placement.<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Background<br />
• American Brachytherapy<br />
Society (ABS) recommends:<br />
• Dose plan based on pre-<br />
implant TRUS images<br />
• Post-implant dosimetry based<br />
on CT at day 30(0) after<br />
implant.<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Method<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
Method<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
• Pre-implant: Determine needle positions<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
• Pre-implant: Determine needle positions<br />
• In OR: Acquire pre-needle-insertion TRUS images<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
• Pre-implant: Determine needle positions<br />
• In OR: Acquire pre-needle-insertion TRUS images<br />
• In OR: Insert needles<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
• Pre-implant: Determine needle positions<br />
• In OR: Acquire pre-needle-insertion TRUS images<br />
• In OR: Insert needles<br />
• In OR: Acquire post-needle-insertion TRUS images<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
• Pre-implant: Determine needle positions<br />
• In OR: Acquire pre-needle-insertion TRUS images<br />
• In OR: Insert needles<br />
• In OR: Acquire post-needle-insertion TRUS images<br />
• In OR: Use post-needle images for seed positioning<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
• Pre-implant: Determine needle positions<br />
• In OR: Acquire pre-needle-insertion TRUS images<br />
• In OR: Insert needles<br />
• In OR: Acquire post-needle-insertion TRUS images<br />
• In OR: Use post-needle images for seed positioning<br />
• Post-implant: Acquire CT images on day 0, 14, 28.<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
• 31 patients, Rx: 115 Gy<br />
• Procedure:<br />
Method<br />
• Pre-implant: Acquire TRUS images<br />
• Pre-implant: Determine needle positions<br />
• In OR: Acquire pre-needle-insertion TRUS images<br />
• In OR: Insert needles<br />
• In OR: Acquire post-needle-insertion TRUS images<br />
• In OR: Use post-needle images for seed positioning<br />
• Post-implant: Acquire CT images on day 0, 14, 28.<br />
• Post-implant: Generate a plan based on pre-implant<br />
TRUS images.<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Functional forms: dose & edema<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Functional forms: dose & edema<br />
Edema<br />
• Vp = Pre-implant prostate vol.<br />
• V0 = Post-implant prosate vol.<br />
• Vt = Prostate volume at time, t.<br />
• M0 = (V0−Vp)/Vp<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Functional forms: dose & edema<br />
Edema<br />
• Vp = Pre-implant prostate vol.<br />
• V0 = Post-implant prosate vol.<br />
• Vt = Prostate volume at time, t.<br />
• M0 = (V0−Vp)/Vp<br />
Dose<br />
• λ = ln(2)/t1/2<br />
• R0 = Initial source dose rate<br />
• N.B. ln(2) = 0.693<br />
∴Total dose, TD = 1.44⋅R0⋅t1/2<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Pre-plan vs. post-needle plan<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Pre-plan vs. post-needle plan<br />
• Other studies: up to<br />
30% difference in<br />
volumes contoured on<br />
CT vs US.<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Pre-plan vs. post-needle plan<br />
• Other studies: up to<br />
30% difference in<br />
volumes contoured on<br />
CT vs US.<br />
• This study none<br />
(p = 0.87)<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Pre-plan vs. post-needle plan<br />
• Other studies: up to<br />
30% difference in<br />
volumes contoured on<br />
CT vs US.<br />
• This study none<br />
(p = 0.87)<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Pre-plan vs. post-needle plan<br />
• Other studies: up to<br />
30% difference in<br />
volumes contoured on<br />
CT vs US.<br />
• This study none<br />
(p = 0.87)<br />
• N.B. The post-implant<br />
plant was that used<br />
for treatment, the pre-<br />
needle plan was<br />
generated a posteriori<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Pre-plan vs. post-needle plan<br />
• Other studies: up to<br />
30% difference in<br />
volumes contoured on<br />
CT vs US.<br />
• This study none<br />
(p = 0.87)<br />
• N.B. The post-implant<br />
plant was that used<br />
for treatment, the pre-<br />
needle plan was<br />
What’s possibly wrong with this? ➛generated<br />
a posteriori<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Δ Edema (cm 3 )<br />
V100<br />
FD90
Conclusion<br />
• Edema adversely effects dose delivery<br />
• Short half life of 131 Cs exacerbates effect w.r.t. other<br />
radionuclides<br />
• Recommend: Use post-needle prostate volume to<br />
plan seed placement.<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Conclusion<br />
• Edema adversely effects dose delivery<br />
• Short half life of 131 Cs exacerbates effect w.r.t. other<br />
radionuclides<br />
• Recommend: Use post-needle prostate volume to<br />
plan seed placement.<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Conclusion<br />
• Edema adversely effects dose delivery<br />
• Short half life of 131 Cs exacerbates effect w.r.t. other<br />
radionuclides<br />
• Recommend: Use post-needle prostate volume to<br />
plan seed placement.<br />
61<br />
Adam Cunha, UCSF Journal Club, 21 Aug. 2009
Next Week<br />
• YuanYuan:<br />
“Comparison of conventional inserts and an add-on electron MLC for chest wall<br />
irradiation of left-sided breast cancer”<br />
Tero Vatanen, Erik Traneus, and Tapani Lahtinen<br />
Acta Oncologica, 2009; 48: 446-451<br />
• Minghui:<br />
“Monte-Carlo-based adaptive EPID dose kernel accounting for different field size<br />
responses of imagers”<br />
Song Wang, Joseph K. Gardner, John J. Gordon, Weidon Li, Luke Clews, Peter B. Greer, and Jeffrey V. Siebers<br />
Med. Phys. 36(8), August 2009, pp 3582-3595<br />
• Andrew:<br />
“Stereotactic radiotherapy of intracranial tumors: A comparison of intensitymodulated<br />
radiotherapy and dynamic conformal arc”<br />
Ruud G. J. WiggenRaad, Anna L. Petoukhova, Lia Versluis, Jan P. C. van Santvoort<br />
Int. J. Radiation Oncology Biol. Phys., Vol. 74, No. 4, pp. 1018–1026, 2009
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