Radiation Oncology/Prostate/Anatomy

Prostate Anatomy and Target Definition

Contouring Landmarks

• Michigan; 2009 PMID 19515511 -- "Radiographic and Anatomic Basis for Prostate Contouring Errors and Methods to Improve Prostate Contouring Accuracy." (McLaughlin PW, Int J Radiat Oncol Biol Phys. 2009 Jun 8. [Epub ahead of print])
  • Retrospective. 300 patients. Comparison of CT and MRI contours using deformable registration
  • Conclusion: Many prostate CT contouring errors can be improved without MRI fusion

Prostate Apex Location

• UT San Antonio; 2008 PMID 18164852 -- "Anatomic-based three-dimensional planning precludes use of catheter-delivered contrast for treatment of prostate cancer." (Boersma M, Int J Radiat Oncol Biol Phys. 2008 May 1;71(1):51-7. Epub 2007 Dec 31.)
  • 15 patients simulated +/- bladder, urethral and rectal contrast. Prostatic base and apex identified
  • Outcome: On lateral view, urethra exits prostate ~17 mm below posterior-most fusion of pubic symphysis
  • Conclusion: Prostatic apex can easily and consistently be identified

Seminal Vesicles

• Michigan; 2009 PMID 19147014 -- "Evaluating the relationships between rectal normal tissue complication probability and the portion of seminal vesicles included in the clinical target volume in intensity-modulated radiotherapy for prostate cancer." (Gluck I, Int J Radiat Oncol Biol Phys. 2009 Feb 1;73(2):334-40.)
  • Treatment planning. 10 patients, 3 matched IMRT plans: SV 1cm, SV 2 cm, and entire SV. Prescribed 79.2 Gy
  • Outcome: Mean rectal NTCP 14% vs. 17% vs 18%; correlated with size of PTV-rectum overlap (r=0.86, SS) but not SV volume. Magnitude of difference modest in high-dose range
  • Conclusion: SV treatment (2cm or comprehensive) is feasible without exceeding RTOG dose-volume limits

• Beaumont; 2002 (1987-2000) PMID 12377319 -- "Treatment of prostate cancer with radiotherapy: should the entire seminal vesicles be included in the clinical target volume?" (Kestin L, Int J Radiat Oncol Biol Phys. 2002 Nov 1;54(3):686-97.)
  • Retrospective. 344 RP specimens reviewed for SV involvement. Low risk 31%. Median SV length 3.5 cm (0.7 - 8.5 cm).
  • Outcome: SV involvement in 15% patients (51 patients, 81 SV+). If low risk, only 1% SV+; if intermediate/high risk, 27% SV+. If only one high-risk feature (PSA >10, GS >=7, or cT2b), 15% SV+
  • SV anatomy: median length of SV involvement 1.0 cm (0.2-3.8 cm). SV+ <1cm in 59%, <2cm 94%. No factor predictive of involved length
  • Conclusion: Proximal 2.0-2.5 cm of SV should be included in CTV if PSA >10, GS >=7, or cT >=T2b

Neurovascular Bundle

• Columbia; 2004 PMID 15145159 -- "Localization of neurovascular bundles on pelvic CT and evaluation of radiation dose to structures putatively involved in erectile dysfunction after prostate brachytherapy." (Wright JL, Int J Radiat Oncol Biol Phys. 2004 Jun 1;59(2):426-35.)
  • Right/left NVB identified on 9 prostate MRIs. Method for localizing NVBs on CT developed

Pelvic Lymph Nodes

• RTOG; 2009
  • RTOG Pelvic LNs Guideline
  • PMID 18947938 (2009) - RTOG consensus guidelines
  • PMID 18947941 (2009) - Variation in definition of CTVs among RTOG GU experts

Post-RP Volumes

• RTOG; 2009
  • RTOG Positive Apex Guideline (.ppt)
  • RTOG Positive SV Guideline (.ppt)
  • PMID 19394158 (2009) - "Development of RTOG Consensus Guidelines for the Definition of the Clinical Target Volume for Postoperative Conformal Radiation Therapy for Prostate Cancer" (Michalski JM, Int J Radiat Oncol Biol Phys. 2010 Feb 1;76(2):361-8.)

• Princess Margaret; 2007 PMID 17967303 -- "Anatomic boundaries of the clinical target volume (prostate bed) after radical prostatectomy." (Wiltshire KL, Int J Radiat Oncol Biol Phys. 2007 Nov 15;69(4):1090-9.)
  • Anatomic boundaries described for CTV (prostate bed)

• EORTC; 2007 PMID 17706307 -- "Guidelines for target volume definition in post-operative radiotherapy for prostate cancer, on behalf of the EORTC Radiation Oncology Group." (Poortmans P, Radiother Oncol. 2007 Aug;84(2):121-7. Epub 2007 Aug 13.)
  • Recommendations for target volumes

Prostadoodle

• Prostadoodle link
• CT and MR atlas for radiographic landmarks for prostate contouring (Microsoft Powerpoint format).

Contouring Intervention

• Princess Margaret (2007) -- interactive prostate MRI/CT vs general anatomy CT contouring
  • Randomized. 31 trainees. Pretest contouring of prostate and rectum. Then randomized Arm 1) interactive session on prostate volumes using fused CT/MRI vs Arm 2) interactive session on general contouring using CT. Then retested
  • 2010 PMID 19467804 -- "Effectiveness of educational intervention on the congruence of prostate and rectal contouring as compared with a gold standard in three-dimensional radiotherapy for prostate." (Szumacher E, Int J Radiat Oncol Biol Phys. 2010 Feb 1;76(2):379-85. Epub 2009 May 19.)
    • Outcome: No difference in score gains between groups. No difference in prostate contour, but improved rectal contour
    • Conclusion: Similar improvement in technical preformance; participants in both groups satisfied

Contouring Webinars

• eContouring Webinar with Michael Zelefsky, M.D.