CPB Ljubljana 2018 course book

Practical session, day 2, Prostate Treatment planning

Learning objectives: -

Treatment planning of a prostate implant; - Different ways of optimization.

Case description: Seventy-four year old male with cT2aN0M0 prostate carcinoma, PSA of 20 ng/ml and Gleason score 3 + 4 = 7 (ISUP grade group 2). On T2-weighted MRI in the left peripheral zone a 1.0 cm large suspicious lesion.

External beam radiotherapy was given to a dose of 20 x 2.2 Gy to the prostate and base of the seminal vesicles followed by a HDR brachytherapy boost of 15 Gy on the periphery of the prostate. 1) Treatment planning. a. For prostate HDR brachytherapy acceptable clinical plans can be made with inverse optimization as a starting point. Specific parameters as weight factors and penalties need to be entered to start planning. Investigate the outcome according to variable weight factors and penalties used. b. Use the dose objectives from the table to create an acceptable clinical plan. Insert the proper weight factors and penalties and fine tune with e.g. graphical optimization. c. Is the suspicious lesion on MRI adequately covered?

VOI

Dose-volume parameter

Dose Recommendation derived from GEC- ESTRO recommendation, Hoskin et al. Radiother. Oncol. 2013;107:325-332

PTV

V 100

≥ 95% > 100%

D 90

Rectum Urethra

D 2cm3

≤ 10.7 Gy (EQD2 75 Gy) ≤ 17.8 Gy (EQD2 120 Gy) ≤ 15.8 Gy (EQD2 105 Gy)

D 0.1cm3

D 30