T staging and target volume definition by imaging in gu tumors

The diagnosis of prostate cancer is usually per formed with random transrectal ultrasonography guided biopsies in patients that are found with elevated serum PSA or positive digital rectal examination. PSMA positron emission tomogra phy/computed tomography (PET/CT) imaging showed good accuracy to stage prostate cancer, but the sensitivity of this method remains subop timal, particularly in the detection of small lymph nodal metastasis. Magnetic resonance imaging (MRI) currently plays a main role in the different phases of pros tate cancer management such as the detection, local staging, active surveillance, and follow-up. Instead CT is limited to the assessment of distant metastases as it shows low sensitivity in the iden tification of both localized lesions and lymph node metastases. The use of multiparametric MRI has been demonstrated to improve the accuracy of tumor localization, making MRI the modality of choice for local staging of prostate tumor. Radiotherapy (RT) for prostate cancer can be modulated in terms of dose, target volumes, and integration with androgen deprivation therapy. This modulation is performed by defining differ ent risk groups based on PSA value, Gleason score, and tumor/nodal stage. According to the different risk groups, the clinical target volume includes only the prostatic gland in low-risk pros tate cancer, and prostate, seminal vesicles, and pelvic lymph nodes (LNs) in high-risk prostate cancer. Using external beam radiotherapy (EBRT), MRI allows reduction of delineated tar get volumes while improving extracapsular extension and seminal vesicle invasion detection with potential impact on clinical outcome. Also, in brachytherapy treatments, MRI can accurately identify prostate gland,