An Improved Method For Computerized Tomography-Planned Transperineal ¹²⁵ Iodine Prostate Implants

Abstract

Transperineal 125iodine implants of the prostate can be performed with ultrasound guidance, a simple technique that has met with widespread acceptance. However, ultrasound does not allow good visualization of the pubic bones in relation to the pelvic outlet, and the pubic bones may interfere with needle placement in the anterior peripheral aspect of the prostate. Adequate irradiation of the entire periphery of the prostate is important to assure tumor control, since most tumors are multicentric and may involve the anterior aspect of the prostate. A computerized tomography-based treatment planning procedure that allows for angulation of transperineal needles to avoid the pubic bones and still reaches the most peripheral aspects of the gland is described. The technique also allows for the use of transrectal ultrasound and fluoroscopy to verify correct needle placement in the prostate at the procedure. Early treatment results, based on prostate specific antigen and regression of palpable tumors, are encouraging.

Permanent prostate seed implant brachytherapy: Report of the American Association of Physicists in Medicine Task Group No. 64

“…Characteristic of the technique is the use of TRUS for preoperative dosimetric planning and intraoperative visualization of needle placement. A somewhat different technique, developed by Wallner et al, 11,12 uses computerized tomography ͑CT͒ to identify the target volume for treatment planning; intraoperative needle placement is verified under fluoroscopy using the urethra as the primary landmark. Compared to the open surgical technique, these contemporary techniques place considerable emphasis on 3D conformal dosimetric planning and precise placement of the planned seed configuration in the patient.…”

Role of Brachytherapy in Patients with Stage Tic, T2a Adenocarcinoma of the Prostate

“…Holm and coworkers12 first described the technique of implanting the prostate transperineally using ultrasound and template guidance, allowing the brachytherapist to reconstruct the prostate gland three dimensionally to provide an ideal treatment planning model and to allow observation of the implant needles for accurate seed placement, treatment-planning computers capable of quickly determining seed numbers, activity, and appropriate seed locations for optimal coverage of the target volume subsequently came on the market. 13 Additionally, a better understanding of the natural history of prostate cancer and the radiobiology of the energy sources led to better patient selection for curative therapy while post-treatment PSA assays and prostate biopsies permitted more accurate evaluation of the treatment results. These advances have helped renew interest in brachytherapy as a treatment for clinically localized prostate cancer.…”

Interstitial implantation techniques in prostate cancer

“…Some use computerized tomography (CT) guidance [24]. Others use transrectal ultrasound (TRUS) guidance with or without fluoroscopy [8,9,14,17].…”

“…This allows homogeneous dosimetry even if occasional seeds are not placed (or do not stay) in the ideal preplanned position [11]. Other centers use a peripherally weighted loading scheme with a fewer number of higher strength seeds in order to decrease the dose to the urethra in hopes of decreasing urethral complications [24,36]. With longer follow-up, we may see that the specific technique variations at different centers result in different local control rates and complication rates.…”