Variation in prostate position relative to adjacent bony anatomy.

PURPOSE: In prostatic cancer, the prostate cannot be discerned from a portal image. Setup information is, therefore, obtained from bony anatomy. To perform high-precision conformal therapy, knowledge about the variation in distance between the prostate and adjacent bony anatomy during an external radiotherapy treatment is mandatory. This report is concerned with that variation. METHODS AND MATERIALS: Nine patients previously treated interstitially for prostatic cancer with implantation of 125I seeds, agreed to cooperate in a study. They underwent a number of simulations of external radiotherapy treatment. After the first patient setup, this setup was repeated five times for each patient as if the patient was treated by external radiotherapy. Simulator radiographs were made from each setup in the anterior-posterior and left-right lateral directions. The seeds were clearly visible in the simulator film images and reflect the position of the prostate. No bladder instructions were given and the filling of the rectum was not quantified. RESULTS: Variation in distance between the prostate and the bony anatomy was measured and is presented in one standard deviation of the normal distribution function: 0.8 mm lateral, 1.5 mm ventrodorsal, and 1.7 mm craniocaudal. CONCLUSIONS: The bone structure of the pelvis reflects fairly well the position of the prostate. The prostate is least mobile in a lateral direction and most mobile in the craniocaudal and ventrodorsal directions.

Verification of source position in interstitial and intralumenal brachytherapy.

In brachytherapy afterloading, the treatment is simulated using dummy sources. In this study, imaging during treatment was performed to see whether the radioactive sources accurately replaced the dummy sources. In low-dose rate afterloading (manually or remote controlled) X-ray radiography was applied for verification. In high dose rate afterloading, the radioactive source was visualised under remote controlled X-ray fluoroscopy. Differences between dummy and treatment source position were observed, justifying verification imaging in brachytherapy.

Evaluation of brachytherapy implants using the "natural" volume-dose histogram.

The "natural" volume-dose histogram as described by Anderson visualises graphically even small differences between source arrangements, making it a useful tool to compare planned and realised source configurations. In this study the histogram is applied to demonstrate that the introduction of an applicator in oral cavity implants or of iridium wire spacers used as templates in bladder implants improved the quality of the implants considerably, resulting in close agreement between the planned and the realised source configuration.

Ultrasonically guided transperineal seed implantation of the prostate: modification of the technique and qualitative assessment of implants.

During the period 1988-1991, 23 patients with prostatic carcinoma were treated by transperineal iodine seed implantation guided by transrectal ultrasound. We introduce a refinement of the implantation technique using a rigid column of seeds and spacers. The uniformity parameter based on the peak width of the natural volume-dose histogram demonstrated quantitatively that this refinement resulted in a more accurate seed arrangement.

[Breast preserving therapy: shorter treatment duration by the peroperative introduction of iridium guide needles]. / Mammasparende therapie: kortere behandelingsduur door peroperatief plaatsen van iridiumgeleidenaalden.

In the Deventer Radiotherapeutic Institute from January 1981 through December 1989, 359 patients who had undergone a breast-saving operation were irradiated. Since 1987, iridium guiding needles were introduced peroperatively in 79 of these patients. Subsequently, irradiation was administered. With this method the total duration of treatment was 16 days shorter on average than in patients who postoperatively were treated with iridium or external irradiation; also, the patients treated peroperatively needed only to be anaesthetized once. In addition, better positioning of the needles was possible, reducing the risk of faulty localization. The follow-up was short but the preliminary results of the treatment were good (one local recurrence after an average follow-up of 20 months) and no adverse effect on wound healing was seen.

Comparison between predicted and actual dose distribution in interstitial therapy of the oral cavity.

During the period 1985-1986, 10 patients with lesions of the floor of the mouth or of the mobile part of the tongue were treated by interstitial curietherapie with iridium-192. In the patients treated with the looping technique essential differences were found between the predicted source configuration and that actually achieved, resulting in a disagreement between precalculated and actual dose distribution. To avoid this undesirable situation, a simple oral cavity applicator was constructed which guarantees parallelism and equidistance between the implanted needles. It was found that the use of this applicator resulted in an almost complete agreement between forecast and actual dose distribution.