Dose to fingertips of staff preparing stranded iodine-125 seeds for permanent prostate implants.

The aim of this study is to measure radiation dose to the fingertips of occupationally exposed workers handling stranded iodine-125 seeds during prostate implants. The doses were measured by thermoluminescence dosimetry at the nail of the index finger of both hands in three hospitals in the Netherlands. In all hospitals, measurements were carried out during the preparation of stranded IBt seeds, type Intersource(®) 1251L. The fingertip doses per procedure (mean ± SD) to the fingertip for workers from the three hospitals were estimated to be 0.29 ± 0.15 mSv (n = 6), <0.03 ± <0.02 mSv (n = 8) and 0.31 ± 0.16 mSv (n=16), respectively. The lower doses found for the hospital 2 workers are presumably related to the heavier shielding and longer utensils used in that hospital. Even in the case of hundreds of implant procedures per year, dose to the fingertips for occupationally exposed workers preparing stranded seeds is expected to be well below the annual limit for extremities of 500 mSv.

Meeting patients' needs with patient information systems: potential benefits of qualitative research methods.

This article reports on our pilot evaluation of an electronic patient information system for children with amblyopia and their parents. The aim was to investigate whether the information system would be able to improve the quality of care, as indicated by an improvement in the effectiveness and efficiency of care, and in an increase in patient satisfaction. In the pilot evaluation, we used qualitative research methods, exploring the impact of the information system on children and their parents, with the aim to find suitable indicators for a potential further, quantitative study. Yet we found that the system was little used and had marginal effects on the quality of care for children with amblyopia and their parents. It appeared that the main problem underlying this patient information system was that the needs of those people who actually would be using the system had never really been investigated. The designers had built their assumptions about these needs into the system. These appeared to be mistaken at so many levels that the system could not become a success. As a result of this pilot evaluation, the patient information project was thoroughly transformed. This study makes clear that a thorough exploration of user needs before building the system, using qualitative research methods, may be crucial because it can prevent mismatches and maximizes the chance that the eventual information system meets its most important aim: to enhance patient empowerment and improve the quality of care.

HDR brachytherapy applied to cervical carcinoma with moderate lateral expansion: modified principles of treatment.

BACKGROUND AND PURPOSE: In order to meet the deficiencies of endocavitary applications, a combined technique was introduced with the aim of achieving better target coverage for improvement of loco-regional tumour control. In high dose rate (HDR) endocavitary applications with tandem and ovoids, enlargement of the distance between the ovoids, shifting of dwell times and also optimization often fail to achieve sufficient expansion of the cervical parametrial area encompassed by the reference isodose. MATERIALS AND METHODS: The Deventer method, whereby HDR endocavitary and HDR interstitial brachytherapy are applied in the same session, was applied for tumours with a lateral expansion of 25 mm or more from the axis of the cervical canal. For the addition of HDR interstitial brachytherapy, each ovoid was provided with a channel which allowed insertion of an afterloading needle into the cervix up to a fixed depth. The dose specifications and dosimetry in neighbouring organs are presented in detail. RESULTS: Seventy-six combined applications were given to 41 patients. The follow-up averaged at 23 months, with a maximum of 59 months. No severe early or persistent late complications were observed. In stage IIB tumours, the most important evaluation of the merits of this technique, the disease-free 3-year survival determined with the Kaplan-Meier method was 75% (n=20). CONCLUSIONS: The Deventer method of HDR endocavitary and HDR interstitial brachytherapy applied in the same session is a feasible method for enlargement of the reference isodose envelope in the cervical parametrial area. The 3-year disease-free survival in stage IIB patients and the low complication rates in all stages together, justify its continuation.

A conformation number to quantify the degree of conformality in brachytherapy and external beam irradiation: application to the prostate.

PURPOSE: This article presents a method of quantitative assessment of the degree of conformality and its designation by a single numerical value. METHODS AND MATERIALS: A conformation number is introduced to evaluate objectively the degree of conformality. A comparison is made between the conformation number as found for external beam treatment plans and ultrasonically guided 125I seed implants for localized prostate cancer. RESULTS: The conformation number in case of a planning target volume irradiated with two opposed open beams, three open beams, and three beams with customized blocks amounted to 0.17, 0.39, and 0.65, respectively. The conformation number as found for ultrasonically guided permanent prostate implants using 125I seeds averaged 0.72. CONCLUSIONS: The conformation number is a convenient instrument for indicating the degree of conformality by a single numerical value. Treatments with a conformation number greater than 0.60 might be termed conformal radiotherapy.

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.

Dose determination in bladder and rectum during intracavitary irradiation of cervix carcinoma.

The radiation dosage in the base of the bladder and in the anterior wall of the rectum during intracavitary irradiation of cervix carcinoma can be determined easily by use of intracavitary transvesical and transrectal ultrasound and simultaneous radiography. In case of excessive doses to the organs at risk, the dose can be lowered by rearrangement of the vaginal gauze packing in the same sitting.

Implications of lung corrections for dose specification in radiotherapy.

The influence of taking into account the lung density in the calculation of the dose distributions was examined for a group of 23 patients with bronchus carcinoma. Anatomical information and electron densities were available by means of CT scans. All calculations were made for cobalt-60 gamma rays using a patient specific multiple field irradiation technique. The effect of lung tissues for the dose distributions was calculated using a generalization of Batho's method. All patients entered into this study were planned to receive a minimum tumor dose of 60 Gy, calculated without correction for lung density. The actual dose in each patient was recalculated with lung correction. In the group of patients the corrected minimum tumor dose varied between 63 Gy and 77 Gy (105-128%). The calculated homogeneity of the dose in the target area and the dose to surrounding normal tissues are also affected by lung correction. For different radiation techniques and different methods of dose specification, the interrelation between corrected and uncorrected dose is presented in tables. The impact of lung correction on the uncorrected dose schedules that are commonly used in the treatment of patients with lung cancer is discussed.

Computerized tomography in carcinoma of the prostate: treatment volume and morbidity in radiotherapy.

Fifty-five patients with adenocarcinoma of the prostate were treated with external beam irradiation. In 31 of them conventional localization was used and in 24 computerized tomography was used in the localization of the treatment volume. In these 24 patients we see a larger treatment volume with a wider distribution. This method would appear to be superior to the use of standard irradiation fields. The larger treatment volume did not increase morbidity.