The Curie-Da Vinci Connection: 5-Years' Experience With Laparoscopic (Robot-Assisted) Implantation for High-Dose-Rate Brachytherapy of Solitary T2 Bladder Tumors.

PURPOSE: To report experience and early results of laparoscopic implantation for interstitial brachytherapy (BT) of solitary bladder tumors and the feasibility of a high-dose-rate (HDR) schedule. METHODS AND MATERIALS: From December 2009 to April 2015, 57 patients with a T2 solitary bladder tumor were treated in Arnhem with transurethral bladder resection followed by external beam irradiation, applied to the bladder and regional iliac lymph nodes, 40 Gy in 20 fractions, 5 fractions per week, and within 1 week interstitial HDR BT, in selected cases combined with partial cystectomy and lymph node dissection. The BT catheters were placed via a transabdominal approach with robotic assistance from a Da Vinci robot after a successful initial experience with a nonrobotic laparoscopic approach. The fraction schedule for HDR was 10 fractions of 2.5 Gy, 3 fractions per day. This was calculated to be equivalent to a reference low-dose-rate schedule of 30 Gy in 60 hours. Data for oncologic outcomes and toxicity (Common Toxicity Criteria version 4) were prospectively collected. RESULTS: These modifications resulted in an average postoperative hospitalization of 6 days, minimal blood loss, and no wound healing problems. Two patients had severe acute toxicity: 1 pulmonary embolism grade 4 and 1 cardiac death. Late toxicity was mild (n=2 urogenital grade 3 toxicity). The median follow-up was 2 years. Using cumulative incidence competing risk analysis, the 2-year overall, disease-free, and disease-specific survival and local control rates were 59%, 71%, 87%, and 82%, respectively. CONCLUSIONS: The benefits of minimally invasive surgery for implantation of BT catheters and the feasibility of HDR BT in bladder cancer are documented. The patient outcome and adverse events are comparable to the best results published for a bladder-sparing approach.

Brachytherapy versus cystectomy in solitary bladder cancer: a case control, multicentre, East-Netherlands study.

PURPOSE: Comparing the outcome of surgery and brachytherapy-based radiotherapy in patients with solitary T1G3/T2 bladder tumour in, a retrospective case-control study, because efforts for a randomised clinical trial comparing these modalities have failed. MATERIALS AND METHODS: Cystectomy group. Patients were selected using the pathological registration system (PALGA). 289 cases of TURT followed by cystectomy, indicated by a muscle--invading bladder tumour were performed in three East-Netherlands medical centres between 1991 and 2001. Out of this group 179 patients with clinical T2N0M0 bladder tumour were selected. All the consecutive files were analysed by a urologist and a radiation oncologist and 65 of those patients (mean age 63.7 years) would have been eligible for brachytherapy, based on an initial analysis: cystoscopy estimated tumour size, post-TURT pathological report, completed by CT-scan and/or, MRI-scan. A final pathological report after radical cystectomy was not considered for patients' selection. Brachytherapy group. Patients were selected using a prospective registration study aiming at determination of our treatment results. 89 Patients (mean age 68.4 years) underwent TURT followed by a course of external beam irradiation and interstitial brachytherapy from 1983 till 2005 in the Arnhem Radiotherapy Institute. RESULTS: The median follow-up for the brachytherapy group was 5.7 years (range 0.2-21.4 years), for the cystectomy group was 5.05 years (range: 0.04-16.8 years). No difference in disease-specific survival (DSS) could be detected with a 5- and 10-year DSS of 71% and 66% in the brachytherapy group and 60% and 57% in the cystectomy group, respectively. Five-year overall survival (OS) was 57% in the brachytherapy group and 52% in the cystectomy group, however, the 10-year OS was better in the cystectomy than in the brachytherapy group (42% and 33%, respectively). This is caused by the significant age difference in favour of the cystectomy group. Cystectomy-free survival in the brachytherapy group was 70%. CONCLUSION: Radical cystectomy is the treatment of choice for patients with muscle-invasive bladder carcinoma. However, in a selected patient population a bladder sparing treatment, i.e. a combination of transurethral tumour resection (TURT), external beam irradiation and interstitial brachytherapy, can be applied successfully. This concerns a solitary, T1G3 or T2 bladder tumour, with a diameter<5 cm.

Bath and shower effect in spinal cord: the effect of time interval.

PURPOSE: To evaluate the time dependency of the sensitizing effect of a large low-dose field on a small high-dose field in the rat cervical spinal cord. METHODS AND MATERIALS: Irradiation experiments with a relatively low dose to a large volume (bath, 2 cm, 4 Gy) were combined with high doses to a small volume (shower, 4.7 mm, 26-43 Gy) at intervals of 8 minutes and 3, 12, and 24 hours. Both a functional score defined as motor impairment and a histologic score characterized as white matter necrosis were used as end points. RESULTS: Application of the 4-Gy bath dose resulted in a significant decrease in 50% isoeffective dose (ED(50)) from 48.7 Gy (small field) to 40.8 Gy. If the interval was extended, the ED(50) increased to 44.4 (3 hours) and 44.8 Gy (12 hours), whereas a 24-hour interval resulted in a significant increase to 51.9 Gy. If the histologic end point was considered, the ED(50) for all dose-response curves decreased slightly with 0.2 to 2.6 Gy without significantly changing the kinetics. CONCLUSIONS: The bath effect as applied in the bath-and-shower experiment lasted for at least 12 hours and disappeared in the 24-hour interval. This time scale clearly deviates from the repair kinetics in spinal cord derived from low-dose-rate and fractionated irradiations.

Changes in prostate shape and volume and their implications for radiotherapy after introduction of endorectal balloon as determined by MRI at 3T.

PURPOSE: To determine the changes in prostate shape and volume after the introduction of an endorectal coil (ERC) by means of magnetic resonance imaging (MRI) at 3T. METHODS AND MATERIALS: A total of 44 consecutive patients with biopsy-proven prostate cancer underwent separate MRI examinations at 3T with a body array coil and subsequently with an ERC inflated with 50 mL of fluid. Prospectively, two experienced readers independently evaluated all data sets in random order. The maximal anteroposterior, right-to-left, and craniocaudal prostate diameters, as well as the total prostate and peripheral zone and central gland volumes were measured before and after ERC introduction. The changes in prostate shape and volume were analyzed using Wilcoxon's test for paired samples. RESULTS: The introduction of the ERC significantly changed the prostate shape in all three directions, with mean changes in the anteroposterior, right-to-left, and craniocaudal diameters of 15.7% (5.5 mm), 7.7% (3.5 mm), and 6.3% (2.2 mm), respectively. The mean total prostate, peripheral zone, and central gland volume decreased significantly after ERC introduction by 17.9% (8.3 cm(3)), 21.6% (4.8 cm(3)), and 14.2% (3.4 cm(3)), respectively. CONCLUSION: ERC introduction as observed by 3T MRI changed the prostate shape and volume significantly. The mean anteroposterior diameter was reduced by nearly one-sixth of its original diameter, and the mean total prostate volume was decreased by approximately 18%. This could cause difficulties and should be considered when using ERC-based MRI for MRI-computed tomography fusion and radiotherapy planning.

Off-line setup corrections only marginally reduce the number of on-line corrections for prostate radiotherapy using implanted gold markers.

PURPOSE: To evaluate the efficiency of combining on-line and off-line corrections for the positioning of patients receiving external beam radiotherapy for prostate cancer. MATERIALS AND METHODS: Daily portal images were acquired during the treatment of 102 patients to verify and correct the position of the prostatic gland using implanted gold markers. In addition to an existing off-line procedure, on-line corrections were applied in the anterior-posterior (AP) direction only, to limit the increase in daily workload. The possible increase in workload of the combined correction procedure for on-line corrections in either two or three directions was further investigated by simulating the required position corrections for 500 treatments. RESULTS: The combined correction procedure in AP-direction resulted in a systematic dispersion and random variation of 0.3mm (1 SD) and 1.0mm (1 SD), respectively. Application of off-line corrections during pre-treatment setup reduced the number of required on-line corrections from 22+/-4 (1 SD) to 17+/-4 (1 SD), at the cost of 1.4+/-1.0 (1 SD) off-line corrections. For on-line corrections in two or three directions, application of a combined on-line/off-line procedure did not noticeably reduce the number of setup corrections. CONCLUSIONS: The on-line procedure is feasible and significantly improves both systematic and random errors to below 1 mm with a limited impact on the workload and treatment time. The application of off-line setup corrections during pre-treatment patient positioning only marginally reduces the number of on-line setup corrections.

Dose-volume effects in rat thoracolumbar spinal cord: the effects of nonuniform dose distribution.

PURPOSE: To investigate dose-volume effects in rat spinal cord irradiated with nonuniform dose distributions and to assess regional differences in radiosensitivity. METHODS AND MATERIALS: A total of 106 rats divided into three groups were irradiated with (192)Ir gamma-rays at a high dose rate. The groups were irradiated with one, two, or six catheters distributed around the thoracolumbar spinal cord to create different dose distributions. After irradiation, the animals were tested for motor function for 9 months. The response was defined as motor dysfunction and WM or nerve root necrosis. Dose-response data were analyzed with a probit analysis as function of the dose level at a percentage of the volume (D(%)) and with different normal tissue complication probability models. Additionally, the histologic responses of the individual dose voxels were analyzed after registration with the histologic sections. RESULTS: The probit analysis at D(24) (24% of the volume) gave the best fit results. In addition, the Lyman Kutcher Burman model and the relative seriality model showed acceptable fits, with volume parameters of 0.17 and 0.53, respectively. The histology-based analysis revealed a lower radiosensitivity for the dorsal (50% isoeffective dose [ED(50)] = 32.3) and lateral WM (ED(50) = 33.7 Gy) compared with the dorsal (ED(50) = 25.9 Gy) and ventral nerve roots (ED(50) = 24.1 Gy). CONCLUSIONS: For this nonuniform irradiation, the spinal cord did not show typical serial behavior. No migration terms were needed for an acceptable fit of the dose-response curves. A higher radiosensitivity for the lumbar nerve roots than for the thoracic WM was found.

Ultrasound-guided transrectal implantation of gold markers for prostate localization during external beam radiotherapy: complication rate and risk factors.

PURPOSE: To report the complication rate and risk factors of transrectally implanted gold markers, used for prostate position verification and correction procedures. METHODS AND MATERIALS: In 209 consecutive men with localized prostate cancer, four gold markers (1 x 7 mm) were inserted under ultrasound guidance in an outpatient setting, and the toxicity was analyzed. All patients received a questionnaire regarding complications after marker implantation. The complications and risk factors were further evaluated by reviewing the medical charts. RESULTS: Of the 209 men, 13 (6.2%) had a moderate complication, consisting of pain and fever that resolved after treatment with oral medication. In 1.9% of the men, minor voiding complaints were observed. Other minor transient complications, defined as hematuria lasting >3 days, hematospermia, and rectal bleeding, occurred in 3.8%, 18.5%, and 9.1% of the patients, respectively. These complications were seen more often in patients with advanced tumor stage, younger age, and shorter duration of hormonal therapy. CONCLUSION: Transrectal gold marker implantation for high-precision prostate radiotherapy is a safe and well-tolerated procedure.

Reduced late rectal mucosal changes after prostate three-dimensional conformal radiotherapy with endorectal balloon as observed in repeated endoscopy.

PURPOSE: The aim of this study was to investigate prospectively the rectal wall (Rwall) spatial dose distribution, toxicity, and mucosal changes after prostate cancer radiotherapy with or without an endorectal balloon (ERB). METHODS AND MATERIALS: A total of 24 patients with ERB and 24 without ERB (No-ERB) were treated with three-dimensional conformal radiotherapy (3D-CRT) to a dose of 67.5 Gy. The Rwall was divided into 16 mucosal areas and Rwall dose surface maps were constructed. After 3 months, 6 months, 1 year, and 2 years a rectosigmoidoscopy was performed, and each mucosal area was scored on telangiectasia, congestion, ulceration, stricture, and necrosis. Late rectal toxicity was correlated with the endoscopic findings. RESULTS: The ERB significantly reduced the Rwall volume exposed to doses >40 Gy. Late rectal toxicity (grade >or=1, including excess of bowel movements and slight rectal discharge) was reduced significantly in the ERB group. A total of 146 endoscopies and 2,336 mucosal areas were analyzed. Telangiectases were most frequently seen and appeared after 6 months. At 1 and 2 years, significantly less high-grade telangiectasia (T 2-3) was observed in the ERB group at the lateral and posterior part of the Rwall. In mucosal areas exposed to doses >40 Gy, less high-grade telangiectases (T 2-3) were seen in the ERB group compared with the No-ERB group. CONCLUSIONS: An ERB reduced the Rwall volume exposed to doses >40 Gy, resulting in reduction of late rectal mucosal changes and reduced late rectal toxicity. Although further analysis is needed, these data suggest an ERB-induced increased tolerance for late Rwall damage.

Fast, daily linac verification for segmented IMRT using electronic portal imaging.

PURPOSE: Intensity modulated radiotherapy (IMRT) requires dedicated quality assurance (QA). Recently, we have published a method for fast (1-2 min) and accurate linac quality control for dynamic multileaf collimation, using a portal imaging device. This method is in routine use for daily leaf motion verification. The purpose of the present study was to develop an equivalent procedure for QA of IMRT with segmented (static) multileaf collimation (SMLC). MATERIALS AND METHODS: The QA procedure is based on measurements performed during 3- to 8-month periods at Elekta, Siemens and Varian accelerators. On each measurement day, images were acquired for a field consisting of five 3 x 22 cm(2) segments. These 10 monitor unit (MU) segments were delivered in SMLC mode, moving the leaves from left to right. Deviations of realized leaf gap widths from the prescribed width were analysed to study the leaf positioning accuracy. To assess hysteresis in leaf positioning, the sequential delivery of the SMLC segments was also inverted. A static 20 x 20 cm(2) field was delivered with exposures between 1 and 50 MU to study the beam output and beam profile at low exposures. Comparisons with an ionisation chamber were made to verify the EPID dose measurements at low MU. Dedicated software was developed to improve the signal-to-noise ratio and to correct for image distortion. RESULTS AND CONCLUSIONS: The observed long-term leaf gap reproducibility (1 standard deviation) was 0.1 mm for the Varian, and 0.2 mm for the Siemens and the Elekta accelerators. In all cases the hysteresis was negligible. Down to the lowest MU, beam output measurements performed with the EPID agreed within 1+/-1% (1SD) with ionisation chamber measurements. These findings led to a fast (3-4 min) procedure for accurate, daily linac quality control for SMLC.

IMRT boost dose planning on dominant intraprostatic lesions: gold marker-based three-dimensional fusion of CT with dynamic contrast-enhanced and 1H-spectroscopic MRI.

PURPOSE: To demonstrate the theoretical feasibility of integrating two functional prostate magnetic resonance imaging (MRI) techniques (dynamic contrast-enhanced MRI [DCE-MRI] and 1H-spectroscopic MRI [MRSI]) into inverse treatment planning for definition and potential irradiation of a dominant intraprostatic lesion (DIL) as a biologic target volume for high-dose intraprostatic boosting with intensity-modulated radiotherapy (IMRT). METHODS AND MATERIALS: In 5 patients, four gold markers were implanted. An endorectal balloon was inserted for both CT and MRI. A DIL volume was defined by DCE-MRI and MRSI using different prostate cancer-specific physiologic (DCE-MRI) and metabolic (MRSI) parameters. CT-MRI registration was performed automatically by matching three-dimensional gold marker surface models with the iterative closest point method. DIL-IMRT plans, consisting of whole prostate irradiation to 70 Gy and a DIL boost to 90 Gy, and standard IMRT plans, in which the whole prostate was irradiated to 78 Gy were generated. The tumor control probability and rectal wall normal tissue complication probability were calculated and compared between the two IMRT approaches. RESULTS: Combined DCE-MRI and MRSI yielded a clearly defined single DIL volume (range, 1.1-6.5 cm3) in all patients. In this small, selected patient population, no differences in tumor control probability were found. A decrease in the rectal wall normal tissue complication probability was observed in favor of the DIL-IMRT plan versus the plan with IMRT to 78 Gy. CONCLUSION: Combined DCE-MRI and MRSI functional image-guided high-dose intraprostatic DIL-IMRT planned as a boost to 90 Gy is theoretically feasible. The preliminary results have indicated that DIL-IMRT may improve the therapeutic ratio by decreasing the normal tissue complication probability with an unchanged tumor control probability. A larger patient population, with more variations in the number, size, and localization of the DIL, and a feasible mechanism for treatment implementation has to be studied to extend these preliminary tumor control and toxicity estimates.

Bladder filling variation during radiation treatment of prostate cancer: can the use of a bladder ultrasound scanner and biofeedback optimize bladder filling?

PURPOSE: To investigate the use of a bladder ultrasound scanner in achieving a better reproducible bladder filling during irradiation of pelvic tumors, specifically prostate cancer. METHODS AND MATERIALS: First, the accuracy of the bladder ultrasound scanner relative to computed tomography was validated in a group of 26 patients. Next, daily bladder volume variation was evaluated in a group of 18 patients. Another 16 patients participated in a biofeedback protocol, aiming at a more constant bladder volume. The last objective was to study correlations between prostate motion and bladder filling, by using electronic portal imaging device data on implanted gold markers. RESULTS: A strong correlation between bladder scanner volume and computed tomography volume (r = 0.95) was found. Daily bladder volume variation was very high (1 SD = 47.2%). Bladder filling and daily variation did not significantly differ between the control and the feedback group (47.2% and 40.1%, respectively). Furthermore, no linear correlations between bladder volume variation and prostate motion were found. CONCLUSIONS: This study shows large variations in daily bladder volume. The use of a biofeedback protocol yields little reduction in bladder volume variation. Even so, the bladder scanner is an easy to use and accurate tool to register these variations.

Rectal wall sparing effect of three different endorectal balloons in 3D conformal and IMRT prostate radiotherapy.

PURPOSE: To investigate the dosimetric consequences and rectal wall (Rwall) sparing effect of three different endorectal balloons (ERBs) for three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) for prostate cancer. METHODS AND MATERIALS: In 20 patients, 4 planning computed tomography scans were made: 1 without ERB and 3 with ERB1, ERB2, or ERB3 inserted. Two different planning target volumes were defined: prostate only, and prostate plus seminal vesicles. The 3D-CRT and IMRT planning techniques were used, and the prescription dose was 78 Gy. In 284 treatment plans, the Rwall mean dose, the Rwall normal tissue complication probability, and the absolute Rwall volumes exposed to > or =50 Gy (V(50)) and > or =70 Gy (V(70)) were calculated. For spatial dose distribution analysis, inner rectal wall dose maps and dose surface histograms were generated. RESULTS: Each ERB was tolerated well. In the case of 3D-CRT, each ERB showed a statistically significant reduction of all the measured parameters. ERB2 and ERB3 performed better than ERB1. In IMRT, a statistically significant reduction in the Rwall dose parameters could not be demonstrated for any of the ERBs. For 3D-CRT and IMRT, as a result of the rectal dilation, ranging from 8 to 20 cm in circumference, the ERBs resulted in a reduction of the relative inner Rwall surface exposed to intermediate and high doses. CONCLUSIONS: In 3D-CRT, any ERB showed a significant rectal wall sparing effect. ERB2 and ERB3 were superior to ERB1. For both 3D-CRT and IMRT, a reduction of the relative inner Rwall surface exposed to intermediate and high doses was found, which may lead to reduced late rectal toxicity. Development of user- and patient-friendly ERBs is warranted to increase their acceptability.

Prostate cancer: precision of integrating functional MR imaging with radiation therapy treatment by using fiducial gold markers.

The use of intensity-modulated radiation therapy for treatment of dominant intraprostatic lesions may require integration of functional magnetic resonance (MR) imaging with treatment-planning computed tomography (CT). The purpose of this study was to compare prospectively the landmark and iterative closest point methods for registration of CT and MR images of the prostate gland after placement of fiducial markers. The study was approved by the institutional ethics review board, and informed consent was obtained. CT and MR images were registered by using fiducial gold markers that were inserted into the prostate. Two image registration methods--a commonly available landmark method and dedicated iterative closest point method--were compared. Precision was assessed for a data set of 21 patients by using five operators. Precision of the iterative closest point method (1.1 mm) was significantly better (P < .01) than that of the landmark method (2.0 mm). Furthermore, a method is described by which multimodal MR imaging data are reduced into a single interpreted volume that, after registration, can be incorporated into treatment planning.

The effect of an endorectal balloon and off-line correction on the interfraction systematic and random prostate position variations: a comparative study.

PURPOSE: To investigate the effect of an endorectal balloon (ERB) and an off-line correction protocol on the day-to-day, interfraction prostate gland motion, in patients receiving external beam radiotherapy for prostate cancer. METHODS AND MATERIALS: In 22 patients, irradiated with an ERB in situ (ERB group) and in 30 patients without an ERB (No-ERB group), prostate displacements were measured daily in three orthogonal directions with portal images. Implanted gold markers and an off-line electronic portal imaging correction protocol were used for prostate position verification and correction. Movie loops were analyzed to evaluate prostate motion and rectal filling variations. RESULTS: The off-line correction protocol reduced the systematic prostate displacements, equally for the ERB and No-ERB group, to 1.3-1.8 mm (1 SD). The mean 3D displacement was reduced to 2.8 mm and 2.4 mm for the ERB and No-ERB group, respectively. The random interfraction displacements, relative to the treatment isocenter, were not reduced by the ERB and remained nearly unchanged in all three directions: 3.1 mm (1 SD) left-right, 2.6 mm (1 SD) superior-inferior, and 4.7 mm (1 SD) for the anterior-posterior direction. These day-to-day prostate position variations can be explained by the presence of gas and stool beside the ERB. CONCLUSIONS: The off-line corrections on the fiducial markers are effective in reducing the systematic prostate displacements. The investigated ERB does not reduce the interfraction prostate motion. Although the overall mean displacement is low, the day-to-day interfraction motion, especially in anterior-posterior direction, remains high compared with the systematic displacements.

Dose-volume effects in rat thoracolumbar spinal cord: an evaluation of NTCP models.

PURPOSE: To evaluate models for normal-tissue-complication probability (NTCP) on describing the dose-volume effect in rat thoracolumbar spinal cord. METHODS AND MATERIALS: Single-dose irradiation of four field lengths (4, 1.5, 1.0, and 0.5 cm) was evaluated by the endpoints paresis and white-matter necrosis. The resulting dose-response data were used to rank phenomenological and tissue architecture NTCP models. RESULTS: The 0.5-cm field length showed a steep increase in radiation tolerance. Statistical analysis of the model fits, which included evaluation of goodness of fit (GOF) and confidence intervals, resulted in the rejection of all the models considered. Excluding the smallest field length, the Schultheiss (D(50) = 21.5 Gy, k = 26.5), the relative seriality (D(50) = 21.4 Gy, s = 1.6, gamma(50) = 6.3), and the critical element (D(50,FSU) = 26.6 Gy, gamma(50,FSU) = 2.3, n = 1.3) model gave the best fit. CONCLUSION: A thorough statistical analysis resulted in a serial or critical-element behavior for the field lengths of 1.0 cm and greater. Including the 0.5-cm field length, the radiation response markedly diverged from serial properties, but none of the models applied acceptably described this dose-response relationship. This study suggests that the commonly assumed serial behavior of the spinal cord might be valid for daily use in external- beam irradiation.

Set-up improvement in head and neck radiotherapy using a 3D off-line EPID-based correction protocol and a customised head and neck support.

PURPOSE: First, to investigate the set-up improvement resulting from the introduction of a customised head and neck (HN) support system in combination with a technologist-driven off-line correction protocol in HN radiotherapy. Second, to define margins for planning target volume definition, accounting for systematic and random set-up uncertainties. METHODS AND MATERIALS: In 63 patients 498 treatment fractions were evaluated to develop and implement a 3D shrinking action level correction protocol. In the comparative study two different HN-supports were compared: a flexible 'standard HN-support' and a 'customised HN-support". For all three directions (x, y and z) random and systematic set-up deviations (1 S.D.) were measured. RESULTS: The customised HN-support improves the patient positioning compared to the standard HN-support. The 1D systematic errors in the x, y and z directions were reduced from 2.2-2.3 mm to 1.2-2.0 mm (1 S.D.). The 1D random errors for the y and z directions were reduced from 1.6 and 1.6 mm to 1.1 and 1.0 mm (1S.D.). The correction protocol reduced the 1D systematic errors further to 0.8-1.1 mm (1 S.D.) and all deviations in any direction were within 5 mm. Treatment time per measured fraction was increased from 10 to 13 min. The total time required per patient, for the complete correction procedure, was approximately 40 min. CONCLUSIONS: Portal imaging is a powerful tool in the evaluation of the department specific patient positioning procedures. The introduction of a comfortable customised HN-support, in combination with an electronic portal imaging device-based correction protocol, executed by technologists, led to an improvement of overall patient set-up. As a result, application of proposed recipes for CTV-PTV margins indicates that these can be reduced to 3-4 mm.

Saving bladders with brachytherapy: implantation technique and results.

PURPOSE: To analyze and report the treatment results of brachytherapy for solitary bladder cancer in the Arnhem Radiotherapy Institute. METHODS AND MATERIALS: Between January 1983 and October 1998, 63 patients with a solitary bladder tumor were treated with a combination of transurethral resection, external beam radiotherapy (EBRT), and interstitial radiotherapy. The indications for bladder-conserving treatment were tumor < or =5 cm, T1G3 (n = 14), T2G2 (n = 8), T2G3 (n = 37), and T3a (n = 4). The prescribed implant dose was either 55 Gy (range 50-65 Gy) in combination with small pelvis external beam RT, 3-4 fractions of 3.5 Gy (n = 58), or 30 Gy in combination with 20 fractions of 2 Gy external beam radiotherapy (n = 5). Brachytherapy was performed with 2-8 137Cs needles until 1995 (n = 48) and 2-5 afterloading catheters (192Ir) since 1996 (n = 15). Follow-up cystoscopies were performed at 3-month intervals during the first 2 years, then every 6 months for 3 years, and annually after the fifth year. The median follow-up was 4.9 years. RESULTS: Twenty patients developed local recurrences, of which 6 were "true in-implant recurrences," 12 were in second bladder locations, and 2 were urethral recurrences. All recurrences developed within 2.5 years after treatment. Of these 20 patients, 13 underwent cystectomy: 6 stayed disease-free, 1 died of postoperative complications, 2 developed regional metastases, and 4 developed distant metastases. The 5-year disease-specific survival rate was 80% for patients with Stage T1 and 60% for those with Stage T2 disease. The local control rate was 70% in the whole patient population and 80% after salvage cystectomy. Forty-four bladders were saved. Acute complications were seen in 14 patients, and no significant late complications occurred. CONCLUSION: Using this treatment technique, a high cure rate with conservation of the bladder and only minor toxicity can be obtained in a selected patient population having a solitary tumor < or =5 cm.