Investigating the impact of breast positioning control on physical treatment parameters in multi-catheter breast brachytherapy.

PURPOSE: To assess the effects of a workflow for reproducible patient and breast positioning on implant stability during high-dose-rate multi-catheter breast brachytherapy. METHODS: Thirty patients were treated with our new positioning control workflow. Implant stability was evaluated based on a comparison of planning-CTs to control-CTs acquired halfway through the treatment. To assess geometric stability, button-button distance variations as well as Euclidean dwell position deviations were evaluated. The latter were also quantified within various separated regions within the breast to investigate the location-dependency of implant alterations. Furthermore, dosimetric variations to target volume and organs at risk (ribs, skin) as well as isodose volume changes were analyzed. Results were compared to a previously treated cohort of 100 patients. RESULTS: With the introduced workflow, the patient fraction affected by button-button distance variations > 5 mm and by dwell position deviations > 7 mm were reduced from 37% to 10% and from 30% to 6.6%, respectively. Implant stability improved the most in the lateral to medial breast regions. Only small stability enhancements were observed regarding target volume dosimetry, but the stability of organ at risk exposure became substantially higher. D0.2ccm skin dose variations > 12.4% and D0.1ccm rib dose variations > 6.7% were reduced from 11% to 0% and from 16% to 3.3% of all patients, respectively. CONCLUSION: Breast positioning control improved geometric and dosimetric implant stability for individual patients, and thus enhanced physical plan validity in these cases.

On the implant stability in adaptive multi-catheter breast brachytherapy: Establishment of a decision-tree for treatment re-planning.

BACKGROUND AND PURPOSE: To assess implant stability and identify causes of implant variations during high-dose-rate multi-catheter breast brachytherapy. MATERIALS AND METHODS: Planning-CTs were compared to control-CTs acquired halfway through the treatment for 100 patients. For assessing geometric stability, Fréchet-distance and button-to-button distance changes of all catheters as well as variations of Euclidean distances and convex hulls of all dwell positions were determined. The CTs were inspected to identify the causes of geometric changes. Dosimetric effects were evaluated by target volume transfers and re-contouring of organs at risk. The dose non-uniformity ratio (DNR), 100% and 150% isodose volumes (V100 and V150), coverage index (CI), and organ doses were calculated. Correlations between the examined geometric and dosimetric parameters were assessed. RESULTS: Fréchet-distance and dwell position deviations >2.5 mm as well as button-to-button distance changes >5 mm were detected for 5%, 2%, and 6.3% of catheters, but for 32, 17, and 37 patients, respectively. Variations occurred enhanced in the lateral breast and close to the ribs, e.g. due to different arm positions. Only small dosimetric effects with median DNR, V100, and CI variations of -0.01 ± 0.02, (-0.5 ± 1.3)ccm, and (-1.4 ± 1.8)% were observed in general. Skin dose exceeded recommended levels for 12 of 100 patients. Various correlations between geometric and dosimetric implant stability were found, based on which decision-tree regarding treatment re-planning was established. CONCLUSION: Multi-catheter breast brachytherapy shows a high implant stability in general, but considering skin dose changes is important. To increase implant stability for individual patients, we plan to investigate patient immobilization aids during treatments.

Seed-displacements in the immediate post-implant phase in permanent prostate brachytherapy.

PURPOSE: To investigate differences in seed-displacements between the immediate post-implant phase (day 0-1) and the time to post-plan computed tomography (CT) (day 1-30) in seed prostate brachytherapy. MATERIALS AND METHODS: Seed positions were identified on the intra-operatively created ultrasound-based treatment plan (day 0) and CT scans of day 1 and 30 for 33 patients. The day 1 (30) seed arrangement was registered onto the day 0 (1) arrangement using a seed-only approach. Based on a 1:1 assignment of seeds via the Kuhn-Munkres algorithm, seed-displacements were analyzed. Displacements were evaluated depending on strand-length and anatomical implant location. Resulting dosimetric effects were calculated. RESULTS: Seed-displacements in the immediate post-implant phase (median displacements: 3.8 ± 3.6 mm) were stronger than in the time to post-plan CT (2.1 ± 2.6 mm) and enhanced along the superior-inferior direction. From day 0 to 1, strands containing one (7.3 ± 5.4 mm) or two (8.1 ± 5.8 mm) seeds showed larger displacements than strands of higher lengths (up to 4.2 ± 7.0 mm), whereas no length-dependency was found to day 30. Seeds implanted in base and apex tended to move towards the prostate midzone during both time periods. D90 (dose that 90% of prostate receives) was with variations of 2 ± 15 Gy more stable from day 1 to 30 than in the immediate post-implant phase (-18 ± 11 Gy). CONCLUSION: Seed-displacements in the immediate post-implant phase was enhanced compared to day 1-30. This may result from uncertainties in the gold-standard ultrasound-based treatment planning and implantation. Adaptive implantation workflows appear useful for ensuring high implant stability from the beginning.

Automating implant reconstruction in interstitial brachytherapy of the breast: A hybrid approach combining electromagnetic tracking and image segmentation.

BACKGROUND AND PURPOSE: To develop a method for automatic reconstruction of catheter implants in interstitial brachytherapy (iBT) of the breast by means of electromagnetic tracking (EMT) with the goal of making treatment planning as time-effective and accurate as possible. MATERIALS AND METHODS: The implant geometry of 64 patients was recorded using an afterloader prototype with EMT functionality immediately after the planning CT. EMT data were transferred to the CT image space by rigidly registering the catheter fixation buttons as landmarks. To further improve reconstruction accuracy, the EMT reconstruction points were used as starting points to define small regions of interest (ROI) in the CT image. Within these ROIs, the catheter track was segmented in the CT using image processing operations such as thresholding and blob detection, thus refining the reconstruction. The perpendicular distance between the refined EMT implant reconstruction points and the manually reconstructed catheters by an experienced treatment planner was calculated as a measure of their geometric agreement. RESULTS: Geometrically, the refined EMT based implant reconstruction shows excellent agreement with the manual reconstruction. The median distance across all patients is 0.25 mm and the 95th percentile is 1 mm. Refinement takes approximately 0.5 s per reconstruction point and typically does not exceed 3 min per implant at no user interaction. CONCLUSION: The refined EMT based implant reconstruction proved to be extremely accurate and fast compared to manual reconstruction. The presented procedure can in principle be easily transferred to clinical routine and therefore has enormous potential to provide significant time savings in iBT treatment planning whilst improving reconstruction accuracy.

Permanent LDR prostate brachytherapy: Comprehensive characterization of seed-dynamics within the prostate on a seed-only level.

PURPOSE: Seed brachytherapy is a well-established treatment modality for prostate cancer. However, there is still a lack of profound characterizations of seed motions within the prostate. We assessed these dynamics between day 0 and day 30 of brachytherapy. METHODS: We considered 45 patients with 2408 implanted seeds, and performed a 1:1 assignment between their positions on post-plan CT (nominal day 30) and intraoperative ultrasound (day 0). Geometric seed arrangement changes were measured for each patient and the entire collective. The impact of seed strand-lengths and implant regions was investigated. Correlations with patient characteristics were evaluated. We determined corresponding dosimetric effects by calculating common dose metrics. RESULTS: We found a median seed displacement of 4.3 mm [interquartile range: 3.1-6.9 mm], occurring preferentially in superior-inferior direction. Single and double strands moved significantly stronger than strands of higher lengths. Seed dynamics was more pronounced in base (5.6 mm [3.7-10.7 mm]) and apex (6.5 mm [4.1-15.0 mm]) than in the mid-gland (3.8 mm [2.7-5.0 mm]), and less pronounced in peripheral (4.3 mm [3.0-6.7 mm]) than in urethra-near (5.5 mm [3.5-10.7 mm]) regions. Correlations of seed dynamics with prostate volume changes and the number of implanted seeds and needles were found. D90 (dose that 90% of the prostate receives) varied by a median of 3 Gy [-6 to 15 Gy] between treatment plan and post-plan, but >40 Gy for individual patients. CONCLUSIONS: Reducing seed dynamics is important to ensure a high treatment quality. For this, strands containing ≥3 seeds may be useful, implantations in base-, apex-, and urethra-near zone should be avoided, and the number of needles and seeds may be minimized where possible.

Brachytherapy focal dose escalation using ultrasound based tissue characterization by patients with non-metastatic prostate cancer: Five-year results from single-center phase 2 trial.

PURPOSE: This prospective trial investigates side effects and efficacy of focal dose escalation with brachytherapy for patients with prostate cancer. METHODS AND MATERIALS: In the Phase II, monocentric prospective trial 101 patients with low-/intermediate- and high-risk prostate cancer were enrolled between 2011 and 2013. Patients received either PDR-/HDR-brachytherapy alone with 86-90 Gy (EQD2, α/ß = 3 Gy) or PDR-/HDR-brachytherapy as boost after external beam radiation therapy up to a total dose of 91-96 Gy (EQD2, α/ß = 3 Gy). Taking place brachytherapy all patients received the simultaneous integrated focal boost to the intra-prostatic tumor lesions visible in computer-aided ultrasonography (HistoScanning™) - up to a total dose of 108-119 Gy (EQD2, α/ß = 3 Gy). The primary endpoint was toxicity. Secondary endpoints were cumulative freedom from local recurrence, PSA-free survival, distant metastases-free survival, and overall survival. This trial is registered with ClinicalTrials.gov, number NCT01409876. RESULTS: Median follow-up was 65 months. Late toxicity was generally low with only four patients scoring urinary grade 3 toxicity (4/101, 4%). Occurrence of any grade of late rectal toxicities was very low. We did not register any grade ≥2 of late rectal toxicities. The cumulative 5 years local recurrence rate (LRR) for all patients was 1%. Five years- biochemical disease-free survival estimates according Kaplan-Meier were 98,1% and 81,3% for low-/intermediate-risk and high-risk patients, respectively. Five years metastases-free survival estimates according Kaplan-Meier were 98,0% and 83,3% for all patients, low-/intermediate-risk and high-risk patients, respectively. CONCLUSIONS: The 5 years-results from this Phase II Trial show that focal dose escalation with computer-aided ultrasonography and brachytherapy for patients with non-metastatic prostate cancer is safe and effective.

First clinical experience with a novel, mobile cone-beam CT system for treatment quality assurance in brachytherapy.

BACKGROUND AND PURPOSE: On-site cone-beam computed tomography (CBCT) has gained in importance in adaptive brachytherapy during recent years. Besides treatment planning, there is increased need particularly for image-guidance during interventional procedures and for image-guided treatment quality assurance (QA). For this purpose, an innovative CBCT device was rolled out at our hospital as the first site worldwide. We present the first clinical images and experiences. MATERIALS AND METHODS: The novel CBCT system is constructed of a 121 cm diameter ring gantry, and features a 43.2â€¯× 43.2 cm2 flat-panel detector, wireless remote-control via tablet-PC, and battery-powered maneuverability. Within the first months of clinical operation, we performed CBCT-based treatment QA for a total of 26 patients (8 with breast, 16 with cervix, and 2 with vaginal cancer). CBCT scans were analyzed regarding potential movements of implanted applicators in-situ during the brachytherapy course. RESULTS: With the presented device, treatment QA was feasible for the majority of patients. The CBCT scans of breast patients showed sufficient contrast between implanted catheters and tissue. For gynecologic patients, a distinct visualization of applicators was achieved in general. However, reasonable differentiations of organic soft tissues were not feasible. CONCLUSION: The CBCT system allowed basic treatment QA measures for breast and gynecologic patients. For image-guidance during interventional brachytherapy procedures, the current image quality is not adequate. Substantial performance enhancements are required for intraoperative image-guidance.

Long-term results of a protocol-based ultrasound-guided salvage brachytherapy as re-irradiation for local recurrent prostate cancer.

BACKGROUND AND PURPOSE: To assess the long-term results of protocol-based ultrasound-guided salvage pulsed-dose rate brachytherapy in locally recurrent prostate cancer following previous radiation therapy. MATERIALS AND METHODS: A total of 82 patients (median age 69 years) with locally recurrent prostate cancer after previous external beam radiation therapy (43/82, 52.4%), prostatectomy and adjuvant radiation therapy (24/82, 29.3%) or brachytherapy (15/82, 18.3%) were treated with sole salvage interstitial pulsed-dose rate brachytherapy (PDR-BT). The treatment regimen consisted of two PDR-BT sections with 30 Gy (single pulse dose 0.6 Gy/h, 24 h per day) each up to a total reference dose of 60 Gy (EQD2 = 71.5 Gy-eq). The endpoints of the present analysis are cumulative local recurrence-rate, PSA-free survival, overall survival and the treatment-associated late toxicity according to the "Common Toxicity Criteria" with a median follow-up of 49 months (range, 12-129 months). RESULTS: The 5-y. overall cumulative local recurrence rate was 17.7% with no significant differences between low, intermediate and high-risk groups. Differences in PSA-free survival were marginally non-significant, at 67.3%, 70.4% and 63.8% for low, intermediate and high risk group, respectively. No grade 3 gastrointestinal late side effects have been observed. The most common late side effect was urinary incontinence grade 1-3 and urinary frequency/urgency grade 1-3 in 18.3% (15/82) and 17.1% (14/82) of patients, respectively. CONCLUSION: PDR salvage brachytherapy in local recurrent previously irradiated prostate cancer is efficient with low late toxicity. Salvage-brachytherapy represents a valuable therapeutic option for the treatment of previously irradiated locally recurrent prostate cancer.

Is adaptive treatment planning in multi-catheter interstitial breast brachytherapy necessary?

PURPOSE: For 55 patients treated with interstitial multi-catheter breast brachytherapy the need for adaptive treatment planning was assessed. METHODS AND MATERIALS: For all patients a treatment planning computed tomography (CT) and a follow-up CT were acquired and used for the retrospective evaluation. Keeping dwell time and dwell positions constant, the treatment plan assessed directly after catheter implantation was compared to the situation 48 h after implantation. Both manual catheter reconstructions, based on the planning and follow-up CT, were rigid registered to each other and the resulting deviations analyzed, like the difference between corresponding dwell positions (ΔDP) or the discrete Fréchet distance. Further, the dosimetric changes, e.g., coverage index (ΔCI), conformal index (ΔCOIN) and dose non-uniformity ratio (ΔDNR) were considered for a deformed planning target volume (PTV) and the rigid warped PTV structure. The PTV was deformed according to the vector field estimated between the two acquired CTs. RESULTS: Over all patients with rigid aligned CTs a mean ΔDP, ΔCI, ΔCOIN and ΔDNR were determined to 2.41 ±â€¯1.73 mm, 3.10 ±â€¯3.17%, 0.009 ±â€¯0.007 and 0.036 ±â€¯0.040, respectively. Considering the deformed PTV ΔCI was estimated to 5.05 ±â€¯4.14%. CONCLUSION: In conclusion, in 4% of the cases re-planning would have been beneficial to ensure the planned dose delivery. Large PTV changes or large DP deviations were found to be the main reasons for dosimetric variations.

Estimation of inter-fractional variations in interstitial multi-catheter breast brachytherapy using a hybrid treatment delivery system.

PURPOSE: Irradiation of the tumor bed using interstitial multi-catheter brachytherapy is one of the treatment options for breast cancer patients. In order to ensure the planned dose delivery an advanced quality intervention method using an electromagnetic tracking (EMT) system is presented. The system is used to assess inter-fractional variations within the framework of a patient study. METHODS AND MATERIALS: Until now 41 patients were included in the study for the evaluation and overall 355 EMT measurements were performed. The catheter traces are measured automatically and sequentially using an afterloader prototype (Flexitron, Elekta, Veenendaal, The Netherlands) equipped with an EMT sensor. The implant geometry is tracked directly after implantation, after CT imaging and after each irradiation fraction. The acquired data is rigidly registered to the catheter traces defined in the treatment plan and the dwell positions (DP) are reconstructed. DPs defined in treatment planning serve as reference. Breathing motion was corrected and recorded using three reference 6DoF sensors placed on the patients' skin. The Euclidean distance between the planned and reconstructed DPs provides information about possible inter-fractional deviations. Further, the influence of various factors on the occurrence of large deviations was investigated, like the patients' age, the length of the catheter, the breast volume, etc. RESULTS: Over all patient measurements a median Euclidean distance of 2.19 mm was determined between the reconstructed DPs and the reference DPs. The median deviation combining all datasets was minimal (1.67 mm) at the measurement directly after CT imaging. The deviations between the different fractions have a median distance of 2.31 mm which could be improved to 2.05 mm by adapting the treatment plan according to the follow-up CT. No correlation between the distance to the skin, ribs, mammilla or the breast volume and the occurrences of large deviations was found. The largest deviations were determined in the upper inner quadrant of the breast. CONCLUSION: The afterloader prototype could be well integrated into the clinical routine and is beneficial for ensuring the quality of the brachytherapy. Overall, a small median DP deviation, lower than the used step size of 2.5 mm, was detected.

Impact of inter- and intra-observer variabilities of catheter reconstruction on multi-catheter interstitial brachytherapy of breast cancer patients.

PURPOSE: The aim of this study was to evaluate inter- and intra-observer variabilities of catheter reconstruction and its dosimetric impact for multi-catheter interstitial breast cancer patients. METHODS AND MATERIALS: In order to evaluate inter-observer variabilities (IOV) three medical physicists reconstructed the catheter traces of 13 patients. These manual reconstructions were further compared to the automatic reconstruction algorithm integrated into the planning system and one on purpose imprecise manual reconstruction. For intra-observer variabilities (IAV) repeated reconstructions of two physicists were compared for 13 patients. In total 426 catheters were considered. Keeping dwell times, dwell positions, the optimization and the normalization relative points constant the geometrical deviations between the corresponding dwell positions of the reference data set and the investigated reconstructions were evaluated. Also, the effect on the quality indices, such as coverage index (CI), dose non-uniformity ratio (DNR) or conformal index (COIN), and the exposure of the organs at risk were analyzed. RESULTS: Over all patients and all different catheter reconstructions considered for IOV a mean deviation between the corresponding dwell positions of 0.60 ±â€¯0.35 mm was detected. The first observer had a mean deviation of 0.54 ±â€¯0.32 mm, whereas the second observer yielded a mean deviation of 0.58 ±â€¯0.37 mm. The length of the catheter traces varied in the mean by 0.51 ±â€¯0.45 mm. The mean relative deviation of the CI, DNR, COIN, mean heart dose and mean lung dose varied by 0.27 ±â€¯0.31%, 0.0027 ±â€¯0.0025, 0.0036 ±â€¯0.0033, 0.024 ±â€¯0.019%, 0.05 ±â€¯0.11%, respectively. The skin dose (D0.2ccm) changed in the maximum 8.52%. On average IAV reached a deviation between the corresponding dwell positions of 0.49 ±â€¯0.30 mm. IOVs and IAVs proved to be significantly different (Wilcoxon's test p < 0.01). CONCLUSIONS: The study proved that a repeated reconstruction of the catheter traces does not lead to large geometrical deviations or to a significant change in the dose exposure. But the lack of ground truth makes the estimation of the quality of the reconstruction challenging. A precise reconstruction mapping the reality is a necessity for the planned dose delivery. With all considered reconstruction techniques reliable quality indices for the target and the organs at risk could be obtained.

Introduction of a hybrid treatment delivery system used for quality assurance in multi-catheter interstitial brachytherapy.

Multi-catheter interstitial brachytherapy (iBT) is a treatment option for breast cancer patients after breast conserving surgery. Typically, only a few additional quality interventions after the first irradiation have been introduced to ensure the planned treatment delivery. Therefore, the purpose of this study is to show the possibilities of an electromagnetic tracking (EMT) system integrated into the afterloader for quality assurance (QA) in high-dose rate (HDR) iBT of patients with breast cancer. The hybrid afterloader system equipped with an electromagnetic sensor was used for all phantom and patient measurements. Phantom measurements were conducted to estimate the quality of different evaluation schemes. After a coherent point drift registration of the EMT traces to the reconstructed catheters based on computed tomograms the dwell positions (DP) were defined. Different fitting and interpolation methods were analyzed for the reconstruction of DPs. All estimated DPs were compared to the DPs defined in treatment planning. Until now, the implant geometry of 20 patients treated with HDR brachytherapy was acquired and explored. Regarding the reconstruction techniques, both fitting and interpolation were able to detect manually introduced shifts and swaps. Nonetheless, interpolation showed superior results (RMSE = 1.27 mm), whereas fitting seemed to be more stable to distortion and motion. The EMT system proved to be beneficial for QA in brachytherapy and furthermore, clinical feasibility was proven.

Electromagnetic tracking (EMT) technology for improved treatment quality assurance in interstitial brachytherapy.

Electromagnetic Tracking (EMT) is a novel technique for error detection and quality assurance (QA) in interstitial high dose rate brachytherapy (HDR-iBT). The purpose of this study is to provide a concept for data acquisition developed as part of a clinical evaluation study on the use of EMT during interstitial treatment of breast cancer patients. The stability, accuracy, and precision of EMT-determined dwell positions were quantified. Dwell position reconstruction based on EMT was investigated on CT table, HDR table and PDR bed to examine the influence on precision and accuracy in a typical clinical workflow. All investigations were performed using a precise PMMA phantom. The track of catheters inserted in that phantom was measured by manually inserting a 5 degree of freedom (DoF) sensor while recording the position of three 6DoF fiducial sensors on the phantom surface to correct motion influences. From the corrected data, dwell positions were reconstructed along the catheter's track. The accuracy of the EMT-determined dwell positions was quantified by the residual distances to reference dwell positions after using a rigid registration. Precision and accuracy were investigated for different phantom-table and sensor-field generator (FG) distances. The measured precision of the EMT-determined dwell positions was ≤ 0.28 mm (95th percentile). Stability tests showed a drift of 0.03 mm in the first 20 min of use. Sudden shaking of the FG or (large) metallic objects close to the FG degrade the precision. The accuracy with respect to the reference dwell positions was on all clinical tables < 1 mm at 200 mm FG distance and 120 mm phantom-table distance. Phantom measurements showed that EMT-determined localization of dwell positions in HDR-iBT is stable, precise, and sufficiently accurate for clinical assessment. The presented method may be viable for clinical applications in HDR-iBT, like implant definition, error detection or quantification of uncertainties. Further clinical investigations are needed.

Reirradiation for recurrent head and neck cancer with salvage interstitial pulsed-dose-rate brachytherapy: Long-term results.

PURPOSE: To assess the long-term results of protocol-based interstitial pulsed-dose-rate (PDR) brachytherapy as reirradiation combined with simultaneous chemotherapy and interstitial hyperthermia in selected patients with recurrent head and neck tumors. MATERIALS AND METHODS: A total of 104 patients with biopsy-proven recurrent head and neck cancer were treated with interstitial PDR brachytherapy. Salvage surgery had also been undergone by 53/104 (51%) patients (R1 or R2 resection in > 80% of patients). Salvage brachytherapy alone was administered in 81 patients (78%), with a median total dose of 56.7 Gy. Salvage brachytherapy in combination with external beam radiotherapy (EBRT) was performed in 23/104 patients (32%), using a median total dose of DREF = 24 Gy. Simultaneously to PDR brachytherapy, concomitant chemotherapy was administered in 58/104 (55.8%) patients. A single session of interstitial hyperthermia was also used to treat 33/104 (31.7%) patients. The analysis was performed after a median follow-up of 60 months. RESULTS: Calculated according to Kaplan-Meier, local tumor control rates after 2, 5, and 10 years were 92.5, 82.4, and 58.9%, respectively. Comparing results of salvage PDR brachytherapy with or without simultaneous chemotherapy, the 10-year local control rates were 76 vs. 39% (p = 0014), respectively. No other patient- or treatment-related parameters had a significant influence on treatment results. Soft tissue necrosis or bone necrosis developed in 18/104 (17.3%) and 11/104 (9.6%) patients, respectively, but only 3% of patients required surgical treatment. CONCLUSION: PDR interstitial brachytherapy with simultaneous chemotherapy is a very effective and, in experienced hands, also a safe treatment modality in selected patients with head and neck cancer in previously irradiated areas.

Re-irradiation with interstitial pulsed-dose-rate brachytherapy for unresectable recurrent head and neck carcinoma.

PURPOSE: To assess the long-term results of protocol-based interstitial pulsed-dose-rate (PDR) brachytherapy combined with simultaneous chemotherapy in selected patients with recurrent head and neck tumors not amenable to salvage surgery. METHODS AND MATERIALS: A total of 51 patients with recurrent head and neck cancer were treated with interstitial PDR brachytherapy. Forty patients (78%) had salvage brachytherapy alone using a median total dose of 60 Gy. Salvage brachytherapy in combination with external beam therapy was performed in 11 patients (22%) using a median total dose of DREF=27 Gy. Simultaneously with the PDR brachytherapy, a concomitant chemotherapy was administered in 35/51 (69%) of patients. The analysis was performed after a median followup of 58 months. RESULTS: Local control rates calculated according to Kaplan-Meier after 2 and 5 years were 71% and 57%, respectively. Comparing results of salvage PDR brachytherapy with or without simultaneous chemotherapy, the 5-year local recurrence-free survival rates were 78.9% vs. 38.5% (p=0.01), respectively. No other patient or treatment-related parameters had a significant influence on treatment results. A total of 9/51 (17.7%) and 6/51 (11.8%) patients developed soft-tissue necrosis or bone necrosis, respectively, but only 2% of patients required surgical treatment. CONCLUSIONS: PDR interstitial brachytherapy with pulse doses between 0.4 and 0.7 Gy/h/24 h with simultaneous chemotherapy is an effective and safe option for curative therapy in selected patients with head and neck cancer in previously irradiated areas, which are not suitable for salvage surgery.

Interstitial pulsed-dose-rate brachytherapy for head and neck cancer--Single-institution long-term results of 385 patients.

PURPOSE: To assess the long-term results of protocol-based pulsed-dose-rate (PDR) interstitial brachytherapy (iBT) in 385 patients with head and neck cancer who underwent PDR-iBT preferably after minimal, nonmutilating surgery. METHODS AND MATERIALS: From 1997 to 2009, a total of 385 patients received protocol-based PDR-iBT for head and neck cancer. Brachytherapy was preceded by surgery in most of our patients (326/385, 84.7%). Altogether, 246 of 385 patients (63.9%) received iBT alone and 135 of 385 patients (36.1%) in combination with external beam radiation therapy. The analysis was done after a median followup of 63 months. RESULTS: The 5-, 10-, and 15-year local relapse-free survival rates according to Kaplan-Meier test for all analyzed patients were 85.8%, 83.1%, and 80.2%, respectively. The 5-, 10-, and 15-year overall survival and disease-free survival rates were 68.9%, 52.2%, and 44.1%, and 81.3%, 79.3%, and 76.3%, respectively. For N0-/N1- vs. N2-patients, we observed significantly different 5-year local recurrence-free survival rates with values of 92.3% and 73.7%, respectively (p=0.007). No other patient or treatment-related parameters had a significant influence on treatment results. Serious late side effects, such as soft tissue or bone necrosis, were observed in 39 of 385 patients (10.2%) and 18 of 385 patients (4.9%), respectively. CONCLUSIONS: The PDR-iBT with 0.4-0.7Gy each hour, 24h per day for patients with head and neck cancer is a proven, effective, and safe treatment method with excellent long-term data.

Long term results of a prospective dose escalation phase-II trial: interstitial pulsed-dose-rate brachytherapy as boost for intermediate- and high-risk prostate cancer.

PURPOSE: We reviewed our seven year single institution experience with pulsed dose rate brachytherapy dose escalation study in patients with intermediate and high risk prostate cancer. MATERIALS AND METHODS: We treated a total of 130 patients for intermediate and high risk prostate cancer at our institution between 2000 and 2007 using PDR-brachytherapy as a boost after conformal external beam radiation therapy to 50.4 Gy. The majority of patients had T2 disease (T1c 6%, T2 75%, T3 19%). Seventy three patients had intermediate-risk and 53 patients had high-risk disease according to the D'Amico classification. The dose of the brachytherapy boost was escalated from 25 to 35 Gy - 33 pts. received 25 Gy (total dose 75 Gy), 63 pts. 30 Gy (total dose 80 Gy) and 34 pts. 35 Gy, (total dose 85 Gy) given in one session (dose per pulse was 0.60 Gy or 0.70 Gy/h, 24h per day, night and day, with a time interval of 1h between two pulses). PSA-recurrence-free survival according to Kaplan-Meier using the Phoenix definition of biochemical failure was calculated and also late toxicities according to Common Toxicity Criteria scale were assessed. RESULTS: At the time of analysis with a median follow-up of 60 months biochemical control was achieved by 88% of patients - only 16/130 patients (12.3%) developed a biochemical relapse. Biochemical relapse free survival calculated according to Kaplan-Meier for all patients at 5 years was 85.6% (83.9% for intermediate-risk patients and 84.2% for high-risk patients) and at 9 years' follow up it was 79.0%. Analysing biochemical relapse free survival separately for different boost dose levels, at 5 years it was 97% for the 35 Gy boost dose and 82% for the 25 and 30 Gy dose levels. The side effects of therapy were negligible: There were 18 cases (15%) of grade 1/2 rectal proctitis, one case (0.8%) of grade 3 proctitis, 18 cases (15%) of grade 1/2 cystitis, and no cases (0%) with dysuria grade 3. No patient had a bulbourethral stricture requiring dilation or new onset incontinence. CONCLUSIONS: Image-guided conformal PDR-brachytherapy using up to 35 Gy as boost dose after 50 Gy of external beam radiation therapy (total dose up to 85 Gy) is a very effective treatment option with very low morbidity in patients with intermediate or high risk prostate cancer. Further dose escalation seems possible.

Radiation exposure of the heart, lung and skin by radiation therapy for breast cancer: a dosimetric comparison between partial breast irradiation using multicatheter brachytherapy and whole breast teletherapy.

BACKGROUND AND PURPOSE: Accelerated partial breast irradiation by means of multicatheter brachytherapy shows great promise in the modern treatment of early breast cancer combining high efficacy in preventing tumour recurrence with low levels of toxicity. The present work attempts a dosimetric comparison between this treatment modality and conventional whole breast external beam radiotherapy by looking at differences in risk organ exposure to radiation. PATIENTS AND METHODS: The planning CT data sets of 16 consecutive patients with left-sided breast cancer who received external beam radiotherapy to the whole breast followed by a boost to the tumour bed using multicatheter interstitial brachytherapy after breast conserving surgery were used to create two independent physical treatment plans - one for an external radiotherapy, one for sole partial breast brachytherapy in each case assuming a total reference dose of 50Gy for each patient. Dose-volume parameters D(0.1cc), D(0.5cc), D(1cc,)D(2cc), D(5cc,)D(10cc), D(25cc), D(50cc), V(100), V(90), V(50), V(10), V(5) for the ipsilateral lung, the heart and the adjacent skin were calculated and compared between the two treatment modalities. RESULTS: All organs at risk showed a substantially lower radiation exposure in the brachytherapy plan. This was most pronounced for the heart with values differing by a factor of four. Although somewhat less marked this was also true for the ipsilateral lung and the adjacent skin with exposure ratios of three and two, respectively. CONCLUSIONS: With the use of multicatheter interstitial brachytherapy substantial reductions in the radiation exposure of risk organs can be achieved in comparison to whole breast external beam radiotherapy. These are likely to translate into profound clinical benefits.