Interstitial brachytherapy for recurrent breast cancer using a high dose rate lr-192 remote afterloading system: a report of two cases

We employed interstitial brachytherapy using a high dose rate Ir-192 remote afterloading unit in two breast cancer patients with locoregional recurrence. In the first case, skin metastasis was treated, with favorable control of the infield tumor but subsequent persistent sequelae and multiple outfield metastases. This experience caused us to be cautious when choosing brachytherapy for the second case, in whom a solitary metastasis to an axillary lymph node was successfully treated. Although this method is still investigational, it may play a critical role in the treatment of locoregional recurrence resistant to other treatment modalities.     

Interstitial high dose-rate brachytherapy: principle, practice and first clinical experiences with a new remote-controlled afterloading system using Ir-192

In our newly developed remote-controlled afterloading system, a single Ir-192-source is moved within hollow stainless steel needles, which are arranged strictly parallel and are uniformly spaced. Dose calculation is performed by an especially designed computer program using geometrical bodies (ellipsoid, cylinder and plane parallel body) as idealized tumor shapes. Reference points for calculation are defined on the surface of the chosen geometrical body. Theoretical base, principles of dosage, handling and first clinical experiences after treatment of 28 patients are presented.     

Accelerated partial breast irradiation using interstitial high dose rate 192iridium brachytherapy: Early Australian experience and review of the literature

Accelerated partial breast irradiation (APBI) is an evolving new technique of adjuvant irradiation in selected women with early‐stage breast cancer. We developed a pilot programme of APBI in 2000 and report end results in seven patients followed for a mean of 42.7 months (range 29–55 months). Good to excellent cosmesis and no loco‐regional relapse or systemic metastases have occurred. The literature related to APBI is reviewed.     

First clinical experience with a remote afterloading system for low dose rate interstitial breast implants

A new remote afterloading system, developed for low or medium dose rate brachytherapy has been clinically evaluated. With this apparatus, the Micro-Selectron, up to 15 ¹⁹²Ir wires or seeds encapsulated in a plastic tubing can be loaded simultaneously into implants. Improved radiological protection for the medical staff has now been achieved with this apparatus. One hundred and sixty patients have been treated so far with breast implants using remote afterloading. The mean error frequency over the last year was about one error every 10 treatments of which about half could be considered as machine failures. All treatments could, however, be finished by using spare channels of the afterloader. We have found that a set of 45 source assemblies is adequate for the loading of the breast-needle implants performed in our institute. Every 6 to 8 weeks a new set of ¹⁹²Ir sources is prepared.     

Intermediate dose rate remote afterloading brachytherapy for intraluminal control of bronchogenic carcinoma.

Forty-five patients with symptomatic proximal malignant airway disease received 128 intraluminal intermediate dose rate (IDR) brachytherapy treatments by remote afterloading technique. Multiple small catheters were bronchoscopically placed. Iridium-192 sources delivering an intermediate dose rate (200-1000 rads/hr) were guided under remote computer control. Treatment times were 1-4 hr. Fourteen of these patients also received YAG laser photoresection. External beam radiation was also given (6000 rads) to 16 patients for curative intent and (3000 rads) to 9 patients for palliative intent. Twenty recurrent disease patients were also treated, but they did not receive external irradiation. An obstruction score (OS) was developed in an attempt to quantitate the improvement in intraluminal narrowing. Patients treated with curative intent showed 66% improvement after initial therapy. Initial therapy for palliative patients showed an 84% improvement and for recurrent disease patients, 64% of luminal narrowing was seen. Patients who received laser in addition to brachytherapy showed a 70% reduction. A 67% improvement was seen in those who did not receive laser therapy. The entire group averaged a 69% improvement of narrowing. Four complications, three minor, (1 bronchospasm, and 2 episodes of transient intratreatment increased ventricular irritability) and one major (pneumothorax) were noted. The relatively short treatment times allowed most of the treatments to be performed on an outpatient basis and were well-tolerated by the patients. Forty-four of the 45 patients experienced significant symptomatic improvement. The remote afterloading technique allowed improved radiation protection for personnel.     

Adjuvant high dose rate brachytherapy (Ir-192) in the management of keloids which have recurred after surgical excision and external radiation.

We describe our experience with adjuvant high dose rate brachytherapy (Ir-192) (HDRB) in patients, who failed surgery and post-operative external radiation therapy. The salvage treatment consisted of excision of the keloid and wound closure followed by HDRB (15 Gy in three fractions given on three consecutive business days beginning the day of surgery). At the time of last follow up, 88% (15/17) of the keloids were without any evidence of recurrence.     

Dosimetric comparisons between high dose rate interstitial and MammoSite balloon brachytherapy for breast cancer.

BACKGROUND AND PURPOSE: To make a quantitative dosimetric comparison between treatment plans of multicatheter-based interstitial brachytherapy (IB) and MammoSite brachytherapy (MSB) for breast cancer. PATIENTS AND METHODS: Seventeen patients treated with IB and twenty-four with MSB were selected for the study. The irradiations for IB patients were planned using conventional two-film reconstruction technique. Following the implantation each patient was CT scanned, then the planning target volume (PTV) was retrospectively defined on the CT data set, and the original plan was reconstructed (CONV plans). Furthermore, conformal plans were also created by dose optimization on target (CONF plans). The planning for MammoSite applicator was based on CT imaging. The dose distributions were evaluated with dose-volume histograms. The following parameters were calculated and compared: volume of the PTV and its percentage receiving 90, 100, 150 and 200% of the prescribed dose (V90, V100, V150 and V200, respectively), percentage dose covering 90% of the PTV (D90), minimum dose in the PTV (D(min)), maximum dose in the PTV (D(max)) for MSB only, dose homogeneity index (DHI), and conformal index (COIN). To assess the dose to organs at risk maximum point dose to skin, lung and heart was used. RESULTS: The median number of implanted catheters for IB was 11 (range: 6-13), the average balloon volume for MSB was 59.1cm(3) (range: 43.4-75.3 cm(3)). The average volume of PTV was 63.4 and 109.6 cm(3) for IB and MSB patients, respectively. The average V90, V100, V150, V200 were 76, 70, 26 and 9% for IB(CONV); 92, 87, 55 and 32% for IB(CONF) and 96, 88, 27 and 3% for MSB, respectively. The average D90 was 72, 94 and 99%, the D(min) was 47, 58 and 67%, respectively. The mean D(max) was 258% for MSB. The average DHI was 0.63, 0.37 and 0.70 for IB(CONV), IB(CONF) and MSB, respectively. D(max) to skin, lung and heart were 45, 54 and 31% for IB(CONV), 50, 55 and 29% for IB(CONF,) 97, 66 and 27% for MSB, respectively. CONCLUSIONS: Target volume coverage was better for MSB than conventional IB, and it was comparable to conformal IB. The suboptimal coverage for IB patients is due to radiography based planning, which is unable to provide 3D information of the target. Dose homogeneity was somewhat better for MSB than IB(CONV), but the dose to skin and lung was higher for MSB. The MSB provides dosimetrically acceptable dose plans. The quality of interstitial implants can be improved with image-guided catheter insertions regarding both homogeneity and conformality.     

Intrauterine high dose rate afterloading brachytherapy: Experience of fractionated therapy using a cervical sleeve technique

Using a standard three-channel Manchester-type tube and ovoid high dose rate applicator system, 46 consecutive patients have been treated for carcinoma of the cervix or endometrium. To facilitate fractionated treatments using high dose rate afterloading, a technique has been developed using an indwelling cervical sleeve inserted under an initial general anaesthetic. All patients received at least two insertions; in five patients we have delivered a total of six consecutive fractions on an outpatient basis without anaesthesia once the sleeve was in situ. Acute morbidity related to the procedure was some degree of uterine pain, which was relieved with nitrous oxide inhalation, and mild, but self-limiting, vaginal discharge. Complete late morbidity data are not yet available, but, in 30% of 25 evaluable patients, minor problems have been observed, particularly vaginal oedema and stenosis. Only one major late event has required surgery.Fractionated afterloading intrauterine brachytherapy can be delivered on an outpatient basis without anaesthesia using this cervical sleeve technique.     

Does inverse planning applied to Iridium192 high dose rate prostate brachytherapy improve the optimization of the dose afforded by the Paris system?

BACKGROUND AND PURPOSE: The purpose of the work is to analyse for 192Ir prostate brachytherapy (BT) some of the different steps in optimizing the dose delivered to the CTV, urethra and rectum. MATERIALS AND METHODS: Between 07/1998 and 12/2001, 166 patients were treated with 192Ir wires providing a low dose rate, according to the Paris system philosophy and with the 2D version of the treatment planning IsisR. 40-45 Gy were delivered after an external beam radiotherapy of 40 Gy. The maximum tolerable doses for BT were 25 Gy to the anterior third of the rectum on the whole length of the implant (R dose) and 52 Gy to the urethra on a 1cm length (Umax). A Umax/CTV dose ratio >1.3 represented a pejorative value as the planned dose of 40-45 Gy could not be achieved. On the other side a ratio 1.25 decreased significantly with optimization required on CTV contours and additional constraints on urethra while the R/CTV ratio was maintained under 0.55. For initial Umax/CTV >1.3 or >1.25 but 相似文献   

Accelerated partial breast irradiation using interstitial high dose rate brachytherapy: preliminary clinical and dosimetric results after 61 patients

PURPOSE: Among all the accelerated and partial breast irradiation (APBI) techniques, low then high dose rate, interstitial brachytherapy (HDIB) was the first to be used in this field. This study presents the preliminary clinical and dosimetric results of the APBI using HDIB, performed in Antoine Lacassagne Cancer Center of Nice. PATIENTS AND METHODS: From June 2004 to March 2008, 61 patients (37 primary tumors and 24 second conservative treatments after local recurrence) presenting with T1-2 pN0 non-lobular invasive breast carcinoma, underwent lumpectomy with sentinel lymph node dissection and intraoperative tube placement for HDIB. Dose distribution analysis, using dose-volume histograms, was achieved based on a postoperative CT scan. A comparative dosimetric study was performed between optimized (O) and non-optimized (NO) dose distribution. Then, based on conformal index calculation, a novel index was proposed taking into account not only the conformity but also the homogeneity of HDIB implant. An analysis of dose gradient impact on HDIB biological equivalence dose was also conducted. Statistical analysis used T test confirmed by Wilcoxon test for cohort including less than 30 patients. RESULTS: The comparative dosimetric analysis between O and NO dose distributions shown that conformity indexes (conformal index, conformal number, and D90%) were significantly increased after optimization. Improving conformity leads to increasing hyperdosage volumes (V150% and V200%). A new index named conformity and homogeneity index (CHI) including V150% values, modified the conformal index. A total dose of 34 Gy, delivered through HDIB in 10 fractions over five days was biologically equivalent to 41.93 Gy assuming alpha/beta = 4 Gy and 75.76 Gy if the dose gradient was considered in the calculation. CONCLUSIONS: HDIB is considered as one of the best IPAS technique. HDIB allows dose distribution optimization, skin spearing and accurate clinical target volume definition. Furthermore, HDIB dose gradient could play a key role for breast cancer local control.     

High dose rate afterloading brachytherapy for prostate cancer: catheter and gland movement between fractions.

Fractionated high dose rate afterloading brachytherapy for prostate cancer requires a robust means of catheter fixation with good quality assurance. Catheter position and dosimetry has been formally evaluated in 20 consecutive patients representing a total of 332 catheters undergoing two HDR afterloading brachytherapy fractions over 36 h. The mean interfraction movement of catheters as measured by external length was less than 1 mm, but within the prostate on consecutive CT scans there was a mean interfraction movement of 11.5 mm away from the prostate base. This has a significant impact on implant dosimetry as measured by D90 and the COIN index, unless corrected by repositioning the catheters.     

Safety aspects of pulsed dose rate brachytherapy: analysis of errors in 1,300 treatment sessions

PURPOSE: To determine the safety of pulsed-dose-rate (PDR) brachytherapy by analyzing errors and technical failures during treatment. METHODS AND MATERIALS: More than 1,300 patients underwent treatment with PDR brachytherapy, using five PDR remote afterloaders. Most patients were treated with consecutive pulse schemes, also outside regular office hours. Tumors were located in the breast, esophagus, prostate, bladder, gynecology, anus/rectum, orbit, head/neck, with a miscellaneous group of small numbers, such as the lip, nose, and bile duct. Errors and technical failures were analyzed for 1,300 treatment sessions, for which nearly 20,000 pulses were delivered. For each tumor localization, the number and type of occurring errors were determined, as were which localizations were more error prone than others. RESULTS: By routinely using the built-in dummy check source, only 0.2% of all pulses showed an error during the phase of the pulse when the active source was outside the afterloader. Localizations treated using flexible catheters had greater error frequencies than those treated with straight needles or rigid applicators. Disturbed pulse frequencies were in the range of 0.6% for the anus/rectum on a classic version 1 afterloader to 14.9% for orbital tumors using a version 2 afterloader. Exceeding the planned overall treatment time by >10% was observed in only 1% of all treatments. Patients received their dose as originally planned in 98% of all treatments. CONCLUSIONS: According to the experience in our institute with 1,300 PDR treatments, we found that PDR is a safe brachytherapy treatment modality, both during and outside of office hours.     

Design of a phantom for the quality control of high dose rate 192Ir source used in brachytherapy.

BACKGROUND AND PURPOSE: A new phantom is proposed for measuring the strength of 192Ir high dose rate sources and for verification of the dose calculated by the treatment planning system. The complete formalism and measurement procedure for this phantom is described, as well as the preliminary results obtained in a number of centers around Brazil. MATERIALS AND METHODS: The measurements are performed using powder thermoluminescent dosimeter capsules; the source strength is measured in air and the verification of the dose calculation algorithm in water phantom. The correction factors required to take into account the specificities related to the geometry and the phantom materials have been assessed using the PENELOPE Monte Carlo code and experimental methods. The dedicated phantom, constructed to use as part of a QA program, in this case specifically for high dose rate 192Ir brachytherapy sources, allows simultaneous irradiation of three thermoluminescent dosimeter capsules, requiring only one source stop (dwell positions). RESULTS: The phantom was mailed to seven radiotherapy institutions in Brazil, and the results show its usefulness in verifying the source air kerma and correctness of treatment planning dose calculation in water phantom. CONCLUSIONS: The comparison made between the phantom measurements, the well-type ionization chamber, and source specifications stated by the hospital (most of the times provided by the source manufacturer) agreed within 3% showing the quality in the HDR dose delivery in Brazilian radiotherapy centers.     

High dose rate interstitial brachytherapy in soft tissue sarcoma: technical aspects and results.

BACKGROUND: Radiation is essential for function preservation in the management of soft tissue sarcoma (STS). One of the advantages of brachytherapy is that it allows for specific localization of radiation dose to the tumor bed. We examined the results of our clinical experiences with immediate postoperative high dose rate (HDR) brachytherapy and external beam radiation treatment (EBRT) for STS. METHODS: A total of 17 patients (11 primary and six recurrent) between 1995 and 1999 were included in this review. The inclusion criteria for HDR and EBRT were as follows: (1) high-grade tumor, (2) low-grade tumor of > or = 10 cm, (3) recurrent tumor, (4) tumor abutting or invading critical structures and (5) positive margin. The catheters (six French) were placed parallel to the long axis of the tumor with a 1-1.5 cm spacing in between. If necessary, muscle or gel-foam was placed over the critical structures to maintain a minimum space of 0.5 cm from the catheters. On postoperative day 6, patients received HDR (2-3 Gy/fraction x6, twice daily). Three weeks later, patients received EBRT (total 36-60 Gy). The follow-up duration was between 13 and 60 months (median 31 months). RESULTS: There was no local failure within the radiation field in any of the patients. One patient required wound revision for delayed healing after brachytherapy. During EBRT, most patients experienced only mild erythema (grade 1 or 2 skin reaction). In long-term follow-up, there were no patients with neuropathy or significant fibrosis. CONCLUSIONS: Our results suggest that immediate postoperative HDR with a total dose of 12-18 Gy over 3 days is an effective treatment combined with EBRT in the management of STS.     

In vivo thermoluminescence dosimetry dose verification of transperineal 192Ir high-dose-rate brachytherapy using CT-based planning for the treatment of prostate cancer

PURPOSE: To evaluate the potential of in vivo thermoluminescence dosimetry to estimate the accuracy of dose delivery in conformal high-dose-rate brachytherapy of prostate cancer. METHODS AND MATERIALS: A total of 50 LiF, TLD-100 cylindrical rods were calibrated in the dose range of interest and used as a batch for all fractions. Fourteen dosimeters for every treatment fraction were loaded in a plastic 4F catheter that was fixed in either one of the 6F needles implanted for treatment purposes or in an extra needle implanted after consulting with the patient. The 6F needles were placed either close to the urethra or in the vicinity of the median posterior wall of the prostate. Initial results are presented for 18 treatment fractions in 5 patients and compared to corresponding data calculated using the commercial treatment planning system used for the planning of the treatments based on CT images acquired postimplantation. RESULTS: The maximum observed mean difference between planned and delivered dose within a single treatment fraction was 8.57% +/- 2.61% (root mean square [RMS] errors from 4.03% to 9.73%). Corresponding values obtained after averaging results over all fractions of a patient were 6.88% +/- 4.93% (RMS errors from 4.82% to 7.32%). Experimental results of each fraction corresponding to the same patient point were found to agree within experimental uncertainties. CONCLUSIONS: Experimental results indicate that the proposed method is feasible for dose verification purposes and suggest that dose delivery in transperineal high-dose-rate brachytherapy after CT-based planning can be of acceptable accuracy.     

Effect of dose rate on local control and complications in the reirradiation of head and neck tumors with interstitial iridium-192

Interstitial Iridium-192 was used as the sole treatment for 23 previously irradiated patients with recurrent or second primary malignancy in the head and neck region. Doses used in initial external beam treatment ranged from 50.0 to 72.0 Gy, in daily fractions of 180 to 200 cGy. Retreatment with interstitial implant using the Quimby system delivered total doses between 38.5 and 60 Gy, with hourly dose rates of 30 to 66 cGy. Local control in the implanted volume was seen in 21 of 23 patients at 5 to 34 months post-implant (median 10 months). Dose rate (hourly dose delivered at 0.5 cm beyond the periphery of the implanted tumor volume) did not affect local control, but did have a significant impact on severe complications (soft tissue necrosis and fistulae; p = 0.26). No effect on either local control or complication rate was found for volume of implant, initial external beam radiation dose, time to recurrence, or anatomic site of treatment. These findings suggest that interstitial irradiation is effective treatment for head and neck cancers in previously irradiated sites. Dose rates as low as 32 cGy/hr provided adequate local control, with few long-term complications to date; doses above 42 cGy/hr may be associated with severe and even fatal complications.     

Response to pulsed dose rate and low dose rate irradiation with and without mild hyperthermia using human breast carcinoma cell lines.

The purpose of this study was to establish whether a pulsed dose rate (PDR) treatment of 1.5 Gy given every 3 h in combination with 41 degrees C mild hyperthermia or a continuous low dose rate (LDR) treatment with mild hyperthermia could radiosensitize two isogenic human breast carcinoma cell lines in comparison to pulsed dose rate or low dose rate irradiation alone. The radiation resistant cell line was derived from the parental cell line and was transfected to over-express DNA polymerase beta. The end-points assessed were the survival of the cells using the clonogenic assay, the amount of residual DSB(s) using the comet assay and gene expression of polymerase beta using RT-PCR. Results showed that the PDR and LDR treatments combined with mild hyperthermia caused significant radiosensitization when compared to PDR and LDR irradiation alone in terms of the clonogenic and comet assays with both cell lines. RT-PCR results showed that polymerase beta levels of expression were not elevated in response to these treatments, implying that this polymerase may not be involved in sub-lethal damage repair or thermal radiosensitization. These results suggest a potential clinical advantage when combining LDR or PDR with hyperthermia, since they indicate that hyperthermia is an effective radiosensitizer.