宫颈癌三维适形近距离治疗腔内联合插植施源器对比研究

目的：比较局部晚期宫颈癌三维适形近距离治疗Utrecht与Ring施源器剂量学差异。方法 MRI引导的三维适形近距离治疗局部晚期宫颈癌患者25例,间隔采用Utrecht与Ring施源器,共96次。按照施源器不同分成2个组,每组48次,其中26次先采用Ring施源器,22次先采用Utrecht施源器。考察高危CTV体积和在A点水平处宽、厚、D90;OAR的D2 cm3;V7 Gy 、W7 Gy,A、T7 Gy,A、W／T7 Gy,A;配对t检验差异。结果 Utrecht与Ring组高危CTV体积、在A点水平处宽、厚、D90均相近（P＝0．487、0．340、0．857、0．921）;膀胱、直肠、乙状结肠、小肠D2 cm3均相近（P＝0．136、0．802、0．985、0．458）;V7 Gy 、T7 Gy,A相近（P＝0．076、0．435）,W／T7 Gy,A为Utrecht组大于Ring组（P＝0．002）。结论高危CTV在A点水平处较宽,且在A点水平处宽厚比大的患者,适合采用Utrecht施源器。     

Multilayer conformal applicator for microwave heating and brachytherapy treatment of superficial tissue disease

Purpose: The purpose of this study was to construct and perform preliminary functionality evaluations of a multilayer conformal applicator with provisions for thermal monitoring, tight conformity and simultaneous microwave heating and brachytherapy treatment of large-area contoured surfaces.

Materials and methods: The multilayer conformal applicator consists of thermal monitoring catheters for fibre-optic monitoring of skin temperatures, a waterbolus, a PCB microwave antenna array, a dielectric spacer for brachytherapy considerations, brachytherapy catheters for delivering HDR radiation and an inflatable air bladder for improving conformity to contoured surfaces. The applicator also includes an elastic attachment structure to hold the applicator securely in place on the patient. The conformity of the applicator to irregular surfaces was evaluated through CT imaging of the applicator fitted onto a life-sized human torso phantom. The fluid flow dynamics of the waterbolus, which impact the effectiveness of temperature control, were evaluated with thermometry during a 19°C step change temperature of the circulating water.

Results: CT imaging showed improved conformity to the torso phantom surface following the application of gentle inward pressure from inflating the outer air bladder. Only a small number of 1–5?mm sized air gaps separated the conformal applicator and tissue surface. Thermometry testing of the bolus fluid flow dynamics demonstrated temperature uniformity within ±0.82°C across a 19?×?34?×?0.6?cm area bolus and ±0.85°C across a large 42?×?32?×?0.6?cm area bolus.

Conclusion: CT scans of the applicator confirmed that the applicator conforms well to complex body contours and should maintain good conformity and positional stability even when worn on a mobile patient. Thermometry testing of two different waterbolus geometries demonstrated that uniform circulation and temperature control can be maintained throughout large, complex bolus shapes.     

Multilayer conformal applicator for microwave heating and brachytherapy treatment of superficial tissue disease.

PURPOSE: The purpose of this study was to construct and perform preliminary functionality evaluations of a multilayer conformal applicator with provisions for thermal monitoring, tight conformity and simultaneous microwave heating and brachytherapy treatment of large-area contoured surfaces. MATERIALS AND METHODS: The multilayer conformal applicator consists of thermal monitoring catheters for fibre-optic monitoring of skin temperatures, a waterbolus, a PCB microwave antenna array, a dielectric spacer for brachytherapy considerations, brachytherapy catheters for delivering HDR radiation and an inflatable air bladder for improving conformity to contoured surfaces. The applicator also includes an elastic attachment structure to hold the applicator securely in place on the patient. The conformity of the applicator to irregular surfaces was evaluated through CT imaging of the applicator fitted onto a life-sized human torso phantom. The fluid flow dynamics of the waterbolus, which impact the effectiveness of temperature control, were evaluated with thermometry during a 19 degrees C step change temperature of the circulating water. RESULTS: CT imaging showed improved conformity to the torso phantom surface following the application of gentle inward pressure from inflating the outer air bladder. Only a small number of 1-5 mm sized air gaps separated the conformal applicator and tissue surface. Thermometry testing of the bolus fluid flow dynamics demonstrated temperature uniformity within +/-0.82 degrees C across a 19 x 34 x 0.6 cm area bolus and +/-0.85 degrees C across a large 42 x 32 x 0.6 cm area bolus. CONCLUSION: CT scans of the applicator confirmed that the applicator conforms well to complex body contours and should maintain good conformity and positional stability even when worn on a mobile patient. Thermometry testing of two different waterbolus geometries demonstrated that uniform circulation and temperature control can be maintained throughout large, complex bolus shapes.     

Radiation dosimetry of a conformal heat-brachytherapy applicator

The purpose of this paper is to report the radiation dosimetric characteristics of a new combination applicator for delivering heat and radiation simultaneously to large area superficial disease <1.5 cm deep. The applicator combines an array of brachytherapy catheters (for radiation delivery) with a conformal printed circuit board microwave antenna array (for heat generation), and a body-conforming 5-10 mm thick temperature-controlled water bolus. The rationale for applying both modalities simultaneously includes the potential for significantly higher response rate due to enhanced synergism of modalities, and lower peak toxicity due to temporal extension of heat and radiation induced toxicities. Treatment plans and radiation dosimetry are calculated with IPSA (an optimization tool developed at UCSF) for 15 x 15 cm(2) and 35 x 24 cm(2) applicators, lesion thicknesses of 5 to 15 mm, flat and curved surfaces, and catheter separation of 5 and 10 mm. The effect on skin dose of bolus thickness and presence of thin copper antenna structures between radiation source and tissue are also evaluated. Results demonstrate the ability of the applicator to provide conformal radiation dose coverage for up to 15 mm deep target volumes under the applicator. For clinically acceptable plans, tumor coverage is > 98%, homogeneity index > 0.95 and the percentage of normal tissue irradiated is < 20%. The dose gradient at the skin surface varies from 3 to 5 cGy/mm depending on bolus thickness and lesion depth. Attenuation of the photon beam by the printed circuit antenna array is of the order 0.25% and secondary electron emissions are absorbed completely within 5 mm of water bolus and plastic layers. Both phenomena can then be neglected in dose calculations allowing commercial software to be used for treatment planning. This novel applicator should prove useful for the treatment of diffuse chestwall disease located over contoured anatomy that may be difficult to treat with single field external beam therapy. By delivering heat and radiation simultaneously, increased synergism is expected with a TER in the range of 2-5. Lowering radiation dose by an equivalent factor may produce lower radiation toxicity with similar efficacy, while preserving the option of subsequent retreatment(s) with thermoradiotherapy in order to further extend patient survival.     

超声引导施源器植入在宫颈癌BT的应用

施源器的精准植入是宫颈癌BT的关键步骤,影像引导的加入保证了施源器植入的准确性。目前用于引导施源器植入的影像主要包括超声、CT、X线,部分单位也报道了MRI、腹腔镜的应用,但国际上无标准推荐影像。本文查阅近50篇文献及调查研究,发现各引导影像中超声引导具有突出的临床价值及指导意义。因此,本文针对超声引导施源器植入在宫颈癌BT的应用作一综述。     

Transperineal templates for brachytherapy treatment of pelvic malignancies--a comparison of standard and customized templates

A technique is described for the design and construction of customized templates for transperineal implants and interstitial hyperthermia of pelvic malignancies. The design of the template and the distribution of the transperineal Iridium-192 seed ribbons are based on prior optimization of the dose distribution. The target volume is defined by means of pelvic examination and pertinent radiographic studies including a CT. The pelvic CT study is obtained with a plastic obturator in the rectum or the vagina. The obturator is used as a reference structure for aligning the target contour from each image plane to form a composite 2-dimensional contour of maximum tumor extent in a plane perpendicular to the obturator. Dose distributions are calculated to determine the placement of the Iridium-192 seed ribbons in the template. Laparoscopic guidance is used for actual placement of brachytherapy source needles together with a rectal or vaginal obturator to stabilize the template and to assure that the needle placement conforms with the planned geometry. Dose distributions for 10 consecutive patients calculated for customized templates as well as for five commercially available standard templates show that the customized templates are superior to standard templates in that the planned dose distribution matches the configuration of the target volume and is more uniform than with standard templates.     

The variability of applicator position among high dose rate intracavitary brachytherapy applications in cervical cancer patients treated with ring & tandem applicators

OBJECTIVE: To evaluate the interindividual and intraindividual applicator position variability in high dose rate ring and tandem intracavitary brachytherapy applications in locally advanced cervical cancer. PATIENTS AND METHODS: Eight patients with locally advanced cervical cancer formed the study population. They had been treated in Dokuz Eylül University Department of Radiation Oncology between the years 2000 and 2005 with high dose rate intracavitary brachytherapy using ring and tandem applicators. The 3-dimensional geometric variation of the applicator center in craniocaudal, mediolateral and anteroposterior directions was determined on the basis of bony reference points in 24 pairs of orthogonal films obtained in the conventional simulator. Then the following evaluations were performed: 1) the applicator position variability in all applications (interindividual variability), 2) the intraindividual applicator position variability relative to the first application, 3) the intraindividual applicator position variability relative to the average of three applications. Among the potential factors that might influence the reproducibility of ring and tandem applications, age, stage, the period between external radiotherapy and brachytherapy were evaluated by univariate analysis. RESULTS: Standard deviation of interindividual applicator variability was 3.83 mm in craniocaudal, 0.39 mm in mediolateral and 2.86 mm in anteroposterior directions. The standard deviation of intraindividual variability relative to the first application was 1.91 mm in craniocaudal, 0.4 mm in mediolateral, and 4.26 mm in anteroposterior directions. The standard deviation of intraindividual variability relative to the average of three applications was 0.95 mm in craniocaudal, 1.86 mm in mediolateral, and 1.24 mm in anteroposterior directions. According to univariate analysis, no factor influenced applicator position variability. CONCLUSIONS: In order to extract definitive conclusions about factors that affect positional reproducibility of ring and tandem applicators, studies are needed that include larger numbers of patients.     

Three-dimensional conformal therapy or standard irradiation in localized carcinoma of prostate: preliminary results of a nonrandomized comparison

PURPOSE: We present preliminary results of a nonrandomized comparison of three-dimensional conformal radiation therapy (3D CRT) and standard radiation therapy (SRT) in localized carcinoma of the prostate in two groups of patients with comparable prognostic factors treated during the same period. METHODS AND MATERIALS: Between January 1992 and December 1997, 146 patients were treated with 3D CRT and 131 with SRT alone for clinical stage T1c or T2 histologically confirmed carcinoma of the prostate. None of these patients received hormonal therapy. Mean follow-up for all patients is 3 years (range, 1-6 years). For 3D CRT, 7 intersecting fields were used (Cerrobend blocking or multileaf collimation) to deliver 68-73.8 Gy to the prostate; 3D dose distributions and dose-volume histograms (DVHs) of the planning target volume, bladder, and rectum were obtained. SRT consisted of bilateral 120 degrees rotational arcs, with portals with 2-cm margins around the prostate to deliver 68-70 Gy to the prostate. The criterion for chemical disease-free survival was a postirradiation prostate-specific antigen (PSA) (Tandem-R, Hybritech) value following the American Society for Therapeutic Radiology and Oncology guidelines. Symptoms during treatment were quantitated weekly, and late effects were assessed every 4-6 months. RESULTS: DVHs showed a two-thirds reduction in normal bladder or rectum receiving 70 Gy or more with 3D CRT. Higher 5-year chemical disease-free survival was observed with 3D CRT (91% for T1c and 96% for T2 tumors) compared with SRT (53% and 58%, respectively). There was no statistically significant difference in chemical disease-free survival in patients with Gleason score of 4 or less (p = 0.83), but with Gleason score of 5-7, the 5-year survival rates were 96% with 3D CRT and 53% with SRT (p < or = 0.01). In 111 patients with pretreatment PSA of 10 ng/mL or less, treated with 3D CRT, the chemical disease-free rate was 96% vs. 65% in 94 patients treated with SRT (p < or = 0.01). In patients with PSA of 10. 1-20 ng/mL, the chemical disease-free survival rate for 26 patients treated with 3D CRT was 88% compared with 40% for 20 patients treated with SRT (p = 0.05). The corresponding values were 71% and 26%, respectively, for patients with PSA levels of greater than 20 ng/mL (p = 0.30). On multivariate analysis, the most important prognostic factors for chemical failure were pretreatment PSA (p = 0. 023), nadir PSA (p = 0.001), and 3D CRT technique (p = 0.033). Moderate dysuria and difficulty in urinating were reported by 2-5% of patients treated with 3D CRT in contrast to 6-9% of patients treated with SRT; moderate urinary frequency and nocturia were reported by 18-24% treated with 3D CRT and 18-27% of patients in the SRT group. The incidence of moderate loose stools/diarrhea, usually after the 4th week of treatment, was 3-5% in the 3D CRT patients and 8-19% in the SRT group. Late intestinal morbidity (proctitis, rectal bleeding) was very low (1.7%) in the 3D CRT group in contrast to the SRT patients (8%). CONCLUSION: Three-dimensional CRT spares more normal tissues, yields higher chemical disease-free survival, and results in less treatment morbidity than SRT in treatment of Stage T1-T2 prostate cancer. Longer follow-up is needed to confirm these preliminary observations.     

多通道施源器用于晚期宫颈癌三维腔内放疗的剂量学研究

目的 探讨中晚期宫颈癌三维后装腔内放疗中三通道施源器的通道设计与OAR、靶区剂量间关系。方法 调取2015—2016年我院三维腔内治疗的15例中晚期宫颈癌数据,其中30次“阴道卵形两半球+宫腔管”的三通道施源器剂量参数纳入研究。在原靶区和OAR勾画、处方剂量不变基础上保留宫腔管单通道施源器,重新进行三维腔内照射设计的剂量参数作为对照组,配对t检验两组OAR剂量参数。结果 三通道、单通道施源器组直肠D_2cc分别为(387.8±96.8)、(340.8±88.1) cGy;两组膀胱和乙状结肠D_2cc分别为(443.2±87.5)、(719.4±243.0) cGy和(330.3±88.8)、(383.1±105.6) cGy。三通道组满足直肠(D_2cc≤500 cGy)、膀胱(D_2cc≤550 cGy)和乙状结肠(D_2cc≤500 cGy)计划限量,单通道组膀胱和乙状结肠D_2cc受量分别为大于和部分大于计划限量。单通道组膀胱和乙状结肠D_2cc受量高于三通道组(P均<0.05)。结论 宫颈癌三维腔内放疗中“阴道卵形两半球+宫腔管”三通道施源器比宫腔管单通道可有效降低膀胱和乙状结肠受量,有利于计划优化和剂量实施。     

Dosimetric characteristics of the MammoSite RTS, a new breast brachytherapy applicator

PURPOSE: A new device has been developed with the goal of making breast-conserving therapy more widely available, by making breast brachytherapy as monotherapy simpler and more accurate. This is the first published report on the dosimetric characteristics of this device. MATERIALS AND METHODS: The experience of a single institution participating in a multi-institutional trial is reported. Twelve patients were enrolled, of whom 8 were treated. Computed tomography scans of all 12 patients were obtained before initiation of treatment. A commercial three-dimensional planning system was used for retrospective detailed analysis of dosimetry, including dose-volume histograms and, in selected patients, skin dose distributions. These data were compared to those of a similar group of patients, analyzed previously, that was treated with interstitial high-dose-rate brachytherapy. RESULTS: Compared with interstitial brachytherapy, the MammoSite device resulted in a treatment dose that was less uniform, with a mean dose homogeneity index of 0.77 vs. 0.93. Coverage and reproducibility were improved, with a mean D90 (minimum dose to 90% of target volume) of 90.0% of prescribed dose (SD 0.5, range: 89.2-90.8%) vs. 69.8% (SD 7.3, range: 61.1-83.5%) for interstitial brachytherapy. CONCLUSIONS: Reproducible placement was easily achieved in this very early experience, indicating a much smaller "learning curve" than for interstitial brachytherapy. Because skin doses can be increased with the use of this device, caution is indicated, although simple maneuvers can significantly reduce skin dose.     

Needle use and dosimetric evaluation in cervical cancer brachytherapy using the Utrecht applicator

Background and purpose

To analyse the clinical use of needles and examine the feasibility to meet the planning criteria in three fractions of cervical cancer brachytherapy. Furthermore, to investigate whether the needles with the largest discrepancy between application and loading are essential to treatment planning.

Comparison of DVH parameters and loading patterns of standard loading, manual and inverse optimization for intracavitary brachytherapy on a subset of tandem/ovoid cases

Purpose

Comparison of inverse planning with the standard clinical plan and with the manually optimized plan based on dose-volume parameters and loading patterns.

Materials and methods

Twenty-eight patients who underwent MRI based HDR brachytherapy for cervix cancer were selected for this study. Three plans were calculated for each patient: (1) standard loading, (2) manual optimized, and (3) inverse optimized. Dosimetric outcomes from these plans were compared based on dose-volume parameters. The ratio of Total Reference Air Kerma of ovoid to tandem (TRAK_O/T) was used to compare the loading patterns.

Results

The volume of HR CTV ranged from 9-68 cc with a mean of 41(±16.2)cc. Mean V100 for standard, manual optimized and inverse plans was found to be not significant (p = 0.35, 0.38, 0.4). Dose to bladder (7.8 ± 1.6 Gy) and sigmoid (5.6 ± 1.4 Gy) was high for standard plans; Manual optimization reduced the dose to bladder (7.1 ± 1.7 Gy p = 0.006) and sigmoid (4.5 ± 1.0 Gy p = 0.005) without compromising the HR CTV coverage. The inverse plan resulted in a significant reduction to bladder dose (6.5 ± 1.4 Gy, p = 0.002). TRAK was found to be 0.49(±0.02), 0.44(±0.04) and 0.40(±0.04)cGy m⁻² for the standard loading, manual optimized and inverse plans, respectively. It was observed that TRAK_O/T was 0.82(±0.05), 1.7(±1.04) and 1.41(±0.93) for standard loading, manual optimized and inverse plans, respectively, while this ratio was 1 for the traditional loading pattern.

Conclusions

Inverse planning offers good sparing of critical structures without compromising the target coverage. The average loading pattern of the whole patient cohort deviates from the standard Fletcher loading pattern.     

Curative radiotherapy with high-dose-rate brachytherapy boost for localized esophageal carcinoma: dose-effect relationship of brachytherapy with the balloon type applicator system.

BACKGROUND AND PURPOSE: This study analyzed the feasibility, local control and toxicity in potentially curable patients with esophageal carcinoma treated with a combination of external irradiation and high-dose-rate (HDR) brachytherapy using a balloon type applicator system to minimize hot spots on the mucosa. MATERIALS AND METHODS: During the 9 years, 124 patients with esophageal carcinoma and no apparent extraesophageal spread were treated with 40-60 Gy of external irradiation followed by 8-24 Gy of HDR brachytherapy. The fraction size of brachytherapy was 4-6 Gy. We developed a new applicator with 15 mm external diameter inflatable balloons. The reference point was a point 12.5 mm depth from the mid source. The study end points were local control, late toxicity and palliative effect. RESULTS: All 124 patients completed the planned radiotherapy. Local control rate was 69/124 (56%). There was a trend toward better local control rate for T1 lesions with increasing dose via brachytherapy. Of 69 patients with local control, treatment-related ulcers occurred in 28 patients, leading to death in four. The incidence of ulcers increased with increasing brachytherapy dose; 1/6 with 12 Gy, 16/43 with 16 Gy, 6/ 12 with 20 Gy, 4/5 with 24 Gy. Esophageal benign strictures occurred in ten patients and in all cases developed from ulcers. The incidence of freedom from dysphagia was not dose-dependent. CONCLUSION: A combination of external irradiation and HDR brachytherapy with the balloon type applicator was feasible and well tolerated. Although better local control was achieved by a higher dose of brachytherapy, the higher dose caused more severe esophageal injury.     

The Vienna applicator for combined intracavitary and interstitial brachytherapy of cervical cancer: clinical feasibility and preliminary results

PURPOSE: The aims of this study were to investigate the clinical feasibility and to report on preliminary treatment outcomes of combined intracavitary/interstitial brachytherapy, using a novel applicator and magnetic resonance imaging (MRI)-based treatment planning in patients with locally advanced cervical cancer. METHODS AND MATERIALS: A total of 22 cervical cancer patients with insufficient response and/or unfavorable topography after external-beam irradiation were included in this study. Parametrial extent of the disease in these patients was judged to exceed the coverage limit of intracavitary brachytherapy alone. A modified tandem/ring (T/R) applicator for guidance of parametrial needles (N) was used to perform high-dose-rate-brachytherapy with MRI-based treatment planning. Clinical feasibility and preliminary treatment outcomes were assessed. RESULTS: A total of 44 interstitial needle implants were performed. The spatial relations between the T/R + N applicator, high-risk clinical target volume, and organs at risk were visible clearly in all cases. Accurate and reproducible needle placement could be achieved in the majority of cases. No severe adverse events were caused by the intervention. The mean follow-up period was 20 months (range, 5-35 months). No G3 to G4 early or persistent late side effects were observed. Complete remission was achieved in 21 patients (95%). One local recurrence was observed within the high-risk clinical target volume area during follow-up. CONCLUSIONS: Our preliminary clinical experience indicates that combined intracavitary and interstitial MRI-based brachytherapy in patients with significant residual disease after external-beam therapy extending up to the distal third of parametria is feasible and allows excellent local control and a low rate of morbidity.     

Applicator reconstruction and applicator shifts in 3D MR-based PDR brachytherapy of cervical cancer

Purpose

To evaluate the methods of applicator reconstruction in 3D MR-based planning for brachytherapy of cervical cancer, and to investigate applicator shifts and changes in DVH parameters during PDR treatment.

Methods

For each application MR scans with applicator in situ were made: three T2-weighted (4.5 mm slices) Turbo Spin Echo (TSE) scans and a balanced Steady State Free Precession scan (1.5 mm). Three observers tested two applicator reconstruction methods: (A) directly on the bSSFP scan and (B) on a resampled combination of the three T2-weighted scans. For 10 patients MR imaging was repeated on the second day of each PDR fraction to determine applicator shifts and changes in DVH parameters.

Results

For both applicator reconstruction methods the interobserver variation for the DVH parameters was comparable (average <1.5% in dose). Differences between the two methods were larger (up to 6.4% for target) and were related to position differences during MR scanning.The average applicator shift relative to the pelvic structures was 5-6 mm into the ventral direction and 3-4 mm cranially. For a single PDR fraction, the average D90 (HR-CTV) on ‘day 2’ was 0.2 (SD 2.0) Gy lower than that for day 1. The average increase in D_2cc (bladder) was 1.0 (SD 3.0) Gy_αβ3 for a single PDR fraction. If the effect of both fractions was combined, for 1 patient a total decrease of D90 of 7 Gy_αβ10 was found, whereas for another patient the total increase in bladder dose was 12 Gy_αβ3.

Conclusions

Applicator reconstruction on MR data is feasible. In the overall accuracy during PDR brachytherapy the reconstruction uncertainty is of minor importance. Applicator and/or organ movement during the course of the PDR fraction produce larger uncertainties.