宫颈癌多模态融合图像引导近距离放射治疗发展现状

以顺铂为基础的全身化疗联合外照射序贯腔内近距离放射治疗(ICBT)已成为局部晚期宫颈癌的标准治疗模式。得益于医学影像设备成像精度的提高和图像融合技术的发展,ICBT已向图像引导的近距离治疗(IGBT)发展,并已走出了仅仅依赖单一影像引导的模式。如何选择适合的影像采集技术、优化多模态成像融合策略以降低IGBT的剂量偏差等因素是决定宫颈癌治疗成败的关键,也是困扰放疗实践的重要因素。基于深度学习的人工智能技术在智能放疗平台搭建及解决方案中崭露头角,已成为解决多模态融合宫颈癌IGBT关键问题的重要抓手,同时也为提升宫颈癌区域整体诊疗水平、减轻医师工作负担、向基层单位推广放疗经验提供一条新途径。     

Toward 3D-TRUS image-guided interstitial brachytherapy for cervical cancer

PURPOSETo qualitatively and quantitatively analyze needle visibility in combined intracavitary and interstitial cervical cancer brachytherapy on 3D transrectal ultrasound (TRUS) in comparison to gold standard MRI.METHODS AND MATERIALSImage acquisition was done with a customized TRUS stepper unit and software (Medcom, Germany; Elekta, Sweden; ACMIT, Austria) followed by an MRI on the same day with the applicator in place. Qualitative assessment was done with following scoring system: 0 = no visibility 1 (= poor), 2 (= fair), 3 (= excellent) discrimination, quantitative assessment was done by measuring the distance between each needle and the tandem two centimeters (cm) above the ring and comparing to the respective measurement on MRI.RESULTSTwenty-nine implants and a total of 188 needles (132 straight, 35 oblique, 21 free-hand) were available. Overall, 79% were visible (87% straight, 51% oblique, 76% free-hand). Mean visibility score was 1.4 ± 0.5 for all visible needles. Distance of the visible needles to tandem was mean ± standard deviation (SD) 21.3 millimeters (mm) ± 6.5 mm on MRI and 21.0 mm ± 6.4 mm on TRUS, respectively. Difference between MRI and TRUS was max 14 mm, mean ± SD -0.3 mm ± 2.6 mm. 11% differed more than 3 mm.CONCLUSIONSStraight needles were better detectable than oblique needles (87% vs. 51%). Detectability was impaired by insufficient rotation of the TRUS probe, poor image quality or anatomic variation. As needles show a rather indistinct signal on TRUS, online detection with a standardized imaging protocol in combination with tracking should be investigated, aiming at the development of real time image guidance and online treatment planning.     

Toward four-dimensional image-guided adaptive brachytherapy in locally recurrent endometrial cancer

PurposeTo evaluate clinical outcome and feasibility of a four-dimensional image-guided adaptive brachytherapy concept in patients with locally recurrent endometrial cancer.Methods and MaterialsForty-three patients with locally recurrent endometrial cancer were included. Treatment consisted of conformal external beam radiotherapy followed by a boost using pulsed-dose-rate brachytherapy (BT). Large tumors were treated with MRI-guided interstitial BT. Small tumors were treated with CT-guided intracavitary BT. The planning aim (total external beam radiotherapy and BT) for high-risk clinical target volume was D₉₀ > 80 Gy, whereas constraints for organs at risk were D_2cc ≤ 90 Gy for bladder and D_2cc ≤ 70 Gy for rectum, sigmoid, and bowel in terms of equivalent dose in 2 Gy fractions.ResultsMedian high-risk clinical target volume was 18 cm³ (range, 0–91). D₉₀ was 82 Gy (range, 77–88). D_2cc to bladder, rectum, and sigmoid were 67 Gy (range, 50–81), 67 Gy (range, 51–77), and 55 Gy (range, 44–68), respectively. Median followup was 30 months (6–88). Two-year local control rate was 92% (standard error [SE], 5). Disease-free survival rate and overall survival rate was 59% (SE, 8) and 78% (SE, 7), respectively. Patients with low- to intermediate-risk for recurrence had a 2-year disease-free survival rate of 72% (SE, 9) compared with 42% (SE, 12) in patients with high risk for recurrence (p = 0.04). Late morbidity Grade 3 was recorded in 5 (12%) patients.ConclusionsFour-dimensional image-guided adaptive brachytherapy is feasible in locally recurrent endometrial cancer. Local control rate is good. Systemic control remains a problem in patients with high risk for recurrence.     

Factors influencing eligibility for breast boost using noninvasive image-guided breast brachytherapy

PurposeNoninvasive image-guided breast brachytherapy (NIBB) allows for accurate targeting of the tumor bed (TB) for breast boost by using breast immobilization and image guidance. However, not all patients are candidates for this technique.MethodsConsecutive patients treated for breast cancer were evaluated. Patients with very small breast size (cup ≤ A) for whom immobilization could not be achieved were treated with electrons. All others underwent simulation for NIBB boost. The rate of eligibility for NIBB, reasons for ineligibility, and related patient and anatomic factors were analyzed.ResultsOf 52 patients evaluated, 6 patients were ineligible for NIBB because of small breast size. Of the remaining patients who underwent simulation for NIBB boost, 33 patients (72%) were treated with NIBB. Reasons for ineligibility were the absence of identifiable TB (n = 5), inability to position patient/breast to adequately target the TB (n = 4), posterior TB location (n = 3), and discomfort during compression (n = 1). The likelihood of being eligible for NIBB boost was dependent on breast size: ≤A (0%), B (50%), C (71%), D-DD (77%), and >DD (80%) (p = 0.002). The presence of surgical clips also predicted eligibility for NIBB: 79% clips vs. 45% without clips (p = 0.05). A posterior TB location was not associated with ineligibility (p = 0.2).ConclusionsNIBB boost is feasible in most patients. Patients with larger breast size are more likely to be good candidates. Posterior TB location can be challenging for NIBB, but most patients are still candidates. Surgical clips are very helpful in defining the TB and greatly increase the likelihood of eligibility for NIBB.     

MR-guided liver tumor ablation employing open high-field 1.0T MRI for image-guided brachytherapy

Objective

To determine the feasibility and safety of image-guided brachytherapy employing a modified open high-field MR system.

Methods

This is a follow-up study of a development project enabling technologies for interventional use of 1.0T open MRI. Modifications included coils and in-bore visualization, fluoroscopic sequences and user interfaces. We recruited 104 patients with 224 liver malignancies to receive MR-guided brachytherapy. Interventions were performed >20 min after Gd-EOB-DTPA. We recorded interventional parameters including the intervention time (from acquisition of the first scout until the final sequence for brachytherapy treatment planning). Two reviewers assessed MR-fluoroscopic images in comparison to plain CT as used in CT intervention, applying a rating scale of 1–10. Statistical analysis included Friedman and Kendall’s W tests.

Results

We employed freehand puncture with interactive dynamic imaging for navigation. Technical success rate was 218 complete ablations in 224 tumours (97%). The median intervention time was 61 min. We recorded no adverse events related to the use of MRI. No major complications occurred. The rate of minor complications was 4%. Local control at 3 months was 96%. Superiority of MR-fluoroscopic, Gd-EOB-DTPA-enhanced images over plain CT was highly significant (P?<?0.001).

Conclusion

MR-guided brachytherapy employing open high-field MRI is feasible and safe.     

3D-printed Magnetic Resonance (MR)-based gynecological phantom for image-guided brachytherapy training

PURPOSE/OBJECTIVESThere is a clinical need to develop anatomic phantoms for simulation-based learning in gynecological brachytherapy. Here, we provide a step-by-step approach to build a life-sized gynecological training phantom based on magnetic resonance imaging (MRI) of an individual patient. Our hypothesis is that this phantom can generate convincing ultrasound (US) images that are similar to patient scans.METHODSOrgans-at-risk were manually segmented using patient scans (MRI). The gynecological phantom was constructed using positive molds from 3D printing and polyvinyl chloride (PVC) plastisol. Tissue texture/acoustic properties were simulated using different plastic softener/hardener ratios and microbead densities. Nine readers (residents) were asked to evaluate 10 cases (1 ultrasound image per case) and categorize each as a “patient” or “phantom” image. To evaluate whether the phantom and patient images were equivalent, we used a multireader, multicase equivalence study design with two composite null hypotheses with proportion (p_r) at H₀₁: p_r ≤ 0.35 and H₀₂: p_r ≥ 0.65. Readers were also asked to review US videos and identify the insertion of an interstitial needle into the pelvic phantom. Computed Tomography (CT) and magnetic resonance (MR) images of the phantom were acquired for a feasibility study.RESULTSReaders correctly classified “patient” and “phantom” scans at p_r = 53.3% ± 6.2% (p values 0.013 for H₀₁ and 0.054 for H₀₂, df = 5.96). Readers reviewed US videos and identified the interstitial needle 100% of the time in transabdominal view, and 78% in transrectal view. The phantom was CT and MR safe.CONCLUSIONSWe have outlined a manufacturing process to create a life-sized, gynecological phantom that is compatible with multi-modality imaging and can be used to simulate clinical scenarios in image-guided brachytherapy procedures.     

Salvage image-guided freehand interstitial brachytherapy for pelvic sidewall recurrence after hysterectomy for uterine malignancies

PURPOSEPelvic sidewall recurrence after hysterectomy for uterine malignances has a poor prognosis, and the salvage therapy for this type of recurrence is still challenging. The purpose of this study was to investigate the efficacy of freehand high-dose-rate interstitial brachytherapy (HDR-ISBT) through the perineum using transrectal ultrasonography for this disease.METHODS AND MATERIALSWe retrospectively evaluated 42 patients with pelvic sidewall recurrence after hysterectomy for uterine cervical and endometrial cancers. We investigated patients' characteristics, the 2-year local control and survival rates, and late adverse events of the rectum and bladder.RESULTSThe 2-year overall survival, local control, and progression-free survival rates were 73.7% (95% confidence interval [CI], 60.8–89.3%), 69.4% (95% CI, 55.4–80.1%), and 37.3% (95% CI, 24.6–56.5%), respectively. In Cox multivariate analysis, tumor size at recurrence (<45 mm vs. ≥45 mm) (p = 0.04) and disease-free periods after hysterectomy (<10 months vs. ≥10 months) (p < 0.01) were significant prognostic factors for overall survival. Lymph node metastasis at recurrence (p < 0.01) was also a significant prognostic factor for progression-free survival. Three patients experienced Grade 3–4 late proctitis (7%).CONCLUSIONSTransperineal freehand salvage HDR-ISBT using transrectal ultrasonography was demonstrated to be a curative treatment option for patients with pelvic sidewall recurrence following hysterectomy. Based on the findings of this study, we emphasize the importance of HDR-ISBT for pelvic sidewall recurrence.     

Characterizing the impact of adaptive planning on image-guided perineal interstitial brachytherapy for gynecologic malignancies

PurposeTo determine the dosimetric impact of organ and implant motion/deformation in the context of adaptive planning in image-guided gynecologic brachytherapy using a 3-fraction transperineal approach.Methods and materialsTwenty-six patients were analyzed. Each patient was treated with three fractions given over a 24-h period using a single insertion. A planning CT scan (±MRI) was acquired before the first fraction. A verification scan was taken within 1 h following the second fraction. A single plan was delivered for Fractions 1 and 2 with an adaptive plan delivered for Fraction 3. Two evaluation frameworks were established. Framework 1 investigated the effects of motion/deformation from both implant and organs. Framework 2 investigated the impact of implant motion/deformation alone. Differences in high-risk clinical target volume (HRCTV) D_90%, V_100%, and bladder/rectum D_2cc were assessed.ResultsFrom implant to verification, the HRCTV D_90% and V_100% decreased significantly (5.0%, p < 0.01; 3.1%, p < 0.01) and rectal D_2cc was significantly higher (12.2%, p = 0.02). Adaptive planning recouped these changes. Implant changes resulted in a reduction in HRCTV dose and coverage, but no significant effect was seen in the bladder or rectum.ConclusionsAdaptive planning represents an important aspect of perineal-based interstitial image-guided brachytherapy given in three fractions; its absence would result in plan degradation.     

Vaginal vault brachytherapy in endometrial cancer: verifying target coverage with image-guided applicator placement

Objective:

This quality assurance study assesses whether CT image-guided verification has led to improvements in the technique when compared with previous studies.

Methods:

The CT images were studied from a cohort of 105 consecutive patients with endometrial cancer having adjuvant brachytherapy to the vaginal vault in 2010. Images were taken at first insertion, checked for air gaps and treatment delivered. Images were later transferred to the planning system and air gaps between vaginal mucosa and vaginal cylinder were measured. Comparisons were made with the 2008 results from this centre and the literature series.

Results:

Images from two patients were not assessable owing to artefacts from hip replacements. Air gaps >2 mm were seen in 11/103 patients. Repositioning or use of a larger cylinder reduced air gaps to 7/103 patients. In total, 96/103 patients (over 93%) were able to achieve good vaginal contact throughout the treatment volume. This shows a significant improvement in applicator positioning in our centre since 2008 and also a significant improvement over the total data published in 2010 (Pearson χ² test=46.19; p<0.0001).

Conclusion:

The vaginal cylinder technique with CT imaging was proven to be effective for 96/103 patients. It is necessary to consider whether there is a better technique for the few patients with air gaps >2 mm.

Advances in knowledge:

For the vast majority of patients, this technique is well tolerated, without the need for analgesia, and will continue to be the first choice technique in this centre.In current practice, there are variations in applicators used in vaginal vault brachytherapy, such as vaginal ovoids or colpostats, custom-made vaginal moulds, but most commonly used is a single line source in a rigid vaginal cylinder. In 2008, in this radiotherapy centre, Cameron et al [1] carried out a retrospective study of 25 patients receiving vaginal vault brachytherapy. It was found that 8 out of 25 patients had air gaps >2 mm in the superior 2 cm of vagina [1]. An observational study by Richardson et al [2] found 90 air pockets in 150 procedures for a cohort of 25 patients, 80% having one or more air pockets. Air gaps between the applicator and the vaginal wall can potentially reduce the dose to the clinical target volume (CTV), which in this case is the mucosal lymphatics of the upper vagina. These lie at 2–3 mm from the stretched mucosal surface according to a study by Choo et al [3]. The Groupe Européen de Curiethérapie and the European Society for Radiotherapy & Oncology (GEC-ESTRO) guidance is to prescribe vaginal brachytherapy to 5 mm from the applicator surface [4], giving a 2-mm tolerance.A new CT scanner was introduced in this centre in 2010 and new clinicians were trained to carry out vault brachytherapy insertions. This quality assurance study considers whether high-resolution CT image-guided verification, as well as the learning curve of image-guided brachytherapy, has led to improvements in the quality of the technique over time.     

Treatment of metastatic,imatinib refractory,gastrointestinal stroma tumor with image-guided high-dose-rate interstitial brachytherapy

Purpose

Evaluation of efficacy and safety of CT- or MRI-guided high-dose-rate interstitial brachytherapy (iBT) in the treatment of advanced, imatinib refractory, metastatic gastrointestinal stroma tumors (GISTs) was the objective of this retrospective study.

Preliminary results of a new workflow for MRI/CT-based image-guided brachytherapy in cervical carcinoma

Purpose

We propose a method of image-guided brachytherapy (IGBT) that combines MRI-based target volume delineation for the first fraction with CT datasets of subsequent fractions, using an automatic, applicator-based co-registration, and report our preliminary experience.

Materials and methods

The MRI of the first fraction was used for the first brachytherapy planning. For each subsequent brachytherapy fraction, after the same applicator insertion, a new CT scan with the applicator in place was obtained. The MR image set was registered to the subsequent brachytherapy treatment planning CT using the applicator for rigid body registration. To demonstrate the registration quality, we used here the Dice index as a measurement of tandem delineation overlap between CT and MRI.

Results

The median Dice index was 0.879 (range 0.610–0.932), which indicated that the contours on CT and MRI fitted well. With this combination method, the median D90 of HR CTV and the calculated D2 cm³ of the bladder, rectum, and sigmoid in each fraction were 7.2 (4.0–10.4), 5.9 (2.3–7.7), 4.0 (1.9–6.7), and 3.8 (0.6–7.2) Gy, respectively.

Conclusion

Our described method of MRI-guided IGBT offers a practical option for the benefits of target delineation.

     

Three-dimensional image-guided combined intracavitary and interstitial high-dose-rate brachytherapy in cervical cancer: A systematic review

PurposeTo evaluate the local control and toxicities of three-dimensional image-guided combined intracavitary and interstitial (IC/IS) high-dose-rate brachytherapy (BT) in cervical cancer through a systematic review.Methods and MaterialsA systematic review of relevant studies was performed through the PubMed, Web of Science, and Cochrane Library databases through May 10, 2020. Articles reporting on IC/IS technology, volumetric doses to high-risk clinical target volume (HR-CTV) and organs at risk (OARs), tumor control and/or treatment-related side effects were identified. The key information, including the type of applicator, implantation technology, characteristics of implantation, volumetric doses, tumor control, and/or treatment-related side effects, was extracted. A probit model analysis between HR-CTV D90 and tumor local control was performed.ResultsTwelve studies encompassing 520 patients were included in the probit model between HR-CTV D90 and the local control rate. The probit model showed a significant relationship between the HR-CTV D90 value and the local control probability, p = 0.003. The prescribed dose of 85 Gy_EQD2,10 would in theory warrant an 87.4% (95% confidence interval 82.5%–90.5%) local control rate.ConclusionIC/IS BT is an appropriate method to achieve a high therapeutic ratio for tumors with large volumes or poor responses after external irradiation in cervical cancer. The probit model showed that the dose escalation of HR-CTV D90 was helpful to improve the local tumor control rate.