Magnetic resonance imaging (MRI) has a number of benefits for the planning of radiotherapy (RT), but its uptake into clinical practice has often been restricted to specialist research sites. There is ...often a lack of detailed MRI knowledge within the RT community and an apprehension of geometric distortions, both of which prevent its best utilization and merit the introduction of a standardized approach and common guidelines. This review sets out to address some of the issues involved in acquiring MRI scans for RT planning in the context of a number of clinical sites of interest and concludes with recommendations for its best practice in terms of imaging protocol and quality assurance. The article is of particular interest to the growing number of cancer therapy centers that are embarking on MRI simulation on either existing systems or their own dedicated scanners.
The aims of this study were to investigate the benefit of the Utrecht interstitial CT/MR applicator for combined intracavitary/interstitial (IC/IS) approach, using magnetic resonance imaging-guided ...brachytherapy, over the intracavitary approach alone in patients with locally advanced cervical cancer and to analyze the clinical use of needles.
This study includes the first 20 patients treated with the new applicator. Brachytherapy consisted of two pulsed dose rate applications, and the second application was performed with the IC/IS approach. The number of needles, chosen guiding holes through the ovoids, and insertion depths were based on the dose distribution and dosimetric shortcomings of the first application (IC alone). We investigated the dosimetric gain by comparing the clinical interstitial optimized plan (IC/IS(clinical)) with an additionally generated optimized plan without needle use (IC(study)). Furthermore, we studied the relation of the inserted needles and their source loading patterns with the high-risk clinical target volume (HR-CTV).
A total of 54 needles (range, 1-6 per application) were applied with an average depth of 25 mm. The chosen needle positions corresponded with the location of the HR-CTV extensions. The total and individual needle treatment times per application were on average 19% (range, 4-35%) and 7% (range, 2-14%) of the implant treatment time, respectively. The total (external-beam radiotherapy + brachytherapy) D90 HR-CTV for the IC(study) and the IC/IS(clinical) were on average 79.5 (SD 7.4) Gy(α/β10) and 83.9 (SD 6.7) Gy(α/β10), respectively, with an average gain of 4.4 (SD 2.3) Gy(α/β10) for the second application.
Needle placement was feasible in all patients and resulted in a gain in dose and better coverage of HR-CTV. Defining the location of HR-CTV protrusions and analyzing the associated needles has given us deeper understanding of the possibilities in magnetic resonance imaging-guided (pre)treatment planning with the IC/IS Utrecht applicator.
To analyze the combined and updated results from the University of Michigan and University Medical Center Utrecht on normal tissue complication probability (NTCP) of the parotid gland 1 year after ...radiotherapy (RT) for head-and-neck (HN) cancer.
A total of 222 prospectively analyzed patients with various HN malignancies were treated with conventional and intensity-modulated RT. Stimulated individual parotid gland flow rates were measured before RT and 1 year after RT using Lashley cups at both centers. A flow ratio <25% of pretreatment was defined as a complication. The data were fitted to the Lyman-Kutcher-Burman model.
A total of 384 parotid glands (Michigan: 157; Utrecht: 227 glands) was available for analysis 1 year after RT. Combined NTCP analysis based on mean dose resulted in a TD(50) (uniform dose leading to 50% complication probability) of 39.9 Gy and m (steepness of the curve) of 0.40. The resulting NTCP curve had good qualitative agreement with the combined clinical data. Mean doses of 25-30 Gy were associated with 17-26% NTCP.
A definite NTCP curve for parotid gland function 1 year after RT is presented, based on mean dose. No threshold dose was observed, and TD(50) was equal to 40 Gy.
Abstract Purpose Whole-gland salvage for recurrent prostate cancer (PCa) shows high failure and toxicity rates. Early and adequate localization of recurrences enables focal salvage, thereby ...potentially improving functional outcomes, while maintaining cancer control. Materials and methods Retrospective analysis yielded 20 focal salvage I125 brachytherapy patients for locally recurrent PCa after primary radiotherapy. Tumor was defined by multiparametric MRI and correspondence with transrectal biopsies. Dose data were obtained intra-operatively. The tumor was prescribed ⩾144 Gy. Toxicity was scored by the Common Terminology Criteria for Adverse Events version 4 (CTCAE-4). Biochemical failure (BF) was defined using the Phoenix criteria (PSA-nadir + 2.0 ng/ml). Quality of life (QoL) was measured by SF-36 Health Survey and European Organization of Research and Treatment of Cancer (EORTC) C30+3 and PR25 questionnaires. Results With a median follow-up of 36 months (range 10–45), six patients experienced BF, of which three had no initial response. Grade 3 genitourinary (GU) toxicity occurred in one patient (a urethral stricture). The five previously potent patients retained erectile function. QoL remained decreased with regard to urinary symptoms. Conclusion Focal salvage I125 brachytherapy showed one grade 3 GU toxicity in the 20 treated patients. Biochemical response and QoL were acceptable.
To quantify the movement of esophageal tumors noninvasively on cine-magnetic resonance imaging (MRI) by use of a semiautomatic method to visualize tumor movement directly throughout multiple ...breathing cycles.
Thirty-six patients with esophageal tumors underwent MRI. Tumors were located in the upper (8), middle (7), and lower (21) esophagus. Cine-MR images were collected in the coronal and sagittal plane during 60 seconds at a rate of 2 Hz. An adaptive correlation filter was used to automatically track a previously marked reference point. Tumor movement was measured in the craniocaudal (CC), left–right (LR), and anteroposterior (AP) directions and its relationship along the longitudinal axis of the esophagus was investigated.
Tumor registration within the individual images was typically done at a millisecond time scale. The mean (SD) peak-to-peak displacements in the CC, AP, and LR directions were 13.3 (5.2) mm, 4.9 (2.5) mm, and 2.7 (1.2) mm, respectively. The bandwidth to cover 95% of excursions from the mean position (c95) was also calculated to exclude outliers caused by sporadic movements. The mean (SD) c95 values were 10.1 (3.8) mm, 3.7 (1.9) mm, and 2.0 (0.9) mm in the CC, AP, and LR dimensions. The end-exhale phase provided a stable position in the respiratory cycle, compared with more variety in the end-inhale phase. Furthermore, lower tumors showed more movement than did higher tumors in the CC and AP directions.
Intrafraction tumor movement was highly variable between patients. Tumor position proved the most stable during the respiratory cycle in the end-exhale phase. A better understanding of tumor motion makes it possible to individualize radiation delivery strategies accordingly. Cine-MRI is a successful noninvasive modality to analyze motion for this purpose in the future.
We sought to identify the intraoperative displacement patterns of seeds and to evaluate the correlation of intraoperative dosimetry with day 30 for permanent prostate brachytherapy.
We analyzed the ...data from 699 patients. Intraoperative dosimetry was acquired using transrectal ultrasonography (TRUS) and C-arm cone beam computed tomography (CBCT). Intraoperative dosimetry (minimal dose to 40%-95% of the volume D40-D95) was compared with the day 30 dosimetry for both modalities. An additional edema-compensating comparison was performed for D90. Stranded seeds were linked between TRUS and CBCT using an automatic and fast linking procedure. Displacement patterns were analyzed for each seed implantation location.
On average, an intraoperative (TRUS to CBCT) D90 decline of 10.6% ± 7.4% was observed. Intraoperative CBCT D90 showed a greater correlation (R2 = 0.33) with respect to Day 30 than did TRUS (R2 = 0.17). Compensating for edema, the correlation increased to 0.41 for CBCT and 0.38 for TRUS. The mean absolute intraoperative seed displacement was 3.9 ± 2.0 mm. The largest seed displacements were observed near the rectal wall. The central and posterior seeds showed less caudal displacement than lateral and anterior seeds. Seeds that were implanted closer to the base showed more divergence than seeds close to the apex.
Intraoperative CBCT D90 showed a greater correlation with the day 30 dosimetry than intraoperative TRUS. Edema seemed to cause most of the systematic difference between the intraoperative and day 30 dosimetry. Seeds near the rectal wall showed the most displacement, comparing TRUS and CBCT, probably because of TRUS probe–induced prostate deformation.
•Recurrences after focal salvage HDR brachytherapy are mostly local and in-field.•3-yrs local recurrence-free survival was 51% after focal salvage HDR brachytherapy.•3-yrs local ADT-free survival was ...86% after focal salvage HDR brachytherapy.
Radiorecurrent prostate cancer is often confined to the prostate, predominantly near the index lesion. The purpose of this study was to look at recurrence characteristics in patients treated with focal salvage high dose-rate (HDR) brachytherapy.
Patients treated with MRI-guided HDR brachytherapy, with a single fraction of 19 Gy from July 2013 to October 2021 as focal salvage treatment, were prospectively included in the current study. Imaging data were collected regarding the occurrence of local, regional and distant recurrences, including location of local recurrences (LR) in relation to the HDR radiotherapy field.
One hundred seventy-five patients were included after focal salvage HDR brachytherapy (median follow-up 36 months (IQR 23–50)). Three-years biochemical recurrence-free survival, LR-free survival, in-field LR-free survival, out-of-field LR-free survival, any-recurrence-free survival and ADT-free survival were 43% (95%CI 34%–52%), 51% (41%–61%), 70% (61%–80%), 92% (88%–97%), 42% (32%–52%) and 86% (80%–92%), respectively. Larger GTV-size and shorter PSA doubling time were associated with in-field LR in multivariable analysis.
After focal salvage HDR brachytherapy with a dose of 1x19 Gy for local prostate cancer recurrence, subsequent recurrences are mostly local and in-field.
Most patients with local prostate cancer recurrence after radiation therapy undergo palliative androgen deprivation therapy because whole-gland salvage treatments have a high risk of severe toxicity. ...Focal treatment reduces this risk while offering a second opportunity for cure. We report updated outcomes of ultrafocal salvage high-dose-rate brachytherapy (HDR-BT).
Prospectively collected data from the first 50 treated patients were analyzed. Disease status was assessed by 3T multiparametric magnetic resonance imaging (MRI), 18F-Choline or 68Ga-prostate-specific membrane antigen positron emission tomography/computed tomography, and systematic or tumor-targeted biopsies. Ultrafocal salvage HDR-BT (1 × 19 Gy) was performed by implanting the clinical target volume (CTV: gross tumor volume + 5 mm margin) under fused transrectal ultrasound/MRI guidance. Follow-up included toxicity grading (using Common Terminology Criteria for Adverse Events 4.0), quality of life assessment, and prostate-specific antigen (PSA) testing.
Median follow-up was 31 months. Median CTV D95% was 18.8 Gy. We observed 2% grade 3 genitourinary toxicity, no grade 3 gastrointestinal toxicity, and 22% newly developed grade 3 erectile dysfunction. Five of 13 patients (38%) with self-reported pretreatment potency (International Index of Erectile Function >17) remained potent. Clinically relevant quality of life deterioration was reported for only 6 of 31 items and was not statistically significant. Biochemical failure (nadir + 2) occurred in 26 patients. Among intraprostatic recurrences, 73% were in field. After 2.5 years, biochemical disease-free survival was 51% (95% confidence interval, 37%-69%), metastases-free survival was 75% (64%-89%), androgen deprivation therapy-free survival was 90% (82%-99%), and overall survival was 98% (94%-100%). Presalvage PSA, CTV size, and stage ≥T3 were significantly associated with biochemical failure. Higher-risk patients (stage ≥T3, PSA ≥10, or PSA double time ≤9 months) had 25% biochemical disease-free survival at 2.5 years versus 71% for lower-risk patients.
At this early stage, MRI-guided ultrafocal HDR-BT seems to be a safe salvage treatment option, with acceptable biochemical control in a well-selected group of patients and potential for effectively postponing androgen deprivation therapy.
In the last decade, there have been significant developments into integration of robots and automation tools with brachytherapy delivery systems. These systems aim to improve the current paradigm by ...executing higher precision and accuracy in seed placement, improving calculation of optimal seed locations, minimizing surgical trauma, and reducing radiation exposure to medical staff. Most of the applications of this technology have been in the implantation of seeds in patients with early‐stage prostate cancer. Nevertheless, the techniques apply to any clinical site where interstitial brachytherapy is appropriate. In consideration of the rapid developments in this area, the American Association of Physicists in Medicine (AAPM) commissioned Task Group 192 to review the state‐of‐the‐art in the field of robotic interstitial brachytherapy. This is a joint Task Group with the Groupe Européen de Curiethérapie‐European Society for Radiotherapy & Oncology (GEC‐ESTRO). All developed and reported robotic brachytherapy systems were reviewed. Commissioning and quality assurance procedures for the safe and consistent use of these systems are also provided. Manual seed placement techniques with a rigid template have an estimated in vivo accuracy of 3–6 mm. In addition to the placement accuracy, factors such as tissue deformation, needle deviation, and edema may result in a delivered dose distribution that differs from the preimplant or intraoperative plan. However, real‐time needle tracking and seed identification for dynamic updating of dosimetry may improve the quality of seed implantation. The AAPM and GEC‐ESTRO recommend that robotic systems should demonstrate a spatial accuracy of seed placement ≤1.0 mm in a phantom. This recommendation is based on the current performance of existing robotic brachytherapy systems and propagation of uncertainties. During clinical commissioning, tests should be conducted to ensure that this level of accuracy is achieved. These tests should mimic the real operating procedure as closely as possible. Additional recommendations on robotic brachytherapy systems include display of the operational state; capability of manual override; documented policies for independent check and data verification; intuitive interface displaying the implantation plan and visualization of needle positions and seed locations relative to the target anatomy; needle insertion in a sequential order; robot–clinician and robot–patient interactions robustness, reliability, and safety while delivering the correct dose at the correct site for the correct patient; avoidance of excessive force on radioactive sources; delivery confirmation of the required number or position of seeds; incorporation of a collision avoidance system; system cleaning, decontamination, and sterilization procedures. These recommendations are applicable to end users and manufacturers of robotic brachytherapy systems.
Abstract Purpose To evaluate dosimetric parameters and clinical outcome for cervical cancer patients treated with chemo-radiation and MR-image guided adaptive brachytherapy (MR-IGABT) using ...tandem-ovoid applicators for intracavitary or combined intracavitary/interstitial approaches. Method This retrospective analysis includes 46 patients treated between 2006 and 2008. Dose–volume parameters D90 HR-CTV (high-risk clinical target volume) and D2cc OARs (organs at risk) were determined and converted into biologically equivalent doses in 2 Gy fractions (EQD2). Clinical outcome parameters (local control (LC), progression free survival (PFS) and overall survival (OS)) were analysed actuarially and late morbidity crude rates were scored using CTCAEv3.0. Results Mean D90 HR-CTV was 84 (SD9) Gy EQD2 for HR-CTV volumes of mean 57 (SD37) cm3 at time of first brachytherapy (BT). Median follow-up was 41 (range, 4–67) months. Three year LC, PFS, and OS rates were 93, 71, and 65%, respectively. Node negative patients had significantly higher 3-year survival rates compared to node positive ones (PFS 85 versus 53% ( p = 0.013), OS 77 versus 50% ( p = 0.032), respectively) with an even larger difference for patients with FIGO stages IB-IIB (PFS 87 versus 42% ( p = 0.002), OS 83 versus 46% ( p = 0.007), respectively). Late grade 3–4 mainly gastrointestinal or vaginal morbidity was observed in 4 patients (9.5%). No correlations were seen between morbidity and D2cc OAR values. Conclusion (Chemo-) radiation and MR-IGABT with tandem-ovoid applicators result in high LC and promising survival rates with reasonable morbidity.
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