Automated treatment planning and/or optimization systems (ATPS) are in the process of broad clinical implementation aiming at reducing inter-planner variability, reducing the planning time allocated ...for the optimization process and improving plan quality. Five different ATPS used clinically were evaluated for advanced head and neck cancer (HNC).
Three radiation oncology departments compared 5 different ATPS: 1) Automatic Interactive Optimizer (AIO) in combination with RapidArc (in-house developed and Varian Medical Systems); 2) Auto-Planning (AP) (Philips Radiation Oncology Systems); 3) RapidPlan version 13.6 (RP1) with HNC model from University Hospital A (Varian Medical Systems, Palo Alto, USA); 4) RapidPlan version 13.7 (RP2) combined with scripting for automated setup of fields with HNC model from University Hospital B; 5) Raystation multicriteria optimization algorithm version 5 (RS) (Laboratories AB, Stockholm, Sweden). Eight randomly selected HNC cases from institution A and 8 from institution B were used. PTV coverage, mean and maximum dose to the organs at risk and effective planning time were compared. Ranking was done based on 3 Gy increments for the parallel organs.
All planning systems achieved the hard dose constraints for the PTVs and serial organs for all patients. Overall, AP achieved the best ranking for the parallel organs followed by RS, AIO, RP2 and RP1. The oral cavity mean dose was the lowest for RS (31.3 ± 17.6 Gy), followed by AP (33.8 ± 17.8 Gy), RP1 (34.1 ± 16.7 Gy), AIO (36.1 ± 16.8 Gy) and RP2 (36.3 ± 16.2 Gy). The submandibular glands mean dose was 33.6 ± 10.8 Gy (AP), 35.2 ± 8.4 Gy (AIO), 35.5 ± 9.3 Gy (RP2), 36.9 ± 7.6 Gy (RS) and 38.2 ± 7.0 Gy (RP1). The average effective planning working time was substantially different between the five ATPS (in minutes): < 2 ± 1 for AIO and RP2, 5 ± 1 for AP, 15 ± 2 for RP1 and 340 ± 48 for RS, respectively.
All ATPS were able to achieve all planning DVH constraints and the effective working time was kept bellow 20 min for each ATPS except for RS. For the parallel organs, AP performed the best, although the differences were small.
•Spine SBRT yields greater complete/partial pain response rates than expected.•Spine SBRT is associated with high rates of local control.•∼10 % get post-SBRT vertebral compression fractures ...with < 2 % needing surgery.•Radiation myelopathy is rare with modern image-guided SBRT and evidence-based dose limits applied to the spinal cord.
Advances in characterizing cancer biology and the growing availability of novel targeted agents and immune therapeutics have significantly changed the prognosis of many patients with metastatic disease. Palliative radiotherapy needs to adapt to these developments. In this study, we summarize the available evidence for stereotactic body radiotherapy (SBRT) in the treatment of spinal metastases.
A systematic review and meta-analysis was performed using PRISMA methodology, including publications from January 2005 to September 2021, with the exception of the randomized phase III trial RTOG-0631 which was added in April 2023. Re-irradiation was excluded. For meta-analysis, a random-effects model was used to pool the data. Heterogeneity was assessed with the I2-test, assuming substantial and considerable as I2 > 50 % and I2 > 75 %, respectively. A p-value < 0.05 was considered statistically significant.
A total of 69 studies assessing the outcomes of 7236 metastases in 5736 patients were analyzed. SBRT for spine metastases showed high efficacy, with a pooled overall pain response rate of 83 % (95 % confidence interval CI 68 %-94 %), pooled complete pain response of 36 % (95 % CI: 20 %-53 %), and 1-year local control rate of 94 % (95 % CI: 86 %-99 %), although with high levels of heterogeneity among studies (I2 = 93 %, I2 = 86 %, and 86 %, respectively). Furthermore, SBRT was safe, with a pooled vertebral fracture rate of 9 % (95 % CI: 4 %-16 %), pooled radiation induced myelopathy rate of 0 % (95 % CI 0–2 %), and pooled pain flare rate of 6 % (95 % CI: 3 %-17 %), although with mixed levels of heterogeneity among the studies (I2 = 92 %, I2 = 0 %, and 95 %, respectively). Only 1.7 % of vertebral fractures required surgical stabilization.
Spine SBRT is characterized by a favorable efficacy and safety profile, providing durable results for pain control and disease control, which is particularly relevant for oligometastatic patients.
To evaluate volumetric modulated arc radiotherapy (RapidArc RA), a novel approach allowing for rapid treatment delivery, for the treatment of vestibular schwannoma (VS).
The RA plans were generated ...for a small (0.5 cm(3)), intermediate (2.8 cm(3)), and large (14.8 cm(3)) VS. The prescription dose was 12.5 Gy to the encompassing 80% isodose. The RA plans were compared with conventional radiosurgery plans using both a single dynamic conformal arc (1DCA) and five noncoplanar dynamic conformal arcs (5DCA). Conformity indices (CI) and dose-volume histograms of critical organs were compared. The RA plan for the medium-sized VS was measured in a phantom using Gafchromic EBT films and compared with calculated dose distributions.
The RA planning was completed within 30 min in all cases, and calculated treatment delivery time (after patient setup) was 5 min vs. 20 min for 5DCA. A superior CI was achieved with RA, with a substantial decrease in low-dose irradiation of the normal brain achieved relative to 5DCA plans. Maximum doses to critical organs were similar for RA and 5DCA but were higher for 1DCA. Film measurements showed the differences between calculated and measured doses to be smaller than 1.5% in the high-dose area and smaller than 3% in the low-dose area.
The RA plans consistently achieved a higher CI and decrease in areas of low-dose irradiation. This, together with shorter treatment delivery times, has led to RA replacing our conventional five-arc radiosurgery technique for VS.
Purpose
Four‐dimensional (4D) cone‐beam computed tomography (CBCT) of the lung is an effective tool for motion management in radiotherapy but presents a challenge because of slow gantry rotation ...times. Sorting the individual projections by breathing phase and using an established technique such as Feldkamp–Davis–Kress (FDK) to generate corresponding phase‐correlated (PC) three‐dimensional (3D) images results in reconstructions (FDK‐PC) that often contain severe streaking artifacts due to the sparse angular sampling distributions. These can be reduced by further slowing down the gantry at the expense of incurring unwanted increases in scan times and dose. A computationally efficient alternative is the McKinnon‐Bates (MKB) reconstruction algorithm that has shown promise in reducing view aliasing‐induced streaking but can produce ghosting artifacts that reduce contrast and impede the determination of motion trajectories. The purpose of this work was to identify and correct shortcomings in the MKB algorithm.
Methods
In the general MKB approach, a time‐averaged 3D prior image is first reconstructed. The prior is then forward‐projected at the same angles as the original projection data creating time‐averaged reprojections. These reprojections are subsequently subtracted from the original (unblurred) projections to create motion‐encoded difference projections. The difference projections are reconstructed into PC difference images that are added to the well‐sampled 3D prior to create the higher quality 4D image. The cause of the ghosting in the traditional 4D MKB images was studied and traced to motion‐induced streaking in the prior that, when reprojected, has the undesirable effect of re‐encoding for motion in what should be a purely time‐averaged reprojection. A new method, designated as the modified McKinnon‐Bates (mMKB) algorithm, was developed based on destreaking the prior. This was coupled with a postprocessing 4D bilateral filter for noise suppression and edge preservation (mMKBbf). The algorithms were tested with the 4D XCAT phantom using four simulated scan times (57, 60, 120, 180 s) and with two in vivo thorax studies (acquisition time of 60 and 90 s). Contrast‐to‐noise ratios (CNRs) of the target lesions and overall visual quality of the images were assessed.
Results
Prior destreaking (mMKB algorithm) reduced ghosting artifacts and increased CNRs for all cases, with the biggest impacts seen in the end inhale (EI) and end exhale (EE) phases of the respiratory cycle. For the XCAT phantom, mMKB lesion CNR was 44% higher than the MKB lesion CNR and was 81% higher than the FDK‐PC lesion CNR (EI and EE phases). The bilateral filter provided a further average CNR improvement of 87% with the highest increases associated with longer scan times. Across all phases and scan times, the maximum mMKBbf‐to‐FDK‐PC CNR improvement was over 300%. In vivo results agreed with XCAT results. Significantly less ghosting was observed throughout the mMKB images including near the lesions‐of‐interest and the diaphragm allowing for, in one case, visualization of a small tumor with nearly 30 mm of motion. The maximum FDK‐PC‐to‐MKBbf CNR improvement for Patient 1's lesion was 261% and for Patient 2's lesion was 318%.
Conclusions
The 4D mMKB algorithm yields good quality coronal and sagittal images in the thorax that may provide sufficient information for patient verification.
Background: Published trials of concurrent chemoradiotherapy (CCRT) in stage III non-small-cell lung cancer (NSCLC) generally excluded patients with significant comorbidity. We evaluated outcomes in ...patients who were selected by using radiation planning parameters and were considered, despite comorbidity, fit enough to receive cisplatin-based chemotherapy.
Patients and methods: From 2003 to 2008, 89 patients with stage III NSCLC fit to receive cisplatin-based chemotherapy and a V20 <42% underwent CCRT at one center outside clinical trials. Most received one cycle of cisplatin–gemcitabine, followed by two to three cycles of cisplatin–etoposide concurrent with involved-field thoracic radiotherapy between 46 and 66Gy.
Results: Median age was 64 years; performance status (PS) of zero, one or two in 20/64/5 patients; one or more comorbidities in 41.6%; 14% were treated previously for NSCLC. Median V20 was 26.6% (range 4%–39.4%). Grade III esophagitis and pneumonitis occurred in 28.1% and 7.9% of patients, respectively, while 4.5% died during treatment. Median overall survival was 18.2 months 95% confidence interval (CI) 13.1–23.3 months. Independent prognostic factors for overall survival were PS (0 versus ≥1, P = 0.041) and planning target volume (P = 0.022).
Conclusions: Patients with significant comorbidity who are fit to undergo cisplatin-based CCRT achieve median survivals similar to that reported in phase III trials and with relatively few late toxic effects.
Recent progress in diagnostics and treatment of metastatic cancer patients have improved survival substantially. These developments also affect local therapies, with treatment aims shifting from ...short-term palliation to long-term symptom or disease control. There is consequently a need to better define the value of stereotactic body radiotherapy (SBRT) for the treatment of spinal metastases.
This ESTRO clinical practice guideline is based on a systematic literature review conducted according to PRISMA standards, which formed the basis for answering four key questions about the indication and practice of SBRT for spine metastases.
The analysis of the key questions based on current evidence yielded 22 recommendations and 5 statements with varying levels of endorsement, all achieving a consensus among experts of at least 75%. In the majority, the level of evidence supporting the recommendations and statements was moderate or expert opinion, only, indicating that spine SBRT is still an evolving field of clinical research. Recommendations were established concerning the selection of appropriate patients with painful spine metastases and oligometastatic disease. Recommendations about the practice of spinal SBRT covered technical planning aspects including dose and fractionation, patient positioning, immobilization and image-guided SBRT delivery. Finally, recommendations were developed regarding quality assurance protocols, including description of potential SBRT-related toxicity and risk mitigation strategies.
This ESTRO clinical practice guideline provides evidence-based recommendations and statements regarding the selection of patients with spinal metastases for SBRT and its safe implementation and practice. Enrollment of patients into well-designed prospective clinical trials addressing clinically relevant questions is considered important.
Background. We conducted a population-based, nation-wide, prospective study to identify who introduced pertussis into the household of infants aged ⩽6 months admitted to the hospital for pertussis in ...the Netherlands. During the period 2006–2008, a total of 560 household contacts of 164 hospitalized infants were tested by polymerase chain reaction, culture, and serological examination to establish Bordetella pertussis infection. Methods. Clinical symptoms and vaccination history were obtained by a questionnaire submitted during sample collection and 4–6 weeks afterwards. Results. Overall, 299 household contacts (53%) had laboratory-confirmed pertussis; 159 (53%) had symptoms compatible with typical pertussis infection, and 42 (14%) had no symptoms. Among children vaccinated with a whole-cell vaccine, 17 (46%) of 37 had typical pertussis 1–3 years after completion of the primary series, compared with 9 (29%) of 31 children who had been completely vaccinated with an acellular vaccine. For 96 households (60%), the most likely source of infection of the infant was established, being a sibling (41%), mother (38%), or father (17%). Conclusions. If immunity to pertussis in parents is maintained or boosted, 35%–55% of infant cases could be prevented. Furthermore, we found that, 1–3 years after vaccination with whole-cell or acellular vaccine, a significant percentage of children are again susceptible for typical pertussis. In the long term, pertussis vaccines and vaccination strategies should be improved to provide longer protection and prevent transmission.
Comments on 'Single-Arc IMRT?' Verbakel, W F A R; Senan, S; Lagerwaard, F J ...
Physics in medicine & biology,
04/2009, Letnik:
54, Številka:
8
Journal Article
Recenzirano
We read with interest the article titled 'Single-Arc IMRT?' (Bortfeld and Webb 2009 Phys. Med. Biol. 54 N9-20) and feel it imperative to draw the attention of your readers to comments suggesting that ...the authors may not be fully aware of current developments in this field. As their paper was first submitted on 19th of August 2008, it could not have taken into account data presented at the AAPM, ESTRO and ASTRO meetings in 2008. In this letter, we would like to clarify some relevant aspects of RapidArc (Varian Medical Systems) as a modality for delivering single-arc treatment.
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