Radiation Oncology

Journal: Radiation Oncology

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BioMed Central

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Publications 1 - 10 of 11

Systematic evaluation of three different commercial software solutions for automatic segmentation for adaptive therapy in head-and-neck, prostate and pleural cancer
La Macchia, Mariangela; Fellin, Francesco; Amichetti, Maurizio; et al. (2012)
Radiation Oncology
Purpose To validate, in the context of adaptive radiotherapy, three commercial software solutions for atlas-based segmentation. Methods and materials Fifteen patients, five for each group, with cancer of the Head&Neck, pleura, and prostate were enrolled in the study. In addition to the treatment planning CT (pCT) images, one replanning CT (rCT) image set was acquired for each patient during the RT course. Three experienced physicians outlined on the pCT and rCT all the volumes of interest (VOIs). We used three software solutions (VelocityAI 2.6.2 (V), MIM 5.1.1 (M) by MIMVista and ABAS 2.0 (A) by CMS-Elekta) to generate the automatic contouring on the repeated CT. All the VOIs obtained with automatic contouring (AC) were successively corrected manually. We recorded the time needed for: 1) ex novo ROIs definition on rCT; 2) generation of AC by the three software solutions; 3) manual correction of AC. To compare the quality of the volumes obtained automatically by the software and manually corrected with those drawn from scratch on rCT, we used the following indexes: overlap coefficient (DICE), sensitivity, inclusiveness index, difference in volume, and displacement differences on three axes (x, y, z) from the isocenter. Results The time saved by the three software solutions for all the sites, compared to the manual contouring from scratch, is statistically significant and similar for all the three software solutions. The time saved for each site are as follows: about an hour for Head&Neck, about 40 minutes for prostate, and about 20 minutes for mesothelioma. The best DICE similarity coefficient index was obtained with the manual correction for: A (contours for prostate), A and M (contours for H&N), and M (contours for mesothelioma). Conclusions From a clinical point of view, the automated contouring workflow was shown to be significantly shorter than the manual contouring process, even though manual correction of the VOIs is always needed.
Monitoring of breathing motion in image-guided PBS proton therapy: comparative analysis of optical and electromagnetic technologies
Fattori, Giovanni; Safai, Sairos; Fernández Carmona, Pablo; et al. (2017)
Radiation Oncology
Background Motion monitoring is essential when treating non-static tumours with pencil beam scanned protons. 4D medical imaging typically relies on the detected body surface displacement, considered as a surrogate of the patient's anatomical changes, a concept similarly applied by most motion mitigation techniques. In this study, we investigate benefits and pitfalls of optical and electromagnetic tracking, key technologies for non-invasive surface motion monitoring, in the specific environment of image-guided, gantry-based proton therapy. Methods Polaris SPECTRA optical tracking system and the Aurora V3 electromagnetic tracking system from Northern Digital Inc. (NDI, Waterloo, CA) have been compared both technically, by measuring tracking errors and system latencies under laboratory conditions, and clinically, by assessing their practicalities and sensitivities when used with imaging devices and PBS treatment gantries. Additionally, we investigated the impact of using different surrogate signals, from different systems, on the reconstructed 4D CT images. Results Even though in controlled laboratory conditions both technologies allow for the localization of static fiducials with sub-millimetre jitter and low latency (31.6 ± 1 msec worst case), significant dynamic and environmental distortions limit the potential of the electromagnetic approach in a clinical setting. The measurement error in case of close proximity to a CT scanner is up to 10.5 mm and precludes its use for the monitoring of respiratory motion during 4DCT acquisitions. Similarly, the motion of the treatment gantry distorts up to 22 mm the tracking result. Conclusions Despite the line of sight requirement, the optical solution offers the best potential, being the most robust against environmental factors and providing the highest spatial accuracy. The significant difference in the temporal location of the reconstructed phase points is used to speculate on the need to apply the same monitoring system for imaging and treatment to ensure the consistency of detected phases.
Technical assessment of the NDI Polaris Vega optical tracking system
Fattori, Giovanni; Lomax, Antony J.; Weber, Damien C.; et al. (2021)
Radiation Oncology
The Polaris product line from Northern Digital Inc. is well known for accurate optical tracking measurements in research and medical environments. The Spectra position sensor, to date often found in image guided radiotherapy suites, has however reached its end-of-life, being replaced by the new Vega model. The performance in static and dynamic measurements of this new device has been assessed in controlled laboratory conditions, against the strict requirements for system integration in radiation therapy. The system accuracy has improved with respect to the Spectra in both static (0.045 mm RMSE) and dynamic (0.09 mm IQR, < 20 cm/s) tracking and brings marginal improvement in the measurement latency (14.2 ± 1.8 ms). The system performance was further confirmed under clinical settings with the report of early results from periodic QA tests within specifications. Based on our tests, the Polaris Vega meets the quality standards of radiotherapy applications and can be safely used for monitoring respiratory breathing motion or verifying patient positioning.
Prognostic impact of the "Sekhar grading system for cranial Chordomas" in patients treated with pencil beam scanning proton therapy: an institutional analysis
Hottinger, Anna-Lena; Bojaxhiu, Beat; Ahlhelm, Frank; et al. (2020)
Radiation Oncology
Background Skull base chordomas are rare and heterogeneously behaving tumors. Though still classified as benign they can grow rapidly, are locally aggressive, and have the potential to metastasize. To adapt the treatment to the specific needs of patients at higher risk of recurrence, a pre-proton therapy prognostic grading system would be useful. The aim of this retrospective analysis is to assess prognostic factors and the “Sekhar Grading System for Cranial Chordomas” (SGSCC) by evaluating the larger cohort of patients treated at our institution as to determine its reproducibility and ultimately to ensure more risk adapted local treatments for these challenging tumors. Methods We analyzed 142 patients treated for skull base chordomas between 2004 and 2016. We focused the analysis on the 5 criteria proposed for the SGSCC (tumor size, number of anatomic regions and vessels involved, intradural invasion, as well as recurrence after prior treatment) and classified our patients according to their score (based on the above mentioned criteria) into three prognostic groups, low-risk, intermediate-risk and high-risk. The three groups were then analyzed in regards of local control, local recurrence-free survival and overall survival. Results The median follow up was 52 months (range, 3–152). We observed 34 (24%) patients with a local recurrence, resulting in a local control of 75% at 5 years. Overall survival was 83% at 5 years, 12 (9%) patients had died due to local progression. When split into the three prognostic groups according to the SGSCC the observed local control was 90, 72 and 64% (p = 0.07) in the low-, intermediate- and high-risk group, respectively. A similar correlation was observed for local recurrence-free survival with 93, 89 and 66% (p = 0.05) and for overall survival with 89, 83 and 76% (p = 0.65) for the same prognostic groups. Conclusions After splitting our patient cohort into the three SGSCC risk groups, we found a trend towards better outcome for those patients with lower as opposed to higher scores. These results suggest that this prognostic grading system published by Sekhar et al. could be integrated in the management decision-tree for patients with skull base chordoma.
Dose-painting intensity-modulated proton therapy for intermediate- and high-risk meningioma
Madani, Indira; Lomax, Antony J.; Albertini, Francesca; et al. (2015)
Radiation Oncology
Background Newly diagnosed WHO grade II-III or any WHO grade recurrent meningioma exhibit an aggressive behavior and thus are considered as high- or intermediate risk tumors. Given the unsatisfactory rates of disease control and survival after primary or adjuvant radiation therapy, optimization of treatment strategies is needed. We investigated the potential of dose-painting intensity-modulated proton beam-therapy (IMPT) for intermediate- and high-risk meningioma. Material and methods Imaging data from five patients undergoing proton beam-therapy were used. The dose-painting target was defined using [68]Ga-[1,4,7,10-tetraazacyclododecane tetraacetic acid]– d-Phe1,Tyr3-octreotate ([68]Ga-DOTATATE)-positron emission tomography (PET) in target delineation. IMPT and photon intensity-modulated radiation therapy (IMRT) treatment plans were generated for each patient using an in-house developed treatment planning system (TPS) supporting spot-scanning technology and a commercial TPS, respectively. Doses of 66 Gy (2.2 Gy/fraction) and 54 Gy (1.8 Gy/fraction) were prescribed to the PET-based planning target volume (PTVPET) and the union of PET- and anatomical imaging-based PTV, respectively, in 30 fractions, using simultaneous integrated boost. Results Dose coverage of the PTVsPET was equally good or slightly better in IMPT plans: dose inhomogeneity was 10 ± 3% in the IMPT plans vs. 13 ± 1% in the IMRT plans (p = 0.33). The brain Dmean and brainstem D50 were small in the IMPT plans: 26.5 ± 1.5 Gy(RBE) and 0.002 ± 0.0 Gy(RBE), respectively, vs. 29.5 ± 1.5 Gy (p = 0.001) and 7.5 ± 11.1 Gy (p = 0.02) for the IMRT plans, respectively. The doses delivered to the optic structures were also decreased with IMPT. Conclusions Dose-painting IMPT is technically feasible using currently available planning tools and resulted in dose conformity of the dose-painted target comparable to IMRT with a significant reduction of radiation dose delivered to the brain, brainstem and optic apparatus. Dose escalation with IMPT may improve tumor control and decrease radiation-induced toxicity.
Investigating the potential of proton therapy for hypoxia-targeted dose escalation in non-small cell lung cancer
Köthe, Andreas; Bizzocchi, Nicola; Safai, Sairos; et al. (2021)
Radiation Oncology
Background Hypoxia is known to be prevalent in solid tumors such as non-small cell lung cancer (NSCLC) and reportedly correlates with poor prognostic clinical outcome. PET imaging can provide in-vivo hypoxia measurements to support targeted radiotherapy treatment planning. We explore the potential of proton therapy in performing patient-specific dose escalation and compare it with photon volumetric modulated arc therapy (VMAT). Methods Dose escalation has been calibrated to the patient specific tumor response of ten stage IIb-IIIb NSCLC patients by combining HX4-PET imaging and radiobiological modelling of oxygen enhancement ratio (OER) to target variable tumor hypoxia. In a dose-escalation-by-contour approach, escalated dose levels were simulated to the most hypoxic region of the primary target and its effectiveness in improving loco-regional tumor control was assessed. Furthermore, the impact on normal tissue of proton treatments including dose escalation was evaluated in comparison to the normal tissue complication probability (NTCP) of conventional VMAT plans. Results Ignoring regions of tumor hypoxia can cause overestimation of TCP values by up to 10%, which can effectively be recovered on average to within 0.9% of the nominal TCP, using patient-specific dose escalations of up to 22% of the prescribed dose to PET defined hypoxic regions. Despite such dose escalations, the use of protons could also simultaneously reduce mean doses to the heart (− 14.3 GyRBE), lung (− 8.3 GyRBE), esophagus (− 6.9 GyRBE) and spinal cord (− 3.8 Gy) compared to non-escalated VMAT plans. These reductions are predicted to lead to clinically relevant decreases in NTCP for radiation-induced pneumonitis (− 11.3%), high grade heart toxicity (− 7.4%) and esophagitis (− 7.5%). Conclusions This study suggests that the administration of proton therapy for dose escalation to patient specific regions of tumor hypoxia in the treatment of NSCLC can mitigate TCP reduction due to hypoxia-induced radio resistance, while simultaneously reducing NTCP levels even when compared to non-escalated treatments delivered with state-of-the-art photon techniques.
Unconscious physiological response of healthy volunteers to dynamic respiration-synchronized couch motion
Jöhl, Alexander; Bogowicz, Marta; Ehrbar, Stefanie; et al. (2017)
Radiation Oncology
Background Intrafractional motion can be a substantial uncertainty in precision radiotherapy. Conventionally, the target volume is expanded to account for the motion. Couch-tracking is an alternative, where the patient is moved to compensate for the tumor motion. However, the couch motion may influence the patient’s stress and respiration behavior decreasing the couch-tracking effectiveness. Methods In total, 100 volunteers were positioned supine on a robotic couch, which moved dynamically and respiration synchronized. During the measurement, the skin conductivity, the heartrate, and the gaze location were measured indicating the volunteer’s stress. Volunteers rated the subjective motion sickness using a questionnaire. The measurement alternated between static and tracking segments (three cycles), each 1 min long. Results The respiration amplitude showed no significant difference between tracking and static segments, but decreased significantly from the first to the last tracking segment (p < 0.0001). The respiration frequency differed significantly between tracking and static segments (p < 0.0001), but not between the first and the last tracking segment. The physiological parameters and the questionnaire showed mild signals of stress and motion sickness. Conclusion Generally, people tolerated the couch motions. The interaction between couch motion and the patient’s breathing pattern should be considered for a clinical implementation. Trial registration The study was registered at ClinicalTrials.gov (NCT02820532) and the Swiss national clinical trials portal (SNCTP000001878) on June 20, 2016.
Adaptive step size algorithm to increase efficiency of proton macro Monte Carlo dose calculation
Kueng, Reto; Frei, Daniel; Volken, Werner; et al. (2019)
Radiation Oncology
Purpose To provide fast and accurate dose calculation in voxelized geometries for proton radiation therapy by implementing an adaptive step size algorithm in the proton macro Monte Carlo (pMMC) method. Methods The in-house developed local-to-global MMC method for proton dose calculation is extended with an adaptive step size algorithm for efficient proton transport through a voxelized geometry by sampling transport parameters from a pre-simulated database. Adaptive choice of an adequate slab size in dependence of material interfaces in the proton’s longitudinal and lateral vicinity is investigated. The dose calculation algorithm is validated against the non-adaptive pMMC and full MC simulation for pencil and broad beams with various energies impinging on academic phantoms as well as a head and neck patient CT. Results For material interfaces perpendicular to a proton’s direction, choice of nearest neighbor slab thickness shows best trade-off between dosimetric accuracy and calculation efficiency. Adaptive reduction of chosen slab size is shown to be required for material interfaces closer than 0.5 mm in lateral direction. For the academic phantoms, dose differences of within 1% or 1 mm compared to full Geant4 MC simulation are found, while achieving an efficiency gain of up to a factor of 5.6 compared to the non-adaptive algorithm and 284 compared to Geant4. For the head and neck patient CT, dose differences are within 1% or 1 mm with an efficiency gain factor of up to 3.4 compared to the non-adaptive algorithm and 145 compared to Geant4. Conclusion An adaptive step size algorithm for proton macro Monte Carlo was implemented and evaluated. The dose calculation provides the accuracy of full MC simulations, while achieving an efficiency gain factor of three compared to the non-adaptive algorithm and two orders of magnitude compared to full MC for a complex patient CT.
Prevention of radiochemotherapy-induced toxicity with amifostine in patients with malignant orbital tumors involving the lacrimal gland
Goldblum, David; Ghadjar, Pirus; Curschmann, Juergen; et al. (2008)
Radiation Oncology
Background To use amifostine concurrently with radiochemotherapy (CT-RT) or radiotherapy (RT) alone in order to prevent dry eye syndrome in patients with malignancies located in the fronto-orbital region. Methods Five patients (2 males, 3 females) with diagnosed malignancies (Non-Hodgkin B-cell Lymphoma, neuroendocrine carcinoma) involving the lacrimal gland, in which either combined CT-RT or local RT were indicated, were prophylactically treated with amifostine (500 mg sc). Single RT fraction dose, total dose and treatment duration were individually adjusted to the patient's need. Acute and late adverse effects were recorded using the RTOG score. Subjective and objective dry eye assessment was performed for the post-treatment control of lacrimal gland function. Results All patients have completed CT-RT or RT as indicated. The median total duration of RT was 29 days (range, 23 – 39 days) and the median total RT dose was 40 Gy (range, 36 – 60 Gy). Median lacrimal gland exposure was 35.9 Gy (range, 16.8 – 42.6 Gy). Very good partial or complete tumor remission was achieved in all patients. The treatment was well tolerated without major toxic reactions. Post-treatment control did not reveal in any patient either subjective or objective signs of a dry eye syndrome. Conclusion The addition of amifostine to RT/CT-RT of patients with tumors localized in orbital region was found to be associated with absence of dry eye syndrome.
Organ-at-risk sparing with dynamic trajectory radiotherapy for head and neck cancer: comparison with volumetric arc therapy on a publicly available library of cases
Bertholet, Jenny; Mackeprang, Paul-Henry; Mueller, Silvan; et al. (2022)
Radiation Oncology
Background Dynamic trajectory radiotherapy (DTRT) extends volumetric modulated arc therapy (VMAT) with dynamic table and collimator rotation during beam-on. The aim of the study is to establish DTRT path-finding strategies, demonstrate deliverability and dosimetric accuracy and compare DTRT to state-of-the-art VMAT for common head and neck (HN) cancer cases. Methods A publicly available library of seven HN cases was created on an anthropomorphic phantom with all relevant organs-at-risk (OARs) delineated. DTRT plans were generated with beam incidences minimizing fractional target/OAR volume overlap and compared to VMAT. Deliverability and dosimetric validation was carried out on the phantom. Results DTRT and VMAT had similar target coverage. For three locoregionally advanced oropharyngeal carcinomas and one adenoid cystic carcinoma, mean dose to the contralateral salivary glands, pharynx and oral cavity was reduced by 2.5, 1.7 and 3.1 Gy respectively on average with DTRT compared to VMAT. For a locally recurrent nasopharyngeal carcinoma, D-0.03 cc to the ipsilateral optic nerve was above tolerance (54.0 Gy) for VMAT (54.8 Gy) but within tolerance for DTRT (53.3 Gy). For a laryngeal carcinoma, DTRT resulted in higher dose than VMAT to the pharynx and brachial plexus but lower dose to the upper oesophagus, thyroid gland and contralateral carotid artery. For a single vocal cord irradiation case, DTRT spared most OARs better than VMAT. All plans were delivered successfully on the phantom and dosimetric validation resulted in gamma passing rates of 93.9% and 95.8% (2%/2 mm criteria, 10% dose threshold). Conclusions This study provides a proof of principle of DTRT for common HN cases with plans that were deliverable on a C-arm linac with high accuracy. The comparison with VMAT indicates substantial OAR sparing could be achieved.

Publications 1 - 10 of 11

Journal: Radiation Oncology

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