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At least 19 recordsLinked to original sources

PubMed2026

Robust optimisation for photon radiotherapy: A scoping review of models, paradigms, and reporting.

BACKGROUND AND PURPOSE: Robust optimisation offers an alternative to conventional margin-based photon radiotherapy planning by explicitly modelling uncertainty, but practice is variable and not standardised. MATERIALS AND METHODS: A scoping review was conducted to map robust optimisation for photon external beam radiotherapy. Electronic searches of Scopus, PubMed and Google Scholar (2000-2025, English language) identified planning studies that incorporated modelled uncertainties into the optimisation process and reported at least one robustness-related outcome. Data were charted on clinical context, uncertainty models, optimisation paradigms, robustness metrics and evidence for clinical implementation. RESULTS: Seventy-one studies were included. Most investigated prostate, breast or lung cancer and used intensity-modulated radiotherapy or volumetric-modulated arc therapy in commercial or research treatment planning systems. Scenario-based worst-case (minimax) optimisation was the dominant paradigm in clinically oriented work, while chance-constrained, conditional value at-risk, distributionally robust and adaptive formulations were confined to small methodological series. Uncertainty modelling focused mainly on rigid set-up error; fewer studies incorporated respiratory motion, inter-fraction anatomical change, dose-calculation uncertainty or biological variation. Robustness was evaluated with diverse scenario-based dose-volume metrics, probabilistic coverage measures, composite robustness indices and, less often, biological endpoints. Direct clinical implementation reports were scarce. CONCLUSION: Robust photon planning is technically feasible and generally maintains or improves target coverage and organ sparing compared with margin-based planning. However, heterogeneity in uncertainty models, optimisation configuration and robustness reporting limits comparison and synthesis. Pragmatic minimum standards are proposed to support future consensus and wider clinical adoption.

Humans↗

PubMed1992

Role for proton beam irradiation in treatment of pediatric CNS malignancies.

The ability to vary the proton energy (depth of beam penetration) and modulate the dose distribution at the end of range permits delivery of an increased dose to the designated cancer-containing volume with a reduced dose to overlying normal brain tissue. The evolution of childhood CNS malignancy following therapy is reviewed to identify radiation response variables indicating where the proton dose distribution will improve the therapeutic ratio. The review documents that of the 1262 children expected to develop CNS malignancy in 1989, only 43% will survive 5 years. About 75% of those with medulloblastoma and over 90% with astrocytoma die from persistent (in-field) disease. When the patient has been treated with radiation, it is accepted that disease persistence indicates the cancer dose was insufficient. Potentially 536 children could show an improved incidence of local control and improved survival from an increased cancer dose available from proton irradiation. As the total dose and volume of brain irradiated is increased about 1800 cGy, brain dysfunction increases, producing a spectrum of functional and intellectual deficits which are age and volume related. About 900 irradiated patients would have fewer in-field histologic and functional changes if the dose to normal brain, or the volume of brain irradiated, is reduced by an improved dose distribution. A proton beam treatment plan, delivering a cancer dose of 7400 cGy, is simulated for a thalamic astrocytoma. The dose distribution of this plan is compared with an x-ray plan used to treat a patient, in which a dose of 5400 cGy was delivered to the astrocytoma. Comparative isodose distributions and dose-volume histograms indicate a decreased integral dose to normal brain and a decreased volume of normal brain irradiated, even as the cancer dose is boosted 2000 cGy with protons.

Brain Neoplasms↗

PubMed1977

Radiotherapy treatment planning using the ACTA-scanner.

Computerized tomography is useful in radiotherapy treatment planning in the following ways: (1) Its image provides the most accurate possible contour of the patient and demonstrates the internal structures in their proper relation to each other. (2) The tumor and its extension are accurately demonstrated. (3) Corrections for tissue heterogeneities can be accomplished in one of two ways, either by arbitrary assignment of densities to tissues or by direct scanning with a therapy source. This latter procedure is under investigation. (4) The computer can be programmed to demonstrate summations of dose delivered from multiple fields.

Dose-Response Relationship, Radiation↗

PubMed2026

Technical note: reconstructing dose distributions from manually planned electron boosts in breast radiotherapy.

PURPOSE: In breast radiotherapy, delivery of manually-calculated electron boosts limits retrospective dose-response analyses as dose distribution is unavailable. This work evaluates the feasibility of reconstructing dose distributions from manually planned electron boosts in breast-conserving radiotherapy. METHODS: Only 72 out of 198 breast cancer patients had complete stored dose distributions from sequential electron boosts in the REQUITE study. Arbitrary data from 70/72 patients were used to develop and validate dose reconstruction method. Twenty patients were used to determine optimal parameters for Monte-Carlo-based (MC) electron dose reconstruction on RayStation (v.11B-R), considering CT-calibration curve, MC-history number, andcalculation grid resolution. Remaining 50 patients were used to quantify dose reconstruction accuracy. The similarity between reconstructed and stored dose was evaluated using 3D-gamma index and dosimetric parameters extracted from breast and tumour bed contours. Dose difference location was evaluated using dose-location histogram. RESULTS: Calculation grid resolution significantly impacted electron dose distribution (p < 0.01), where the finest grid (0.15 cm) showed highest similarity to stored doses. CT-calibration curve and MC-history number had a negligible influence on dose reconstruction. Dosimetric difference between reconstructed and stored doses was < 1 Gy for breast and tumour bed. Reconstructed dose was achieved > 90% gamma passing rate in the validation set. However, around 2.5 Gy dose differences were observed at the skin and tissue interface regions. CONCLUSIONS: Retrospective electron boost dose reconstruction is feasible with acceptable accuracy, and could increase data completeness in large cohort studies. Caution is advised when assessing dose near tissue interface and further validation is needed outside the REQUITE dataset.

Electrons↗

PubMed1992

Comparative treatment planning: proton vs. x-ray beams against glioblastoma multiforme.

The survival of patients with glioblastoma multiforme is extremely poor, the 5-year survival rate being almost zero. The cause of failure is almost exclusively local progression of tumor, the remainder is due to complications of treatment. Although this tumor is clearly radiation resistant, there is evidence of a dose response relationship. Using a thin slice CT scan of the entire head of a patient with glioblastoma multiforme, 3-dimensional radiation treatment plans were developed for treatment to a dose of 90 cobalt-Gray-equivalent (CGE). Dose distributions using protons were compared to those using x-rays. The results showed advantages for the proton beam technique. Namely the proton plan irradiated less non-target brain than the x-ray plan; this was especially so in the decrease of coverage of deep-seated structures. The volume of non-target brain that received more than 70 CGE was 175 ml for the x-ray plan and 94 ml for the proton plan. This study indicates that for a subpopulation of patients with glioblastoma multiforme, at least 90 CGE could be delivered with proton beam techniques to the target with only small volumes of normal brain structures receiving more than 70 CGE.

Brain Neoplasms↗

PubMed1992

Potential improvement of three dimension treatment planning and proton therapy in the outcome of maxillary sinus cancer.

Carcinomas arising in the maxillary sinus are challenging technical problems for radiotherapists due to the complexity of the regional anatomy and the close relations of the tumor to dose-limiting critical structures (eyes, optic nerves, optic chiasm, and brain stem). This study shows that an improvement in the dose distribution can be achieved with the use of three dimensional treatment planning and a combination of x-ray and proton beam arrangements. Although tumor coverage was identical when comparing dose distributions of X rays alone to X rays plus proton beam boost, the critical structures received less dose in the X rays plus proton beam plan. Because a superior dose distribution should yield an improved local control and reduced morbidity, a benefit in survival could be expected.

Carcinoma, Squamous Cell↗

PubMed2026

Failure modes and effects analysis for clinical implementation of online adaptive radiotherapy: A systematic review.

BACKGROUND: The accuracy of radiotherapy is limited by anatomical variations occurring over time scales ranging from sub-seconds to days. Online Adaptive Radiotherapy (OART) addresses this by enabling daily plan adaptation based on real-time imaging. While OART offers improved dose conformity, its dynamic, time-constrained workflow introduces novel failure modes that challenge traditional quality assurance protocols. PURPOSE: This study aims to synthesize the existing literature on Failure Modes and Effects Analysis (FMEA) for OART to systematically catalog risks and identify mitigation strategies. METHODS: A systematic literature search was conducted to identify studies applying FMEA to OART workflows. Eleven studies were included, covering MR-guided (ViewRay MRIdian, Elekta Unity), CBCT-guided (Varian Ethos), and MR-enhanced C-arm linac systems. To address heterogeneity in risk scoring methodologies (e.g., TG-100 10-point scales vs. 5-point rankings), extracted failure modes were harmonized into a standardized three-tier risk classification system (Class I: Low, Class II: Intermediate, Class III: High). RESULTS: A total of 300 unique failure modes were identified, with 49.6 percent classified as high-risk (Class III). Analysis revealed that the majority of high-risk failures were concentrated in the online treatment delivery phase, specifically within human-computer interactions and anatomical contouring steps. CONCLUSIONS: This study supports the development of tailored, robust QA frameworks that prioritize human factors and process consistency to guide safe implementation in diverse clinical settings.

Humans↗

PubMed2026

One Year After a Cyberattack: Lessons Learned and Dosimetric Analysis of Contingency Radiotherapy Plans.

PURPOSE: Cyberattacks on health care institutions pose significant risks to patient care, particularly in radiotherapy departments, which are heavily reliant on digital systems. This study examines the impact of a ransomware attack on our hospital and evaluates the effectiveness of the contingency measures implemented to resume radiotherapy treatments. METHODS AND MATERIALS: Following the cyberattack, our radiotherapy department faced a complete shutdown. After an initial estimate considering a shutdown of several weeks, a contingency plan was executed, including manual patient data retrieval and collaboration with a backup hospital. Contingency plans were prepared and delivered within hours, despite a partial lack of information. These plans allowed some patients to restart treatment 3 days after the attack. A dosimetric analysis was performed for the contingency plans, including various pathologies, mainly glioblastoma, head and neck cancers, and lung cancer. We compared the original and contingency plans in terms of dose coverage to the clinical target volume, biological effective dose, and their clinical impact as assessed at the 1‑year follow‑up after the cyberattack. RESULTS: Treatments resumed within 12 days at our hospital. Patients with glioblastoma showed good target coverage because of generous margins, resulting in favorable outcomes. In head and neck cases, the lack of detailed imaging led to significant target volume misses, suggesting that more conservative initial treatments could have been beneficial. Lung cases demonstrated accurate peripheral lesion targeting but faced challenges in central lesions because of the absence of positron emission tomography information. In most cases, the approach of using a contingency plan, even with limited information, led to a higher biological effective dose than would have been achieved if treatment had been stopped until full recovery at our hospital. CONCLUSIONS: The study highlights the critical importance of robust contingency planning in radiotherapy departments, emphasizing the need for backup systems and tailored approaches based on tumor location and available diagnostic information. These lessons emphasize that preparedness for digital disruptions should not focus exclusively on information and technology infrastructure.

Humans↗

PubMed1977

A computerized tomographic evaluation of malignancies of the bladder and prostate.

Twenty cases of malignancies of the bladder and prostate were evaluated by computed tomography. This study was performed in a community hospital adjacent to a large retirement community in Southern California. Although the series was small, the results indicate that, for example, staging of carcinoma of the bladder malignancy beyond Jewitt-Marshall A can be accomplished with some ease using this modality. The extensive malignancies are easily demonstrated and their extents, in relationship to surrounding pelvic structures, are seen with considerable clarity. The use in radiation treatment planning is obvious.

Aged↗

PubMed1992

Three-dimensional imaging for brachytherapy planning.

A computerized 3-D brachytherapy treatment planning program has been developed which simulates catheter trajectories, radioisotope seed positioning and percentage dosimetry zones about a catheter/seed array in relationship to CT or MRI images. The high activity 125I seed is used in this program. A visual and a non-linear mathematical optimization program will also be described.

Brachytherapy↗

PubMed1992

Template-guided stereotactic implantation of malignant brain tumors for interstitial thermoradiotherapy.

A phase I trial of 25 patients with anaplastic astrocytoma or glioblastoma multiforme is described. Hyperthermia and radiation were delivered stereotactically by means of template-guided interstitial catheters loaded with ferromagnetic wires and then 192Ir seeds. Implant volumes ranged from 15 to 113 ml (mean 54 ml) involving 9-38 catheters (mean 18); parallel catheters used hexagonal spacing of 1.0-1.5 cm. Patient tolerance of these procedures was excellent. Postoperative morbidity due to additional mass effect or edema was low, but there has been one death and one complication of hydrocephalus, bleeding and symptomatic pneumocephalus, each.

Adult↗

PubMed1977

Computer-aided medical decision making in radiotherapy.

Radiotherapy departments are becoming sophisticated in working with computers for isodose computations, treatment machine verifications and administrative and medical records. The next step lies in computer-assisted medical decision making. The logic for a patient's diagnostic work-up and treatment protocol can be stored in a computer. It can then be used as an aid in making the diagnosis, in prescribing the treatment and for quality control. For patients who fit established protocols the computer can select and list treatment using the logic of that protocol. Such a system has been implemented for the postoperative radiotherapy of breast cancer on a trial basis. Its potential usefulness is illustrated by results in 25 consecutive patients. Physician acceptance and costs of the program are under investigation.

Breast Neoplasms↗

PubMedDate not supplied

Bayesian statistics: a guided tour.

An overview of Bayesian statistical decision theory is presented in the tutorial spirit. A section on fundamental principles is followed by selected applications of the Bayesian approach to parameter estimation, pattern recognition, image processing, computer-aided medical diagnosis, optimal diagnostic test selection, and radiotherapy treatment planning.

Decision Making↗

PubMed1978

[Ultrasound in tumor diagnostics and treatment planning (author's transl)].

The fundamental requirements of irradiation planning are discussed delimitating the minimum and maximum demands of planning. Different possibilities to represent the topographic relations within the irradiation plane of the patient's cross-section are described. The computer-assisted system for irradiation planning, installed at our hospital by means of MAT construction, is discussed. A pathway is shown which leads to individual treatment planning and considers dosimetrically the actual conditions of the patient who will undergo radiation therapy. The possibilities and limits of ultrasonic cross-sectional imaging are demonstrated.

Diagnosis, Computer-Assisted↗

PubMed1976

New methods of imaging in diagnostic radiology Sylvanus Thompson Memorial Lecture.

A brief history of the recent developments in computer-assisted tomography (CAT) is presented. The development of whole-body scanners from the basic brain scanner, the trend towards higher-speed scanners using multiple detectors in a fan-type geometry, and some of the unsolved problems related to CAT scanners are discussed, as well as the potential use of whole-body scanning in radiotherapy treatment planning and in radiobiology. A review of recent developments in electrostatic imaging is presented and a new method of imaging called ionography is described in detail. It is shown how a single exposure can be used to produce a number of copies, each with a different amount of edge contrast, under the control of the radiologist. Further, it is shown how this can be done using a closed system so that the ionography chamber never needs to be opened. Some of the recent commercial developments in this field are described. It is suggested that in the future radiology departments may be replaced by departments of imaging, which will include all ways of obtaining diagnostic information and where such a department would be problem oriented rather than technique oriented. The need for basic scientific support by a medical physics and engineering group in such a department is emphasized.

Electrons↗

PubMed1978

A computer-assisted three-dimensional treatment planning system.

The three-dimensional treatment planning system developed at the Rhode Island Hospital visualizes the spatial interrelationships of the radiation beam, the tumor, and the adjacent organs within the patient. It is possible to rotate and vary the scale of the display to better comprehend the extent of these structures. By viewing the display as if from along the radiation beam, one can design shaped treatment fields which best suit the three-dimensional nature of the disease. With this system, it is possible to reduce the volume of normal tissue which would typically be irradiated if two-dimensional treatment planning techniques and assumptions were employed.

Computers↗

PubMed1975

Backgrounds of computer-assisted treatment planning in radiation therapy.

Interaction of ionising radiation and living materials causes biological damage of tempory or permanent nature. In radiation therapy this phenomenon is used in a controlled fashion in order to stop the proliferation of malignant cells, while at the same time limiting the permanent damage to healthy tissues and organs to at least tolerable levels. Because of the often relatively small differences in response of malignant growths and normal tissues, the margins between tolerable and intolerable are so small that the greatest precision in treatment planning and execution is required. The nature of this treatment agent implies that the radiation therapist has to rely very much on instrumentally obtained and processed information, in all phases of this medical activities around the patient. In this paper a description is given of the backgrounds of computer-assisted methods which have enabled modern individualised and optimised planning for therapy with high enery X - and gamma beams.

Cobalt Radioisotopes↗

PubMed1977

[Optimization in planning and application of 60 Co gamma irradiations - analysis of the problem (author's transl)].

As an aspect of the complex problem of optimization in therapeutical transmission of radiation energy to Man, the dose distribution within a cross-sectional area of the body is considered. For the judgement on optimal dose distributions, involving judgement on irradiation technique, boundary conditions are needed which encompass important parameters of a dose distribution (= criterion for optima). For computer-assisted optimization the boundary conditions are to be scheduled by an appropriate algorithm. The parameters describing a dose distribution are indicated. Practical utilization of computer-assisted optimization of dose is represented by means of two optimization schedules.

Cobalt Radioisotopes↗