Specification of the Dose to Organs at Risk in External Beam Radiotherapy

1997 ◽  
Vol 36 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Einar Dale ◽  
Dag R. Olsen
Keyword(s):  
At Risk ◽  
Organs At Risk ◽  
External Beam Radiotherapy ◽  
External Beam

scholarly journals A novel external beam radiotherapy method for cervical cancer patients using virtual straight or bending boost areas; an in-silico feasibility study

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Luca Cozzi ◽  
Sushil Beriwal ◽  
Esa Kuusela ◽  
Supriya Chopra ◽  
Hester Burger ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
At Risk ◽  
Organs At Risk ◽  
External Beam Radiotherapy ◽  
Locally Advanced ◽  
Target Volume ◽  
Cervix Uteri ◽  
External Beam ◽  
Dose Volume Histograms ◽  
Variable Position

Abstract Aim To investigate the potential role of a novel spatially fractionated radiation therapy (SFRT) method where heterogeneous dose patterns are created in target areas with virtual rods, straight or curving, of variable position, diameter, separation and alignment personalised to a patient’s anatomy. The images chosen for this study were CT scans acquired for the external beam part of radiotherapy. Methods Ten patients with locally advanced cervical cancer were retrospectively investigated with SFRT. The dose prescription was 30 Gy in 5 fractions to 90% target volume coverage. Peak-and-valley (SFRT_1) and peak-only (SFRT_2) strategies were applied to generate the heterogeneous dose distributions. The planning objectives for the target (CTV) were D90% ≥ 30 Gy, V45Gy ≥ 50–55% and V60Gy ≥ 30%. The planning objectives for the organs at risk (OAR) were: D2cm3 ≤ 23.75 Gy, 17.0 Gy, 19.5 Gy, 17.0 Gy for the bladder, rectum, sigmoid and bowel, respectively. The plan comparison was performed employing the quantitative analysis of the dose-volume histograms. Results The D2cm3 was 22.4 ± 2.0 (22.6 ± 2.1) and 13.9 ± 2.9 (13.2 ± 3.0) for the bladder and the rectum for SFRT_1 (SFRT_2). The results for the sigmoid and the bowel were 2.6 ± 3.1 (2.8 ± 3.0) and 9.1 ± 5.9 (9.7 ± 7.3), respectively. The hotspots in the target volume were V45Gy = 43.1 ± 7.5% (56.6 ± 5.6%) and V60Gy = 15.4 ± 5.6% (26.8 ± 6.6%) for SFRT_1 (SFRT_2). To account for potential uncertainties in the positioning, the dose prescription could be escalated to D90% = 33–35 Gy to the CTV without compromising any constraints to the OARs Conclusion In this dosimetric study, the proposed novel planning technique for boosting the cervix uteri was associated with high-quality plans, respecting constraints for the organs at risk and approaching the level of dose heterogeneity achieved with routine brachytherapy. Based on a sample of 10 patients, the results are promising and might lead to a phase I clinical trial.

scholarly journals The Use of Ultrasound Imaging in the External Beam Radiotherapy Workflow of Prostate Cancer Patients

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Saskia M. Camps ◽  
Davide Fontanarosa ◽  
Peter H. N. de With ◽  
Frank Verhaegen ◽  
Ben G. L. Vanneste
Keyword(s):  
Prostate Cancer ◽  
Cancer Patients ◽  
Ultrasound Imaging ◽  
Organs At Risk ◽  
External Beam Radiotherapy ◽  
Treatment Options ◽  
Current Status ◽  
Tumor Control ◽  
External Beam ◽  
Image Guided Radiotherapy

External beam radiotherapy (EBRT) is one of the curative treatment options for prostate cancer patients. The aim of this treatment option is to irradiate tumor tissue, while sparing normal tissue as much as possible. Frequent imaging during the course of the treatment (image guided radiotherapy) allows for determination of the location and shape of the prostate (target) and of the organs at risk. This information is used to increase accuracy in radiation dose delivery resulting in better tumor control and lower toxicity. Ultrasound imaging is harmless for the patient, it is cost-effective, and it allows for real-time volumetric organ tracking. For these reasons, it is an ideal technique for image guidance during EBRT workflows. Review papers have been published in which the use of ultrasound imaging in EBRT workflows for different cancer sites (prostate, breast, etc.) was extensively covered. This new review paper aims at providing the readers with an update on the current status for prostate cancer ultrasound guided EBRT treatments.

Deriving optimal planning organ at risk volume margins in prostate external beam radiotherapy

2021 ◽  
Author(s):  
Yutong Zhao ◽  
Martin A. Ebert ◽  
David Waterhouse ◽  
Simon Goodall ◽  
Pejman Rowshanfarzad ◽  
...  
Keyword(s):  
At Risk ◽  
External Beam Radiotherapy ◽  
External Beam ◽  
Optimal Planning ◽  
Organ At Risk

scholarly journals External beam accelerated partial breast irradiation: dosimetric assessment of conformal and three different intensity modulated techniques

2019 ◽  
Vol 53 (1) ◽  
pp. 123-130 ◽  
Author(s):  
Gábor Stelczer ◽  
Tibor Major ◽  
Norbert Mészáros ◽  
Csaba Polgár ◽  
Csilla Pesznyák
Keyword(s):  
At Risk ◽  
Organs At Risk ◽  
Target Volume ◽  
Accelerated Partial Breast Irradiation ◽  
Partial Breast Irradiation ◽  
External Beam ◽  
Breast Irradiation ◽  
Plan Quality ◽  
Intensity Modulated ◽  
3D Crt

Abstract Background The aim of the study was to evaluate and compare four different external beam radiotherapy techniques of accelerated partial breast irradiation (APBI) considering target coverage, dose to organs at risk and overall plan quality. The investigated techniques were three dimensional conformal radiotherapy (3D-CRT), “step and shoot” (SS) and “sliding window” (SW) intensity-modulated radiotherapy (IMRT), intensity-modulated arc therapy (RA). Patients and methods CT scans of 40 APBI patients were selected for the study. The planning objectives were set up according to the international recommendations. Homogeneity, conformity and plan quality indices were calculated from volumetric and dosimetric parameters of target volumes and organs at risk. The total monitor units and feasibility were also investigated. Results There were no significant differences in the coverage of the target volume between the techniques. The homogeneity indices of 3D-CRT, SS, SW and RA plans were 0.068, 0.074, 0.058 and 0.081, respectively. The conformation numbers were 0.60, 0.80, 0.82 and 0.89, respectively. The V50% values of the ipsilateral breast for 3D-CRT, SS, SW and RA were 47.5%, 40.2%, 39.9% and 31.6%, respectively. The average V10% and V40% values of ipsilateral lung were 13.1%, 28.1%, 28%, 36% and 2.6%, 1.9%, 1.9%, 3%, respectively. The 3D-CRT technique provided the best heart protection, especially in the low dose region. All contralateral organs received low doses. The SW technique achieved the best plan quality index (PQI). Conclusions Good target volume coverage and tolerable dose to the organs at risk are achievable with all four techniques. Taking into account all aspects, we recommend the SW IMRT technique for APBI.

scholarly journals Optimal modality selection in external beam radiotherapy

2018 ◽  
Vol 36 (3) ◽  
pp. 361-380 ◽  
Author(s):  
Sevnaz Nourollahi ◽  
Archis Ghate ◽  
Minsun Kim
Keyword(s):  
Physical Properties ◽  
Numerical Experiments ◽  
Organs At Risk ◽  
External Beam Radiotherapy ◽  
Mathematical Formulation ◽  
Biological Properties ◽  
Selection Problem ◽  
External Beam ◽  
Quartic Equation ◽  
Protons And Neutrons

Abstract The goal in external beam radiotherapy (EBRT) for cancer is to maximize damage to the tumour while limiting toxic effects on the organs-at-risk. EBRT can be delivered via different modalities such as photons, protons and neutrons. The choice of an optimal modality depends on the anatomy of the irradiated area and the relative physical and biological properties of the modalities under consideration. There is no single universally dominant modality. We present the first-ever mathematical formulation of the optimal modality selection problem. We show that this problem can be tackled by solving the Karush–Kuhn–Tucker conditions of optimality, which reduce to an analytically tractable quartic equation. We perform numerical experiments to gain insights into the effect of biological and physical properties on the choice of an optimal modality or combination of modalities.

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