scholarly journals Comparison of the Dosimetric Influence of Applicator Displacement on 2D and 3D Brachytherapy for Cervical Cancer Treatment

2021 ◽  
Vol 20 ◽  
pp. 153303382110412
Author(s):  
Ailin Wu ◽  
Du Tang ◽  
Aidong Wu ◽  
Yunqin Liu ◽  
Liting Qian ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Organs At Risk ◽  
Three Dimensional ◽  
Target Volume ◽  
Posterior Direction ◽  
3D Volume ◽  
The Right ◽  
2D And 3D ◽  
Dose Change ◽  
Anterior Posterior

To compare the dosimetric influence of applicator displacement on two-dimensional brachytherapy (2D-BT) and three-dimensional brachytherapy (3D-BT) for cervical cancer. Nineteen patients who received computed tomography-guided tandem-and-ovoid (T&O) brachytherapy were retrospectively selected. Both 2D (point-based) and 3D (volume-based) plans with and without virtual applicator displacement in the 3 axes were created for each patient. Dose changes at point A, D90 of the high-risk clinical target volume (HR-CTV) and intermediate-risk CTV (IR-CTV), and the D0.1cc, D1cc, D2cc, and D5cc of organs-at-risk (OARs) caused by applicator displacement were evaluated. Both 2D-BT and 3D-BT plans were sensitive to T&O applicator displacement. The D90 of the CTV and the dose at point A were very sensitive to applicator displacement in the right–left direction ( X-axis). An applicator shift of >2 mm in the X-axis resulted in a change of >5% in the dose at point A and D90 of HR-CTV and IR-CTV. In addition, the doses to the OARs were mostly affected by applicator displacement in the anterior–posterior direction ( Z-axis). A displacement of <1.5 mm in the Z-axis was required to avoid a dose change of >10% for OARs. For both 2D-BT and 3D-BT plans, T&O displacement greater than  ± 2 mm in the X-axis or T&O applicator displacement  ± 1.5 mm in the Z-axis resulted in significant dose changes to the tumor and OARs. In comparison with 3D-BT plans, 2D-BT plans delivered a higher dose to the tumor, and the OARs received more undesirable doses when applicator displacement occurred. The influence of applicator displacement on the doses to the tumor and OARs differed between 2D-BT and 3D-BT. Physicians should take individual patient differences into account when selecting a brachytherapy plan to mitigate the influence of applicator displacement.

Clinical dosimetry optimization in spinal metastases

2009 ◽  
Vol 8 (1) ◽  
pp. 35-40
Author(s):  
P. Pedrosa ◽  
C. Lucena ◽  
I.J. Sainz
Keyword(s):  
Organs At Risk ◽  
Three Dimensional ◽  
Spinal Metastases ◽  
Target Volume ◽  
The Body ◽  
High Dose ◽  
Prescription Dose ◽  
The Mean ◽  
Posterior Anterior ◽  
Anterior Posterior

AbstractIntroduction: Radiotherapy is commonly used to treat spinal metastases. The aim of this study was to compare conventional dosimetry (posterior–anterior fields) with an optimized three-dimensional conformal plan (using oblique fields).Material and Methods: Fifteen patients were selected, and split into three groups of five based on tumour localization: cervical, dorsal and lumbar. Reference planning comprised of two fields: anterior–posterior. The planning target volume (PTV) was covered with 90% of the prescribed doses, minimizing anterior field weight and not exceeding 120%. The alternative consisted of three fields: two oblique posterior fields with wedge and anterior field. The PTV was covered with 95% of the prescription dose, minimizing the anterior field weight with 107% of overdose as a limit. The patient received 8 Gy in one fraction; retreatment with an additional fraction was feasible, safe and effective if persistent or recurrent bone pain was present. Five fractions of 4 Gy were used for cervical cases. To consider the future patients toxicity we evaluated the mean dose, V90 and V70 parameters in each plan.Results: Dosimetric parameters of organs at risk were not significantly different from one trial to another. The optimized plan followed ICRU criteria, reaching PTV coverage of 95–107% range of the prescription dose. In the conventional plan, high dose had to be accepted to obtain 90% of coverage in the target.Conclusions: In contrast with the anterior–posterior configuration, oblique fields improve dose conformity and limit high dose all of the body except the spinal cord.

Impact of CT-based planning and bladder volume changes on the dosimetry of vaginal vault brachytherapy

2021 ◽  
pp. 1-7
Author(s):  
Jeyaanth Venkatasai ◽  
Jebakarunya Ramireddy ◽  
Arvind Sathyamurthy ◽  
Henry Finlay Godson ◽  
Reka Karuppusami ◽  
...  
Keyword(s):  
Clinical Target Volume ◽  
Organs At Risk ◽  
Three Dimensional ◽  
Target Volume ◽  
Bladder Distension ◽  
Full Bladder ◽  
The Mean ◽  
2D And 3D ◽  
Planning Ct ◽  
Empty Bladder

Abstract Aim: To compare dose to target and organs at risk (OARs) in conventional plan (2D) versus computed tomography (CT)-based three-dimensional (3D) plan in vaginal cuff brachytherapy (VBT) and to compare the effect of bladder distension on target and OARs dosimetry. Materials and methods: Post-hysterectomy patients with an indication for VBT were included in the study. All patients underwent planning CT scans with a full bladder and an empty bladder protocol. For each CT, two plans were generated—one library-based 2D plan and another CT-based 3D plan. Dosimetric parameters were recorded for clinical target volume (CTV) and OARs. Results: A total of 92 observations were made from data collected from 46 patients. Difference between CTV dose in terms of 2D and 3D plans were not statistically significant for CTV (p = 0·11). Significant reduction in D0·1cc, D1cc and D2cc dose parameters were observed in bladder, rectum, sigmoid and bowel doses with the 3D plan (p < 0·001). Bladder distension showed a 20% reduction in dose for bowel (p < 0·001). Bladder distension also showed a 6·12% (p = 0·047) increase in D2cc, but there was a significant reduction in the mean dose to the bladder. Conclusion: Our study demonstrates the dosimetric benefits with 3D CT-based planning for VBT over 2D-based conventional planning and benefit of bladder distension in the reduction of bowel dose without compromising dose to the target volume.

scholarly journals Posture as index for approach-avoidance behavior

2017 ◽  
Author(s):  
Anita Eerland ◽  
Tulio M. Guadalupe ◽  
Ingmar H.A. Franken ◽  
Rolf Antonius Zwaan
Keyword(s):  
Avoidance Behavior ◽  
Affective State ◽  
Behavioral Responses ◽  
Lateral Movement ◽  
Approach And Avoidance ◽  
Posterior Direction ◽  
Approach Avoidance ◽  
The Right ◽  
Balance Board ◽  
Anterior Posterior

Approach and avoidance are two behavioral responses that make people tend to approach positive and avoid negative situations. This study examines whether postural behavior is influenced by the affective state of pictures. While standing on the Wii™ Balance Board, participants viewed pleasant, neutral, and unpleasant pictures (passively viewing phase). Then they had to move their body to the left or the right (lateral movement phase) to make the next picture appear. We recorded movements in the anterior-posterior direction to examine approach and avoidant behavior. During passively viewing, people approached pleasant pictures. They avoided unpleasant ones while they made a lateral movement. These findings provide support for the idea that we tend to approach positive and avoid negative situations.

scholarly journals The importance of mesorectum motion in determining PTV margins in rectal cancer patients treated with neoadjuvant radiotherapy

2019 ◽  
Vol 61 (2) ◽  
pp. 335-342
Author(s):  
Zumre Arican Alickikus ◽  
Ahmet Kuru ◽  
Barbaros Aydin ◽  
Dogukan Akcay ◽  
Ilknur Bilkay Gorken
Keyword(s):  
Rectal Cancer ◽  
Cone Beam Ct ◽  
Volumetric Modulated Arc Therapy ◽  
Neoadjuvant Chemoradiotherapy ◽  
Target Volume ◽  
Neoadjuvant Radiotherapy ◽  
Arc Therapy ◽  
Posterior Direction ◽  
Precision Radiotherapy ◽  
Anterior Posterior

Abstract New precision radiotherapy (RT) techniques reduce the uncertainties in localizing soft and moving tumors. However, there are still many uncontrollable internal organ movements. In our study, patients who underwent neoadjuvant chemoradiotherapy (NA-CRT) for rectal cancer were evaluated to determine inter-fraction mesorectum motion and dosimetric changes. Fourteen patients treated with NA-CRT for rectal cancer between 2014 and 2016 were included in the analysis. The mesorectum and clinical target volume (CTV) were delineated on planning computed tomography (CT) and cone-beam CT (CB-CT) scans. After planning with a volumetric modulated arc therapy (VMAT) plan, re-planning was performed on all CB-CTs. Finally, the volumetric and dosimetric changes of PTV and mesorectum were evaluated in all CB-CTs compared with the initial CT and VMAT plans. The geometrical center of mesorectum volume in CB-CTs had moved 1 (0.2–6.6), 1.6 (0.2–3.8) and 1.6 (0–4.9) mm in the x, y and z-axis respectively compared with the initial CT. The dosimetric parameters of PTV including D2, D95 and D98 on CB-CT showed a median 47.19 (46.70–47.80), 45.05 (44.18–45.68) and 44.69 (43.83–45.48) Gy and median 1% (1–2), 0% (0–2) and 1% (0–2) dosimetric change compared with the initial VMAT plan. In our study, we have shown that the mesorectum has moved up to 20 mm in the lateral and anterior–posterior direction and almost 10 mm in the superior/inferior direction during RT, causing a median of ~2% change in dosimetric parameters. Therefore, these movements must be considered in determining PTV margins to avoid dosimetric changes.

Tonotopy of the Auditory-Evoked Field Component N100m in Patients with Schizophrenia

2000 ◽  
Vol 14 (3) ◽  
pp. 131-141 ◽  
Author(s):  
T. Rosburg ◽  
I. Kreitschmann-Andermahr ◽  
T. Ugur ◽  
H. Nestmann ◽  
H. Nowak ◽  
...  
Keyword(s):  
Right Hemisphere ◽  
Temporal Cortex ◽  
Dipole Orientation ◽  
Global Field Power ◽  
Functional Reorganization ◽  
Schizophrenic Patients ◽  
Posterior Direction ◽  
The Right ◽  
Main Effects ◽  
Anterior Posterior

Abstract A number of clinical studies on the auditory neuromagnetic evoked field (AEF) component N100m have reported an altered lateralization in schizophrenic patients. This study addresses the problem of a possible functional reorganization of the temporal cortex in schizophrenia by examining the tonotopic organization of the N100m. Thirty-two patients with schizophrenia and 33 healthy controls of both sexes took part. Two tone frequencies (1000 and 5000 Hz tone) were applied for auditory stimuli, and AEF were recorded over both hemispheres successively using a 31-channel biomagnetometer. The comparison of N100m dipole location and orientation between hemispheres revealed no alterations in male or female patients. Between tone frequencies highly significant differences were found for N100m peak latency, mean global field power, dipole orientation, and dipole location in the anterior-posterior direction. Although the main effects of frequency were found to be the same in patients and controls, the balance between hemispheres was altered in patients with schizophrenia, with respect to the dependence between frequency and dipole location in the anterior-posterior direction as well as between frequency and latency. In patients, the influence of frequency on these variables was more pronounced in the right hemisphere and less pronounced in the left, compared to controls.

scholarly journals Reconstruction of Brachytherapy Catheters and Needles Using EM Sensor-Based Navigation System

2017 ◽  
Author(s):  
Fan Liang ◽  
Bryan Traughber ◽  
Raymond Musiz ◽  
Rodney Ellis ◽  
Tarun K. Podder
Keyword(s):  
Clinical Outcome ◽  
Dose Rate ◽  
Dose Distribution ◽  
Organs At Risk ◽  
Target Volume ◽  
Ct Images ◽  
High Dose Rate ◽  
Treatment Modalities ◽  
High Dose ◽  
The Right

Brachytherapy is one the most effective treatment modalities for both gynecological (GYN) cancer and prostate cancer. The clinical outcome of brachytherapy, both high-dose-rate (HDR) and low-dose-rate (LDR), depends on the precision of the desired or planned dose distribution and delivery. In HDR procedure, the accuracy of reconstruction of catheters or needles (e.g. Syed catheter or Simon-Heyman capsule for GYN or needles for prostate) from CT images can significantly affect the accuracy of dose distribution in the treatment (dosimetric) plan, which can result in unwanted clinical outcome. In current practice, an authorized medical physicist manually reconstructs the catheters or needles for dosimetric plan, which determines the position and dwell time for the radiation source for delivering the prescription dose to the target volume sparing organs at risk (OARs) as much as possible. It is not only challenging but also time consuming for reconstructing all the catheters or needles (ranging 15–20) manually, slice-by-slice in CT images. As shown in Fig. 1, the needles on the right (HDR catheters) have created so much artifacts in CT images that it is almost impossible to reconstruct those applicators (catheters/ needles) manually. Additionally, the reconstruction can be operator dependent and can be inaccurate and inconsistent. In this study, we have investigated the applicability of electromagnetic (EM) sensor-based navigation for fast and accurate reconstruction of HDR catheters and needles.

scholarly journals Long-term results of robotic radiosurgery for non brachytherapy patients with cervical cancer

2020 ◽  
Author(s):  
Janis Morgenthaler ◽  
Christhardt Köhler ◽  
Volker Budach ◽  
Jalid Sehouli ◽  
Carmen Stromberger ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Cancer Patients ◽  
Local Control ◽  
Organs At Risk ◽  
Progression Free Survival ◽  
Distant Metastases ◽  
Residual Tumor ◽  
Target Volume ◽  
Long Term Results ◽  
Robotic Radiosurgery

Abstract Background Consolidation brachytherapy is a critical treatment component for cervical cancer patients undergoing primary chemoradiation. Some patients are unsuitable for brachytherapy for a variety of reasons. The use of alternatives (LINAC-based stereotactic radiosurgery or external beam boosts) compromise oncologic results in cervical cancer patients. Thus, we evaluated the value of brachytherapy-like doses prescriptions using robotic radiosurgery (CyberKnife®, CR, Acuuray, Sunnyvale, CA, USA). Methods From 06/2011 to 06/2015, 31 patients (median age 53 years; range 30–77 years) with histologically proven FIGO stages IB-IVB cervical cancer underwent primary chemoradiation. All patients were either not suitable for intracervical brachytherapy for a variety of reasons or refused the brachytherapy. To achieve an adequate dose within the tumor, a CK boost was applied after fiducial implantation. In 29 patients, a dose of either five times 6 Gy or five times 5 Gy was prescribed to the target volume. Two patients received three times 5 Gy. The target dose was prescribed to the 70% isodose. Treatment toxicity was documented once weekly regarding vaginal mucositis, bladder, and bowel irritation according to CTCAE v. 4.03. If possible 3 months after completion of treatment intracervical curettage was performed to exclude residual tumor and the patients were followed up clinically. Sparing of organs at risk (OAR) and outcome in terms of local control (LC), overall survival (OS), and progression-free survival (PFS) were assessed. Results Of the 31 patients, 30 have completed CK boost therapy. The median follow-up time was 40 months (range 5–84 months). General treatment tolerability was good. Except for 1 patient, who had diarrhea grade 3, no treatment related side effects above grade 2 were reported. Sparing of OAR was excellent. The 1‑, 3‑, and 5‑year OS rates were 89, 60, and 57% respectively across all stages. Seven patients showed progression (28%), only two of them with local relapse (8%), resulting in an LC rate of 92% after 3 and 5 years. Mean PFS was 41 months (range 2–84 months). Patients with local recurrence had PFS of 5 and 8 months. Five patients developed distant metastases. Fifteen patients (48%) underwent intracervical curettage 3 months after completion of treatment of which 14 (93%) had complete pathologic response. Conclusion Brachytherapy remains the standard of care for patients diagnosed with cervical cancer and indication for primary chemoradiation. In terms of local control, CyberKnife®-based boost concepts provide excellent local control. It can be an alternative for patients who cannot receive adequate brachytherapy. Distant relapse still remains a challenge in this context.

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