scholarly journals Quantitative assessment of dosimetric parameters of the radiation treatment plan for unplanned changes in the fractionation scheme

2021 ◽  
Vol 18 (2) ◽  
pp. 244-251
Author(s):  
K. V. Hancharova ◽  
I. G. Tarutin ◽  
M. N. Piatkevich
Keyword(s):  
Radiation Dose ◽  
Radiation Treatment ◽  
Treatment Time ◽  
Treatment Plan ◽  
Absorbed Dose ◽  
Tumor Control ◽  
Normal Tissues ◽  
Results Of Treatment ◽  
Total Treatment Time ◽  
Fractionation Scheme

Changes in the fractionation scheme of the radiotherapy course have an impact on the results of treatment of cancer patients. If changes in the fractionation scheme are not taken into account, this leads to under-irradiation of tumor cells and a possible occurrence of subsequent relapses. There are radiobiological models in order to take into account the errors in the radiation dose delivered to the tumor. They allow predicting the tumor control, as well as the toxicity level in normal tissues after traditional RT.The objective of the work is to assess the effectiveness of the absorbed dose in the event, if the fractionation scheme in the RT course changes, and to develop an algorithm that takes into account breaks between treatment sessions.In the study, the effectiveness of the radiation dose delivered to the tumor due to a change in the total treatment time is assessed analytically, a graphical dependence of the radiation dose efficiency on the duration of the unplanned interruption in the treatment of patients is built for the most common oncological localizations, an algorithm for radiotherapy procedures taking into account deviations from the standard radiation treatment pattern is developed.

scholarly journals Radioprotective Agents and Enhancers Factors. Preventive and Therapeutic Strategies for Oxidative Induced Radiotherapy Damages in Hematological Malignancies

Antioxidants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1116
Author(s):  
Andrea Gaetano Allegra ◽  
Federica Mannino ◽  
Vanessa Innao ◽  
Caterina Musolino ◽  
Alessandro Allegra
Keyword(s):  
Radiation Treatment ◽  
Protective Action ◽  
Critical Role ◽  
Therapy Response ◽  
Hematologic Malignancies ◽  
Tumor Control ◽  
Post Irradiation ◽  
Normal Tissues ◽  
Wide Range ◽  
Other Substances

Radiation therapy plays a critical role in the management of a wide range of hematologic malignancies. It is well known that the post-irradiation damages both in the bone marrow and in other organs are the main causes of post-irradiation morbidity and mortality. Tumor control without producing extensive damage to the surrounding normal cells, through the use of radioprotectors, is of special clinical relevance in radiotherapy. An increasing amount of data is helping to clarify the role of oxidative stress in toxicity and therapy response. Radioprotective agents are substances that moderate the oxidative effects of radiation on healthy normal tissues while preserving the sensitivity to radiation damage in tumor cells. As well as the substances capable of carrying out a protective action against the oxidative damage caused by radiotherapy, other substances have been identified as possible enhancers of the radiotherapy and cytotoxic activity via an oxidative effect. The purpose of this review was to examine the data in the literature on the possible use of old and new substances to increase the efficacy of radiation treatment in hematological diseases and to reduce the harmful effects of the treatment.

Chemotherapy followed by accelerated fractionated radiation for larynx preservation in patients with advanced laryngeal cancer.

1996 ◽  
Vol 14 (8) ◽  
pp. 2322-2330 ◽  
Author(s):  
A Eisbruch ◽  
A F Thornton ◽  
S Urba ◽  
R M Esclamado ◽  
W R Carroll ◽  
...  
Keyword(s):  
Laryngeal Cancer ◽  
Treatment Time ◽  
Complete Response ◽  
Definitive Treatment ◽  
Tumor Control ◽  
Total Study Population ◽  
Larynx Preservation ◽  
Locoregional Failure ◽  
Total Treatment Time ◽  
Total Treatment

PURPOSE Larynx preservation in advanced, resectable laryngeal cancer may be achieved using induction chemotherapy (CT) followed in responding patients by definitive radiation (RT). To address potential accelerated repopulation of clonogenic tumor cells during the prolonged total treatment time, we studied the feasibility of accelerated fractionated RT after CT. METHODS Patients with advanced laryngeal cancer received two cycles of cisplatin 100 mg/m2 and fluorouracil (5-Fu) 1,000 mg/m2/d for 5 days. Responding patients received a third cycle after which those who had complete response or tumor down-staging to T1 proceeded with accelerated RT: 70.4 Gy delivered over 5.5 weeks. Patients who achieved a lesser response to CT underwent total laryngectomy and postoperative RT. RESULTS Thirty-three patients were accrued. Three died during the course of CT and two declined definitive treatment after CT. Twenty-one patients had a major response to CT, 20 of whom received accelerated RT. Median weight loss during RT was 11%. Late severe morbidity was observed in five patients (25%). All four patients who underwent salvage laryngectomy after accelerated RT experienced major postoperative complications. The locoregional failure rate was 25%. The larynx was preserved in 48% of the total study population and in 80% of the patients irradiated according to the study protocol. CONCLUSION Accelerated RT after CT as delivered in this study may increase both acute and long-term morbidity rates compared with studies using standard RT after CT. It did not seem to improve local/regional tumor control or survival despite stringent patient selection criteria.

Composite MRI Task Construction from CT Images based on Deep Convolution Neural Network

2021 ◽  
Author(s):  
Liang Min ◽  
Yi Gu ◽  
Rui Xue ◽  
Yi Ren ◽  
Bo Gao
Keyword(s):  
Radiation Dose ◽  
Network Model ◽  
Treatment Plan ◽  
Image Synthesis ◽  
Ct Images ◽  
Ct Image ◽  
Electronic Density ◽  
Normal Tissues ◽  
To Receive ◽  
Mri Image

In traditional CBCT guided radiotherapy, the conventional process is to scan a planned CT image of the patient before treatment, and use the CT image to prepare a treatment plan for the patient, and calculate the radiation dose with the electronic density information of the CT image to obtain the radiation dose that the patient needs to receive. Because CT images cannot be directly used to calculate the amount of data, in order to solve the problem of CT image attenuation corresponding to MRI image synthesis, the deep convolution network model is used to map the CT image to the MRI image, input the CT image, and synthesize the corresponding MRI image with the convolution network model in this article. The synthetic MRI image can be used for the same mode registration with the patient’s positioning MRI image, so as to solve the problem of inaccurate cross-membrane registration. The multi-mode synthesis and transformation of CT/MRI images have been realized. Experiments have proved that the method presented in this article is beneficial to reducing the radiation dose of patients, enabling patients to receive more accurate radiotherapy, so that the tumor part can be irradiated as much as possible and the normal tissues around the tumor can be irradiated less, so as to improve the therapeutic effect of tumor patients.

Estimation of Radiotherapy Efficiency of Head-and-Neck Cancer Based

2021 ◽  
Vol 66 (5) ◽  
pp. 95-100
Author(s):  
E. Sukhikh ◽  
L. Sukhikh ◽  
Ya. Sutygina ◽  
P. Izhevsky ◽  
I. Sheino ◽  
...  
Keyword(s):  
Lymph Nodes ◽  
Neck Cancer ◽  
Treatment Time ◽  
Tumor Control ◽  
Head Neck Cancer ◽  
Tumor Control Probability ◽  
Total Treatment Time ◽  
Total Treatment ◽  
Treatment Plans ◽  
Head Neck

Purpose: Evaluation of the expected effectiveness of radiation therapy based on models of the local tumor control probability (Tumor Control Probability – TCP) for the head-neck cancer. Material and methods: The study used data from 11 patients with locally advanced head-neck cancer (larynx, oropharynx, and oral cavity). For each patient two dosimetric treatment plans have been prepared: SIB-VMAT (70 Gy per tumor, 50 Gy per lymph nodes, 25 fractions) and SEQ-VMAT (70 Gy per tumor, 50 Gy per lymph nodes, 35 fractions). The developed plans were analyzed using A. Niemierko's TCP model with parameters obtained by B. Maciejewski (TCD50 = 70.26 Gy with a 49-day total treatment time), taking into account the dose–volume histograms and the total treatment time. Results: The developed plans ensured a high level of coverage (98–98 %) of the Clinical treatment volume (CTV) in all but one patient. The average TCP SIB-VMAT is 99.9 % due to the very short total treatment time. The average TCP for SEQ-VMAT is 61.0%. For one patient, both SIB-VMAT and SEQ-VMAT showed zero expected efficacy due to 95–95 % CTV coverage. Conclusion: The use of TCP model allows analyzing personalized treatment plans for patients and developing adaptive treatment regimens with an increase in the total dose, dose per fraction, and a decrease in the total treatment time.

scholarly journals Evaluation of Target Autocrop Function in Nasopharyngeal Carcinoma SIB IMRT Plan

2021 ◽  
Author(s):  
Xiaojuan Duan ◽  
Lu chen ◽  
Yibing Zhou
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Treatment Time ◽  
Treatment Plan ◽  
Nasopharyngeal Cancer ◽  
Normal Tissue Complication Probability ◽  
Tumor Control ◽  
Tumor Control Probability ◽  
Plan Quality ◽  
Delivery Accuracy ◽  
Delivery Efficiency

Abstract Purpose A new target autocrop function was introduced in the Varian Eclipse™ treatment planning software (version 15.5 above). The study aimed to evaluate this new target autocrop impact on nasopharyngeal carcinoma (NPC) plan quality and delivery efficiency. Methods Randomly 66 approved NPC simultaneous integrated boost (SIB) intensity modulated radiation therapy (IMRT) treatment plans were retrospectively studied. The manual cropping-based plans served as reference and were designed using sliding-window IMRT. Reference plans were re-optimized with identical planning parameters following the institutional clinical protocol except for the optimization objective of the manual cropping targets deleted. Additionally, each target within 5mm of another had one lower objective at 100% volume and one upper objective at 0% volume for the autocrop plans. Plan quality was assessed based on selected parameters, including TCP (tumor control probability), NTCP (normal tissue complication probability), conformality index (CI), homogeneity index (HI), and dose-volume characteristics. Additionally, the delivery efficiency, the total plan treatment time defined as a sum of monitor units (MUs) for each treated field, and delivery accuracy, γ passing rate of treatment plan quality assurance (QA) also were compared. Results Both the manual cropping plans and the autocrop plans could be approved by an experienced oncologist. Overall, the autocrop plans could provide approximately a 13% reduction in linac MU while maintaining comparable plan quality, radiobiological ranking, and accuracy to that of the manual cropping plans. Conclusions The new target autocrop tip facilitated the SIB IMRT plans for nasopharyngeal cancer patients. The autocrop could guarantee the quality and delivery accuracy of the radiotherapy plan, improved the planning efficiency, treatment efficiency, and reduced machine wear and tear. It was a promising tool for optimal plan selection for NPC SIB IMRT.

scholarly journals Mini implant orthodontic sebagai penjangkaran pada perawatan maloklusi kelas II skeletal dengan protrusi beratMini implant orthodontic as an anchorage in skeletal class II maloclussion with severe dental protrusion

2021 ◽  
Vol 33 (1) ◽  
pp. 71
Author(s):  
Maureen Antolis ◽  
Haru Setyo Anggani
Keyword(s):  
Case Report ◽  
Treatment Time ◽  
Treatment Plan ◽  
Class Ii ◽  
Skeletal Class ◽  
Skeletal Class Ii ◽  
Total Treatment Time ◽  
Soft Tissue Profile ◽  
Division 1 ◽  
Class Ii Division 1

Pendahuluan: Maloklusi kelas II skeletal memiliki gambaran morfologis yang khas, antara lain adalah protrusi gigi anterior atas, serta profil skeletal dan jaringan lunak cembung. Penatalaksanaan yang cermat terutama penjangkaran, diperlukan agar perawatan ortodonti berhasil, guna mengurangi derajat protrusi gigi anterior atas serta perbaikan profil. Tujuan laporan kasus ini menyampaikan keberhasilan mini implant orthodontic sebagai penjangkaran pada perawatan maloklusi kelas II skeletal dengan protrusi berat.Laporan kasus: Kasus pasien perempuan usia 22 tahun 2 bulan dengan Maloklusi kelas II skeletal, yang memiliki profil cembung, mandibula retrognatis, tipe wajah dolichofacial, jarak gigit besar, dengan riwayat rhinitis. Perawatan preadjusted edgewise dilakukan setelah ekstraksi kedua gigi premolar pertama atas yang diikuti dengan pemasangan Mini implant orthodontic sebagai penjangkaran. Total waktu perawatan adalah 38 bulan. Jarak dan tumpang gigit normal berhasil dicapai pada akhir perawatan, Adapun profil wajah pasien menunjukkan perubahan yang cukup bermakna.  Simpulan: Perawatan ortodonti dengan penjangkaran mini implant orthodontic efektif dalam penatalaksanaan pasien pada Maloklusi kelas II skeletal dengan protrusi berat.Kata kunci: Mini implant orthodontic, maloklusi kelas II skeletal, Protrusi gigi ABSTRACTIntroduction: Class II division 1 malocclusion is commonly associated with several specific morphological features, such as proclination of upper incisor and convex skeletal or soft tissue profile. Therefore, a meticulous treatment plan, particularly anchorage preparation, is needed to achieve satisfying improvement of these condition. Therefore, nowadays mini implants orthodontic have become a new strategy for treating skeletal Class II patients with severe protrusion. Case report: The case report describes the camouflage treatment of a 22-year-old woman with a Class II division 1 malocclusion, characterized by a large overjet, convex profile, retrognathic mandible, dolichofacial, and a history of rhinitis. Treatment involved extraction of upper first premolars and mini implant orthodontic as anchorage during space closure. The total treatment time was 38 months. Ideal overjet and overbite were achieved, and the facial profile was improved significantly. Conclusion: Orthodontic treatment with Orthodontic mini implant as an anchorage is effective in management of Class II division 1 malocclusion with severe protrusion.Keywords : Mini implant orthodontic, Class II malocclusion, dental protrusion

scholarly journals Clinical and practical considerations in the design of appropriate compensation schedules following treatment interruptions

BJR|Open ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 20200041
Author(s):  
Bleddyn Jones ◽  
RG Dale
Keyword(s):  
Radiation Treatment ◽  
Treatment Plan ◽  
Field Size ◽  
Dose Calculations ◽  
Medical Risk ◽  
Normal Tissues ◽  
Medical Risk Factors ◽  
Treatment Interruptions ◽  
Dose Limits ◽  
Key Issues

Compensatory dose calculations to mitigate the deleterious effect of unscheduled treatment interruptions remain important. They may be increasingly required during and after epidemics, as with the present Covid-19 virus. The information presented to those involved in the actual dose estimations is often limited, thereby increasing the likelihood of confusion, further time delays and possibly incorrect decisions. This article sets out what aspects need to be considered by the Clinical Oncologist (or Radiation Oncologist), and the reasons why, in order to provide greater clarity. The key issues are: (a) the biological nature of the tumour (and hence its repopulation potential), (b) patient age and pre-existing medical risk factors that influence radiation tolerance, the use of chemotherapy, surgery etc, (c) the acceptable dose limits of the relevant normal tissues at risk and (d) consideration of the possibility of further field size adjustments, a change in treatment plan or acceptance of a greater role for alternative forms of radiation treatment (e.g. brachytherapy, electron boosts, etc.) or reliance on radical surgery. Only then can a compensatory schedule be more safely estimated.

Toward improving the therapeutic ratio in stereotactic radiosurgery: selective modulation of the radiation responses of both normal tissues and tumor

2007 ◽  
Vol 107 (1) ◽  
pp. 84-93 ◽  
Author(s):  
John W. Hopewell ◽  
William T. Millar ◽  
K. Kian Ang
Keyword(s):  
Single Dose ◽  
Stereotactic Radiosurgery ◽  
Radiation Treatment ◽  
Repeated Administration ◽  
Tissue Response ◽  
Tumor Control ◽  
Cns Injury ◽  
Repair Capacity ◽  
Normal Tissues ◽  
Radiation Enhancers

✓A review of the radiobiological factors that influence the response of the brain to radiation is provided in relation to stereotactic radiosurgery (SRS). The prospects for intervention after radiation treatment to selectively modulate the expression of late central nervous system (CNS) injury is considered, as well as an account of recent interest in the use of radiation enhancers to selectively increase the response of tumors to radiation. Brain necrosis in humans, after conventional irradiation, indicates that the risk of necrosis increases rapidly after an equivalent single dose of 12 or 13 Gy. When single-dose treatments are extended due to 60Co decay or planned extension of treatment times, account should be taken of the effects of the repair of sublethal radiation damage to DNA on the efficacy of treatment. Both repair capacity and repair kinetics will also influence tumor control, but parameters to quantify this effect have not yet been established. The volume of CNS tissue that has been irradiated affects the tissue response, but this effect is only significant for volumes less than 0.05 cm3. The gain obtained from irradiation of small volumes is reduced, however, when focal irradiation is given within a wider field of irradiation. Based on a vascular hypothesis explaining the pathogenesis of late CNS damage, approaches designed to selectively modulate the frequency of late CNS damage have been validated. Given the high intrinsic radioresistance of some tumors, as opposed to the presence of hypoxia, an interest has developed in the use of selective radiation enhancers in the treatment of tumors. The compound presently available has proved to be disappointing clinically due to toxicity at effective doses, when repeated administration is required. However, when given at high single doses it is less toxic and may be more effective. Less toxic radiation enhancers need to be developed.

Vital Tooth Whitening Techniques. A literature Review

2020 ◽  
Vol 02 ◽  
Author(s):  
Pia Chatterjee Kirk
Keyword(s):  
Soft Tissues ◽  
Treatment Time ◽  
Tooth Bleaching ◽  
Tooth Whitening ◽  
Easy Method ◽  
Tooth Structure ◽  
Dental Esthetics ◽  
Total Treatment Time ◽  
Restorative Materials ◽  
Total Treatment

Background: Vital tooth whitening has become an integral part of esthetic dentistry and remains one of the safest and most economic options today to improve dental esthetics without removing tooth structure. The tooth whitening materials have evolved into three categories: dentist-prescribed/dispensed (in office and patient home-use), and over-thecounter purchased and applied by patients. Objective: This review outlines the latest advances in dentist prescribed vital teeth whitening techniques, effects on tooth structure, soft tissues, and dental restoratives. Areas requiring additional research are also discussed. Methods: Electronic and manual literature search was conducted for key words such as tooth bleaching, and dental bleaching techniques using PubMed/MEDLINE, followed by manual selection of the studies that included whitening procedures in vital teeth. Results: The two main whitening agents are carbamide peroxide (CP) and hydrogen peroxide (HP or H2O2) whose concentration, duration of contact, and total treatment time can alter results. In addition, factors including the type of stain, and age of patient can affect results. Although whitening agents can affect tooth structure, restorative materials, and gingival tissues, the changes are temporary or can be treated using minimally invasive techniques. Conclusion: Areas requiring further research include the actual mechanism of whitening, its effect on tooth structure and restorative materials, and the development of an easy method to quantitate the degree of whitening in the dental office.

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