A fluence-convolution method to calculate radiation therapy dose distributions that incorporate random set-up error

2002 ◽  
Vol 47 (19) ◽  
pp. 3465-3473 ◽  
Author(s):  
W A Beckham ◽  
P J Keall ◽  
J V Siebers
1997 ◽  
Vol 44 (3) ◽  
pp. 259-263 ◽  
Author(s):  
Gabriela Ragazzi ◽  
Paola Mangili ◽  
Claudio Fiorino ◽  
Giovanni Mauro Cattaneo ◽  
Angelo Bolognesi ◽  
...  

Author(s):  
Daryoush Khoramian ◽  
Soroush Sistani ◽  
Bagher Farhood

Abstract Aim: In radiation therapy, accurate dose distribution in target volume requires accurate treatment setup. The set-up errors are unwanted and inherent in the treatment process. By achieving these errors, a set-up margin (SM) of clinical target volume (CTV) to planning target volume (PTV) can be determined. In the current study, systematic and random set-up errors that occurred during prostate cancer radiotherapy were measured by an electronic portal imaging device (EPID). The obtained values were used to propose the optimum CTV-to-PTV margin in prostate cancer radiotherapy. Materials and methods: A total of 21 patients with prostate cancer treated with external beam radiation therapy (EBRT) participated in this study. A total of 280 portal images were acquired during 12 months. Gross, population systematic (Σ) and random (σ) errors were obtained based on the portal images in Anterior–Posterior (AP), Medio-Lateral (ML) and Superior–Inferior (SI) directions. The SM of CTV to PTV were then calculated and compared by using the formulas presented by the International Commission on Radiation Units and Measurements (ICRU) 62, Stroom and Heijmen and Van Herk et al. Results: The findings showed that the population systematic errors during prostate cancer radiotherapy in AP, ML and SI directions were 1·40, 1·95 and 1·94 mm, respectively. The population random errors in AP, ML and SI directions were 2·09, 1·85 and 2·29 mm, respectively. The SM of CTV to PTV calculated in accordance with the formula of ICRU 62 in AP, ML and SI directions were 2·51, 2·68 and 3·00 mm, respectively. And according to Stroom and Heijmen, formula were 4·23, 5·19 and 5·48 mm, respectively. And Van Herk et al. formula were 4·96, 6·17 and 6·45 mm, respectively. Findings: The SM of CTV to PTV in all directions, based on the formulas of ICRU 62, Stroom and Heijmen and van Herk et al., were equal to 2·73, 4·98 and 5·86 mm, respectively; these values were obtained by averaging the margins in all directions.


2021 ◽  
Vol 66 (3) ◽  
pp. 68-75
Author(s):  
E. Sukhikh ◽  
L. Sukhikh ◽  
A. Vertinsky ◽  
P. Izhevsky ◽  
I. Sheino ◽  
...  

Purpose: Carrying out the analysis of the physical and radiobiological equivalence of dose distributions obtained during the planning of hypofractionated stereotactic radiation therapy of the prostate cancer and verification using a three-dimensional cylindrical dosimeter. Material and Methods: Based on the anatomical data of twelve patients diagnosed with prostate carcinoma, stage T2N0M0 with low risk, plans were developed for stereotactic radiation therapy with volumetric modulates arc therapy (VMAT). The dose per fraction was 7,25 Gy for 5 fractions (total dose 36,25 Gy) with a normal photon energy of 10 MV. The developed plans were verified using a three-dimensional cylindrical ArcCHECK phantom. During the verification process, the three-dimensional dose distribution in the phantom was measured, based on which the values of the three-dimensional gamma index and the dose–volume histogram within each contoured anatomical structures were calculated with 3DVH software. The gamma index value γ (3 %, 2 mm, GN) at a threshold equal to 20 % of the dose maximum of the plan and the percentage of coincidence of points at least 95 % was chosen as a criterion of physical convergence of the calculated and measured dose distribution according to the recommendations of AAPM TG-218. To analyze the radiobiological equivalence of the calculated and measured dose distribution, the local control probability (TCP) and normal tissue complication probability (NTCP) criteria were used based on the calculated and measured dose–volume histograms. Contours of the target (PTV) and the anterior wall of the rectum were used for the analysis. The approach based on the concept of equivalent uniform dose (EUD) by A. Niemierko was used to calculate the values of TCP/NTCP criteria. Results: The results of physical convergence of plans for all patients on the contour of the whole body were higher than 95 % for the criteria γ (3 %, 2 mm, GN). The convergence along the PTV contour is in the range (75.5–95.2)%. The TCP and NTCP values obtained from the measured dose-volume histograms were higher than the planned values for all patients. It was found that the accelerator delivered a slightly higher dose to the PTV and the anterior wall of the rectum than originally planned. Conclusion: The capabilities of modern dosimetric equipment allow us move to the verification of treatment plans based on the analysis of TCP / NTCP radiobiological equivalence, taking into account the individual characteristics of the patient and the capabilities of radiation therapy equipment.


Doklady BGUIR ◽  
2020 ◽  
Vol 18 (7) ◽  
pp. 31-39
Author(s):  
M. N. Piatkevich ◽  
E. V. Titovich ◽  
G. V. Belkov

Due to the rapid development and further improvement of radiation treatment technologies oncologists have an opportunity to precisely deliver individual dose distributions to the tumor, minimizing the doses obtained by critical organs and healthy structures. For the correct and successful application of these complex methods of radiation therapy, it was necessary to enforce the requirements for the technical and dosimetric parameters of the radiotherapy equipment. The purpose of the research is to determine the magnitude of the possible error for patients’ positioning during their radiotherapy treatments using medical linear accelerators by modeling the impact of the patient’s body on the treatment couch. To determine the values of a possible error, the authors have considered the design and characteristics of a typical treatment couch, developed a model of the “average” patient’s body (phantom), which allowed changing the load to the treatment couch with a step of 1 kg. The position parameters of treatment couches were determined for the main types of localization of radiation therapy for malignant tumors: head and neck tumors, breast tumors and pelvic tumors. Numerical values of the treatment coach deviations from prescribed horizontal position were experimentally established for a load from 40 to 180 kg for a treatment couch used at the N.N. Alexandrov National Cancer Centre of Belarus. Based on the obtained experimental data, the necessity to correct the patient's treatment conditions at the stage of treatment planning were confirmed in order to ensure the delivery accuracy of individual dose distributions as required by the radiation therapy protocols. Authors stated that an analysis of the dependence of the deviations in the dose delivered to the patients on the deviation of the radiotherapy table from its horizontal position should be carried out for each radiotherapy table used in clinical practice. The development and implementation of a mechanism that will allow considering this information when choosing the parameters of the patient’s treatment session and prescribing the dose for any localization of malignant neoplasms is needed.


2008 ◽  
Vol 47 (7) ◽  
pp. 1344-1350 ◽  
Author(s):  
Faisal Siddiqui ◽  
Chengyu Shi ◽  
Niko Papanikolaou ◽  
Martin Fuss

Author(s):  
Anh Phuong Le

TÓM TẮT Đối với ung thư vú (UTV) xạ trị là điều trị bổ túc cần thiết giúp giảm tái phát tại chỗ tại vùng, gia tăng sống còn. Tuy nhiên, xạ trị có tác dụng phụ lên tim mạch nhất là với UTV trái. Nhiều nghiên cứu đã chứng minh biến chứng và tử vong do tim mạch tăng tỉ lệ thuận với liều trung bình lên tim. Các kỹ thuật xạ trị mới trong xạ trị ung thư vú trái giúp tối ưu hóa liều vào thể tích xạ và bảo vệ tốt hơn cơ quan lành, càng đòi hỏi độ chính xác cao khi đặt bệnh. Các sai số do thiết bị hoặc đặt bệnh sẽ dẫn đến nguy cơ quá liều dung nạp hoặc thiếu liều và có nguy cơ tái phát. Vì vậy, xạ trị đòi hỏi sự chính xác cao trong suốt quá trình từ mô phỏng đến lập kế hoạch và tiến hành xạ trị. Xạ trị ung thư vú trái phối hợp hít sâu nín thở (DIBH - Deep Inspiration Breath - hold) và hệ thống quản lý bề mặt quang học (OSMS - Optical Surface Management System) làm cho tim di chuyển ra xa hơn khỏi vú, thành ngực trong quá trình xạ trị, giúp giảm liều tim một cách rõ rệt, vẫn đảm bảo được liều xạ lên thể tích đích. Ưu điểm của OSMS ngoài áp dụng cho đặt bệnh nhanh không cần xăm dấu trên da còn giám sát thời gian thực trong toàn bộ quá trình điều trị. Khi nhịp thở của bệnh nhân vượt quá một ngưỡng nhất định (0,3cm) chùm tia bức xạ sẽ bị tắt để ngăn ngừa độc tính. Do đó, hiểu và nắm rõ lợi ích quy trình đặt bệnh giúp đạt mục tiêu điều trị đồng thời giảm thời gian đặt bệnh để người bệnh có tâm lý thoải mái hơn, giảm áp lực về số lượng bệnh, nhất là đối với các trung tâm xạ trị lớn. ABSTRACT BENEFITS OF LEFT BREAST CANCER RADIATION COMBINATION OF DEEP INSPIRATION BREATH - HOLD AND OPTICAL SURFACE MANAGEMENT SYSTEM OF TRUEBEAM MACHINE AT CANCER HOSPITAL HO CHI MINH CITY Background: For breast cancer, radiation therapy is an essential adjuvant treatment to help reduce local recurrence and increase survival. However, radiation therapy has adverse effects on the cardiovascular systemespecially for left breast cancer. Several studies have demonstrated that cardiovascular morbidity and mortality increase in proportion to the mean cardiac dose. New radiotherapy techniques in radiation therapy for left breast cancer help optimize dose to radiation volume and better protect healthy organs, which requires high accuracy when patient set - up. Errors due to equipment or patient set - up will lead to the risk of overdosage or underdosage and risk of relapse. Therefore, radiation therapy requires high precision throughout the process from simulation to planning and conducting radiation therapy. Radiation therapy for left breast cancer combined with Deep Inspiration Breath - hold (DIBH) and Optical Surface Management System (OSMS)causes the heart to move further away from the breast and chest wall during radiation therapy, helping to reduce the cardiac dose significantly, still ensuring the radiation dose to the target volume. The advantage of OSMS is that in addition to being applied for fastpatient set - up, without tattooing on the skin, it also provides real - time monitoring during the entire treatment process. When the patient’s breathing rate exceeds a certain threshold (0,3cm) the radiation beam is turned off to prevent toxicity. Therefore, understanding and understanding the benefits of patient set - up helps to achieve treatment goals, while reducing patient set - up time for more comfort, reducing pressure on the number of patients, especially for patients large radiotherapy center. Keyword: Radiation therapy for left breast cancer, Deep Inspiration Breath - hold, Optical Surface Management System, cardiovascular risk.


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