scholarly journals Random and systematic set-up errors in three-dimensional conformal radiotherapy – impact on planning target volume margins: the experience of the Radiation Oncology Centre of Sassari

2013 ◽  
Vol 13 (2) ◽  
pp. 166-179
Author(s):  
Matteo Tamponi ◽  
Angela Poggiu ◽  
Maria F. Dedola ◽  
Rossella Madeddu ◽  
Antonella Carnevale ◽  
...  
Keyword(s):  
Planning Target Volume ◽  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Target Volume ◽  
Patient Specific ◽  
Geometric Uncertainties ◽  
Three Dimensional Conformal Radiotherapy ◽  
Set Up ◽  
Oncology Centre ◽  
The Impact

AbstractPurposeGeometric uncertainties limit the accuracy of three-dimensional conformal radiotherapy treatments. This study aims to evaluate typical random and systematic set-up errors and analyse the impact of no action level (NAL) correction protocol on systematic set-up errors and clinical target volume (CTV)–planning target volume (PTV) margins.Materials and methodsA total 668 pairs of orthogonal electronic portal images were compared with digitally reconstructed radiographs from computed tomography planning scans for 100 patients consecutively treated during 2011. Patients were divided into groups depending on the treated anatomical region. Patient-specific and population random and systematic set-up errors were calculated. Impact of application of NAL correction protocol on systematic set-up errors and CTV–PTV expansions were evaluated.ResultsPopulation set-up errors resulted from about 1 mm in head and neck to 2–3 mm in prostate, rectum, lung, breast and gynaecological districts. Patient-specific systematic set-up errors were higher for breast and gynaecological districts and application of NAL correction protocol gave significant reductions, even higher than 30%. Calculated CTV–PTV margins ranged from 10 mm on left–right direction for prostate to 20 mm on superior–inferior direction for lung.ConclusionsSet-up errors resulted reasonably controlled and application of NAL correction protocol could further improve the level of accuracy. However, the NAL application alone did not seem to add any substantial benefit on CTV–PTV total margins without the adoption of corrective strategies to reduce other important uncertainties limiting accuracy of three-dimensional conformal radiotherapy.

scholarly journals Strategies to evaluate the impact of rectal volume on prostate motion during three-dimensional conformal radiotherapy for prostate cancer

2016 ◽  
Vol 49 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Ana Paula Diniz Fortuna Poli ◽  
Rodrigo Souza Dias ◽  
Adelmo José Giordani ◽  
Helena Regina Comodo Segreto ◽  
Roberto Araujo Segreto
Keyword(s):  
Prostate Cancer ◽  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Prostate Motion ◽  
Rectal Volume ◽  
Three Dimensional Conformal Radiotherapy ◽  
Interfraction Motion ◽  
The Impact ◽  
Anterior Posterior ◽  
3D Crt

Abstract Objective: To evaluate the rectal volume influence on prostate motion during three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. Materials and Methods: Fifty-one patients with prostate cancer underwent a series of three computed tomography scans including an initial planning scan and two subsequent scans during 3D-CRT. The organs of interest were outlined. The prostate contour was compared with the initial CT images considering the anterior, posterior, superior, inferior and lateral edges of the organ. Variations in the anterior limits and volume of the rectum were assessed and correlated with prostate motion in the anteroposterior direction. Results: The maximum range of prostate motion was observed in the superoinferior direction, followed by the anteroposterior direction. A significant correlation was observed between prostate motion and rectal volume variation ( p = 0.037). A baseline rectal volume superior to 70 cm3 had a significant influence on the prostate motion in the anteroposterior direction ( p = 0.045). Conclusion: The present study showed a significant interfraction motion of the prostate during 3D-CRT with greatest variations in the superoinferior and anteroposterior directions, and that a large rectal volume influences the prostate motion with a cutoff value of 70 cm3. Therefore, the treatment of patients with a rectal volume > 70 cm3 should be re-planned with appropriate rectal preparation.

scholarly journals Utilization of PET-CT in target volume delineation for three-dimensional conformal radiotherapy in patients with non-small cell lung cancer and atelectasis

2013 ◽  
Vol 8 ◽  
Author(s):  
Li-Jie Yin ◽  
Xiao-Bin Yu ◽  
Yan-Gang Ren ◽  
Guang-Hai Gu ◽  
Tian-Gui Ding ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Target Volume ◽  
Target Volume Delineation ◽  
Target Delineation ◽  
Volume Delineation ◽  
Pet Ct ◽  
Treatment Plans ◽  
Three Dimensional Conformal Radiotherapy ◽  
Nsclc Patients

Background: To investigate the utilization of PET-CT in target volume delineation for three-dimensional conformal radiotherapy in patients with non-small cell lung cancer (NSCLC) and atelectasis. Methods: Thirty NSCLC patients who underwent radical radiotherapy from August 2010 to March 2012 were included in this study. All patients were pathologically confirmed to have atelectasis by imaging examination. PET-CT scanning was performed in these patients. According to the PET-CT scan results, the gross tumor volume (GTV) and organs at risk (OARs, including the lungs, heart, esophagus and spinal cord) were delineated separately both on CT and PET-CT images. The clinical target volume (CTV) was defined as the GTV plus a margin of 6-8 mm, and the planning target volume (PTV) as the GTV plus a margin of 10-15 mm. An experienced physician was responsible for designing treatment plans PlanCT and PlanPET-CT on CT image sets. 95% of the PTV was encompassed by the 90% isodose curve, and the two treatment plans kept the same beam direction, beam number, gantry angle, and position of the multi-leaf collimator as much as possible. The GTV was compared using a target delineation system, and doses distributions to OARs were compared on the basis of dose-volume histogram (DVH) parameters. Results: The GTVCT and GTVPET-CT had varying degrees of change in all 30 patients, and the changes in the GTVCT and GTVPET-CT exceeded 25% in 12 (40%) patients. The GTVPET-CT decreased in varying degrees compared to the GTVCT in 22 patients. Their median GTVPET-CT and median GTVPET-CT were 111.4 cm3 (range, 37.8 cm3-188.7 cm3) and 155.1 cm3 (range, 76.2 cm3-301.0 cm3), respectively, and the former was 43.7 cm3 (28.2%) less than the latter. The GTVPET-CT increased in varying degrees compared to the GTVCT in 8 patients. Their median GTVPET-CT and median GTVPET-CT were 144.7 cm3 (range, 125.4 cm3-178.7 cm3) and 125.8 cm3 (range, 105.6 cm3-153.5 cm3), respectively, and the former was 18.9 cm3 (15.0%) greater than the latter. Compared to PlanCT parameters, PlanPET-CT parameters showed varying degrees of changes. The changes in lung V20, V30, esophageal V50 and V55 were statistically significant (Ps< 0.05 for all), while the differences in mean lung dose, lung V5, V10, V15, heart V30, mean esophageal dose, esophagus Dmax, and spinal cord Dmax were not significant (Ps> 0.05 for all). Conclusions: PET-CT allows a better distinction between the collapsed lung tissue and tumor tissue, improving the accuracy of radiotherapy target delineation, and reducing radiation damage to the surrounding OARs in NSCLC patients with atelectasis.

An investigation of rotational issues for rectal carcinoma treated with radiotherapy

2013 ◽  
Vol 13 (2) ◽  
pp. 195-202
Author(s):  
Dominique A. Taylor ◽  
Thomas ffrench ◽  
Charlotte A. Sale ◽  
Paul Foulstone
Keyword(s):  
Rectal Carcinoma ◽  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Target Volume ◽  
Dose Volume Histograms ◽  
Action Threshold ◽  
Prescription Dose ◽  
Pre Treatment ◽  
Clinically Significant ◽  
Three Dimensional Conformal Radiotherapy

AbstractPurposeTo quantify the amount of inter-fractional pitch for rectal carcinoma patients, to investigate the dosimetric impact of pitch on the target volume and critical structures and to determine a tolerance where no pitch correction is required.Materials and methodsDaily pre-treatment images of rectal carcinoma patients were analysed to determine the residual pitch compared with the computed tomography (CT) planning scan. The dosimetric impact of pelvic rotation was modelled. The dose coverage of the clinical target volume (CTV) and small bowel were evaluated using dose–volume histograms.ResultsPre-treatment images had a mean of 0·27° and standard deviation was 2·23°. The volume of CTV receiving 95% of the prescription dose altered by 0·1% when up to ±10° of pitch was simulated.ConclusionsNo clinically significant change in CTV coverage was found (when ±10° of pitch was simulated). A tolerance of ±10° of pitch has been implemented for rectal carcinoma patients treated with three-dimensional conformal radiotherapy in our institution, when daily pre-treatment imaging with a zero action threshold for translational shifts is used.

scholarly journals Development of Cylindrical Head and Neck Phantom Using 3d Printing for Dosimetric Verification in Radiation Therapy

2017 ◽  
Vol 35 (4) ◽  
pp. 351
Author(s):  
Sarayut Kornsopa ◽  
Nuntawat Udee ◽  
Sararat Mahasaranon ◽  
Chirapa Tannanonta
Keyword(s):  
Soft Tissue ◽  
Head And Neck ◽  
Three Dimensional ◽  
Acrylonitrile Butadiene Styrene ◽  
Conformal Radiotherapy ◽  
Target Volume ◽  
Ct Number ◽  
Calculated Dose ◽  
Three Dimensional Conformal Radiotherapy ◽  
Dosimetric Verification

 Objective: To construct the cylindrical head and neck phantom using the three-dimensional printer for dosimetric verification in radiation therapy.Material and Medthod: The cylindrical head and neck phantom was constructed the using the three-dimensional printer. Inside the model is composed of soft tissue was constructed from para rubber latex, for planning target volume (PTV), organ at risk (OAR) and wall of phantom using acrylonitrile butadiene styrene from a three-dimensional printer, bone was made from resin mixed with calcium carbonate.Results: The computed tomography (CT) number of head and neck phantom was simulated with a CT simulator show that the soft tissue, PTV and OAR lie between -2 to 56 Hounsfield units (HU), -282 to -196 HU respectively, bone lies between 731 to 852 HU and wall of phantom lie between -152 to -89 HU. The average percent dose difference between calculated dose and measured dose in three-dimensional conformal radiotherapy (3DCRT) was 0.7%.Conclusion: The cylindrical head and neck phantom can be used to evaluate 3DCRT dose treatment planning and delivery.  

Dosimetric study on the use of Eclipse beam angle optimiser for conformal planning

2021 ◽  
pp. 1-4
Author(s):  
Yousif A. M. Yousif ◽  
Ali Judge ◽  
Jackson Zifodya
Keyword(s):  
Radiation Therapy Oncology Group ◽  
Three Dimensional ◽  
Conformal Radiotherapy ◽  
Target Volume ◽  
Radiotherapy Planning ◽  
Beam Angle ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Collimator Angle ◽  
Three Dimensional Conformal Radiotherapy

Abstract Aim: The aim of this study was to evaluate the use of Eclipse’s beam angle optimiser (BAO) for three-dimensional conformal radiotherapy planning. Materials and methods: Eleven 3D conformal lung plans, with varied tumour volumes, were retrospectively studied. For each clinical plan, a BAO plan was produced and then optimised by an experienced planner. Plan quality was assessed using International Commission on Radiation Units and Measurements (ICRU)-83 and  Radiation Therapy Oncology Group (RTOG) recommended dose reporting metrics for dose volume prescribing and reporting. Results: Differences in dose volume histograms for both methods showed no clinical significance. Planning target volume Dmax for both plans was comparable and within ICRU guidelines. Reported spinal cord Dmax and the doses to 33% and 67% volume of the heart were within the RTOG recommended limits. Mean lung V20 values for BAO and non-BAO plans were 20 and 16%, respectively. The average monitor units for the BAO plans were about 11% lower. The conformity and homogeneity indices were within the acceptable range for both cases. On average, it took 23 minutes to plan using the BAO compared to 68 minutes for the non-BAO plans. Conclusion: Eclipse BAO shows the potential to produce good quality conformal plans and reduce planning time. This process could be further refined with multi-leaf collimator and optimal collimator angle options.

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