scholarly journals Computed Tomography-Based Evaluation of Volume and Position Changes of the Target Region and Organs at Risk During Radiotherapy for Esophageal Cancer: A Pilot Study

2021 ◽  
Vol 11 ◽  
Author(s):  
Yi-mei Liu ◽  
Ying-lin Peng ◽  
Qi-wen Li ◽  
Guanzhu Shen ◽  
Ya-ru Ma ◽  
...  
Keyword(s):  
Computed Tomography ◽  
At Risk ◽  
Esophageal Cancer ◽  
Cancer Patients ◽  
Organs At Risk ◽  
Three Dimensional ◽  
Intensity Modulated Radiation Therapy ◽  
Conformal Radiotherapy ◽  
Target Volume ◽  
Target Volumes

ObjectiveTo analyze changes in volume and position of target regions and organs at risk (OARs) during radiotherapy for esophageal cancer patients.MethodsOverall, 16 esophageal cancer patients who underwent radiotherapy, including 10 cases of intensity-modulated radiation therapy (IMRT) and six of three-dimensional conformal radiotherapy (3D-CRT), were enrolled. The prescription doses for the planning target volumes (PTVs) were as follows: PTV1, 64 Gy/32 fractions; and PTV2, 46 Gy/23 fractions. Repeat computed tomography (CT) was performed for patients after the 5th, 10th, 15th, 20th, and 25th fractions. Delineation of the gross tumor volume (GTV) and OAR volume was determined using five repeat CTs performed by the same physician. The target and OAR volumes and centroid positions were recorded and used to analyze volume change ratio (VCR), center displacement (ΔD), and changes in the distance from the OAR centroid positions to the planned radiotherapy isocenter (distance to isocenter, DTI) during treatment.ResultsNo patient showed significant changes in target volume (TV) after the first week of radiotherapy (five fractions). However, TV gradually decreased over the following weeks, with the rate slowing after the fourth week (40 Gy). The comparison of TV from baseline to 40 Gy (20 fractions) showed that average GTVs decreased from 130.7 ± 63.1 cc to 92.1 ± 47.2 cc, with a VCR of −29.21 ± 13.96% (p<0.01), while the clinical target volume (CTV1) decreased from 276.7 ± 98.2 cc to 246.7 ± 87.2 cc, with a VCR of −10.34 ± 7.58% (p<0.01). As TVs decreased, ΔD increased and DTI decreased. After the fourth week of radiotherapy (40 Gy), centroids of GTV, CTV1, and prophylactic CTV (CTV2) showed average deviations in ΔD of 7.6 ± 4.0, 6.9 ± 3.4, and 6.0 ± 3.0 mm, respectively. The average DTI of the heart decreased by 4.53 mm (from 15.61 ± 2.96 cm to 15.16 ± 2.27 cm).ConclusionDuring radiotherapy for esophageal cancer, Targets and OARs change significantly in volume and position during the 2nd–4th weeks. Image-guidance and evaluation of dosimetric changes are recommended for these fractions of treatment to appropriate adjust treatment plans.

Target volume coverage and dose to organs at risk in prostate cancer patients

2014 ◽  
Vol 190 (3) ◽  
pp. 310-316 ◽  
Author(s):  
P. Hüttenrauch ◽  
M. Witt ◽  
D. Wolff ◽  
S. Bosold ◽  
R. Engenhart-Cabillic ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
At Risk ◽  
Cancer Patients ◽  
Organs At Risk ◽  
Target Volume

scholarly journals Can volumetric modulated arc radiation therapy reduce organ at risk dose in stage 4 sinonasal tumors in dogs treated with boost irradiation?

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0259112
Author(s):  
Valeria Meier ◽  
Felicitas Czichon ◽  
Linda Walsh ◽  
Carla Rohrer Bley
Keyword(s):  
At Risk ◽  
Radiation Therapy ◽  
Degrees Of Freedom ◽  
Organs At Risk ◽  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiation Therapy ◽  
Target Volume ◽  
Normal Tissue Complication Probability ◽  
Lacrimal Glands ◽  
Stage 4

Intensity modulated radiation therapy (IMRT) introduced marked changes to cancer treatment in animals by reducing dose to organs at risk (OAR). As the next technological step, volumetric modulated arc therapy (VMAT) has advantages (increased degrees-of-freedom, faster delivery) compared to fixed-field IMRT. Our objective was to investigate a possible advantage of VMAT over IMRT in terms of lower OAR doses in advanced-disease sinonasal tumors in dogs treated with simultaneously-integrated boost radiotherapy. A retrospective, analytical, observational study design was applied using 10 pre-existing computed tomography datasets on dogs with stage 4 sinonasal tumors. Each dataset was planned with both, 5-field IMRT and 2 arc VMAT with 10x4.83 Gy to the gross tumor volume and 10x4.2 Gy to the planning target volume. Adequate target dose coverage and normal tissue complication probability of brain ≤5% was required. Dose constraints aspired to were D60 <15 Gy for eyes, D2 <35.4 Gy for corneae, and Dmean <20 Gy for lacrimal glands. OAR dose was statistically significantly higher in IMRT plans than in VMAT plans. Median eye D60% was 18.5 Gy (interquartile range (IQR) 17.5) versus 16.1 Gy (IQR 7.4) (p = 0.007), median lacrimal gland dose 21.8 Gy (IQR 20.5) versus 18.6 Gy (IQR 7.0) (p = 0.013), and median cornea D2% 45.5 Gy (IQR 6.8) versus 39.9 Gy (IQR 10.0) (p<0.005) for IMRT versus VMAT plans, respectively. Constraints were met in 21/40 eyes, 7/40 corneae, and 24/40 lacrimal glands. Median delivery time was significantly longer for IMRT plans than for VMAT plans (p<0.01). Based on these results, VMAT plans were found to be superior in sparing doses to eyes, lacrimal glands, corneae. However, not all ocular OAR constraints could be met while ensuring adequate dose coverage and restricting brain toxicity risk for both planning techniques.

Dosimetric study of three-dimensional conformal radiotherapy, electronic compensator technique, intensity-modulated radiation therapy and volumetric-modulated arc therapy in whole breast irradiation

2017 ◽  
Vol 16 (4) ◽  
pp. 431-443 ◽  
Author(s):  
Chonnipa Nantavithya ◽  
Kitwadee Saksornchai ◽  
Puntiwa Oonsiri ◽  
Kanjana Shotelersuk
Keyword(s):  
Radiation Therapy ◽  
Volumetric Modulated Arc Therapy ◽  
Three Dimensional ◽  
Intensity Modulated Radiation Therapy ◽  
Conformal Radiotherapy ◽  
Target Volume ◽  
Whole Breast Irradiation ◽  
Breast Irradiation ◽  
Lung Dose ◽  
3D Crt

AbstractBackgroundWhole breast irradiation is an essential treatment after breast-conserving surgery (BCS). However, there are some adverse effects from inhomogeneity and dose to adjacent normal tissues.ObjectiveAim of this study was to compare dosimetry among standard technique, three-dimensional conformal radiotherapy (3D-CRT), and advanced techniques, electronic compensator (ECOMP), inverse intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT).MethodsWhole breast irradiation treatment plans of patients who had underwent BCS and whole breast irradiation were re-planned with all four techniques. Clinical target volume was contoured according to the Radiation Therapy Oncology Group atlas for breast only in patients who had negative node or ductal carcinoma in situ and breast with chest wall for patients with positive node. Planning target volume was non-uniformly expanded. Dose prescription was 50 Gy in 25 fractions with 6 MV photon energy.ResultsIn total, 25 patients underwent whole breast irradiation with computed tomography simulation from November 2013 to November 2014 were included. Six patients with positive nodes were re-planned for breast with chest wall irradiation and 19 patients with negative nodes were re-planned for breast only irradiation. Primary outcome, radical dose homogeneity index (HI) of 3D-CRT, ECOMP, IMRT and VMAT were 0·865, 0·889, 0·890 and 0·866, respectively. ECOMP and IMRT showed significant higher HI than 3D-CRT (p-value<0·001). Secondary outcome, conformity index (CI) of advanced technique were significantly better than 3D-CRT. Lung V20, mean ipsilateral lung dose (MILD), mean heart dose (MHD), heart V25, heart V30 of advanced techniques were also lower than 3D-CRT. ECOMP had better mean lung dose (MLD), mean contralateral lung dose (MCLD) and mean contralateral breast dose (MCBD) when compared with 3D-CRT. Monitor units of advanced techniques were significantly higher than 3D-CRT.ConclusionsHI of ECOMP and IMRT were significantly higher than 3D-CRT technique. All advanced techniques showed statistically better in CI. Lung V20, MILD, heart V25 and heart V30 of advanced techniques were lower than 3D-CRT. However, only ECOMP showed decreased MLD, MHD, MCLD and MCBD when compared with 3D-CRT.

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