A comparative dosimetric study comparing dose to the carotid artery using 3D conformal radiotherapy and intensity-modulated radiotherapy for T1-T2 glottic cancer at Gharbia Cancer Society, Egypt

AbstractPurposeThis is a dosimetric study to compare the feasibility of carotid artery sparing as a primary objective, as well as planning target volume coverage and dose to spinal cord as a secondary objective, by using 3D conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) for patients with early glottis cancer.Patients and methodsSix patients who had been treated for early stage glottic carcinoma (stage T1-2 N0M0) were included in this study. All patients were immobilised in the supine position with a thermoplastic mask and treatment planning computed tomography scans were obtained from the top of the skull to the top of aortic arch with a 3-mm slice thickness. Two plans were created for every patient, one using 3DCRT and the second using IMRT. Comparison between the two plans was undertaken and analysis was made regarding the dose to the carotids arteries, target coverage and doses to the organs at risk.ResultsFor target coverage, theV95%for both plans was the same with no significant difference, hot spots were the highest in 3DCRT withp=0·002, the homogeneity index for IMRT plan was better than 3DCRT (p=0·0001). Regarding the dose to the carotids, it was significantly lower in the IMRT plan compared with the 3DCRT plan (p=0·01). The spinal cord dose was significantly higher in the IMRT plan.ConclusionIMRT significantly reduces the radiation dose to the carotid arteries compared with 3DCRT while maintaining clinical target volume coverage. Such a results assists in decreasing the incidence of radiation-induced carotid stenosis, thus improving the quality of life for patients.

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Impact of Geometric Uncertainties on Dose Distribution During Intensity Modulated Radiotherapy of Head-and-neck Cancer: The Need for a Planning Target Volume and A Planning Organ-at-Risk Volume

Current Oncology ◽

10.3390/curroncol13030010 ◽

2006 ◽

Vol 13 (3) ◽

pp. 108-115 ◽

Cited By ~ 1

Author(s):

O. Ballivy ◽

W. Parker ◽

T. Vuong ◽

G. Shenouda ◽

H. Patrocinio

Keyword(s):

Spinal Cord ◽

At Risk ◽

Neck Cancer ◽

Intensity Modulated Radiotherapy ◽

Target Volume ◽

Ct Scans ◽

Target Coverage ◽

Geometric Uncertainties ◽

Intensity Modulated ◽

Organ At Risk

We assessed the effect of geometric uncertainties on target coverage and on dose to the organs at risk (OARS) during intensity-modulated radiotherapy (IMRT) for head-and-neck cancer, and we estimated the required margins for the planning target volume (PTV) and the planning organ-at-risk volume (PRV). For eight headand- neck cancer patients, we generated IMRT plans with localization uncertainty margins of 0 mm, 2.5 mm, and 5.0 mm. The beam intensities were then applied on repeat computed tomography (CT) scans obtained weekly during treatment, and dose distributions were recalculated. The dose–volume histogram analysis for the repeat CT scans showed that target coverage was adequate (V100 ≥ 95%) for only 12.5% of the gross tumour volumes, 54.3% of the upper-neck clinical target volumes (CTVS), and 27.4% of the lower-neck CTVS when no margins were added for PTV. The use of 2.5-mm and 5.0-mm margins significantly improved target coverage, but the mean dose to the contralateral parotid increased from 25.9 Gy to 29.2 Gy. Maximum dose to the spinal cord was above limit in 57.7%, 34.6%, and 15.4% of cases when 0-mm, 2.5-mm, and 5.0-mm margins (respectively) were used for PRV. Significant deviations from the prescribed dose can occur during IMRT treatment delivery for headand- neck cancer. The use of 2.5-mm to 5.0-mm margins for PTV and PRV greatly reduces the risk of underdosing targets and of overdosing the spinal cord.

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Intensity modulated radiotherapy and 3D conformal radiotherapy for whole breast irradiation: a comparative dosimetric study and introduction of a novel qualitative index for plan evaluation, the normal tissue index

Journal of Medical Radiation Sciences ◽

10.1002/jmrs.126 ◽

2015 ◽

Vol 62 (3) ◽

pp. 184-191 ◽

Cited By ~ 8

Author(s):

Jackie Yim ◽

Clare Suttie ◽

Regina Bromley ◽

Marita Morgia ◽

Gillian Lamoury

Keyword(s):

Normal Tissue ◽

Intensity Modulated Radiotherapy ◽

Conformal Radiotherapy ◽

Whole Breast Irradiation ◽

Breast Irradiation ◽

Plan Evaluation ◽

Intensity Modulated ◽

3D Conformal Radiotherapy ◽

Dosimetric Study ◽

Qualitative Index

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Dosimetric Comparisons of Three-dimensional Conformal Radiotherapy, Intensity-Modulated Radiotherapy, and Helical Tomotherapy in Whole Abdominopelvic Radiotherapy for Gynecologic Malignancy

Technology in Cancer Research & Treatment ◽

10.1177/153303460900800507 ◽

2009 ◽

Vol 8 (5) ◽

pp. 369-377 ◽

Cited By ~ 14

Author(s):

Yong Bae Kim ◽

Joo Ho Kim ◽

Kyung Keun Jeong ◽

Jinsil Seong ◽

Chang Ok Suh ◽

...

Keyword(s):

Spinal Cord ◽

Helical Tomotherapy ◽

Gynecologic Cancer ◽

Three Dimensional ◽

Intensity Modulated Radiotherapy ◽

Conformal Radiotherapy ◽

Target Volume ◽

Intensity Modulated ◽

Target Volumes ◽

Three Dimensional Conformal Radiotherapy

Objectives The goal of this study was to dosimetrically compare 3-dimensional radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and helical tomotherapy (TOMO) plans for whole abdominopelvic radiotherapy (WART) in patients with gynecologic cancer. Methods Ten patients were selected for WART planning. Doses were prescribed to planning target volumes (PTVs) as the followings: 30 Gy to PTV-whole abdominopelvis (PTV-WA), 40 Gy to PTV-para-aortic lymph node (PTV-PALN), 44 Gy to PTV-pelvis, and 50 Gy to gross target volume (GTV) in 20 fractions. Dose to whole liver, both kidneys, and spinal cord were constrained below each tissue tolerance, and bone marrow (BM)-sparing technique was adopted in IMRT and TOMO. Dosimetric parameters and treatment times were compared among plans. Results Calculated doses in TOMO came most closely to the prescribed dose for coverage of PTV-WA, PTV-PALN, PTV-pelvis, and GTV compared to 3DCRT, and IMRT. In normal organs, TOMO had significantly better dosimetric profiles compared to IMRT and 3DCRT. TOMO significantly reduced V20Gy, and mean dose of whole liver, both kidneys, and spinal cord. The use of BM-sparing technique (BMS) did not impair coverage of target volume in IMRT and TOMO. While IMRT showed no differences of irradiated BM dose using BMS, TOMO with BMS reduced half V20Gy of BM compared to TOMO without BMS. Conclusions TOMO showed dosimetric superiority in target coverage, sparing BM, and other normal organs compared to 3DCRT and IMRT. Clinical experiences will be needed for evaluation of feasibility of WART using TOMO in patients with gynecologic cancer.

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