scholarly journals Dosimetry of conformal dynamic arc radiotherapy and intensity modulated radiotherapy in unresectable cholangiocarcinoma

2010 ◽  
Vol 4 (1) ◽  
pp. 131-139
Author(s):  
Thanarpan Peerawong ◽  
Chonlakiet Khorprasert ◽  
Sivalee Suriyapee ◽  
Taweap Sanghangthum ◽  
Isra Israngkul Na Ayuthaya ◽  
...  
Keyword(s):  
Planning Target Volume ◽  
Left Kidney ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Intensity Modulated ◽  
Dose Volume ◽  
Organ At Risk ◽  
The Right ◽  
Upper Abdomen ◽  
Critical Structure

Abstract Background: Radiotherapy in cholangiocrcinoma has to overcome organ tolerance of the upper abdomen. Hi-technology radiotherapy may improve conformity and reduce dose to those organ. Objective: Quantitatively compare the dosimetry of conformal dynamic arc radiotherapy (CD-arcRT) and intensity modulated radiotherapy (IMRT) in unresectable cholangiocarcinoma. Material and methods: Eleven cases of unresectable cholangiocarcinoma were re-planned with IMRT and CDarcRT at King Chulalongkhorn Memorial Hospital between 20 September 2004 and 31 December 2005. Both the planning techniques were evaluated using the dose volume histogram of the planning target volume and organ at risk. The conformation number and dose to critical normal structures were used to determine the techniques. Results: IMRT technique was significantly conformed to the planning target volume than CD-arcRT in term of conformation number. For critical structure, IMRT significantly reduced the radiation dose to liver in terms of mean liver dose, V30Gy and V20Gy of the right kidney. Conclusion: The advantage of IMRT was more conformity and reduced dose to critical structure compared with CD-arcRT, but there was no difference between these techniques in terms of V20Gy of left kidney and maximum dose to the spinal cord.

Dosimetric comparison between the prostate intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans using the planning target volume (PTV) dose–volume factor

2016 ◽  
Vol 15 (3) ◽  
pp. 263-268 ◽  
Author(s):  
James C. L. Chow ◽  
Runqing Jiang ◽  
Alexander Kiciak ◽  
Daniel Markel
Keyword(s):  
Planning Target Volume ◽  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Conformity Index ◽  
Volume Factor ◽  
Dose Volume Histograms ◽  
Intensity Modulated ◽  
Dose Volume ◽  
Arc Therapy

AbstractBackgroundWe demonstrated that our proposed planning target volume (PTV) dose–volume factor (PDVF) can be used to evaluate the PTV dose coverage between the intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans based on 90 prostate patients.PurposePDVF were determined from the prostate IMRT and VMAT plans to compare their variation of PTV dose coverage. Comparisons of the PDVF with other plan evaluation parameters such as D5%, D95%, D99%, Dmean, conformity index (CI), homogeneity index (HI), gradient index (GI) and prostate tumour control probability (TCP) were carried out.Methods and materialsProstate IMRT and VMAT plans using the 6 MV photon beams were created from 40 and 50 patients, respectively. Dosimetric indices (CI, HI and GI), dose–volume points (D5%, D95%, D99% and Dmean) and prostate TCP were calculated according to the PTV dose–volume histograms (DVHs) of the plans. All PTV DVH curves were fitted using the Gaussian error function (GEF) model. The PDVF were calculated based on the GEF parameters.ResultsFrom the PTV DVHs of the prostate IMRT and VMAT plans, the average D99% of the PTV for IMRT and VMAT were 74·1 and 74·5 Gy, respectively. The average prostate TCP were 0·956 and 0·958 for the IMRT and VMAT plans, respectively. The average PDVF of the IMRT and VMAT plans were 0·970 and 0·983, respectively. Although both the IMRT and VMAT plans showed very similar prostate TCP, the dosimetric and radiobiological results of the VMAT technique were slightly better than IMRT.ConclusionThe calculated PDVF for the prostate IMRT and VMAT plans agreed well with other dosimetric and radiobiological parameters in this study. PDVF was verified as an alternative of evaluation parameter in the quality assurance of prostate treatment planning.

scholarly journals 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

2006 ◽  
Vol 13 (3) ◽  
pp. 108-115 ◽  
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.

scholarly journals Short-term efficacy comparison between helical tomotherapy and intensity-modulated radiotherapy in patients with locally advanced nasopharyngeal carcinoma

2020 ◽  
Author(s):  
Zhen Cui ◽  
Jia Liu ◽  
Qiaoyu Sun ◽  
Chaoge Wang ◽  
Meifang Fang ◽  
...  
Keyword(s):  
Nasopharyngeal Carcinoma ◽  
Planning Target Volume ◽  
Helical Tomotherapy ◽  
Locally Advanced ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Short Term ◽  
Intensity Modulated ◽  
Significant Difference ◽  
Better Than

Abstract Background: To evaluate short-term safety and efficacy of helical tomotherapy (HT) versus intensity-modulated radiotherapy (IMRT) in patients with nasopharyngeal carcinoma (NPC).Methods: Retrospective analysis of locally advanced nasopharyngeal carcinoma treated with radiotherapy and concurrent platinum based neoadjuvant chemotherapy (cisplatin 80 mg/m2 every 3 weeks for 1 cycle) in our hospital from February 2017 to October 2019, including 70 patients in HT group and 70 in IMRT group. The target area of ​​the tumor was delineated by magnetic resonance (MRI) imaging. The prescription doses delivered to the gross tumor volume (pGTVnx) and positive lymph nodes (pGTVnd), the high risk planning target volume (PTV1), and the low risk planning target volume (PTV2), were 69.96 Gy, 66-70 Gy, 60 Gy and 50-54 Gy, in 33 fractions, respectively. Acute reactions were evaluated according to the RTOG/EORTC criteria, whereas the therapeutic efficacy was assessed according to RECTST version 1.1 criteria in a 3-months period.Results: The CI of PGTVnx, PGTVnd, PTV1 and PTV2, and HI of PGTVnx, PTV1 and PTV2 in HT group was significantly better than those in IMRT group. The OAR Dmax and Dmean in HT group were better than those in IMRT group with a significant difference (all p <0.05). Patients in the HT group were significantly better than those in the IMRT group in the protection of acute parotid gland injury and hearing damage (p <0.05), but not other acute adverse reaction. No significant difference was found on the short-term efficacy illustrated by ORR between HT group and IMRT group (x2 = 0.119; p = 0.730).Conclusions: Compared with IMRT, HT has better radiophysical-related dosimetric advantages in radiotherapy for locally advanced nasopharyngeal carcinoma. Despite similar on short-term effects, HT has lower incidence of adverse reactions than IMRT.

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