A simple algorithm to predict non‐compliance with organ at risk dose‐volume constraints when planning intensity modulated post‐prostatectomy radiation treatment: ‘Why we should put the CART before the horse’

2019 ◽  
Vol 63 (4) ◽  
pp. 546-551
Author(s):  
Natalie Collier ◽  
Andrew Kneebone ◽  
George Hruby ◽  
Philip McCloud ◽  
Jeremy Booth ◽  
...  
Keyword(s):  
At Risk ◽  
Radiation Treatment ◽  
Simple Algorithm ◽  
Intensity Modulated ◽  
Dose Volume ◽  
Organ At Risk

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 Dosimetric Comparison Between Jaw Tracking and No Jaw Tracking in Intensity-Modulated Radiation Therapy

2019 ◽  
Vol 18 ◽  
pp. 153303381984106 ◽  
Author(s):  
Shengyu Yao ◽  
Yin Zhang ◽  
Tingfeng Chen ◽  
Guoqi Zhao ◽  
Zhekai Hu ◽  
...  
Keyword(s):  
At Risk ◽  
Radiation Therapy ◽  
Nasopharyngeal Carcinoma ◽  
Brain Metastasis ◽  
Intensity Modulated Radiation Therapy ◽  
Large Tumor ◽  
Intensity Modulated ◽  
Passing Rates ◽  
Passing Rate ◽  
Organ At Risk

Purpose: This article compares the dosimetric differences between jaw tracking and no jaw tracking technique in static intensity-modulated radiation therapy plans of large and small tumors. Methods: Eight plans with large tumor (nasopharyngeal carcinoma, volume range: 510.9 to 768.0 cm3) and 8 plans with small tumor (single brain metastasis, volume range: 5.3 to 9.9 cm3) treated with jaw tracking on Varian EDGE LINAC were chosen and recalculated with no jaw tracking to study the dosimetric differences. We compared the differences of organ-at-risk doses (Dmax, Dmean), monitor units, and γ passing rate of plan verification (3mm/3%, threshold 10%; 2mm/2%, threshold 10%) between the 2 techniques. Results: The organ-at-risk doses of nasopharyngeal carcinoma cases having jaw tracking are all less than those with no jaw tracking. The Dmax and Dmean of organ-at-risks reduced 0.61% to 17.65% and 2.17% to 19.32%, P < .05, respectively. In cases with single brain metastasis, the organ-at-risk doses with jaw tracking were also lower than no jaw tracking. The Dmax and Dmean of organ-at-risk doses reduced 0.84% to 1.52% and 0.90% to 1.86%, P < .05, respectively. The monitor units for the large tumor and small tumor were increased by 2.41% and 1.1%, respectively. The γ passing rates (3mm/3%, th10%; 2mm/2%, th10%) of nasopharyngeal carcinoma plans are 99.89% ± 0.06% (jaw tracking) versus 99.56% ± 0.19% (no jaw tracking; P = .127); 97.15% ± 0.98% (jaw tracking) versus 91.90% ± 1.40% (no jaw tracking; P = .000), and the γ passing rates (3mm/3%, th10%; 2mm/2%, th10%) of brain metastasis plans are 99.97% ± 0.05% (jaw tracking) versus 99.44% ± 1.24% (no jaw tracking; P = .251), 98.65% ± 1.27% (jaw tracking) versus 93.35% ± 2.72% (no jaw tracking; P = .000). Conclusion: Jaw tracking can reduce the dose of organ-at-risks compared to no jaw tracking, and the effect is more significant for plans with large tumor. The γ passing rate of plans with jaw tracking is also higher than the plans with no jaw tracking. Although the monitor units in plans of jaw tracking will increase slightly, it is recommended to use jaw tracking in static intensity-modulated radiation therapy both in large and in small tumors.

scholarly journals PO-0632: Dose-volume related dysphagia in head and neck cancer Intensity Modulated Radiation Treatment

2015 ◽  
Vol 115 ◽  
pp. S307
Author(s):  
F. Ricchetti ◽  
R. Mazzola ◽  
A. Fiorentino ◽  
S. Fersino ◽  
N. Giaj Levra ◽  
...  
Keyword(s):  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Radiation Treatment ◽  
Intensity Modulated ◽  
Dose Volume

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.

The impact of varying rectal contours on rectal dose in prostate cancer patients treated with hypofractionated radiation

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 15598-15598
Author(s):  
B. B. Joshua ◽  
S. Faria ◽  
H. Patrocinio ◽  
F. DeBlois ◽  
M. Duclos ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
At Risk ◽  
Radiation Treatment ◽  
Rectal Wall ◽  
Organs At Risk ◽  
Anal Verge ◽  
Rectal Toxicity ◽  
Rectal Dose ◽  
Organ At Risk ◽  
Definition Of

15598 Background: In curative radiation treatment of prostate cancer,the advent of 3DCRT has made a reduction in the incidence of normal tissue toxicities while optimizing tumor control. To optimize 3DCRT, the ICRU has published standard definitions of target volumes and organs at risk such that the tumor can receive the optimal dose with as little as possible dose to the organs at risk. However, the definition of the rectum as an organ at risk in radiation treatment of the prostate varies widely among institutions and so does the report of toxicities. We studied the effect of varying rectal contouring on rectal dose obtained from DVHs in a homogenous group of prostate cancer patients treated with hypo fractionationed radiation. Methods: 71 patients with favorable risk prostate cancer treated with a total of 66Gy in 3Gy/day fractionation.18 MV photons in a 5-field technique was used. None of the patients received hormonal therapy. Their treatment plans were archived and the rectum was re-contoured by a single investigator. 4 different contours were drawn to compare the rectal dose: i) the whole rectum from the anal verge to the recto sigmoid junction (WR); ii) the rectum from 1cm below the PTV to 1cm above (RPTV); iii) the rectal wall (i.e. the inner and outer rectal wall) from the anal verge to the recto sigmoid junction (RW); iv) the rectal wall from 1cm below the PTV to 1cm above (RWPTV) Results: There were significant differences in the median volume, minimum, mean rectal doses and dose to 50% of the volume, (p=0.0001). The whole rectum (WR) is having the lowest and the rectal wall with 1cm above and below the PTV (RWPTV) having the highest in all the parameters. The only parameter not significantly different among the 4 contours is the maximum rectal dose. Conclusion: the varied rectal contouring across different institutions is a possible reason for the broadly different reports of rectal toxicity after prostate irradiation. Our results suggest significant differences in rectal doses with varied contouring. Contouring the rectal wall only and limiting the volume to 1cm above and below the PTV confers the highest mean rectal dose. Comparison of rectal toxicity between institutions can only be meaningful if a consensual volume definition of the organ at risk is agreed upon. No significant financial relationships to disclose.

scholarly journals Dose–volume-related dysphagia after constrictor muscles definition in head and neck cancer intensity-modulated radiation treatment

2014 ◽  
Vol 87 (1044) ◽  
pp. 20140543 ◽  
Author(s):  
R Mazzola ◽  
F Ricchetti ◽  
A Fiorentino ◽  
S Fersino ◽  
N Giaj Levra ◽  
...  
Keyword(s):  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Radiation Treatment ◽  
Intensity Modulated ◽  
Dose Volume

scholarly journals The minimum knowledge base for predicting organ-at-risk dose–volume levels and plan-related complications in IMRT planning

2010 ◽  
Vol 55 (7) ◽  
pp. 1935-1947 ◽  
Author(s):  
Hao H Zhang ◽  
Robert R Meyer ◽  
Leyuan Shi ◽  
Warren D D'Souza
Keyword(s):  
At Risk ◽  
Knowledge Base ◽  
Dose Volume ◽  
Imrt Planning ◽  
Organ At Risk
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