2091 MRI-assisted versus conventional treatment planning in brachytherapy of cervical and endometrial carcinoma: The impact of individual anatomy on dose distribution in target volume and organs at risk

1996 ◽  
Vol 36 (1) ◽  
pp. 322 ◽  
Author(s):  
Joern Wulf ◽  
Otto A. Sauer ◽  
Michael Herbolsheimer ◽  
Ulrich Oppitz ◽  
Michael Flentje
Keyword(s):  
At Risk ◽  
Endometrial Carcinoma ◽  
Treatment Planning ◽  
Dose Distribution ◽  
Conventional Treatment ◽  
Organs At Risk ◽  
Target Volume ◽  
The Impact

Evaluation of plan optimisers in prostate VMAT using the dose distribution index

2019 ◽  
Vol 18 (4) ◽  
pp. 323-328 ◽  
Author(s):  
James C. L. Chow ◽  
Runqing Jiang ◽  
Lu Xu
Keyword(s):  
At Risk ◽  
Dose Distribution ◽  
Organs At Risk ◽  
Volumetric Modulated Arc Therapy ◽  
Target Volume ◽  
Weighting Factor ◽  
Target Coverage ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Distribution Index

AbstractPurpose:Dose distribution index (DDI) is a treatment planning evaluation parameter, reflecting dosimetric information of target coverage that can help to spare organs at risk (OARs) and remaining volume at risk (RVR). The index has been used to evaluate and compare prostate volumetric modulated arc therapy (VMAT) plans using two different plan optimisers, namely photon optimisation (PO) and its predecessor, progressive resolution optimisation (PRO).Materials and methods:Twenty prostate VMAT treatment plans were created using the PO and PRO in this retrospective study. The 6 MV photon beams and a dose prescription of 78 Gy/39 fractions were used in plans with the same dose–volume criteria for plan optimisation. Dose–volume histograms (DVHs) of the planning target volume (PTV), as well as of OARs such as the rectum, bladder, left and right femur were determined in each plan. DDIs were calculated and compared for plans created by the PO and PRO based on DVHs of the PTV and all OARs.Results:The mean DDI values were 0·784 and 0·810 for prostate VMAT plans created by the PO and PRO, respectively. It was found that the DDI of the PRO plan was about 3·3% larger than the PO plan, which means that the dose distribution of the target coverage and sparing of OARs in the PRO plan was slightly better. Changing the weighting factors in different OARs would vary the DDI value by ∼7%. However, for plan comparison based on the same set of dose–volume criteria, the effect of weighting factor can be neglected because they were the same in the PO and PRO.Conclusions:Based on the very similar DDI values calculated from the PO and PRO plans, with the DDI value in the PRO plan slightly larger than that of the PO, it may be concluded that the PRO can create a prostate VMAT plan with slightly better dose distribution regarding the target coverage and sparing of OARs. Moreover, we found that the DDI is a simple and comprehensive dose–volume parameter for plan evaluation considering the target, OARs and RVR.

scholarly journals Assessing the impact of magnetic resonance treatment simulation (MRSIM) on target volume delineation and dose to organs at risk for oropharyngeal radiotherapy

2021 ◽  
Author(s):  
Haylea Richardson ◽  
Mahesh Kumar ◽  
Minh Thi Tieu ◽  
Joel Parker ◽  
Jason A. Dowling ◽  
...  
Keyword(s):  
At Risk ◽  
Magnetic Resonance ◽  
Organs At Risk ◽  
Target Volume ◽  
Target Volume Delineation ◽  
Volume Delineation ◽  
The Impact

Comparative dosimetry of brachytherapy treatment planning between a volume-based plan by CT and a point-based plan by TAUS in CT datasets for brachytherapy

2021 ◽  
pp. 1-8
Author(s):  
Chaiyaporn Pintakham ◽  
Ekkasit Tharavichitkul ◽  
Somsak Wanwilairat ◽  
Wannapha Nobnop
Keyword(s):  
At Risk ◽  
Treatment Planning ◽  
Sigmoid Colon ◽  
Clinical Target Volume ◽  
Organs At Risk ◽  
Target Volume ◽  
Reference Points ◽  
Uterine Perforation ◽  
Target Dose ◽  
The Mean

Abstract Aim: To evaluate comparative dosimetry of brachytherapy treatment planning between a volume-based plan by computed tomography (CT) and a point-based plan by transabdominal ultrasound (TAUS) in CT datasets for brachytherapy. Materials and methods: From 2019 to 2021, 59 different datasets of CT images were collected from 38 patients treated by intracavitary brachytherapy with tandem ovoid or tandem ring applicators. At that time, TAUS was performed to prevent uterine perforation and to evaluate topography of the cervix during application. In volume-based planning by CT, the target dose was used to keep the dose at 90% of high-risk clinical target volume (HR-CTV), to give a dose of at least 7Gy, while in the point-based plan by TAUS, the target dose was used to keep the minimum dose to eight cervix reference points (measured by TAUS), to give a dose of at least 7Gy. The doses to targets and organs at risk were evaluated and compared between volume-based planning by CT and the point-based plan by TAUS. Results: Of 59 fractions, a tandem ovoid applicator was used in 48 fractions (81·3%). In the volume-based plan by CT, the mean doses to HR-CTV(D90), intermediate-risk clinical target volume (IR-CTV)(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 7·0, 3·9, 4·9, 2·9 and 3·3 Gy, respectively, while in the point-based plan by TAUS, the mean doses to HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 8·2, 4·6, 5·9, 3·4 and 3·9 Gy, respectively. The percentages of mean dose differences between TAUS and CT of HR-CTV(D90), IR-CTV(D90), bladder(D2cc), rectum(D2cc) and sigmoid colon(D2cc) were 17·7, 19·5, 20·5, 19·5, 21·3 and 19·8%, respectively. With the target dose to the point-based plan by TAUS (7 Gy to the cervix reference points), this was close to D98 of HR-CTV with a mean percentage of difference of 0·6%. Findings: The point-based plan by TAUS showed higher values to targets and organs at risk than the volume-based plan by CT. With the point-based plan by TAUS, it was close to D98 of HR-CTV.

scholarly journals Comparative study between Acuros XB algorithm and Anisotropic Analytical Algorithm in the case of heterogeneity for the treatment of lung cancer

2018 ◽  
Vol 24 (3) ◽  
pp. 115-119
Author(s):  
Mohammed El Adnani Krabch ◽  
Abdelouahed Chetaine ◽  
Abdelati Nourreddine ◽  
Fatim Zohra Er-Radi ◽  
Laila Baddouh
Keyword(s):  
Lung Cancer ◽  
At Risk ◽  
Heterogeneous Media ◽  
Maximum Dose ◽  
Organs At Risk ◽  
Target Volume ◽  
Conformity Index ◽  
Acuros Xb ◽  
Significant Difference ◽  
The Impact

Abstract The aim of this study was to investigate the impact of heterogeneity on the dose calculation for two algorithms implemented in the TPS “Analytical Anisotropic Algorithm (AAA) and Acuros XB” and validated the use of Acuros XB algorithm in clinical routine. First, we compare the dose calculated by these algorithms and the dose measured at the given point P, which is found after heterogeneity insert. Second, we extend our work on clinical cases that present a complex heterogeneity. By evaluating the impact of the choice of the algorithm on the dose coverage of the tumor, and the dose received by the organs at risk for 20 patients affected by lung cancer. The result of our phantom study showed a good agreement with several studies that showed the superiority of the Acuros XB over the AAA in predicting dose when it concerns heterogeneous media. The treatment plans for 20 lung cancers were calculated by two algorithms AAA and Acuros XB, the results show a statistical significant difference between algorithms for Homogeneity Index and the maximum dose of planning target volume (HI: 0.11±0.01 vs 0.05±0.01 p = 0.04; Dmax: 69.30±3.12 vs 68.51±2.64 p = 0.02). Instead, no statistically significant difference was observed for conformity index CI and mean dose (CI: 0.98±0.18 vs 0.99±0.14 p = 0.33; Dmean: 66.3±0.65 vs 66.10 ±0.61 p = 0.54). For organs at risk, the maximum dose for spinal cord, mean dose and D37 % of lung minus GTV (dose receiving 37% of lung volume) were found to be lower for AAA plans than Acuros XB and the differences were statistically significant (p<0.05). For the heart D33% and D67% were found to be higher for AAA plans than Acuros XB and the differences were statistically significant (p<0.05), but No difference was observed for D100% of the heart. The use of the AXB algorithm is suitable in the case of presence of heterogeneity, because it allows to have a better accuracy close to the Monte Carlo calculation.

scholarly journals Impact of 68Ga-DOTATOC PET/MRI on robotic radiosurgery treatment planning in meningioma patients: first experiences in a single institution

2019 ◽  
Vol 46 (6) ◽  
pp. E9 ◽  
Author(s):  
Güliz Acker ◽  
Anne Kluge ◽  
Mathias Lukas ◽  
Alfredo Conti ◽  
Diana Pasemann ◽  
...  
Keyword(s):  
Treatment Planning ◽  
Organs At Risk ◽  
Target Volume ◽  
Data Sets ◽  
Robotic Radiosurgery ◽  
Volume Delineation ◽  
Complex Shapes ◽  
Target Volumes ◽  
Skull Base Lesions ◽  
The Impact

OBJECTIVEFor stereotactic radiosurgery (SRS) planning, precise contouring of tumor boundaries and organs at risk is of utmost importance. Correct interpretation of standard neuroimaging (i.e., CT and MRI) can be challenging after previous surgeries or in cases of skull base lesions with complex shapes. The aim of this study was to evaluate the impact of 68Ga-DOTATOC PET/MRI on treatment planning for image-guided SRS by CyberKnife.METHODSThe authors retrospectively identified 11 meningioma treatments in 10 patients who received a 68Ga-DOTATOC PET/MRI prior to SRS. The planning target volume (PTV) used for the patients’ treatment was defined as the reference standard. This was contoured by a treating radiosurgeon (RS0) using fused planning CT and PET/MRI data sets. The same tumors were then contoured by another experienced radiosurgeon (RS1) and by a less-experienced radiosurgeon (RS2), both blinded to PET data sets. A comparison of target volumes with focus on volume-based metrics and distance to critical structures was performed. RS1 and RS2 also filled in a questionnaire analyzing the confidence level and the subjective need for the implementation of PET data sets for contouring.RESULTSAnalysis showed a subjective personal preference for PET/MRI in all cases for both radiosurgeons, particularly in proximity to critical structures. The analysis of the planning volumes per physician showed significantly smaller RS2-PTV in comparison to RS1-PTV and to RS0-PTV, whereas the median volumes were comparable between RS1-PTV and RS2-PTV (median: RS0: 4.3 cm3 [IQR 3.4–6.5 cm3] and RS1: 4.5 cm3 [IQR 2.7–6 cm3] vs RS2: 2.6 cm3 [IQR 2–5 cm3]; p = 0.003). This was also reflected in the best spatial congruency between the 2 experienced physicians (RS0 and RS1). The percentage of the left-out volume contoured by RS1 and RS2 compared to RS0 with PET/MRI demonstrated a relevant left-out-volume portion in both cases with greater extent for the less-experienced radiosurgeon (RS2) (RS1: 19.1% [IQR 8.5%–22%] vs RS2: 40.2% [IQR 34.2%–53%]). No significant differences were detected regarding investigated critical structures.CONCLUSIONSThis study demonstrated a relevant impact of PET/MRI on target volume delineation of meningiomas. The extent was highly dependent on the experience of the treating physician. This preliminary study supports the relevance of 68Ga-DOTATOC PET/MRI as a tool for radiosurgical treatment planning of meningiomas.

scholarly journals Helical Tomotherapy® is a Safe and Feasible Technique for Total Scalp Irradiation

Rare Tumors ◽  
2016 ◽  
Vol 9 (1) ◽  
pp. 7-8 ◽  
Author(s):  
Francesco Cuccia ◽  
Vanessa Figlia ◽  
Antonella Palmeri ◽  
Francesco Verderame ◽  
Antonio Lo Casto ◽  
...  
Keyword(s):  
At Risk ◽  
Elderly Patients ◽  
Dose Distribution ◽  
Helical Tomotherapy ◽  
Organs At Risk ◽  
Intensity Modulated Radiotherapy ◽  
Target Volume ◽  
Extensive Disease ◽  
Intensity Modulated ◽  
Aggressive Tumor

Angiosarcoma of the scalp is a rare aggressive tumor that affects elderly patients. Chemoradiation is the treatment of choice for multicentric and extensive disease. The shape of the scalp represents a dosimetric challenge in terms of achieving a homogeneous concave dose distribution with coverage of the entire target volume and an acceptable organs-at-risk sparing. We report a case of an 81-year-old man with a multifocal angiosarcoma of the scalp treated with Helical TomoTherapy® (Accuray Inc., Sunnyvale, CA, USA) intensity modulated radiotherapy. This technique allows precise and daily verifiable coverage of the target keeping the dose to the organs at risk within the constraints.

26 CT-based treatment planning in gynecological IDR-brachytherapy — questions on PTV and tolerance dose in organs at risk

1998 ◽  
Vol 47 ◽  
pp. S7 ◽  
Author(s):  
E. Weiss ◽  
O. Pradier ◽  
D. Laurent ◽  
C.F. Hess
Keyword(s):  
At Risk ◽  
Treatment Planning ◽  
Organs At Risk ◽  
Tolerance Dose
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