Conformal radiotherapy planning of cervix carcinoma: differences in the delineation of the clinical target volume

this paper aims to evaluate the range of techniques available to minimise both interfraction and intrafraction errors. the main interfraction errors are due to changes in volume of the rectum and bladder. intrafraction errors are mainly due to respiration and to a lesser extent cardiac motion. there are various methods of minimising internal organ motion that attempt to permit reduction of the internal margin around the clinical target volume (ctv).techniques such as rectal balloon insertion and breathing control are evaluated to determine their role in reduction of margins for improved conformal radiotherapy. the paper concludes that rectal balloons have been shown to permit limited reduction of internal margins and morbidity levels. breathing control has not increased reproducibility, but has allowed for reduction in lung morbidity. reduction of margins can only be recommended when using breathing control in conjunction with daily ctv relocalisation.although these techniques do have a role to play at the moment, it appears that attempting to maintain a static environment within the highly mobile patient is fraught with difficulties and we must accept that there is always going to be motion. rather than attempting to control the position of the tumour, future developments such as adaptive radiotherapy and tomotherapy may account for the movement.

Download Full-text

Probability of mediastinal involvement in non–small-cell lung cancer: a statistical definition of the clinical target volume for 3-dimensional conformal radiotherapy?

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2005.06.043 ◽

2006 ◽

Vol 64 (1) ◽

pp. 127-135 ◽

Cited By ~ 22

Author(s):

Philippe Giraud ◽

Yann De Rycke ◽

Armelle Lavole ◽

Bernard Milleron ◽

Jean-Marc Cosset ◽

...

Keyword(s):

Lung Cancer ◽

Clinical Target Volume ◽

Conformal Radiotherapy ◽

Target Volume ◽

Small Cell ◽

Small Cell Lung ◽

3 Dimensional ◽

Mediastinal Involvement ◽

Definition Of ◽

Statistical Definition

Download Full-text

Pattern of Recurrence of Glioblastoma Versus Grade 4 IDH-Mutant Astrocytoma Following Chemoradiation

10.21203/rs.3.rs-1079782/v1 ◽

2021 ◽

Author(s):

James Stewart ◽

Arjun Sahgal ◽

Aimee K.M. Chan ◽

Hany Soliman ◽

Chia-Lin Tseng ◽

...

Keyword(s):

Gross Tumor Volume ◽

Clinical Target Volume ◽

Tumor Volume ◽

Extent Of Resection ◽

Target Volume ◽

Radiotherapy Planning ◽

Recurrence Pattern ◽

Wild Type ◽

Failure Patterns ◽

Pattern Of Recurrence

Abstract Purpose To quantitatively compare the recurrence pattern of glioblastoma (IDH-wild type) versus grade 4 IDH-mutant astrocytoma (herein referred to as wtIDH and mutIDH, respectively) following primary chemoradiation. Methods Twenty-two wtIDH and 22 mutIDH patients matched by sex, extent of resection, and corpus callosum involvement were enrolled. The recurrent gross tumor volume (rGTV) was compared with both the gross tumor volume (GTV) and clinical target volume (CTV) from radiotherapy planning. Failure patterns were quantified by the incidence and volume of the rGTV outside the GTV and CTV, and positional differences of the rGTV centroid from the GTV and CTV. Results The GTV was smaller in wtIDH compared to the mutIDH group (mean±SD: 46.5±26.0 cm3 v. 72.2±45.4 cm3, p=0.026). The rGTV was 10.7±26.9 cm3 and 46.9±55.0 cm3 smaller than the GTV for the same groups (p=0.018). The rGTV extended outside the GTV in 22 (100%) and 15 (68%) (p=0.009) of wtIDH and mutIDH patients, respectively; however, the volume of rGTV outside the GTV was not significantly different (12.4±16.1 cm3 vs. 8.4±14.2 cm3, p=0.443). The rGTV metrics extending outside the CTV was not different between the groups. The rGTV centroid was within 5.7 mm of the closest GTV edge for 21 (95%) and 22 (100%) of wtIDH and mutIDH patients, respectively. Conclusion The rGTV extended beyond the GTV less often in mutIDH patients, suggesting limited margin radiotherapy could be beneficial in this group. The results support the study of small margin adaptive radiotherapy per the ongoing UNITED MR-Linac 5 mm CTV trial (NCT04726397).

Download Full-text

Geometric contour variation in clinical target volume of axillary lymph nodes in breast cancer radiotherapy: an AIRO multi-institutional study

British Journal of Radiology ◽

10.1259/bjr.20201177 ◽

2021 ◽

pp. 20201177

Author(s):

Maria Cristina Leonardi ◽

Matteo Pepa ◽

Simone Giovanni Gugliandolo ◽

Rosa Luraschi ◽

Sabrina Vigorito ◽

...

Keyword(s):

Breast Cancer ◽

Lymph Nodes ◽

Clinical Target Volume ◽

Target Volume ◽

Radiotherapy Planning ◽

Axillary Lymph Nodes ◽

Dice Similarity Coefficient ◽

Axillary Lymph ◽

Computed Tomography Images ◽

Breast Cancer Radiotherapy

Objectives: To determine interobserver variability in axillary nodal contouring in breast cancer (BC) radiotherapy (RT) by comparing the clinical target volume of participating single centres (SC-CTV) with a gold-standard CTV (GS-CTV). Methods: The GS-CTV of 3 patients (P1, P2, P3) with increasing complexity was created in DICOM format from the median contour of axillary CTVs drawn by BC experts, validated using the simultaneous truth and performance level estimation and peer-reviewed. GS-CTVs were compared with the correspondent SC-CTVs drawn by radiation oncologists, using validated metrics and a total score (TS) integrating all of them. Results: Eighteen RT centres participated in the study. Comparative analyses revealed that, on average, the SC-CTVs were smaller than GS-CTV for P1 and P2 (by −29.25% and −27.83%, respectively) and larger for P3 (by +12.53%). The mean Jaccard index was greater for P1 and P2 compared to P3, but the overlap extent value was around 0.50 or less. Regarding nodal levels, L4 showed the highest concordance with the GS. In the intra patient comparison, L2 and L3 achieved lower TS than L4. Nodal levels showed discrepancy with GS which was not statistically significant for P1, and negligible for P2, while P3 had the worst agreement. DICE Similarity Coefficient did not exceed the minimum threshold for agreement of 0.70 in all the measurements. Conclusions: Substantial differences were observed between SC- and GS-CTV, especially for P3 with altered arm set-up. L2 and L3 were the most critical levels. The study highlighted these key points to address. Advances in knowledge The present study compares, by means of validated geometric indexes, manual segmentationsof axillary lymph nodes in breast cancer from different observers and different institutionsmade on radiotherapy planning computed tomography images. Assessing such variability is ofparamount importance, as geometric uncertainties might lead to incorrect dosimetry andcompromise oncological outcome.

Download Full-text