Recommendations from gynaecological (GYN) GEC ESTRO working group (II): Concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy—3D dose volume parameters and aspects of 3D image-based anatomy, radiation physics, radiobiology

doi:10.1016/j.radonc.2005.11.014

Radiotherapy and Oncology

Volume 78, Issue 1, January 2006, Pages 67-77

https://doi.org/10.1016/j.radonc.2005.11.014 Get rights and content

Abstract

The second part of the GYN GEC ESTRO working group recommendations is focused on 3D dose-volume parameters for brachytherapy of cervical carcinoma. Methods and parameters have been developed and validated from dosimetric, imaging and clinical experience from different institutions (University of Vienna, IGR Paris, University of Leuven).

Cumulative dose volume histograms (DVH) are recommended for evaluation of the complex dose heterogeneity. DVH parameters for GTV, HR CTV and IR CTV are the minimum dose delivered to 90 and 100% of the respective volume: D90, D100. The volume, which is enclosed by 150 or 200% of the prescribed dose (V150, V200), is recommended for overall assessment of high dose volumes. V100 is recommended for quality assessment only within a given treatment schedule. For Organs at Risk (OAR) the minimum dose in the most irradiated tissue volume is recommended for reporting: 0.1, 1, and 2 cm³; optional 5 and 10 cm³. Underlying assumptions are: full dose of external beam therapy in the volume of interest, identical location during fractionated brachytherapy, contiguous volumes and contouring of organ walls for >2 cm³. Dose values are reported as absorbed dose and also taking into account different dose rates. The linear-quadratic radiobiological model—equivalent dose (EQD₂)—is applied for brachytherapy and is also used for calculating dose from external beam therapy. This formalism allows systematic assessment within one patient, one centre and comparison between different centres with analysis of dose volume relations for GTV, CTV, and OAR.

Recommendations for the transition period from traditional to 3D image-based cervix cancer brachytherapy are formulated.

Supplementary data (available in the electronic version of this paper) deals with aspects of 3D imaging, radiation physics, radiation biology, dose at reference points and dimensions and volumes for the GTV and CTV (adding to [Haie-Meder C, Pötter R, Van Limbergen E et al. Recommendations from Gynaecological (GYN) GEC ESTRO Working Group (I): concepts and terms in 3D image-based 3D treatment planning in cervix cancer brachytherapy with emphasis on MRI assessment of GTV and CTV. Radiother Oncol 2005;74:235–245]).

It is expected that the therapeutic ratio including target coverage and sparing of organs at risk can be significantly improved, if radiation dose is prescribed to a 3D image-based CTV taking into account dose volume constraints for OAR. However, prospective use of these recommendations in the clinical context is warranted, to further explore and develop the potential of 3D image-based cervix cancer brachytherapy.

Section snippets

Dose volume parameters for GTV and HR/IR CTVs

Dose volume parameters are introduced and then demonstrated following the example of one patient with advanced disease: The series of figures includes diagnostic imaging and localisation imaging with applicator in place (Fig. 1a–h), a schematic diagram with GTV, HR/IR CTV and dose volume parameters (Fig. 2), a 3D MRI-based treatment plan with display of GTV, HR/IR CTV contours and dose volume parameters (Fig. 3), and DVHs for GTV and HR/IR CTV (Fig. 4).

Dose volume parameters for organs at risk

In cervical cancer, the location of organs at risk close to the brachytherapy sources (rectum, sigmoid, bladder) significantly influences the treatment planning process and the dose that can be prescribed. The vagina should be taken into consideration. Other parts of bowel may also receive a significant dose.

Dose volume parameters for OAR are introduced and demonstrated following the same example for one patient as above (Fig. 1, Fig. 3, Fig. 4). In addition, a schematic diagram indicates the

Recommendations for reporting

Parameters to be reported for image-based brachytherapy of cervical carcinoma are listed in Table 1. Dose values of single fractions should be reported in absorbed dose (optional in addition in biologically weighted form). For the whole treatment, total dose values should be reported as physical dose, indicating the fractionation and dose rate, and in addition as biologically weighted dose (EQD2).

As only few studies have evaluated 3D dose volume parameters in correlation with outcome, the

Acknowledgements

The GYN GEC ESTRO working group has been supported by an unrestricted grant from VARIAN to ESTRO. The working group would like to thank Daniel Berger, MSc, from the Department of Radiotherapy and Radiobiology, Medical University of Vienna, who assisted in preparing images and drawings for this manuscript.

References (54)

S.M. Bentzen et al.
Clinical evidence for tumor clonogen regeneration: interpretations of the data
Radiother Oncol
(1991)
E. Briot et al.
Dose–volume histogram analysis for tumor and critical organs in intracavitary brachytherapy of cervical cancer with the use of MRI
Radiother Oncol
(2001)
M. Cengiz et al.
Comment on Correlation between the treated volume, the GTV and the CTV at the time of brachytherapy and histopathologic findings in 33 patients with operable cervix carcinoma
Radiother Oncol
(2005)
R.G. Dale et al.
Calculation of integrated biological response in brachytherapy
Int J Radiat Oncol Biol Phys
(1997)
R.G. Dale et al.
Allowance for the radiobiological effects of dose gradients in gynaecological applications
Radiother Oncol
(2001)
C. Fellner et al.
Comparison of radiography- and computed tomography-based treatment planning in cervix cancer in brachytherapy with specific attention to some quality assurance aspects
Radiother Oncol
(2001)
J.F. Fowler et al.
Biological effect of pulsed dose rate brachytherapy with stepping sources if short half-times of repair are present in tissues
Int J Radiat Oncol Biol Phys
(1997)
N. Gerstner et al.
The benefit of Beam's eye view based 3D treatment planning for cervical cancer
Radiother Oncol
(1999)
S. Gillis et al.
An inter-centre quality assurance network for IMRT verification: results of the ESTRO QUASIMODO project
Radiother Oncol
(2005)
C. Haie-Meder et al.
Recommendations from Gynaecological (GYN) GEC ESTRO Working Group (I): concepts and terms in 3D image-based 3D treatment planning in cervix cancer brachytherapy with emphasis on MRI assessment of GTV and CTV
Radiother Oncol
(2005)

R.G. Dale

The application of the linear–quadratic dose–effect equation to fractionated and protracted radiotherapy

Br J Radiol

(1985)

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A systematic search was performed and articles evaluating the relationship between predictors and toxicities in women with LACC treated with primary chemoradiation were included. The Quality In Prognosis Studies tool was used to assess risk of bias, with high-risk studies being excluded from further analysis. Relationships between dose-volume parameters, patient and treatment characteristics, and toxicity endpoints were analyzed.
Seventy-three studies were identified. Twenty-six had a low or moderate risk of bias and were therefore included. Brachytherapy-related dose-volume parameters of the GI tract, including rectum and bowel equivalent dose in 2 Gy fractions (EQD2) D2 cm³, were frequently related to toxicities, unlike GU dose-volume parameters. Furthermore, (recto)vaginal point doses predicted toxicities. Few studies evaluated external beam radiation therapy dose-volume parameters and identified rectum EQD2 V30 Gy, V40 Gy, and V55 Gy, bowel and bladder EQD2 V40 Gy as toxicity predictors. Also, total reference air kerma and vaginal reference length were associated with toxicities. Relationships between patient characteristics and GI toxicity were inconsistent. The extent of vaginal involvement at diagnosis, baseline symptoms, and obesity predicted GU or vaginal toxicities. Only 1 study evaluated insufficiency fractures and demonstrated lower pretreatment bone densities to be associated.
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¹⁰⁶Ru eye plaque brachytherapy (BT, interventional radiotherapy) is an eye-preserving treatment for uveal melanoma performed in about 100 clinics worldwide. Despite this relatively low number, there is a considerable variation in clinical practice. In 2022, the BRAPHYQS and Head & Neck and Skin GEC-ESTRO working groups conducted a survey to map the current clinical practice. The survey consisted of a physicist and a physician part. This paper describes the physicist results. However, three physician questions with overlapping interest are included here as well.
The survey questions pertained to commissioning and quality control (QC) of the plaques, treatment planning, radiobiological correction, as well as more general questions on practice improvement. The questions overlapping with the physician survey were related to dose prescription and margins.
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End-to-end dosimetry audit for brachytherapy is challenging due to the steep dose gradient. However, it is an efficient method to detect unintended errors in actual clinical practice.
We aimed to develop an on-site end-to-end test phantom for three-dimensional image-guided brachytherapy (IGBT) for cervical cancer.
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The measured and calculated doses at point A were compared for each applicator. We observed that the values obtained using metal applicators were consistently lower, on an average by −2.3%, than the calculated values, while those obtained using carbon applicators were comparable to the calculated values. This difference can be attributed to the attenuation of the dose by the metal applicators, resulting in a lower dose at point A. The majority of treatment planning system, including the one used in this study, do not account for the material of applicator.
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Prospectively measure change in vaginal length after definitive chemoradiation (C-EBRT) with Intracavitary Brachytherapy (ICBT) for locally advanced cervix cancer (LACC) and correlate with vaginal dose (VD).
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The mean initial VL was 8.7 cm (6.5–12) with median value of 8.5 cm. The mean VL after 6 months was 8.6 cm (6.5–12) and VL change was not found to be statistically significant. The median values (interquartile ranges) for vaginal D0.1cc, D1cc, and D2cc were 129.2 Gy (99.6–252.2), 96.9 Gy (84.2–114.9), and 89.6 Gy (82.4–102.2), respectively. No significant correlation was found between vaginal length change and the dosimetric parameters calculated for all patients.
Definitive C-EBRT and ICBT did not significantly impact VL in this prospective cohort probably related to acceptable doses per ICRU constraints. Estimate of vaginal stenosis and sexual function was not performed in this cohort which is a limitation of this study and which we hope to study prospectively going forward.
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ESTRO projectRecommendations from gynaecological (GYN) GEC ESTRO working group (II): Concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy—3D dose volume parameters and aspects of 3D image-based anatomy, radiation physics, radiobiology

Abstract

Section snippets

Dose volume parameters for GTV and HR/IR CTVs

Dose volume parameters for organs at risk

Recommendations for reporting

Acknowledgements

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Radiother Oncol

Int J Radiat Oncol Biol Phys

Radiother Oncol

Radiother Oncol

Int J Radiat Oncol Biol Phys

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Radiother Oncol

Int J Radiat Oncol Biol Phys

Radiother Oncol

Int J Radiat Oncol Biol Phys

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Radiother Oncol

Int J Radiat Oncol Biol Phys

Radiother Oncol

Radiother Oncol

Radiother Oncol

Radiother Oncol

Radiother Oncol

Radiother Oncol

The application of the linear–quadratic dose–effect equation to fractionated and protracted radiotherapy

Br J Radiol

ESTRO project
Recommendations from gynaecological (GYN) GEC ESTRO working group (II): Concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy—3D dose volume parameters and aspects of 3D image-based anatomy, radiation physics, radiobiology