Preliminary Reports Comparison of the GTV coverage by PTV and isodose of 90% in 2D and 3D planning during endobronchial brachytherapy in the palliative treatment of patients with advanced lung cancer. Pilot study

Abstract

PurposeEndobronchial brachytherapy (EB) is one way of treatment of patients with advanced lung cancer. Technological progress and the introduction of computed tomography for use in 3D planning allows one to define the area being treated very precisely, which gives an opportunity to extend survival, even in groups of patients receiving palliative care.Material and methodsIn 2011, in the Brachytherapy Department of the Subcarpathian Oncological Center, a group of 12 consecutive patients with advanced cancer of the bronchus underwent palliative EB. We compared the coverage of GTV (gross tumor volume), seen in the computed tomography study with intravenous contrast, by the PTV (planning target volume) planned in 3D and 2D.ResultsIn 2D planning GTV coverage ranged from 15% to 89%. By analyzing the isodose of 90%, it was found that 2D planning covered GTV in 15-35% of the dose. In 3D planning, this coverage changed positively, and ranged from 85% to 100%. The GTV coverage in 3D planning was 100% by definition. In addition, it should be noted that in the 3D planning one can spare critical organs or pacemakers.ConclusionsPlanning for HDR brachytherapy in all locations should be based on dynamic imaging at present, especially in centers that are equipped with CT. Evaluation should be a routine test in treatment planning. The use of CT, even in palliative treatment planning, allows for much better coverage of GTV areas as well, which is very important to reduce radiation doses to critical organs and thereby reduce the toxic effects of treatment.

The evaluation of treatment plans in high-dose-rate endobronchial brachytherapy by utilizing 2D and 3D computed tomography imaging methods

“…Applying treatment with the 3D method, the target area can be defined with high precision. For the 3D method, there is a possibility for dose optimization, decreasing the dose for the critical organs, and as a result, reducing the toxic effects of treatment on healthy tissue [ 6 , 12 , 13 ]. Computed tomography imaging is used in HDR in the treatment of bronchial carcinoma [ 14 ].…”

Treatment Planning in Brachytherapy HDR Based on Three‐Dimensional Image

“…Then, the treatment plan is being optimized. Generally, treatment plan is optimized onto dose reference points usually situated 1 cm from catheter axis [9]. Reference dose should be calculated for the target area.…”

Brachytherapy in the treatment of lung cancer – a valuable solution

“…When a single catheter is used and if there is minimal curvature in the area to be irradiated, it is possible to minimize the treatment planning time by using pre-calculated standard treatment plans for 3-10 cm lengths to be irradiated from 5 to 10 Gy at 1 cm from the source using equal dwell times. However, individualized image-based treatment planning must be performed if multiple catheters are used [ 35 , 36 ]. Examples of implanted catheters in bronchi are presented in Figures 6 and 7 .…”

“… Visualization and delineation of the esophagus, particularly in tumors of the trachea and the left primary bronchus. Generation of a 3D dosimetric database for correlation with toxicity [ 18 , 25 , 35 , 36 , 47 – 49 ]. …”

“…Comparison of GTV coverage by the 90% isodose achieved in 3D planning system. Legend: purple triangles – GTV volume, orange volume – 3D 90% isodose, blue – catheters [ 36 ]…”