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Purpose
This study aimed to investigate 3 planning target volume (PTV) margin expansions and determine the most appropriate volume to be used in bladder preservation therapy when using daily cone beam computed tomography (CBCT). We aimed to establish whether a smaller PTV expansion is feasible without risking geographical miss.Methods and materials
The study included patients with bladder cancer who were treated with a hypofractionated course of radiation therapy delivered with intensity modulated radiation therapy. The clinical target volume (CTV) was the whole empty bladder, and the PTV consisted of a 1.5-cm margin around the bladder (PTV1.5 cm). Patients underwent daily CBCT imaging before treatment to assess the bladder volume and ensure accurate positioning. We investigated 2 additional smaller PTV margin expansions to determine the most appropriate volume to be used with CBCT as a daily image guided radiation therapy modality. These margins were created retrospectively on every CBCT. The first additional volume was a uniform PTV margin of the surrounding 1 cm (PTV1 cm). When considering that the majority of the internal bladder movement was due to the variation in filling that occurs in the superior and anterior directions, a second volume of an anisotropic PTV margin with a 1.5-cm superior/anterior and 1 cm in other directions (PTV1/1.5 cm) was created. We recorded the frequency and measured the volume of bladder falling out of each PTV based on the daily CBCT.Results
For the purpose of this study, we considered an arbitrary 5 cm3 of CTV falling out of the designated PTV as a clinically significant volumetric miss. The frequency of such a miss when applying the uniform PTV1 cm was 1%. However, when applying the uniform PTV1.5 cm and anisotropic PTV1/1.5 cm margins, the frequency was 0.5% and 0.5%, respectively.Conclusions
The anisotropic PTV expansion of 1.5 cm superiorly and anteriorly and 1 cm in all other directions around the bladder (CTV) provides a safe PTV approach when daily CBCT imaging is used to localize an empty bladder. 相似文献Methods: All women who were diagnosed with cutaneous endometriosis and underwent HIFU ablation and 4-year follow-up were included. Patient symptoms, imaging performed, HIFU ablation, recurrence, lesion location, size and number were collected and analyzed.
Results: A total of 51 women with 57 painful abdominal wall masses with a median volume of 4.00?cm3 and a mean age of 30.5±2.12 years were treated with HIFU. The main symptoms were a palpable painful abdominal mass (93%), protrusion of the skin (28.1%, 16) or lack of protrusion of the skin (71.9%, 41). Ultrasound was initially performed in 100% (51) of women, whereas 6% (3) required MRI examinations to distinguish the features and range of the masses. Ablation was performed with a median 300?s of sonication time, 40?min treatment time, 150?W of power and 41800?J of total energy to treat lesions that were a median volume of 3.83?cm3. No severe complications occurred, except in one patient with a first-degree skin burn, during the 48-month follow-up period. The pooled recurrence of cutaneous endometriosis occurred in 3.9% (2) of women.
Conclusion: The diagnosis of AWE should be confirmed with imaging of the lesion number, location, size and features before HIFU ablation. HIFU should be the first choice for the treatment of AWE as it is a non-invasive method, with high efficiency and safety and rapid postoperative recovery. 相似文献