Journal of Contemporary Brachytherapy最新文献

Purpose: The purpose of this study was to determine a comprehensive in vivo source tracking error thresholds in high-dose-rate (HDR) brachytherapy for cervical cancer. Achieving this enables the definition of an action level for imminent in vivo source tracking technologies and treatment monitoring devices, preventing clinically relevant changes to the applied dose.

Material and methods: Retrospective HDR interstitial (n = 10) and intra-cavitary (n = 20) cervical brachytherapy patients were randomly selected to determine the feasibility of implementing in vivo source tracking error thresholds. A script was developed to displace all dwell positions in each treatment plan, along all major axes from their original position. Dose-volume histogram (DVH) indices were calculated without re-optimization of modified plans to determine the appropriate in vivo source tracking error thresholds in each direction.

Results: In vivo source tracking error thresholds were directionally dependent; the smallest were found to be 2 mm in the anterior and posterior directions for both interstitial and intra-cavitary treatments. High-risk clinical treatment volume (HR-CTV) coverage was significantly impacted by displacements of 4 to 5 mm along each axis. Critically, there was a large variation in DVH metrics with displacement due to change in dwell weightings and patient anatomy.

Conclusions: Determining the dosimetric impact of dwell position displacement provides a clinical benchmark for the development of pre-treatment verification devices and an action level for real-time treatment monitoring. It was established that an in vivo source tracking error threshold needs to be patient-specific. In vivo source tracking error thresholds should be determined for each patient, and can be conducted with extension of the method established in this work.

Purpose: This study quantifies the dosimetric impact of incorporating two iodine-125 (¹²⁵I) seed source strengths in Eye Physics eye plaques for treatment of uveal melanoma.

Material and methods: Plaque Simulator was used to retrospectively plan 15 clinical cases of three types: (1) Shallow tumors (< 5.5 mm) with large base dimensions (range, 16-19 mm); (2) Tumors near the optic nerve planned with notched plaques; and (3) Very shallow (< 3.0 mm) tumors with moderate base dimensions (range, 13.5-15.5 mm) planned with larger plaques than requested by the ocular oncologist. Circular plaques were planned with outer ring sources twice the source strength of inner sources, and notched plaques with the six seeds closest to the notch at twice the source strength.

Results: In cases of type (1), the dual-source strength plan decreased prescription depth, and doses to critical structures were lower: inner sclera -25% ±2%, optic disc -7% ±3%, and fovea -6% ±3%. In four out of five cases of type (2), the dual-source strength plan decreased prescription depth, and dose to inner sclera was lower (-22% ±5%), while dose to optic disc (17% ±7%) and fovea (20% ±12%) increased. In cases of type (3), a smaller dual-source strength plaque was used, and scleral dose was lower (-45% ±3%), whereas dose to optic disc (1% ±14%) and fovea (5% ±5%) increased.

Conclusions: Dual-source strength loading as described in this study can be used to cover tumor margins and decrease dose to sclera, and therefore the adjacent retina, but can either decrease or increase radiation dose to optic disc and fovea depending on location and size of the tumor. This technique may allow the use of a smaller plaque, if requested by the ocular oncologist. Clinical determination to use this technique should be performed on an individual basis, and additional QA steps are required. Integrating the use of volumetric imaging may be warranted.

Purpose: We sought to investigate functional parameters and morphologic changes of the renal parenchyma after treatment with image-guided brachytherapy using single-fraction irradiation (high-dose-rate brachytherapy - HDR-BT) of primary kidney lesions, and primary and secondary lesions of the liver, lymph node, and adrenal gland close to renal structures.

Material and methods: Patients ineligible for surgery were included. We prospectively investigated renal function loss within one year via renal scintigraphy and laboratory parameters (KDOQI stage). Radiation exposure to the kidney was measured by volume receiving 5 Gy (V₅). We observed morphologic changes on CT or MRI, with follow-up every three months.

Results: In total, 35 patients were included (21 males, 14 females). Eight patients were treated for extra-renal malignancies. The mean V₅ of the ipsilateral kidney was 70.0 ±42.4 ml equaling to 44.9% parenchymal volume. After renal treatment, V₅ renal volume was 77.8 ±42.2 ml (48.7%) compared with 44.0 ±33.0 ml (32.0%) after extra-renal treatment. No significant reduction in KDOQI stage after 12 months of follow-up were found. Three patients developed morphologic changes in the renal parenchyma, with only one showing a decrease in renal function after 12 months.

Conclusions: CT-guided HDR-BT is a viable treatment modality for local ablative treatment of renal and adjacent masses, with no significant reduction of the KDOQI stage as a predictor for complications of chronic kidney disease. However, larger cohorts need to be analyzed to identify vulnerable patients, as in rare cases, plain dosimetry seems insufficient to predict renal function loss after HDR-BT.

Purpose: To explore the efficacy of computed tomography (CT)-guided iodine-125 (¹²⁵I) radioactive seed implantation for the treatment of small-cell lung cancer (SCLC).

Material and methods: A total of 12 SCLC patients were retrospectively enrolled. All patients underwent CT-guided ¹²⁵I seed implantation therapy, and were followed up until death, the last visit time, or study end time. Primary endpoint was the overall response rate (ORR). Secondary endpoints were local control rate (LCR), progression-free survival (PFS), overall survival (OS), and safety.

Results: All patients were successfully implanted with ¹²⁵I radioactive seeds. The ORR at 2, 6, 12, and 24 months after implantation was 83.3%, 63.6%, 50%, and 40%, respectively; the LCR at 1 and 2 years were 75% (6/8) and 60% (3/5), respectively; the median PFS and OS were 8 and 12 months, respectively; and the OS rate at 6, 12, and 24 months after implantation was 91.67%, 66.67%, and 41.67%, respectively. No surgery-related deaths occurred. During the follow-up period, mild complications were observed in patients, including worsening cough, hemoptysis, and pneumothorax.

Conclusions: CT-guided ¹²⁵I seed implantation therapy is a safe and effective supplementary treatment for SCLC patients, who cannot tolerate radiotherapy.

Purpose: The aim of the present study was to assess the clinical efficacy and safety of stereotactic ablative brachytherapy (SABT) for unresectable or inoperable head and neck cancers.

Material and methods: This study retrospectively assessed clinical data of 37 patients with unresectable or inoperable head and neck cancers treated with SABT from October 2016 to October 2021. Variables evaluated included local efficacy, local control rate (LCR), overall survival (OS) rate, and radiological adverse effects.

Results: The median follow-up was of 34 months (range, 5-59 months), and LCR at 6, 12, and 24 months was 89.2%, 78.2%, and 69.4%, respectively. The median survival time was 16 months [95% confidence interval (CI): 10.5-21.5 months], and the OS rate at 6, 12, and 24 months was 97.3%, 70.3%, and 34.5%, respectively. The results of univariate analysis revealed that the type of pathology and gross tumor volume (GTV) D₉₀ were related to LCR (p < 0.05). However, the type of pathology, GTV D₉₀, age, and implantation site were related to OS rate (p < 0.05). The results of multivariate analysis showed that the type of pathology and GTV D₉₀ were substantially related to LCR and OS rate (p < 0.05). The evaluation of post-operative radiological adverse reactions revealed that seven cases (18.9%) developed grade 1-2 skin reactions, four cases (10.8%) developed grade 1-2 oral mucosal outcomes, and no cases developed grade 3 or higher adverse reactions. Post-operative seed dislocation occurred in three patients with tongue cancer.

Conclusions: SABT has produced good local control and mild adverse reactions in the treatment of unresectable or inoperable head and neck cancers. Additionally, it is safe, feasible, minimally invasive, and has fewer adverse effects than other treatment modalities.

Purpose: To evaluate the reliability of algebraic sum with respect to rigid fusion of treatment plans related to adjuvant external beam pelvic radiotherapy (APR) and vaginal cuff high-dose-rate brachytherapy (BT) in uterine cancer patients.

Material and methods: For algebraic sum, APR and BT doses were mathematically added. Rigid fusion was realized overlapping computed tomography (CT) images of APR and BT treatment plans. Rectum and bladder were considered reference organs at risk (OARs). Following dose (D) parameters were examined: D_max (0.5 cc), D_20% and D_50% for rectum, D_max (0.5 cc) and D_50% for bladder; for each parameter, differences between the two adopted methods were reported as Δ-values.

Results: Twenty uterine cancer patients submitted to radical surgery followed by APR plus vaginal cuff BT were reviewed. APR was done with a dose of 25 × 2 Gy. All patients also receveid a vaginal cuff boost with BT at the dose of 2 × 5 Gy. Differences between mean cumulative doses calculated with rigid fusion and algebraic sum were evaluated. For the rectum and bladder ΔD_50%, there were no significant differences, and BT contribution resulted minimal. An apparent significant difference value was registered in bladder ΔD_max (0.5 cc). No toxicity was observed.

Conclusions: In uterine cancer patients submitted to APR and vaginal cuff BT, algebraic sum and rigid plan fusion of doses allowed to obtain similar results in evaluating cumulative OARs' doses. Further investigations and increased number of patients are recommended to confirm our findings.

Purpose: Brachytherapy is well positioned to safely deliver highly conformal single-fraction doses of radiation, which can lower costs and improve efficiency. Traditionally, high-dose-rate brachytherapy (HDR-BT) has been delivered over multiple treatments. A scoping literature review was conducted to better understand the available literature on single-fraction HDR-BT for all disease sites.

Material and methods: According to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, PubMed database was queried from 1994-2021 using the following search terms: 'brachytherapy', 'high-dose-rate', and 'single-fraction'. A total of 53 studies met our exclusion criteria.

Results: Liver had the highest number of studies, with a total of 618 patients treated with doses ranging from 8 to 25 Gy. Median follow-up ranged from 11-33 months. Local control (LC) rates ranged from 37% to 98%. G3 acute/late toxicities or higher were reported in 3 patients. Prostate cancer included a total of 1,474 patients treated with doses ranging from 19 to 21 Gy. Median follow-up ranged from 20 to 72 months. Prostate specific antigen (PSA) control outcomes after definitive treatment ranged from 65% to 94%, and salvage treatments from 5% to 84%. G3 acute/late toxicities or higher ranged from 0 to 6%. Breast cancer included a total of 268 patients treated with doses ranging from 16 to 20 Gy. Median follow-up ranged from 24 to 72 months. LC rates were 100%. G3 acute toxicities or higher ranged from 0 to 6%. Regarding other cancers, conclusions were limited given the small number of patients within each respective site.

Conclusions: Currently used regimens appear safe, but efficacy vary by different disease sites. Outcomes are more promising for breast and liver, while are less encouraging for prostate. Additional prospective evaluation of single-fraction HDR-BT regimens are warranted.

Purpose: The recommended treatments for basal cell carcinoma (BCC) in the head and neck (H&N) region are Mohs surgery, standard surgical excision (SSE), and radiotherapy. According to the literature, local recurrence after surgical treatment in this area is associated with a worse prognosis in case of re-treatment. To our knowledge, there are no reports on high-dose-rate brachytherapy (HDR-BT) for BCC of the H&N region, both in primary lesions and relapses after SSE. This study aimed to fill this gap in the literature.

Material and methods: Inclusion criteria were pathologically confirmed BCC, tumor location in the H&N region, treatment performed with superficial HDR-BT, and a minimum follow-up of 12 months. An analysis was performed on a group of 90 patients, in whom a total of 102 tumors were treated. Subsequently, tumors were divided into two sub-groups, including those treated initially, and treated due to local recurrence after previous SSE. Primary treatment group (PrG) included 59 tumors, whereas 43 tumors were included in recurrent group (ReG).

Results: Statistical analysis did not reveal any significant differences between the groups in terms of age (p = 0.43), treatment duration (p = 0.17), follow-up time (p = 0.96), sex (p = 0.18), local advancement (p = 0.83), and location (p = 0.68). The estimated 5-year relapse-free survival was 96.4% in the PrG and 94.6% in the ReG group, and the difference was not statistically significant (p = 0.72). In the PrG, skin toxicity was as follows: early G1 - 20.3%, G2 - 28.8%, G3 - 42.4%, G4 - 8.5%; late G1 - 33.9%, G2 - 50.8%, G3 - 1.7%, G4 - 11.9%. Whereas, in the ReG, toxicity was as follows: early G1 - 16.3%, G2 - 41.9%, G3 - 37.2%, G4 - 4.6%; late G1 - 30.2%, G2 - 62.8%, G3 - 4.6%. There were no statistically significant differences in the early nor late toxicity between the groups (p = 0.54, p = 0.16).

Conclusions: Superficial HDR-BT is a highly effective treatment for both primary and recurrent BCC of the H&N region, and is associated with acceptable skin toxicity.

Purpose: To compare the pre-plan and post-plan dosimetric parameter differences of 3D-printed non-coplanar templates (3D-PNCT)-assisted computed tomography (CT)-guided iodine-125 (¹²⁵I) radioactive seed implantation brachytherapy (RISI) in patients with inguinal lymph node metastasis (ILNM).

Material and methods: This was a retrospective study of 15 patients with ILNM carcinomas treated with 3D-PNCT-assisted CT-guided RISI between May, 2015 and April, 2018. All patients underwent prior external beam radiotherapy (EBRT) or surgery. Dosimetric parameters included D₉₀, D₁₀₀ (dose delivered to 90% and 100% of the volume, respectively), V₁₀₀, V₁₅₀, V₂₀₀ (percentage of target volume receiving 100%, 150%, and 200% of the prescribed dose, respectively). Quality parameters included conformal index (CI), external index (EI), and homogeneity index (HI). Paired t-test and Bland-Altman analysis were applied to compared pre-plan and post-plan parameters.

Results: The median gross tumor volume (GTV) in the pre-plan was 8.7 ml (range, 0.8-185.1 ml). There were statistically significant differences in V₁₀₀, V₁₅₀, CI, and EI (p < 0.05). Bland-Altman analysis indicated that accidental error of RISI was small. In 1 of the 15 cases, D₉₀ and D₁₀₀ exceeded the prescribed therapeutic accuracy. In 1 of the 15 cases, V₁₅₀, EI, and GTV were outside the specified accuracy range (95% confidence interval).

Conclusions: 3D-PNCT-assisted CT-guided RISI is a safe, accurate, and feasible choice in ILNM treatment. The procedure of RISI has significantly improved. The pre-plan can be accurately executed by 3D-PNCT-assisted CT-guided RISI.

Purpose: A proportion of patients are not directly eligible for prostate brachytherapy (BT) due to pubic arch interference (PAI). Constraints in positioning sources behind the pubic arch due to linear, horizontal needle paths, may hamper effective irradiation of the target volume. This work evaluated the effect of prostate volume (V_p) and patient posture change on the amount of PAI, and demonstrated that steerable needles may broaden the inclusion criteria for patients with enlarged prostates and observed PAI.

Material and methods: Twenty-seven patients (V_p > 60 cc) were included in this study. Access obstruction to the prostate was evaluated using diagnostic magnetic resonance imaging (MRI) scans, after six upward rotations of the pelvis and the prostate in 5 degree steps, to indicate the effect of patient posture change from supine to lithotomy position. For patients with PAI, we evaluated if the steerable needle could access the obstructed volume of the prostate.

Results: The data showed no clear relation between V_p and PAI. In 23 of the 27 patients, in which PAI was observed, 14 showed obstruction of the prostate of ≥ 10 mm in the supine position (mean PAI ± standard deviation: 15.2 ±3.8 mm). Anatomical rotation reduced PAI by 4.8 mm after every 10 degrees of upward rotation, still resulting in obstructions of 8.1 ±2.4 mm in 10 of the 14 cases after 15 degree rotation. The steerable needle enabled access to all the required coordinates of the prostate.

Conclusions: The ability to steer along curved paths enables prostate BT in patients with enlarged prostates and PAI, and reduces the change of needing to abandon treatment.