Journal of Contemporary Brachytherapy最新文献

Purpose: To investigate a semi-automatic hybrid inverse treatment planning optimization (HIPO) approach for gynecological brachytherapy that preserves the pear-shaped dose distribution without relying on dummy structures.

Material and methods: We retrospectively analyzed 29 patients with gynecological cancers, who underwent combined intracavitary and interstitial (IC/IS) brachytherapy. HIPO enables optimization of dwell times for specific applicators, while other applicators are fixed in Oncentra^® Brachy. Clinical treatment plans (CPs) were compared based on manual adjustments using four HIPO methods: H_ovoid, H_free, H_MS, and H_MS*. H_ovoid optimized tandem and IS needles with ovoid dwell time fixed; H_free optimized all applicators with no fixation; H_MS optimized IS needles with fixation using modified Manchester system, with safe organs at risks (OARs) doses generated in advance by graphical optimization. In H_MS* plan, optimization parameters were adjusted to improve high-risk clinical target volume (HR-CTV) dose coverages based on comparisons between CPs and H_MS.

Results: H_ovoid, H_free, H_MS, and H_MS* achieved clinically acceptable DVH parameters in terms of HR-CTV dose coverage and OARs sparing. However, considerable deviations from the conventional pear-shaped dose distributions were observed, particularly with H_free, which exhibited zero dose contribution from ovoid applicators. Among all HIPO plans, H_MS* with adjusted optimization parameters demonstrated the closest HR-CTV D_90% to that of the CP, while maintaining a conventional pear-shaped dose distribution.

Conclusions: We recommend applying the modified Manchester system with safe OARs doses as the object of fixation, given its consistency with the conventional pear-shaped dose distribution. The proposed method demonstrated clinically acceptable dose distribution and DVH parameters.

Purpose: This study primarily aimed to evaluate the effects of a hydrogel spacer (HS) on dosimetric distribution in the planning target volume as well as on rectal and urethral doses in high-dose-rate brachytherapy (HDR-BT) for prostate cancer, and to identify prostate sub-regions with improved dosimetric parameters and patient conditions that particularly benefit from the use of HS.

Material and methods: This study included 28 patients, who underwent HDR-BT using HS. Treatment plans with HS and simulated plans without HS were compared. The prostate was divided into six regions: ventral and dorsal in the dorsoventral direction, and apex, mid-gland, and base in the craniocaudal direction. V_100% and D_90% were evaluated in each region, along with dose assessments for the rectum and urethra. Paired t-tests were performed to analyze significance, and effect sizes were calculated using Cohen's d.

Results: HS significantly improved V_100% in the dorsal regions (p < 0.05), particularly in the dorsal apex and dorsal mid regions (median V_100% with and without HS: apex, 100.00 vs. 97.10; mid, 100.00 vs. 97.22). D_90% showed improvement across all regions (p < 0.05), with greater effects observed in the dorsal apex and dorsal mid regions (median D_90% with and without HS: apex, 110.15 vs. 103.56; mid, 113.31 vs. 106.21; d ≥ 0.8). Rectal dose parameters improved significantly (p < 0.05), whereas urethral dose changes were not significant (p = 0.14).

Conclusions: HS effectively reduced rectal doses and improved V_100% and D_90% in the dorsal apex and dorsal mid regions of the prostate. These regions are anatomically closer to the rectum and are often subject to dose constraints as well as critical areas for sufficient dose delivery because of the frequent localization of prostate cancer lesions. Therefore, HS is particularly beneficial for patients with dominant lesions in these regions.

Purpose: While both surgery and brachytherapy are treatment options for oral tongue squamous cell carcinoma (OTSCC), the impact of surgery vs. brachytherapy on the swallowing function remains inadequately explored. Therefore, we aimed to analyse the differential impacts of surgery and brachytherapy on swallowing outcomes among OTSCC patients.

Material and methods: This cross-sectional study enrolled 30 histologically confirmed OTSCC patients - 14 in the brachytherapy group (HyBIRT) and 16 in the surgery group (SG) - between June 2022 and October 2023. Patients were enrolled only if imaging confirmed a radiological complete response and they remained disease-free for at least 6 months after treatment. Swallowing was assessed using the Swallowing Capacity Scale (SCS), the Malay Eating Assessment Tool-10 (Malay EAT-10), and the Penetration-Aspiration Scale (PAS).

Results: The Swallowing Capacity Scale showed that the patients in the HyBIRT had a superior swallowing capacity, with a mean score of 6.5 compared to the SG (mean score of 4.7). The difference between the two groups was significant (p < 0.01). In the Malay EAT-10 score, the HyBIRT reported a better median score of 5, which contrasted significantly with the surgical group's median of 22. The p-value < 0.01 was considered significant. Similarly, for the Penetration-Aspiration Scale, where both liquid and semisolid boluses were used, HyBIRT (median score 1) consistently outperformed the SG (median score 2). This result had a p-value of 0.02, which confirmed its statistical significance.

Conclusions: The organ-preserving HyBIRT technique is a promising alternative for managing OTSCC, particularly in preserving swallowing function, and should be further explored in larger, stratified studies with longer follow-up periods to validate these findings.

Purpose: Brachytherapy plays a critical role in managing gynecological cancers. However, for patients who have a poor response to chemoradiation or present with complex anatomy, delivering tumoricidal doses may be challenging. In this case series, we present a descriptive narrative of techniques adopted for brachytherapy, dosimetric and early clinical outcomes for such clinical challenging cases.

Material and methods: Patients who had a poor response to chemoradiation or with challenging anatomy received individualized brachytherapy between 2021 and 2023. All underwent pre-brachytherapy clinical assessment and MRI. These patients were treated with personalized brachytherapy techniques based on tumor extent and anatomy. Manual dose optimization and adjustments to dose fractionation were tailored on a case-by-case basis maximizing tumor control and limiting organ-at-risk doses.

Results: In the six patients included in this report, the median high-risk clinical target volume (HR-CTV) volume was 51.1 cc. For each patient, the implant was individualized using a combination of applicators, 3D-printed applicators or freehand needles. At a median follow-up of 31 months, three out of six patients were locally controlled. Out of the three patients with locally controlled disease, one patient developed grade 2 posterior fourchette necrosis.

Conclusions: Though the results provide a descriptive narrative, they also highlight a clinical care gap that brachytherapy alone cannot yet address for patients. Advancing individualized brachytherapy by incorporating novel agents and techniques may help improve treatment outcomes.

Purpose: Interventional radiotherapy (IRT, brachytherapy) for perineal malignancies, such as anal canal cancer, is challenged by complex pelvic anatomy and procedural limitations. Therefore, TIMER^® applicator was developed to address these issues, offering innovative and adaptable design, compatible with multimodal imaging (MRI, CT, PET/CT, US).

Material and methods: TIMER^® applicator features MRI/CT compatibility, dual anchoring options, and optimized needle layout to improve dose distribution and anatomical conformity. A dosimetric comparison with two commercial applicators was conducted, evaluating dose non-homogeneity ratio (DNR) across varying clinical target volumes (CTVs).

Results: The TIMER^® applicator demonstrated superior dose uniformity, achieving lower DNR values across most configurations and depths. It outperformed both commercially available templates, except for shallow posterior CTVs, where one applicator showed slightly better performance.

Conclusions: The TIMER^® applicator enhances dose precision and adaptability in IRT for perineal cancers, outperforming commercial devices in most scenarios. Further refinements and clinical validation will establish its role in advancing IRT protocols.

Purpose: To evaluate the feasibility and clinical value of computed tomography (CT)-guided radioactive iodine-125 (¹²⁵I) seeds implantation combined with strontium chloride (⁸⁹SrCl₂) in relieving pain after failure of external irradiation in patients with prostate cancer bone metastases.

Material and methods: Clinical data of 48 patients (aged, 56-85 years) with prostate cancer bone metastases admitted to the Department of Nuclear Medicine of the General Hospital of Northern Theatre Command from January 2019 to December 2023 were retrospectively analyzed. They underwent ¹²⁵I seeds implantation brachytherapy combined with ⁸⁹SrCl₂ treatment (Group A), and ⁸⁹SrCl₂ treatment alone (Group B).

Results: A total of 722 seeds were implanted in 39 bone metastases of 23 patients in group A; the implantation success rate was 97.44% (38/39), while there were 25 patients in group B. The worst pain, average pain, and present pain scores of group A decreased over time (F-values: 22.47, 5.22, 3.71; p-values: < 0.001, 0.001, 0.007), and the differences in the worst pain, average pain, and present pain scores compared with before treatment were statistically significant at 12 weeks after treatment (t-values: 6.14, 3.36, 2.86; p-values: < 0.001, 0.002, 0.007). The worst pain at 3 days, 4 weeks, 8 weeks, and 12 weeks after treatment was not statistically significant compared with pre-treatment (t = 2.01, p = 0.0501), while statistical significance was observed at the remaining 4 weeks, 8 weeks, and 12 weeks (t = 7.11, 5.31, 6.14; all p < 0.0001). Also, differences in the worst pain, average pain, and present pain scores of group B before and after treatment were documented.

Conclusions: CT-guided radioactive ¹²⁵I seeds implantation combined with ⁸⁹SrCl₂ for the treatment of pain after failure of external irradiation in patients with prostate cancer bone metastases, is a feasible and effective treatment. The effect is relatively significant for breakthrough pain, which improves the quality of life of patients with bone metastasis-related pain.

Purpose: Magnetic resonance (MRI)-based image-guided brachytherapy (IGBT) is the gold standard technique for carcinoma cervix. We aimed to evaluate doses to target and organs at risk (OARs), and report clinical outcomes of locally advanced carcinoma cervix (LACC) patients treated with a hybrid approach of using MRI- and computed tomography (CT)-based IGBT.

Material and methods: Twenty-two LACC patients, after receiving external beam radiotherapy of 50 Gy in 25 fractions with concurrent cisplatin 40 mg/m² weekly, underwent 7 Gy in 3 fractions of IGBT planning with MRI alone at first fraction, and CT at second (CT-1) and third (CT-2) fractions. Dose received by at least 90% of volume (D₉₀) for high-risk clinical target volume (HR-CTV), and dose to 0.1 cm³, 1 cm³, and 2 cm³ for OARs was evaluated during each fraction and compared.

Results: The median age was 50 years. Fourteen (63.6%) patients were FIGO (2010) stage II. HR-CTV volumes (mean ±SD) of MRI, CT-1, and CT-2 were 24.23 cc ±9.26 cc, 27.82 cc ±15.37 cc, and 24.82 cc ±11.14 cc, respectively (p = N.S.). HR-CTV D₉₀ (mean ±SD) was significantly higher in MRI-based plans compared with CT-based plans at second fraction (MRI: 108.86 ±24.21% vs. CT-1: 98 ±23.18%, p = 0.03), but not different than CT-based plans at third fraction (MRI: 108.86 ±24.21% vs. CT-2: 106.86 ±17.36%, p = 0.68). No statistically significant differences in doses to the rectum, bladder, and sigmoid colon were observed between MRI- and CT-based plans (all p > 0.05). 5-year loco-regional control, disease-free survival, and overall survival rates were 85.2%, 80.7%, and 79.0%, respectively.

Conclusions: Hybrid approach in IGBT using MRI at first fraction and CT for subsequent fractions yields comparable dosimetric parameters and decent long-term clinical outcomes. This approach could be considered resource-sparing brachytherapy technique.

Purpose: To determine whether hemi-gland seed brachytherapy (HGBT) is as effective as whole-gland seed brachytherapy (WGBT) in patients with single-lobe, low-risk and favorable intermediate-risk prostate cancer (PCa).

Material and methods: Phase II clinical trial in patients with low- and favorable intermediate-risk PCa with HGBT. Enrolment took place between 2016 and 2020. All patients (n = 38) underwent HGBT with iodine-125 (¹²⁵I) seeds. Inclusion criteria: single-lobe prostate cancer, ≤ 2 positive cores in one lobe (≥ 10 core samples), < 50% core invasion, Glea-son ≤ 7 (3 + 4), non-visible or unilaterally visible tumor. Patient-reported expanded prostate cancer index (EPIC-26) questionnaire was administered to assess quality of life (QoL). Treatment outcomes were compared with a historical cohort of patients (n = 700), who underwent transperineal, ultrasound-guided ¹²⁵I WGBT between 2000 and 2012.

Results: The mean age was 64.9 years (range, 50-78), the mean baseline prostate-specific antigen (PSA) was 6.12 ng/ml (range, 1.53-10), and the mean nadir was 1.4 ng/ml (range, 0.17-4.24). Most patients (37/38) had Gleason 3 + 3. The mean follow-up was 71.4 months (range, 44-93). Seventeen patients developed biochemical relapse, and 14 presented local clinical progression (contralateral, n = 9, ipsilateral + contralateral, n = 4; and regional, n = 1). Salvage therapy was: contralateral low-dose-rate (LDR) BT (n = 6), high-dose-rate (HDR) BT (n = 2), nodal radiation therapy (RT) + hormonotherapy (n = 2), hormonotherapy alone (n = 1), and prostatectomy (n = 1). Thirty-five patients (92.1%) remained alive (12 with biochemical failure) at the final follow-up, while three patients died of other causes. A slight impairment was observed on all EPIC domains (urinary incontinence, urinary obstruction, bowel, sexual, and hormonal summaries). Compared with the WGBT cohort, urinary irritative/obstructive scores were significantly lower (p = 0.002). At 5 years, biochemical relapse-free survival (BRFS) was 54% in the HGBT group vs. 95% in the WGBT cohort.

Conclusions: In this trial, patients treated with hemi-gland brachytherapy had significantly higher biochemical failure and contralateral relapse rates than a historical cohort of patients treated with WGBT. Larger, well-designed clinical trials are needed to better assess the efficacy of HGBT in the treatment of low-risk PCa.

Purpose: Long-course chemoradiation followed by a brachytherapy boost is one of the acceptable treatment options for watch-and-wait (W&W) eligible rectal cancer patients. However, MRI acquisition, planning, and treatment delivery delays can affect patient satisfaction and treatment success. This study used the classical quality improvement methodology to optimise the MRI-based rectal brachytherapy process.

Material and methods: A multidisciplinary core team was formed, including a radiation oncologist, radiologist, medical physicist, specialist technologist and nurse. Data on wait times from MRI to brachytherapy treatment were collected for patients receiving rectal brachytherapy between August and November 2022. We aimed to reduce the number of days of the gap between the planning MRI day and the treatment delivery day from a median (D_median) and mean (D_mean) of 14 and 15 days, respectively, to < 1 day each (primary goal) and to increase the number of same-day treatments (D_0%) from currently 0% to at least 70% (secondary goal) by 31^st January 2023. The balancing measure was treatment errors or delays. Quality improvement measures were implemented using the Plan-Do-Study-Act (PDSA) cycles.

Results: The post-implementation data at PDSA 1 and 2 from 14 patients each were analysed. The post-change D_median, D_mean and D_0% improved to 3, 3 days and 35.7% for PDSA 1. This further improved to zero, 0.2 days and 78.9%, respectively, for PDSA 2. A sustained shift in the process was apparent on a control run chart, suggesting sustainability. Further in the sustenance phase, the D_median, D_mean and D_0% were maintained at 0.3, 0 days and 74%, respectively, for over 42 patients.

Conclusions: Using the classical quality improvement methodology, we sustainably reduced the delay between the planning MRI day and the treatment delivery day. These strategies may serve as a model for other institutions implementing MRI-based brachytherapy programmes for the W&W approach in suitable rectal cancer patients.