Journal of Contemporary Brachytherapy最新文献

Purpose: The aim of this study was to evaluate the dosimetric impacts of transit doses in various brachytherapy techniques, e.g., intra-cavitary, interstitial, and hybrid brachytherapy, on prostate and gynecological cancers using commercially available treatment planning system (TPS).

Material and methods: For the evaluation, 36 gynecological cancer and 12 prostate cancer treatment plans were investigated, and transit doses were calculated using effective transit time to the middle of dwell positions in TPS. Effective transit times varied with step size, and movements were determined with a high-speed camera. The increment of Δ in dose-volume histogram parameters for clinical target volume (CTV) V_100% and CTV D_90%, rectum D_2cc and D_1cc, and bladder D_2cc and D_1cc were evaluated, after which dwell time distribution for each technique was analyzed to examine relationships between dosimetric change in CTV D_90% and dwell time.

Results: The median Δ for interstitial technique in prostate cancer was larger than those in other techniques: that of CTV V_100% was 0.7%, and those of bladder and rectum D_2cc and D_1cc were over 1.0%. In CTV D_90%, the median Δ values for interstitial technique in gynecological and prostate cancers were 1.0% and 1.6%, respectively. The interstitial techniques displayed a positive correlation between Δ of CTV D_90% and the percentage of dwell times of < 2 s of the total dwell times.

Conclusions: In this study, the dosimetric impacts of transit doses in various brachytherapy techniques were comprehensively clarified. A relatively large impact was observed in interstitial techniques, and the percentage of dwell times of less than 2 s could be a rough indicator of the necessity of considering the transit dose.

Purpose: Modern applicators in cervical cancer brachytherapy (BT) have an integrated option for using interstitial needles. Even though this allows improved dose coverage in large tumors, there are cases where pre-positioned needle arrangements within applicator are not optimal. In such cases, free-hand needles (FHNs) can be inserted into tumor without using applicator's positions. However, this requires a skilled professional, because the depth of tissue must be estimated without any help of needle insertion tools, and the angle of needle is critical. Improved dose coverage of the tumor and the effect on critical organ doses are yet to be estimated, if they constitute the time used and possible additional complication risk using FHNs.

Material and methods: In this work, clinical brachytherapy treatment plans using FHNs were compared with hypothetical plans, in which the best possible effort was applied to produce acceptable treatment plans without FHNs. Twenty-four cervix cancer patients with FHNs were re-planned without FHNs. Biological total doses were calculated for target volumes (high-risk clinical target volume [HR-CTV], gross tumor volume [GTV], and intermediate-risk clinical target volume [IR-CTV]) and organs at risk. External beam radiation therapy (EBRT) dose distributions were summed to brachytherapy plans, and total doses were compared.

Results: The statistically significant differences favoring FHNs usage were observed, with HR-CTV D₉₀ (p = 0.043), bladder (D_2cc) (p = 0.017), rectum (D_2cc) (p = 0.022), and sigmoid (D_2cc) (p = 0.065). The average 2 Gy equivalent total doses and p-values, without/with FHNs were respectively: HR-CTV D₉₀ = 88.8/91.5 (p = 0.043); bladder (D_2cc) = 87.5/86.2 (p = 0.017); rectum (D_2cc) = 70.2/69.2 (p = 0.022); sigmoid (D_2cc) = 70.1/69.3 (p = 0.065) (α/β = 10 Gy for targets and α/β = 3 Gy for OARs, respectively).

Conclusions: The utilization of FHNs resulted in higher dose coverage to HR-CTV, and lower doses to bladder and rectum. There was no difference in GTV, bowel, or vaginal point doses.

Purpose: The study was conducted to provide support for the delivery of electronic brachytherapy (EBx) in patients with low-risk non-melanoma skin cancer (NMSC) lesions who prefer and benefit a non-surgical treatment.

Material and methods: This study included 205 patients with a total of 236 lesions. Six centers participated in this study using high-dose-rate EBx in NMSC. Eligible patients had pathologically confirmed basal cell or squamous cell carcinoma of clinical stage Tis, T1, or T2, with two or fewer high-risk clinical or pathologic features. Treatment doses were chosen from a set of fractionation schemes delivering 69-72 Gy (BED). Maximum follow-up was 5 years.

Results: The median age was 74 (range, 56-96) years, and 62% of the subjects were males and 38% females. The median follow-up was 24.2 months, with a maximum of 73.5 months. Healthcare professional (HCP) and patient-rated cosmesis were rated excellent/good (E/G) by both groups at 90-100% rates, except for HCP ratings of 1-3 months post-EBx, where cosmesis was rated 83-87% E/G. Erythema was the most common acute adverse event (34.1% at 1 month), rebounding back to zero by 6 months. There was a single lesion recurrence.

Conclusions: This report provides additional phase IV clinical data on NMSC treated with electronic brachytherapy. With 2-year median follow-up, there was one recurrence (0.42%). Patients tolerated the treatments well, as evidenced by strong and longitudinal scores on the skin cancer index as well as cosmetic evaluations performed by both patients and healthcare providers. Adverse rates were low, except for expected acute erythema, chronic hypopigmentation, and telangiectasia. The study provides additional information on EBx delivery for low-risk NMSC lesions in patents who prefer non-surgical treatment, especially those at risk for surgical complications, surgical cosmesis issues, keloid formation, wound care issues, and use of anticoagulant therapy.

Purpose: This study evaluated the efficacy and safety of a high-dose-rate (HDR) brachytherapy regimen with an abbreviated schema for patients with cervical cancer during the COVID-19 pandemic.

Material and methods: Patients underwent external beam radiation therapy combined with cisplatin-based chemotherapy. Subsequently, brachytherapy (7 × 4 Gy) was administered for 10 days using an abbreviated schema. The treatment plan aimed to deliver a cumulative dose of at least 85 Gy EQD₂ for α/β = 10 Gy to high-risk clinical target volume (HR-CTV), while minimizing exposure to the bladder, rectum, and sigmoid colon.

Results: Sixty-nine patients with cervical cancer received definitive chemoradiation therapy, with a median overall treatment time of 56.2 days. The incidence of acute grade 3 hematological toxicity was 62.3%, and grade 4 toxicity was 11.6%. Grade 3 or higher gastrointestinal and genitourinary toxicity rates were 5.8%, 2.9%, 2.8%, and 4.3%, respectively. Late gastrointestinal toxicities of grade ≥ 2 and grade ≥ 3 occurred in 14 (20.3%) and 3 (4.3%) patients, respectively. Late genitourinary toxicities of grade ≥ 2 and grade ≥ 3 occurred in 8 (11.6%) and 3 (4.3%) patients, respectively. As of December 2023, with a median follow-up of 40 months, 1-year PFS and OS rates were 81.2% and 94.2%, respectively, while 3-year PFS and OS rates were 71.0% and 85.5%, respectively.

Conclusions: The abbreviated HDR brachytherapy regimen offered a viable alternative for patients with cervical cancer during the COVID-19 pandemic, suggesting that this treatment schedule maintains therapeutic efficacy and safety, and avoids prolonged treatment duration.

Purpose: The purpose of this study was to explore the overall survival (OS) rate of late-stage lung cancer patients after receiving iodine-125 (¹²⁵I) particle implantation brachytherapy.

Material and methods: 436 late-stage lung cancer patients who underwent ¹²⁵I radioactive particle brachytherapy in the Department of Nuclear Medicine of the General Hospital of Northern Theater Command from December 2013 to June 2019 were retrospectively analyzed. Patients were randomly divided into training set and validation set in a 7 : 3 ratio. Univariate and multivariate Cox proportional hazards models were employed to show independent factors affecting the prognosis of late-stage lung cancer patients. Based on these factors, a nomogram model was constructed to predict OS at 1, 3, and 5 years after ¹²⁵I particle implantation brachytherapy for late-stage lung cancer as well as 1-year progression-free survival (PFS).

Results: The results of univariate and multivariate Cox proportional hazards model analyses of OS time showed that smoking, lung atelectasis, superior vena cava obstruction syndrome, and surgical time were significantly associated with OS of patients, and were independent influencing factors. The results of univariate and multivariate Cox proportional hazards model analyses of PFS demonstrated that planning target volume, maximum dose, average dose, pre-operative D₉₀ and V₁₀₀ at 1 cm around the lesion, and surgical time were significantly associated with PFS of patients, and were independent influencing factors. Based on these independent prognostic factors, nomogram models were constructed to predict the 1-, 3-, and 5-year OS and 1-year PFS of late-stage lung cancer patients.

Conclusions: This study revealed the potential benefits of ¹²⁵I particle implantation brachytherapy for the OS rate of late-stage lung cancer patients.

Purpose: To evaluate the efficacy and toxicity of interstitial temporary brachytherapy boost for prostate cancer patients using real-world data.

Material and methods: Between 2008 and 2016, 115 patients treated with external beam radiotherapy (EBRT) followed by a brachytherapy boost (BT boost) were eligible for this retrospective analysis. Patients received either interstitial high-dose-rate brachytherapy (HDR-BT) with 2 x 9-9.5 Gray (Gy) schedule or pulsed-dose-rate brachytherapy (PDR-BT) with 35 Gy as boost after EBRT (50.4 Gy), up to a total dose of 86-98 Gy (EQD_2α/β = 3). Primary endpoints of the present analysis were cumulative local recurrence rate (LRR), biochemical recurrence-free survival (bRFS), tumor-specific survival, and overall survival (OS). As secondary objective, treatment-related toxicity was evaluated.

Results: The median follow-up time was 87 (range, 9-159) months, and the median age was 72 (range, 48-83) years. The median prostate specific antigen value (PSA) was 12.2 (range, 2.4-288) ng/ml. 78/115 (68%) patients had high-risk prostate cancer according to the D'Amico classification. At 7 years, the cumulative LRR for the whole cohort was 1.8%. The 7-year bRFS, cancer-specific survival, and OS were 85.2%, 97.3%, and 88.9%. The 5-year prevalence of late toxicity grade 3 or higher according to the LENT-SOMA scale was 4%. There were no significant differences for treatment outcome or toxicity for HDR vs. PDR treatment. A prostate gland of 50 cm³ or more was not associated with worse treatment efficacy or increased side effects, apart from the prevalence of urethritis after 5 years (p = 0.035).

Conclusions: BT boost in patients with prostate cancer is efficient and well-tolerated, with low rates of side effects also in elderly patients. HDR- and PDR-BT were equally efficient and well-tolerated. A large prostate gland is no contraindication for BT. Therefore, BT boost should be offered to all eligible patients.

Purpose: Squamous cell carcinoma of oral tongue (TSCC) poses a significant health challenge. Radiotherapy is the mainstay of treatment, with external beam radiotherapy (EBRT) and brachytherapy (BT) offering distinct advantages. This study investigated the long-term outcomes associated with each technique.

Material and methods: A retrospective analysis was done reviewing medical records of patients diagnosed with TSCC between 2012 and 2022, who underwent surgery and received adjuvant curative-intent radiotherapy. Patients were categorized based on treatment modality: EBRT alone, EBRT combined with brachytherapy (EBRT+ BT boost), or BT alone. Overall survival (OS) and disease-free survival (DFS) were evaluated at 5 years.

Results: A total of 84 patients were included, with 57 receiving EBRT, 14 receiving BT alone, and 13 receiving EBRT + BT boost. The median follow-up was 70 months. The 5-year OS rates were 68% for EBRT, 88% for BT alone, and 92% for EBRT + BT boost. The 5-year DFS rates were 62% for EBRT, 88% for BT alone, and 84% for EBRT + BT boost. The 5-year LRC rates were 85% for EBRT, 100% for BT alone, and 92% for EBRT + BT boost. No significant differences between these modalities in terms of median OS, DFS, and LRC were observed.

Conclusions: This study explored the long-term outcomes of EBRT and EBRT + BT boost in TSCC patients. While the initial findings suggest potentially improved outcomes with the combined approach, more studies are necessary for validation. Future research should investigate the impact of these techniques on treatment-related toxicities, providing a more comprehensive picture.

Purpose: Insertion of a spacer between tumor and an adjacent organ at risk may improve the therapeutic ratio in gynecological cancer brachytherapy. The purpose of this review was to assess the available literature on the use of injectable bio-absorbable spacers in brachytherapy for gynecological cancers.

Material and methods: Embase, PubMed, Medline, and Cochrane Central Register of Controlled Trials were searched until March 28, 2024. Studies reporting on injectable bio-absorbable spacers in gynecological cancer brachytherapy were included. Two independent reviewers completed screening, assessment for eligibility, and data extraction of included studies. Data were collected on spacer material, technique, safety, feasibility, spacer quality, dosimetric values, clinical outcomes, and cost-effectiveness.

Results: Seventeen studies met inclusion criteria, with a total of 312 patients and 169 spacers. Clinical application was primarily in cervix cancer brachytherapy (47%) and spacer placement in the recto-vaginal space (88%). Eight different products were used, with no significant spacer-related adverse effects reported. Spacer insertion reduced rectal dose in eight studies, bladder dose in one study, sigmoid dose in four studies, and permitted tumor dose escalation in three studies. Five studies reported on tumor outcomes and eight studies on late toxicities. There were no studies evaluating patient-reported outcomes and cost-effectiveness.

Conclusions: Injectable bio-absorbable spacers offer a promising approach for improving the therapeutic ratio in gynecological cancer brachytherapy. There is low certainty evidence available in the literature for their use, and rigorous prospective studies are needed to provide evidence on outcomes.

Purpose: To investigate the clinical outcomes and toxicities of using 3D-printed applicators for image-guided adaptive brachytherapy (IGABT) in gynecological cancer patients.

Material and methods: Fourteen patients with gynecological cancers, both primary and recurrent, treated with in-house 3D-printed applicators between 2021 and 2022 were included in the study, and their data were retrospectively reviewed. Timing and patterns of response to treatment were recorded. Kaplan-Meier estimates at 2 years post-treatment were analyzed to obtain local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) rates. Actuarial rates of genitourinary (GU), gastrointestinal (GI), and skin and mucosal toxicities were also reported.

Results: The median follow-up time for all patients was 27 (IQR: 15.4-32.5) months. Among the primary cases, 2 patients had cervical cancer and 3 had extra-mammary Paget's disease of the vulva. For the recurrent cases, all patients had vaginal relapses. The most common primary cancers were cervical cancer (44.4%) and ovarian cancer (33.3%). At 3 months post-treatment, 13 patients (92.9%) achieved a complete response (CR), and 1 patient (7.1%) showed a partial response (PR). The 2-year rates of LRFS, DMFS, PFS, and OS for primary/recurrent cases were 100%/74.07%, 100%/88.9%, 100%/64.8%, and 100%/88.9%, respectively. The actuarial rates of ≥ grade 2 acute GU and GI toxicities were 7.1% for both groups. For late GU and GI toxicities, the actuarial rates were 14.3% and 21.4%, respectively. In terms of skin and mucosal toxicities, 4 patients (28.6%) developed acute grade 3 toxicity, and 1 patient (7.1%) experienced persistent grade 3 vaginal toxicity.

Conclusions: IGABT treatment using 3D-printed applicators for HDR brachytherapy in challenging cases due to incompatibility of the standard applicators with the patient's anatomy or highly advance disease, has demonstrated encouraging outcomes and acceptable toxicity profiles.

Purpose: Dose calculation in clinical treatment plans must be verified by an independent dose calculation prior to treatment. This study presented an independent second check dose calculation software developed for clinical use.

Material and methods: A software developed using Python 3 tool on Google Colab platform enabled its deployment on standard computer systems. The software utilized AAPM TG-43 formalism and AAPM consensus dataset for TG-43 parameters, which were consistent with those of a commercial treatment planning system (TPS; Varian Brachy-Vision). As input, the software only used treatment plan report from TPS. Dosimetric comparisons were performed between software-calculated dose at reference points and corresponding TPS values across 117 clinical treatment plans (102 gynecological cases and 15 intra-operative radiation therapy [IORT] cases using high-dose-rate [HDR] brachytherapy). Gynecological cases were categorized into 12 applicator groups, depending on various combination of tandem, ovoids, and needles, and dose calculation points were manually selected close to prescribed dose.

Results: 234 dose points (2 points per plan) were calculated. The dose discrepancy between software and TPS was -1% ±0.36% (mean ± standard deviation), with maximum of -3%. The accuracy of the software met AAPM guideline requirement (< 5% deviation). The simplicity of input file in graphical user interface (GUI) environment enabled the software to operate on any computer without additional software, data transfer, or manual data entry. This capability can be particularly advantageous in IORT procedures, which require quick turn-around second check without network connectivity to TPS for DICOM data transfer.

Conclusions: A streamlined second check software using TG-43 formalism was developed in Python 3 tool and converted into independent executable GUI, to verify commercial TPS dose calculations in HDR brachytherapy. The software meets current practice guideline and is compatible with commonly used computer systems (Windows, MacOS, and Linux), requiring no additional software, manual data entry, or connection to TPS. The software will also be published online with free public access.