Journal of Contemporary Brachytherapy最新文献

Purpose: The purpose of the study was to analyze patients with vaginal-involving recurrences of gynecological tumors and primary vaginal tumors, treated with transperineal interstitial brachytherapy (P-ISBT). Dosimetric, clinical, and toxicity analysis of these patients was conducted, incorporating MRI in volume definition and dose-volume dosimetry.

Material and methods: Forty-two patients were retrospectively analyzed. They were treated with radical or adjuvant intent (in hysterectomized patients with high-risk of relapse). P-ISBT was performed with MUPIT (CT-based planning) in 18 patients (42.9%) and with Template Benidorm (TB) (MRI-based planning) in 24 patients (57.1%).

Results: Median age was 59 years (range, 39-78 years). Median clinical target volume (CTV) was 81.4 cc (range, 33.8-286.2 cc) in MUPIT, and 47.5 cc (range, 10-156.4 cc) in TB-treated patients (p = 0.01). Median EQD₂ for EBRT and brachytherapy D₉₀ CTV was 69.2 Gy (range, 27.9-88.8 Gy) in MUPIT, and 77.2 Gy (range, 31-84.3 Gy) in TB. Median rectal D_2cc was 69.2 Gy (range, 23.5-82.6 Gy) in MUPIT, and 66.3 Gy (range, 16.4-75 Gy) in TB. Median bladder D_2cc was 71.5 Gy (range, 23.6-90.8 Gy) in MUPIT, and 66.9 Gy (range, 18.2-78.3 Gy) in TB. Median follow-up was 36.5 months (range, 4-188 months). Local control was 95% at 3 and 5 years. Overall survival was 77% at 3 years, and 66% at 5 years. Disease-specific survival was 81% at 3 years, and 75% at 5 years. Chronic grade 1-2 proctitis presented in 10 patients (24%; 8 treated with MUPIT and 2 treated with TB; p = 0.01). Grade 3 toxicity was documented in 4 patients (9.6%).

Conclusions: MRI-based planning is superior to CT-based planning in P-ISBT. It allows for better definition of CTV, resulting in smaller and more selective treatment volumes. Our results show a tendency towards higher D₉₀ CTV dose and lower rectal/bladder D_2cc dose, leading to less events of late rectal toxicity.

Purpose: Soft tissue sarcomas (STS) due to their aggressive nature, pose challenges in achieving optimal local control (LC) rates following surgery. Brachytherapy offers precise delivery of high radiation doses to target tissues, potentially enhancing LC rates. This feasibility study explored the efficacy of perioperative high-dose-rate brachytherapy (PHDRB) and external beam radiation therapy (EBRT) in improving LC rates for STS, with a particular focus on interstitial brachytherapy and dose escalation strategies for high-risk patient sub-groups.

Material and methods: Seven patients with STS underwent conservative surgery and PHDRB between October 2020 and October 2023. PHDRB doses ranged from 3.0 to 3.5 Gy BID in 10 fractions, with or without subsequent EBRT, as indicated. EBRT was delivered in 4-5 weeks after surgical procedure at a dose of 45-50 Gy in 25 treatments, with daily dose of 1.8-2.0 Gy. Brachytherapy techniques and dosimetry guidelines were meticulously implemented to ensure optimal treatment delivery and minimize toxicity.

Results: All seven patients tolerated treatment well without acute or late radiation-related complications. Excellent local disease control was achieved in all cases, but three patients developed distant metastases. The overall feasibility and efficacy of PHDRB in combination with EBRT were promising.

Conclusions: This study underscores the feasibility and potential efficacy of PHDRB and EBRT for STS treatment. Despite limitations in sample size, the results are promising, warranting further investigation through multi-centric studies. The use of dose-escalated PHDRB in high-risk cases enabled more intensive treatment delivery directly to the tumor bed, which may be critical for enhancing local control in patients with aggressive or large tumors. In facilities with limited resources and a high patient burden, where conformal radiotherapy is unavailable, brachytherapy remains an excellent modality for boosting the tumor bed or serving as a radical radiotherapy treatment.

Purpose: Non-melanoma skin cancer (NMSC) is the most prevalent cancer worldwide, particularly affecting head and neck region. Surgical excision, especially Moh's microsurgery, is the gold standard for treatment. However, certain patients' factors, such as age, comorbidities, and tumor location, require alternative therapies. Radiotherapy, particularly surface mold brachytherapy, offers a viable option for these inoperable or high-risk surgical candidates.

Material and methods: This retrospective cohort study included 22 patients with histologically confirmed NMSC, treated with high-dose-rate (HDR) surface mold brachytherapy at the Cancer Institute of Iran between 2019 and 2021. The study focused on primary outcomes, including local control and overall survival, with follow-up assessments for acute and late toxicities, treatment response, and cosmetic outcomes.

Results: Twenty-two patients (mean age, 70.94 years) with NMSC were treated. The median lesion size was 2.46 cm. The basal cell carcinoma (BCC) to squamous cell carcinoma (SCC) ratio was 14 : 8. The median maximum depth of clinical target volume was 10 (IQR: 9-15). The median dose was 39 Gy in 13 fractions, with a D₉₀ of 3.04 Gy. Lesions were mainly located on the nose, scalp, and cheek. The 2-year local control rates were 92.9% for BCC and 87.5% for SCC. The 2-year overall survival rate was 71%, with 80% for BCC and 55% for SCC. Eight patients died during the follow-up period, of these, five were due to cancer. Recurrence occurred in one BCC patient (7.1%) and one SCC (12.5%) case. Acute toxicities were mild, and no severe late complications were observed, indicating good tolerance and favorable cosmetic outcomes.

Conclusions: Surface mold brachytherapy using cobalt-60 source is an effective and safe treatment for head and neck NMSC, even in thicker than 5 mm lesions, offering high local control rates and favorable cosmetic outcomes. This technique presents a valuable alternative for patients unsuitable for surgery, warranting further research with larger cohorts for confirmation and treatment protocol optimization.

Purpose: To present an innovative deformable applicator that used Freiburg flap as vaginal applicator with or without free-hand interstitial needles in three-dimensional (3D) high-dose-rate (HDR) brachytherapy for vaginal stump recurrence of cervical cancer.

Material and methods: Between September 2017 and January 2020, all patients with vaginal stump recurrence after radical hysterectomy of cervical cancer treated with vaginal stump brachytherapy using Freiburg flap as vaginal applicator with or without free-hand interstitial needles were retrospective analyzed. Characteristics related to patients and treatment modality as well as preliminary outcomes and side effects were investigated.

Results: Thirteen patients were enrolled, aged between 44 and 77 years, with a median age of 53 years. The number of fractions in Freiburg flap vaginal applicator was 1-5, with a median of 3. At the median follow-up of 54 months (range, 6-72 months), three-year local control and three-year overall survival were 90% and 75%, respectively. Nine patients (69.2%) were evaluated with grade 1 early side effects upon completion of treatment. For late side effects, one patient experienced grade 3 rectal and urinary side effects, with rectum and bladder D_2cc EQD₂ of 69.8 and 76.7 Gy. Another patient developed grade 3 rectal side effect, with rectum D_2cc EQD₂ of 63.2 Gy.

Conclusions: Based on the limited cohort, external beam radiotherapy (EBRT) combined with 3D HDR brachytherapy using Freiburg flap vaginal applicator with or without free-hand interstitial needles is an effective treatment option for patients with vaginal stump recurrence of cervical cancer.

Purpose: Displacement minimization of seeds is crucial during surgery in brachytherapy; however, only a few reports have compared the operability of different seeds. TheraStrand-SL is a seed, in which TheraAGX100 is wrapped in polyglactin 910 thread, and intra-prostatic displacement is expected to be reduced compared with that of Thera-AGX100, owing to the complex shape of TheraStrand-SL. We conducted a prospective study on the operability and treatment outcomes of TheraAGX100 and TheraStrand-SL placement by a single operator.

Material and methods: The study included 69 patients who received brachytherapy for prostate cancer. Endpoints were comparisons of intra- and post-treatment dose-volume histograms, seed displacement incidence rate, seed displacement distance, seed migration/dropout incidence rate, and adverse events incidence rate between TheraAGX100 (n = 25) and TheraStrand-SL (n = 44) groups.

Results: The intra-prostatic displacement incidence rate was significantly lower in the TheraStrand-SL group than in the TheraAGX100 group (TheraAGX100 group: 96.0%; TheraStrand-SL group: 11.4%). Further, the intra-prostatic displacement count per case tended to be lower in the TheraStrand-SL group than in the TheraAGX100 group. Additionally, a comparison of displacement distance per case showed that the TheraStrand-SL group (2.01 mm) had a statistically significantly shorter distance than the TheraAGX100 group (9.22 mm). No significant differences between the two groups were observed in terms of migration, explanted dropout seed count, dose-volume histograms, and adverse events incidence rate.

Conclusions: Our study demonstrated the usefulness of TheraStrand-SL against intra-prostatic displacement. We expect TheraStrand-SL to have further applications in brachytherapy, including focal therapy.

Purpose: This systematic review aimed to assess the feasibility, safety, and efficacy of using modern external beam radiotherapy (EBRT) techniques, such as intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic body radiotherapy (SBRT) as alternative approaches to brachytherapy (BRT) in adjuvant treatment of endometrial cancer (EC).

Material and methods: A systematic review was conducted following PRISMA guidelines. The research question was framed using the PICO method, focusing on patients with EC [P] and comparing modern EBRT techniques (IMRT, VMAT, SBRT) [I] vs. BRT [C], to evaluate their feasibility, safety, and effectiveness, particularly in terms of tumor local control (LC) [O]. Both planning and clinical outcomes, including acute toxicity, late side effects, and LC were analyzed with quality assessments performed using the GRADE framework and ROBINS-I tool.

Results: Planning studies revealed that while IMRT and VMAT provided comparable or improved target coverage and dose homogeneity compared with BRT, brachytherapy was associated with lower doses to critical organs. Post-operative SBRT and SIB-VMAT studies reported high LC rates (up to 100%) with minimal acute toxicity. However, the overall quality of evidence was low to very low, with significant risks of bias, mainly related to participant selection.

Conclusions: This review highlights that, although modern EBRT techniques, such as IMRT and VMAT are feasible alternative approaches to BRT for post-operative vaginal cuff irradiation, the current evidence does not support their superiority over BRT. Brachytherapy remains a highly effective treatment modality with well-established benefits. Future research should focus on more robust comparisons between EBRT and BRT, considering not only local control and toxicity, but also psychological impact and quality of life, especially in low-resource settings, where access to BRT may be limited.

Purpose: To investigate sensitivity of contributing factors to heterogeneity corrections in ocular brachytherapy using iodine-125 (¹²⁵I) Collaborative Ocular Melanoma Study (COMS) plaques.

Material and methods: Using egs_brachy, Monte Carlo (MC) simulations were performed for ¹²⁵I COMS plaques (model: IsoAid IAI-125A). Homogeneous dose (D_HOMO) was estimated under the American Association of Physicists in Medicine Task Group-43 assumptions, with 85 Gy prescribed to a 5 mm depth. Heterogeneous doses (D_HETERO#1-#7) were determined with medium-heterogeneity for the following scenarios: #1. Modulay backing (M) alone, #2. Silastic insert (S) alone, #3. Interseed attenuation effects (I) alone, #4. M + S, #5. M + I, #6. S + I, and #7. M + S + I. For scenarios #1-#7, heterogeneity correction factors (HCFs) were derived from D_HETERO#1-#7/D_HOMO for central axis points up to 22 mm, and for off-axis points (i.e., optic disc, macula, and lens) as a function of distance from tumor to optic disc (DT) or macula (MT), and tumor dimensions in the direction of optic disc (BD) or macula (BM).

Results: For a 16-mm diameter COMS plaque, in central axis, the dominant factor to heterogeneity corrections (dose reduction by 9.5-13.8% with heterogeneity) was Silastic insert at a depth ≤ 5 mm, whereas both Modulay backing and Silastic insert were contributing (range, 12.2-19.0%) at deeper depths. For off-axis, Silastic insert was the major factor to heterogeneity corrections (≥ 11.8%) at DT (MT) ≤ 6.9 (7.6) mm for optic disc (macula) and (range, 8.9-10.0%) at MT > 18.5 mm for lens, but both Modulay backing and Silastic insert were contributing (range, 18.3-24.4%) at farther DT (MT) for optic disc (macula) and (range, 12.8-18.2%) at MT ≤ 18.5 mm for lens. Interseed effects were small (≤ 1.7% for central axis and ≤ 2.3% for off-axis). Data for the other six plaques (10-14 mm and 18-22 mm diameter) presented similar trends.

Conclusions: The use of universal HCF(s) for the two dominant factors determined in this study will facilitate heterogeneous dose estimates for each clinical scenario without an MC tool.

Purpose: Currently, there are many schedules for exclusive vaginal cuff brachytherapy (VCB). In 3D treatment planning for VCB dosimetry, parameters have not been analyzed. The aim of this study was to compare the most common schedules using dose-volume histogram metrics.

Material and methods: Three different computed tomography (CT) studies for vaginal cylinders of 3.5 cm, 3 cm, and 2.5 cm were performed. Clinical target volume (CTV) was delineated for 3 cm and 4 cm of vaginal length. Twelve schedules were analyzed obtaining overall vaginal surface dose (Gy) (EQD₂ α/β = 10 and α/β = 3), overall D₉₀ CTV _{(α/β = 10)} (Gy), and overall D_{2cc (α/β = 3)} for organs at risk (OARs), such as vagina, rectum, sigmoid, rectum, and bladder. Prescription at 5 mm from the applicator surface and at the surface were analyzed for each case.

Results: The overall vaginal surface dose and dose to CTV varied widely among the different schedules, and CTV delineation was necessary in case of surface prescription. The applicator diameter of 3.5 cm showed the best dosimetry results for vaginal surface dose. The overall D_2cc OARs' doses changed in the different CT studies.

Conclusions: This dosimetry study allows for better selection of fractionation schedules, and helps to unify treatments among centers. Prospective studies are needed to establish the best schedule and CTV length in each patient using clinical data, such as late toxicity and relapses.

Purpose: For cervical cancer patients, intra-cavitary brachytherapy (ICBT) is utilized with various dose-rate systems, such as low-dose-rate (LDR), high-dose-rate (HDR), and pulsed-dose-rate (PDR). This retrospective analysis aimed to compare the therapeutic outcomes of cervical cancer patients treated with either LDR-, HDR-, or PDR-ICBT.

Material and methods: A total of 613 patients were treated with pelvic external beam radiation therapy (EBRT), followed by either LDR- (271 patients), HDR- (259 patients), or PDR- (83 patients) ICBT. Point-based planning was performed according to orthogonal radiographs in LDR patients, and computed tomography (CT) imaging in HDR and PDR patients. ICBT prescribed dose was as follows: for LDR treatment, 30 Gy in a single-session; for HDR: 7 Gy × 3 fractions (once a week fraction); and for PDR: 27 Gy in an hourly pulse of 70 cGy, with all the doses prescribed at point A. Radioactive source used was cesium-137 for LDR, and iridium-192 for HDR and PDR treatments.

Results: Loco-regional control (LRC) rate was 74%, 75%, and 77% in LDR, HDR, and PDR groups, respectively (p = 0.80). The 5-year overall survival (OS) in the three groups, i.e., LDR, HDR, and PDR was 63%, 64%, and 68%, respectively (p = 0.77). Severe late toxicity (RTOG grade ≥ 3) rate in the three groups was comparable (LDR, 12%; HDR, 8%; and PDR, 8.9%, p = 0.36).

Conclusions: Our study revealed comparable LRC, 5-year OS, and late toxicity rates using three dose-rate systems. Lower OS rates were observed in LDR group for stage III patients compared with patients in HDR and PDR groups. Therefore, we suggest that LDR should be used with caution while treating stage III patients.

Purpose: The aim of this study was to develop a new in-house low-cost surface mould, and to evaluate its performance and dosimetric properties for high-dose-rate (HDR) cobalt-60 (⁶⁰Co) brachytherapy.

Material and methods: A water-equivalent surface mould was developed using medical silicone. Mould performance and dosimetry characteristics were evaluated with Monte Carlo N-particle (MCNP2.6) simulation, Gafchromic™ EBT3 film measurements, and treatment planning system (TPS) output. Three sample moulds with different thicknesses (i.e., 0.5 cm, 1 cm, and 1.5 cm) were constructed, and a phantom study was performed. Treatment plans prescribing 3 Gy to 0.5 cm under pseudo-skin were designed, and film dosimetry was completed. TPS dose distributions were compared using Monte Carlo (MC) simulation and film dosimetry.

Results: Good consistency was observed between TPS results and film dosimetry at the prescribed depth of 0.5 cm, with mean differences of 0.70%, 0.40%, and 0.19% for mould thicknesses of 0.5 cm, 1 cm, and 1.5 cm, respectively. However, higher discrepancies were found at the phantom surface with 1.00%, 0.80%, and 0.56% dose differences for the considered mould thicknesses, respectively. These increased differences could be due to a higher dose gradient at the phantom surface, and a greater impact of uncertainties on the obtained results in this part. Moreover, mean differences between the results obtained from MC simulations and output of TPS at the prescribed depth of 0.5 cm were 0.73%, 0.60%, and 0.08% for mold thicknesses of 0.5 cm, 1 cm, and 1.5 cm, respectively. Higher variations were observed between TPS and MC at the phantom surface with 1.30%, 0.70%, and 0.13% dose differences for the considered mould thicknesses, respectively.

Conclusions: The developed surface mould demonstrated water equivalence at ⁶⁰Co energies, and was consistent with TPS calculations at routine treatment depths. Its effectiveness in non-melanoma skin cancer (NMSC) lesion treatment is highlighted. However, due to mould attenuation, TG-43-based TPS overestimated the dose delivered using this mould, especially at pseudo-skin surface, emphasizing the necessity for a model-based TPS algorithm.