Journal of Contemporary Brachytherapy最新文献

Purpose: Advances in three-dimensional image-guided brachytherapy technique allow for using intra-cavitary and interstitial brachytherapy (ICIS-BT), and sole interstitial brachytherapy (ISBT) in addition to conventional intra-cavitary brachytherapy (ICBT). However, no consensus has been reached regarding the choice of these techniques. The aim of this study was to propose the size criteria for indication of interstitial techniques.

Material and methods: We examined initial gross tumor volume (GTV) at presentation and at each brachytherapy session. Also, dose volume histogram parameters for each modality were compared in 112 patients with cervical cancer treated with brachytherapy (ICBT, 54; ICIS-BT, 11; and ISBT, 47).

Results: The average GTV at diagnosis was 80.9 cm³ (range, 4.4-343.2 cm³), which shrank to 20.6 cm³ (25.5% of initial volume, range, 0.0-124.8 cm³) at initial brachytherapy. GTV > 30 cm³ at brachytherapy and high-risk clinical target volume > 40 cm³ were good threshold values for indication of interstitial technique, and tumors with initial GTV > 150 cm³ could be candidates for ISBT. An ISBT dose of 89.10 Gy can be prescribed in equivalent dose in 2 Gy fractions (range, 65.5-107.6 Gy), which was higher than those of ICIS (73.94 Gy, range, 71.44-82.50 Gy) and ICBT (72.83 Gy, range, 62.50-82.27 Gy) (p < 0.0001).

Conclusions: Initial tumor volume is an important predictor for indication of ICBT and ICIS-BT. ISBT or at least an interstitial technique is recommended for initial GTV > 150 cm³.

Purpose: International guidelines recommend urethral dose volume constraints to minimize the risk of urinary toxicity after prostate brachytherapy. An association between dose to the bladder neck (BN) and toxicity has previously been reported, and we sought to evaluate the impact of this organ at risk on urinary toxicity, based on intra-operative contouring.

Material and methods: Rates of acute and late urinary toxicity (AUT and LUT, respectively) were graded according to CTCAE version 5.0 for 209 consecutive patients who underwent low-dose-rate (LDR) brachytherapy monotherapy, with approximately equal numbers treated before and after we began routinely contouring the BN. AUT and LUT were compared in patients treated before and after we began contouring the OAR, and also for those treated after we began contouring who had a D_2cc of greater than or less than 50% prescription dose.

Results: AUT and LUT fell after intra-operative BN contouring was instituted. Rates of grade ≥ 2 AUT fell from 15/101 (15%) to 9/104 (8.6%), p = 0.245. Grade ≥ 2 LUT decreased from 32/100 (32%) to 18/100 (18%), p = 0.034. Grade ≥ 2 AUT was observed in 4/63 (6.3%) and 5/34 (15%) of those with a BN D_2cc >/≤ 50%, respectively, of prescription dose. Corresponding rates for LUT were 11/62 (18%) and 5/32 (16%).

Conclusions: There were lower urinary toxicity rates for patients treated after we commenced routine intra-operative contouring of the BN. No clear relationship was observed between dosimetry and toxicity in our population.

Purpose: Locally recurrent prostate cancer after previous radiation therapy remains challenging. One of the curative options for these patients is salvage brachytherapy. There are no reports available on the use of a biodegradable rectal balloon implantation (RBI) in combination with brachytherapy in patients with recurrent prostate cancer after previous radiotherapy.

Case presentation: Here, we report on a patient with a local recurrence at five years after previous low-dose-rate brachytherapy with a prescribed dose of 145 Gray (Gy) for a low-risk prostate adenocarcinoma. The patient experienced grade 3 rectal toxicity, which was resolved at the time of local recurrence. He was treated with focal high-dose-rate (HDR) brachytherapy of 2 fr. × 13 Gy after RBI implantation. Four years post-salvage treatment, there was no evidence of biochemical recurrence according Phoenix definition, and no gastro-intestinal or genitourinary toxicity.

Conclusions: This case describes the use of RBI implantation in combination with a focal salvage HDR in a patient with recurrent disease, with significant initial grade 3 rectal toxicity after previous irradiation. The use of a biodegradable RBI proved to be a promising solution for such a patient; however, this method needs to be further investigated.

Purpose: To report an intra-operative catheter insertion technique into the base of skull tumor bed following surgical resection for maxillary tumors.

Material and methods: A 42-year-old male patient diagnosed with carcinoma of the maxilla was treated with neoadjuvant chemotherapy followed by chemo-radiation using external beam technique combined with brachytherapy boost to post-operative bed. Brachytherapy was delivered via intra-operative catheter placement at the base of skull to residual disease, which was surgically unresectable. Initially, catheters were placed cranio-caudally. This was later changed into an infra-zygomatic approach to improve planning and dose coverage. High-risk clinical tumor volume (CTV) was generated with a 3 mm margin to residual gross tumor. Planning was done using Varian Eclipse brachytherapy planning system, and an optimal plan was generated.

Conclusions: An innovative, beneficial, and safe brachytherapy approach is necessary in a difficult and critical area, such as the base of skull. Our novel method of implant insertion through infra-zygomatic approach resulted in a safe and successful procedure.

Purpose: Manufacturing of miniaturized high activity iridium-192 (¹⁹²Ir) sources have been made a market preference in modern brachytherapy. Smaller dimensions of the sources are flexible for smaller diameter of the applicators, and it is also suitable for interstitial implants. Presently, cobalt-60 (⁶⁰Co) sources have been commercialized as an alternative to ¹⁹²Ir sources for high-dose-rate (HDR) brachytherapy, since ⁶⁰Co source have an advantage of longer half-life comparing with ¹⁹²Ir source. One of them is the HDR ⁶⁰Co Flexisource manufactured by Elekta. The purpose of this study was to compare the TG-43 dosimetric parameters of HDR flexi ⁶⁰Co and HDR microSelectron ¹⁹²Ir sources.

Material and methods: Monte Carlo simulation code of Geant4 (v.11.0) was applied. Following the recommendations of AAPM TG-43 formalism report, Monte Carlo code of HDR flexi ⁶⁰Co and HDR microSelectron ¹⁹²Ir was validated by calculating radial dose function, anisotropy function, and dose-rate constants in a water phantom. Finally, results of both radionuclide sources were compared.

Results: The calculated dose-rate constants per unit air-kerma strength in water medium were 1.108 cGy h^-1U^-1 for HDR microSelectron ¹⁹²Ir, and 1.097 cGy h^-1U^-1 for HDR flexi ⁶⁰Co source, with the percentage uncertainty of 1.1% and 0.2%, respectively. The values of radial dose function for distances above 22 cm for HDR flexi ⁶⁰Co source were higher than that of the other source. The anisotropic values sharply increased to the longitudinal sides of HDR flexi ⁶⁰Co source, and the rise was comparatively sharper to that of the other source.

Conclusions: The primary photons from the lower-energy HDR microSelectron ¹⁹²Ir source have a limited range and are partially attenuated when considering the results of radial and anisotropic dose distribution functions. This implies that a HDR flexi ⁶⁰Co radionuclide could be used to treat tumors beyond the source compared with a HDR microSelectron ¹⁹²Ir source, despite the fact that ¹⁹²Ir has a lower exit dose than HDR flexi ⁶⁰Co radionuclide source.

Purpose: To determine the quality of life (QoL) of patients with muscle-invasive bladder cancer (MIBC) who underwent bladder-sparing treatment with high-dose-rate brachytherapy, and compare their QoL with an age-matched general Dutch population.

Material and methods: We conducted a single-center, prospective, descriptive cross-sectional study. MIBC patients who underwent brachytherapy-based bladder sparing treatment in Arnhem, The Netherlands from January 2016 to June 2021, were requested to complete the following questionnaires: European Organization for Research and Treatment of Cancer (EORTC) generic (QLQ-C30), bladder cancer-specific (QLQ-BLM30), and expanded prostate cancer index composite bowel (EPIC-50). Mean scores were calculated and compared with general Dutch population.

Results: The mean global health status/QoL score of the treated patients was 80.6. High scores were noted in the functional scales, including physical (86.8), role (85.6), emotional (88.6), cognitive (88.3), and social functioning (88.9), while the main reported complains were related to fatigue (21.9) and urinary symptoms (25.1). Compared to the general Dutch population, significant differences were visible in global health status/QoL (80.6 vs. 75.7), pain (9.0 vs. 17.8), insomnia (23.3 vs. 15.2), and constipation (13.3 vs. 6.8). However, in no case did the mean score differ by more than ten points, which was considered clinically relevant.

Conclusions: With a mean global health status/QoL score of 80.6, the patients after brachytherapy-based bladder sparing treatment have a good QoL. We found no clinically relevant difference in QoL comparing with an age-matched general Dutch population. The outcome strengthens the idea that this treatment option should be discussed with all patients eligible for brachytherapy-based treatment.

Purpose: To identify efficacy, complication, and pathologic response of high-dose-rate endorectal brachytherapy (HDR-BRT) boost in neo-adjuvant chemoradiotherapy (nCRT) of locally advanced rectal cancer.

Material and methods: Forty-four patients who met eligibility criteria were included in this non-randomized comparative study. Control group was recruited retrospectively. nCRT (50.40 Gy/28 fr. plus capecitabine 825 mg/m² twice daily) was administered to both groups before surgery. In the case group, HDR-BRT (8 Gy/2 fr.) was supplemented after chemoradiation. Surgery was done 6-8 weeks after completion of neo-adjuvant therapy. Pathologic complete response (pCR) was the study's primary endpoint.

Results: From 44 patients in the case and control groups, pCR was 11 (50%) and 8 (36.4%), respectively (p = 0.27). According to Ryan's grading system, tumor regression grade (TRG) TRG1, TRG2, and TRG3 were 16 (72.7%), 2 (9.1%), and 4 (18.2%) in the case, and 10 (45.5%), 7 (31.8%), and 5 (22.7%) in the control group (p = 0.118). T down-staging was found in 19 (86.4%) and 13 (59.1%) patients in the case and control groups, respectively. No grade > 2 toxicity was identified in both the groups. Organ preservation was achieved in 42.8% and 15.3% in the case and control arm (p = 0.192). In the case group, 8-year overall survival (OS) and disease-free survival (DFS) were 89% (95% CI: 73-100%) and 78% (95% CI: 58-98%), respectively. Our study did not reach median OS and median DFS.

Conclusions: Treatment schedule was well-tolerated, and neo-adjuvant HDR-BRT could achieve better T down-staging as a boost comparing with nCRT, without significant complication. However, the optimal dose and fractions in the context of HDR-BRT boost needs further studies.

Purpose: The purpose of this study was to investigate the precision of deep learning (DL)-based auto-reconstruction in localizing interstitial needles in post-operative cervical cancer brachytherapy (BT) using three-dimensional (3D) computed tomography (CT) images.

Material and methods: A convolutional neural network (CNN) was developed and presented for automatic reconstruction of interstitial needles. Data of 70 post-operative cervical cancer patients who received CT-based BT were used to train and test this DL model. All patients were treated with three metallic needles. Dice similarity coefficient (DSC), 95% Hausdorff distance (95% HD), and Jaccard coefficient (JC) were applied to evaluate the geometric accuracy of auto-reconstruction for each needle. Dose-volume indexes (DVI) between manual and automatic methods were used to analyze the dosimetric difference. Correlation between geometric metrics and dosimetric difference was evaluated using Spearman correlation analysis.

Results: The mean DSC values of DL-based model were 0.88, 0.89, and 0.90 for three metallic needles. Wilcoxon signed-rank test indicated no significant dosimetric differences in all BT planning structures between manual and automatic reconstruction methods (p > 0.05). Spearman correlation analysis demonstrated weak link between geometric metrics and dosimetry differences.

Conclusions: DL-based reconstruction method can be used to precisely localize the interstitial needles in 3D-CT images. The proposed automatic approach could improve the consistency of treatment planning for post-operative cervical cancer brachytherapy.

Purpose: As the oncological results of prostate brachytherapy (BT) are excellent for low-risk (LR) or favorable intermediate-risk (FIR) prostate cancer (PCa), evaluating the side effects has become a major issue, especially for young men. The objective of the study was to compare the oncologic and functional results of BT using Quadrella index for patients aged 60 or less compared with older patients.

Material and methods: From June, 2007 to June, 2017, 222 patients, including 70 ≤ 60 years old and 152 > 60 years old, underwent BT for LR-FIR PCa, with good erectile function at baseline according to International Index of Erectile Function-5 (IIEF-5) > 16. Quadrella index was achieved under the following circumstances: 1) Absence of biological recurrence (Phoenix criteria); 2) Absence of erectile dysfunction (ED) (IIEF-5 > 16); 3) No urinary toxicity (international prostate score symptom) IPSS < 15 or IPSS > 15, and ΔIPSS < 5; 4) No rectal toxicity (RT) (Radiation Therapy Oncology Group, RTOG = 0). Patients were treated on demand with phosphodiesterase inhibitors (PDE5i) post-operatively.

Results: The Quadrella index was satisfied for about 40-80% of patients ≤ 60 years vs. 33-46% for older patients during 6-year follow-up (significant difference from the second year). At year 5, 100% of evaluable patients aged ≤ 60 and 91.8% > 60 (p = 0.29) reached Phoenix criteria. The criterion of ED (IIEF-5 < 16) largely explained the validity rate of Quadrella alone. There was no ED for 67.2-81.4% of patients ≤ 60 years compared with 40.0-56.1% for patients > 60 (significant difference since year 4 in favor of young men). After two years of follow-up, more than 90% of patients in both the groups showed neither urinary nor rectal toxicities.

Conclusions: For young men displaying LR-FIR PCa, BT appears to be a first-class therapeutic option, as the oncological results were at least equivalent to those of older patients with good long-term tolerance.

Purpose: The incidence of local prostate cancer recurrences after monotherapy with high-dose-rate brachytherapy (HDR-BT) is low. However, a cumulated number of local recurrences during follow-up is naturally observed in highly specialized oncological centers. This retrospective study aimed to present the treatment of local recurrences after HDR-BT with low-dose-rate brachytherapy (LDR-BT).

Material and methods: Nine patients with low- and intermediate-risk prostate cancer with a median age of 71 years (range, 59-82 years) were diagnosed with local recurrences after previous monotherapy HDR-BT, 3 × 10.5 Gy (from 2010 to 2013). Median time to biochemical recurrence was 59 months (range, 21-80 months). All patients received 145 Gy with salvage LDR-BT (iodine-125). Gastrointestinal and urological toxicities were evaluated based on patients' records following CTCAE v. 4.0 and IPSS scales.

Results: The median follow-up after salvage treatment was 30 months (range, 17-63 months). Local recurrences (LR) were detected in two cases, and the actuarial 2-year local control was 88%. Biochemical failure was observed in four cases. Distant metastases (DM) were observed in 2 patients. In one patient, both LR and DM were diagnosed simultaneously. Four patients had no relapse of the disease, and a 2-year disease-free survival (DSF) was 58.3%. Before salvage treatment, median IPSS scores were 6.5 points (range, 1-23 points). At the first follow-up visit, after one month, the mean IPSS score was 20 points, and at the last follow-up visit, it was 8 points (range, 1-26 points). One patient had urinary retention after treatment. There was no significant change in IPSS scores before and after the treatment (p = 0.68). Two patients had grade 1 toxicity in the gastrointestinal tract.

Conclusions: Salvage LDR-BT for patients with prostate cancer previously treated with HDR-BT monotherapy is characterized by acceptable toxicity, and may result in local disease control.