β和γ射线照射肿瘤细胞的生物效应比较

目的 比较低剂量率β射线和高剂量率γ射线照射诱发肿瘤细胞生物效应特点。方法采用^32Pβ射线和^60Coγ射线照射人宫颈癌HeLa细胞系，用台盼蓝排除法和X-gal衰老细胞染色法比较两种照射肿瘤细胞死亡方式的差异。结果 ^32Pβ射线(0．375cGy/min)和^60Coγ射线(206cGy/min)照射HeLa细胞后72h的结果表明，低剂量率β射线抑制细胞增殖为渐进性，使多数的细胞在一个或几个细胞倍增周期后死亡，以增殖性死亡为主；高剂量率γ射线对细胞的抑制作用直接、迅速，细胞坏死比例高，增殖性死亡(衰老)比例低于持续低剂量照射方式。结论 不同的辐射方式对细胞的杀伤方式不同，了解其放射生物学机理有助于临床治疗方案的选择。     

Dosimetry modeling for focal high-dose-rate prostate brachytherapy

PurposeThe dosimetry of focal high-dose-rate prostate brachytherapy was assessed. Dose volume histogram parameters, robustness to source position errors, and Monte Carlo (MC) simulations were compared for whole-gland (WG), hemi-gland (HEMI), and ultra-focal (UF) treatment plans.Methods and MaterialsTumor volumes were delineated based on MRI and template biopsy results for 9 patients. WG, HEMI, and UF plans were produced assuming 19 Gy single fraction monotherapy treatments. For UF plans, a 6-mm margin was applied to the visible tumor to create a focal-planning target volume (F-PTV). Systematic source position shifts of 1–4 mm were applied to assess plan robustness. The dosimetric impact of steel catheters was assessed using MC simulation.ResultsMean D₉₀ and V₁₀₀ were 20.4 Gy and 97.9% for prostate in WG plans, 22.2 Gy and 98.1% for hemi-prostate in HEMI plans, and 23.0 Gy and 98.2% for F-PTV in UF plans. Mean urethra D₁₀ was 20.3, 19.7, and 9.2 Gy in WG, HEMI, and UF plans, respectively. Mean rectal D_2cc was 12.5, 9.8, and 4.6 Gy in WG, HEMI, and UF plans, respectively. Focal treatment plans were sensitive to source position errors—2 mm systematic shifts reduced mean prostate D₉₀ by 0.7%, hemi-prostate D₉₀ by 2.6%, and F-PTV D₉₀ by 8.3% in WG, HEMI, and UF plans, respectively. MC simulation results were similar for all plan types with most dose volume histogram parameters reduced by <2%.ConclusionsHEMI and UF treatments can achieve higher D₉₀ values compared with WG treatments with reduced organ at risk dose. Focal treatments are more sensitive to systematic source position errors than WG treatments.     

Individualized 3D-printed templates for high-dose-rate interstitial multicathether brachytherapy in patients with breast cancer

Purpose

High-dose-rate, multicatheter interstitial brachytherapy is technically complex and operator-dependent, requiring lengthy training and specialized skills. Furthermore, until the advent of contouring on computerized tomography (CT) images, difficulties existed in locating the target volume precisely. The present article reports the results of a study that aimed at producing and validating a 3D-printed template to aid in target volume localization for multicatheter interstitial brachytherapy in patients with breast cancer.

Perioperative high-dose-rate brachytherapy in locally advanced and recurrent gynecological cancer: Final results of a Phase II trial

PurposeTo determine the long-term results of a Phase II trial of perioperative high-dose-rate brachytherapy (PHDRB) in primary advanced or recurrent gynecological cancer.Methods and MaterialsFifty patients with locally advanced and recurrent gynecological cancer suitable for salvage surgery were included. Unirradiated patients (n = 25) received preoperative chemoradiation followed by surgery and PHDRB (16–24 Gy). Previously irradiated patients (n = 25) received surgery and PHDRB alone (32–40 Gy).ResultsMedian followup was 11.5 years. Eight unirradiated patients (32%) developed Grade ≥3 toxic events including two fatal events. Local and locoregional control rates at 16 years were 87.3% and 78.9%, respectively. Sixteen-year disease-free and overall survival rates were 42.9% and 46.4%, respectively. Ten previously irradiated patients (40.0%) developed Grade ≥3 adverse events, including four fatal events. Local and locoregional control rates at 14 years were 59.6% and 42.6%, respectively. Fourteen-year disease-free and overall survival rates were 16.0% and 19.2%, respectively.ConclusionsPHDRB allows effective salvage of a subset of unfavorable gynecological tumors with high-risk surgical margins. Toxicity was unacceptable at the initial dose levels but deescalation resulted in the absence of severe toxicity without a negative impact on locoregional control. A substantial percentage of patients remain alive and controlled at >10 years including a few previously irradiated cases with positive margins.     

Interstitial high-dose-rate brachytherapy in the treatment of keloids: Moving toward a volumetric approach

PurposeBrachytherapy (BT) after surgical resection of keloids reduces the risk of local recurrence, but standardization of dose/technique is lacking. Typical keloid BT treatment utilizes a single-channel source prescribed to 5-mm depth. We investigated the dosimetry of a volume-based target definition for interstitial high-dose-rate BT treatment of keloids.Methods and MaterialsWe retrospectively identified consecutive 14 patients who had a total of 20 keloids treated with interstitial high-dose-rate BT for keloids at our institution between 2004 and 2014. Keloids were treated with a single 8 Gy fraction prescribed to 5 mm beneath the scar within 36 h of surgery. Retrospectively, a 3-mm skin high-risk clinical target volume (HR-CTV) was contoured under the scar for volume-based dose calculations.ResultsMean (SD) HR-CTV was 3.91 cm³ (3.1) and mean (SD) HR-CTV dose was 11.3 Gy (3.6). Mean D₉₀ (SD) was 62.9% (25.8) and mean V₁₀₀ (SD) was 56.5% (26.4). The mean V₁₅₀ (SD), V₂₀₀ (SD), and V₃₀₀ (SD) were as follows: 37.6% (19.9), 25.1% (14.4), and 11.3% (6.5), respectively. No local failures were reported at 9 months median followup. There were no Grade 2 or higher late toxicities.ConclusionsUsing a volume-based target definition, a wide range of target coverage was observed. This is likely a consequence of the curvature of the skin and the challenges of keeping the catheter equidistant from the skin across the target. Additional data are needed to define the potential clinical impact on outcomes/toxicities of dosimetric correlates with single-catheter BT keloid treatment.     

Image-guided interstitial high-dose-rate brachytherapy for dose escalation in the radiotherapy treatment of locally advanced lung cancer: A single-institute experience

PurposeTo evaluate the clinical outcome after CT-guided interstitial high-dose-rate (HDR) brachytherapy for dose escalation in the radiotherapy treatment of inoperable locally advanced non–small-cell lung cancer (NSCLC).Methods and MaterialsFrom 2005 to 2015, 16 patients with unresectable NSCLC were treated. Median age was 65.7 years (range, 52–86). The median tumor volume was 95.3 cm³ (range, 20.0–2000.0). The median prescribed HDR was 15.0 Gy (range, 7.0–32.0) delivered in twice-daily fractions of 6.0–8.0 Gy in 4 patients and in once-daily fractions of 7.0–15.0 Gy in 12 patients, respectively.ResultsAfter a median followup of 12.5 months, median overall survival and local control was 12.9 and 24.9 months, respectively. The corresponding median overall survival and local control rates at 1, 2, and 3 years were 56.2%, 37.5%, and 12.5% as well as 68.9%, 57.4%, and 43%, respectively. Apart from one Grade 1 cough episode persisting for 1 week and one patient developing a minor hemopneumothorax requiring no postprocedural drainage, no other adverse events were recorded.ConclusionsCT-guided interstitial HDR brachytherapy is a safe modality for radiation dose escalation which may play a role in the definitive radiotherapy treatment of locally advanced NSCLC.     

Nineteen-year single-center experience in 76 patients with penile cancer treated with high-dose-rate brachytherapy

PURPOSETo report the outcomes for 76 patients with penile cancer treated with high-dose-rate brachytherapy (HDR-BT) at a single institution.METHODSSeventy-six patients with penile cancer treated with HDR-BT in our department between October 1998 and September 2018 were analyzed. Seventy underwent interstitial HDR-BT (fractionation dose range of 3–3.5 Gy given twice a day with an interval of at least six hours between the fractions), and six underwent superficial treatment with mold applicators (fractionation dose range of 4–7 Gy given once or twice a week).RESULTSMedian follow-up was 76 months (7–204 months). In the whole group, 22/76 local failures (28.9%) were observed: 14/76 (18.4%) local recurrences and 8/76 (10.5%) cases of persistent disease. Median time to recurrence was 24 months (9–54 months). Inguinal lymph node metastases were observed in 18/76 cases (23.7%). Distant metastases occurred in 12/76 (15.8%) cases. Patients with local recurrence and persistent disease underwent salvage penectomies, except four who refused surgery and underwent a second course of interstitial HDR-BT. Five- and 10-year cause-specific survival were 85.0% and 77.8%, respectively. Local control at 5 and 10 years was 65.6%. Five- and 10-year penile preservation were 69.5% and 66.9%, respectively. There was no G3 or G4 acute toxicity. One urethral stenosis (1.3%) occurred in a patient with a T3 tumor and was treated successfully with dilatation.CONCLUSIONSHDR-BT provides good local control of penile cancer and is a good option for penis preservation therapy and in our experience achieves a penile preservation rate at 10 years of 66.9%.     

中晚期宫颈癌 CT 引导下三维插植高剂量率后装近距离放疗的临床价值

目的 探讨 CT 引导下三维插植高剂量率后装近距离放疗（HDR-ISBT）在治疗中晚期宫颈癌中的临床价值。 方法以 2011 年 12 月 1 日至 2014 年 12 月 30 日收治的 175 例中晚期宫颈癌患者为研究对象,其中 100 例行体外三维适形调强放疗（IMRT）+HDR-ISBT（A 组）,75 例行 IMRT+ 常规后装近距离放疗（B 组）,比较两组患者的疗效与不良反应。 结果 近期疗效：A 组完 全缓解（CR）95 例,部分缓解（PR）2 例,稳定（SD）1 例,进展（PD）2 例;B 组 CR 55 例,PR 10 例,SD 4 例,PD 6 例。肿瘤直径≥4cm 时,A 组有效率为 95.24%,高于 B 组的 80.00%（P=0.026）。A 组部分患者出现轻中度膀胱反应、直肠反应、骨髓毒性等近期不良反应, 但均能耐受。 结论 当宫颈癌肿瘤直径≥4cm 时,HDR-ISBT 近期疗效优于常规后装近距离放疗,不良反应轻且可耐受。