High-dose-rate endorectal brachytherapy for locally advanced rectal cancer in previously irradiated patients

PurposePreoperative high-dose-rate (HDR) endorectal brachytherapy is well tolerated among patients with locally advanced rectal cancer. However, these studies excluded patients who previously received pelvic radiation therapy (RT). Because a favorable toxicity profile has been published for HDR endorectal brachytherapy, we evaluated this technique in patients who have previously received pelvic irradiation.Methods and MaterialsWe included patients who had received pelvic irradiation for a previous pelvic malignancy and later received preoperative HDR endorectal brachytherapy for rectal cancer. Brachytherapy was delivered to a total dose of 26 Gy in 4 consecutive daily 6.5 Gy fractions.ResultsWe evaluated 10 patients who previously received pelvic external beam radiation therapy (EBRT) alone (n=6), EBRT and brachytherapy (n=2), or brachytherapy alone (n=2). The median interval between the initial course of RT and endorectal brachytherapy was approximately 11 years (range, 1-19 years). Two patients experienced a complete pathologic response while 1 patient had a near complete pathologic response. No acute grade ≥3 toxicity was observed. No intraoperative or postoperative surgical complications were observed.ConclusionsPreoperative HDR endorectal brachytherapy is an alternative to EBRT for patients with locally advanced rectal cancer who have previously received pelvic RT.     

Radiobiological optimization comparison between pulse-dose-rate and high-dose-rate brachytherapy in patients with locally advanced cervical cancer

PurposeOnly scarce data are available on the possibility to include radiobiological optimization as part of the dosimetric process in cervical cancer treated with brachytherapy (BT). We compared dosimetric outcomes of pulse-dose-rate (PDR) and high-dose-rate (HDR)-BT, according to linear-quadratic model.Methods and MaterialsThree-dimensional dosimetric data of 10 consecutive patients with cervical cancer undergoing intracavitary image-guided adaptive PDR-BT after external beam radiation therapy were examined. A new HDR plan was generated for each patient using the same method as for the PDR plan. The procedure was intended to achieve the same D₉₀ high-risk clinical target volume with HDR as with PDR planning after conversion into dose equivalent per 2 Gy fractions (EQD2) following linear-quadratic model. Plans were compared for dosimetric variables.ResultsAs per study's methodology, the D₉₀ high-risk clinical target volume was strictly identical between PDR and HDR plans: 91.0 Gy (interquartile: 86.0–94.6 Gy). The median D₉₈ intermediate-risk clinical target volume was 62.9 Gy_EQD2 with HDR vs. 65.0 Gy_EQD2 with PDR (p < 0.001). The median bladder D_2cc was 65.6 Gy_EQD2 with HDR, vs. 62 Gy_EQD2 with PDR (p = 0.004). Doses to the rectum, sigmoid, and small bowel were higher with HDR plans with a median D_2cc of 55.6 Gy_EQD2 (vs. 55.1 Gy_EQD2, p = 0.027), 67.2 Gy_EQD2 (vs. S 64.7 Gy_EQD2, p = 0.002), and 69.4 Gy_EQD2 (vs. 66.8 Gy_EQD2, p = 0.014), respectively. For organs at risk (OARs), the effect of radiobiological weighting depended on the dose delivered. When OARs BT contribution to D_2cc doses was <20 Gy_EQD2, both BT modalities were equivalent. OARs EQD2 doses were all higher with HDR when BT contribution to D_2cc was ≥20 Gy_EQD2.ConclusionBoth BT modalities provided satisfactory target volume coverage with a slightly higher value with the HDR technique for OARs D2_cc while intermediate-risk clinical target volume received higher dose in the PDR plan. The radiobiological benefit of PDR over HDR was predominant when BT contribution dose to OARs was >20 Gy.     

Outcomes of freehand interstitial brachytherapy in advanced gynecologic malignancies

PurposeThe purpose of the study is to present the first results of freehand interstitial brachytherapy (ISBT) used to treat patients with carcinoma of the cervix and the vagina.Methods and MaterialsPatients diagnosed with carcinoma of the cervix or carcinoma of the vagina who were not suitable for intracavitary brachytherapy were treated with freehand ISBT. The implant was performed transperineally using C arm or transrectal ultrasound guidance. Patients received an external beam radiotherapy dose of 50 Gy in 25 fractions. The dose delivered by high-dose-rate ISBT was 18 Gy in three fractions, 6 Gy per fraction, 6 h apart. The brachytherapy dose volume parameters were analyzed after CT-based planning using GEC ESTRO image-guided brachytherapy-based guidelines.ResultsFrom June 2018 till November 2018, 14 patients were treated with freehand ISBT. The mean dose received by 90% of the high-risk clinical target volume (D₉₀) was 82 Gy EQD2₁₀ for patients with carcinoma of the cervix and 80 Gy EQD2₁₀ for patients with carcinoma of the vagina_. The mean dose received by 2 cc volume of the bladder and rectum was 80 Gy EQD2₃ and 70 Gy EQD2₃ for patients with carcinoma of the cervix and 75 Gy EQD2₃ and 72 Gy EQD2₃ for patients with carcinoma of the vagina, respectively. The mean dose received by 2 cc of the sigmoid was 65 Gy EQD2₃ for cervical carcinoma and 58 Gy EQD2₃ for vaginal carcinoma, respectively. At a median followup of 14 months, 2 patients developed local recurrence. Two patients developed Grade 2 gastro intestinal toxicity, and 1 patient developed Grade 2 genitourinary toxicity. None of the patients developed Grade 3 or 4 toxicities.ConclusionA freehand interstitial implant is feasible in resource limited settings and provides acceptable local control with minimal acute toxicity.     

High-dose-rate brachytherapy for localized prostate adenocarcinoma post abdominoperineal resection of the rectum and pelvic irradiation: Technique and experience

PurposeTreatment options are limited for patients with localized prostate cancer and a prior history of abdominoperineal resection (APR) and pelvic irradiation. We have previously reported on the successful utility of high-dose-rate (HDR) brachytherapy salvage for prostate cancer failing definitive external beam radiation therapy (EBRT). In this report, we describe our technique and early experience with definitive HDR brachytherapy in patients post APR and pelvic EBRT.Patients and MethodsSix men with newly diagnosed localized prostate cancer had a prior history of APR and pelvic EBRT. Sixteen to 18 HDR catheters were placed transperineally under transperineal ultrasound–guidance. The critical first two catheters were placed freehand posterior to the inferior rami on both sides of the bulbar urethra under cystoscopic visualization. A template was used for subsequent catheter placement. Using CT-based planning, 5 men received 36 Gy in six fractions as monotherapy. One patient initially treated with EBRT to 30 Gy, received 24 Gy in four fractions.ResultsMedian age was 67.5 (56–74) years. At a median followup of 26 (14–60) months, all patients are alive and with no evidence of disease per the Phoenix definition of biochemical failure, with a median prostate-specific antigen nadir of 0.19 ng/mL. Three men have reported grade 2 late genitourinary toxicity. There has been no report of grade 3–5 toxicity.ConclusionTransperineal ultrasound–guided HDR brachytherapy using the above technique should be considered as definitive therapy for patients with localized prostate cancer and a prior history of APR and pelvic EBRT.     

Can we reduce dose to ureters as avoidance organs for MRI based brachytherapy for cervical cancer? A dosimetric feasibility study

BACKGROUND AND PURPOSEUreteral stenosis (US) is an underreported complication of brachytherapy (BT) for cervical cancer (CC), with limited data on toxicity risk reduction. A previous study demonstrated ureter EQD2 D0.1cc > 77 Gy correlated with US development. We sought to assess feasibility of this constraint while maintaining similar HR-CTV coverage.MATERIALS AND METHODSPatients with locally advanced CC treated with EBRT plus HDR MRI-based brachytherapy boost without hydronephrosis at diagnosis and with ureter dose EQD2 D0.1cc > 77 Gy were included. Replan was attempted to achieve HR-CTV D90 ≥ 80–85 Gy and ureter dose reduction. Ureter distance from lateral margin of HR-CTV and tandem was recorded. t-test was performed to compare ureteral dose and HR-CTV D90.RESULTsOf 25 patients were identified. Hundred percent received 45 Gy in 25 fractions to the pelvis ± paraaortic lymph nodes and 80% receiving median additional parametrial dose of 5.4 Gy. Replan meeting ureteral dose of ≤77 Gy was feasible in 18 of 25 patients, with a reduction in median ureter D0.1cc from 82.3 to 76.8 Gy (p < 0.001). Median HR-CTV D90 was similar (84.7 vs. 85.0 Gy). Replan achieved D0.1cc ≤77 Gy in 56% of patients who experienced US. All unilateral US cases occurred in the ureter closest to HR-CTV.CONCLUSIONSOptimization to reduce ureter dose to ≤77 Gy is feasible when ureters are visible and contoured. Ureters may be considered as potential OAR during MRI-based brachytherapy treatment. Reduced ring to tandem total reference air kerma (TRAK) ratio may provide an additional metric by which to lower US risk.     

High-dose-rate interstitial brachytherapy for vaginal endometrial cancer recurrence after prior surgery and radiotherapy

PurposeCharacterize the clinical outcomes of endometrial cancer vaginal recurrences after previous surgery and radiation therapy treated with reirradiation including image-guided interstitial high-dose-rate (HDR) brachytherapy.Methods and materialsA single-institution retrospective study identifying women receiving reirradiation for vaginal recurrence of endometrial cancer between 2004 and 2017.ResultsTwenty-three women had vaginal recurrences of endometrial cancer, median 13.7 months (range 3.5–104.9) from initial radiation. All received reirradiation with interstitial HDR brachytherapy, and seven also received external beam radiation. Median reirradiation EQD2_10 was 48 Gy (range 24.0–68.81), and median cumulative EQD2_10 was 106.25 Gy (range 62.26–122.0). Median follow-up after reirradiation was 40.2 months (range 4.5–112.7). At 3 years, overall survival was 56%, cancer-specific survival was 61%, and disease-free survival was 46%. 14 patients experienced disease recurrence; 10 including distant sites, one at a regional node only. Three patients experienced local recurrences, two of whom did not complete the prescribed course of reirradiation. The overall crude local control rate was 87%. Three patients experienced Grade 3 vaginal toxicity. There was no bladder or rectal toxicity with Grade >2.ConclusionsReirradiation including interstitial HDR brachytherapy is a promising option for vaginal recurrences of endometrial cancer after prior radiation, with high rate of local control and acceptable toxicity. However, distant failure is common. Further studies are needed to determine cumulative radiation dose limits and the role of systemic therapy in this scenario.     

Image-guided brachytherapy following external-beam radiation therapy for patients with inoperable endometrial cancer

ObjectiveTo investigate the outcomes of definitive external-beam radiation therapy (EBRT) plus image-guided brachytherapy (IGBT) in patients with endometrial cancer (EC) unsuitable for surgery.MethodsA total of 50 patients with inoperable EC were included. The patients received EBRT in a median dose of 45 Gy to the pelvis over 5 weeks. Thereafter, the patients received brachytherapy using tandem and ovoid applicators. High-risk clinical target volume (HR-CTV) and gross tumor volume in brachytherapy (GTVp) were defined by the assistance of patients’ pre-IGBT magnetic resonance imaging.ResultsThe medical records of the 50 patients were analyzed. The main causes of inoperability were anesthesia contraindications, namely medical comorbidities and obesity. The median cumulative D90s (the minimum dose delivered to 90% of the volume) in EQD2 (equivalent dose in 2-Gy fractions) to the HR-CTV and GTVp were 72.9 Gy10 (range, 64.9 to 80.3) and 166.2 Gy10 (range, 123.0 to 189.8), respectively. Over a median follow-up period of 27 months, 8 of the patients died of cancer. The 2-year overall and cancer-specific survival rates were 75% and 83%, respectively. The cumulative incidences of pelvic and distant failure were 4% (n = 2) and 16% (n = 8), respectively. Gastrointestinal complications of grade 2 or above were noted in 2 patients (4%), and a grade 2 genitourinary complication was noted in one.ConclusionsFor patients with inoperable EC, EBRT followed by IGBT is an effective approach for achieving high local control without a high risk of complications.     

Deformable image registration–based contour propagation yields clinically acceptable plans for MRI-based cervical cancer brachytherapy planning

PurposeTo study the dosimetric impact of deformable image registration–based contour propagation on MRI-based cervical cancer brachytherapy planning.Methods and MaterialsHigh-risk clinical target volume (HRCTV) and organ-at-risk (OAR) contours were delineated on MR images of 10 patients who underwent ring and tandem brachytherapy. A second set of contours were propagated using a commercially available deformable registration algorithm. “Manual-contour” and “propagated-contour” plans were optimized to achieve a maximum dose to the most minimally exposed 90% of the volume (D₉₀) (%) of 6 Gy/fraction, respecting minimum dose to the most exposed 2cc of the volume (D_2cc) OAR constraints of 5.25 Gy and 4.2 Gy/fraction for bladder and rectum/sigmoid (86.5 and 73.4 Gy equivalent dose in 2 Gy fractions [EQD₂] for external beam radiotherapy [EBRT] + brachytherapy, respectively). Plans were compared using geometric and dosimetric (total dose [EQD₂] EBRT + brachytherapy) parameters.ResultsThe differences between the manual- and propagated-contour plans with respect to the HRCTV D₉₀ and bladder, rectum, and sigmoid D_2cc were not statistically significant (per-fraction basis). For the EBRT + brachytherapy course, the D_2cc delivered to the manually contoured OARs by the propagated-contour plans ranging 98–107%, 95–105%, and 92–108% of the dose delivered by the manual-contour plans (max 90.4, 70.3, and 75.4 Gy for the bladder, rectum, and sigmoid, respectively). The HRCTV dose in the propagated-contour plans was 97–103% of the dose in the manual-contour plans (maximum difference 2.92 Gy). Increased bladder filling resulted in increased bladder dose in manual- and propagated-contour plans.ConclusionsWhen deformable image registration–propagated contours are used for cervical brachytherapy planning, the HRCTV dose is similar to the dose delivered by manual-contour plans and the doses delivered to the OARs are clinically acceptable, suggesting that our algorithm can replace manual contouring for appropriately selected cases that lack major interfractional anatomical changes.     

Reirradiation using high-dose-rate brachytherapy in recurrent carcinoma of uterine cervix

PurposeTo assess the feasibility of reirradiation with image-based high-dose-rate brachytherapy in previously irradiated patients with recurrent carcinoma of uterine cervix.Methods and MaterialsThirty previously irradiated patients diagnosed with central recurrence were treated with reirradiation. Martinez Universal Perineal Implant Template was used in 24 patients and Vienna applicator in 6 patients. Median interval between two radiation schedules was 25 months. Median delivered dose was 42 Gy equivalent dose at 2 Gy (EQD2; interquartile range, 37–46 Gy EQD2).ResultsAll 30 patients tolerated reirradiation well. Complete response was seen in 23 (76%) patients. With a median followup of 25 months, 2-year local control, disease-free survival, and overall survival were 44%, 42%, and 52%, respectively. Fifteen patients developed local recurrences; Local control rate was significantly higher with doses >40 Gy EQD2 (52% vs. 34%; p = 0.05). Disease-free survival was better for patients with longer interval (>25 months) between two radiotherapy schedules. Grade III radiation proctitis and cystitis was seen in 3 patients each, and Grade II small bowel toxicity was seen in 3 patients.ConclusionsReirradiation using high-dose-rate brachytherapy is feasible with acceptable outcomes in isolated local recurrence deemed unsuitable for surgery. The outcome is better with higher doses.     

Clinical outcomes of high-dose-rate brachytherapy and external beam radiotherapy in the management of clinically localized prostate cancer

PurposeTo report prostate-specific antigen (PSA) relapse-free survival and treatment-related toxicity outcomes after combining high-dose-rate (HDR) brachytherapy with external beam radiotherapy (EBRT) for patients with clinically localized prostate cancer.Methods and MaterialsBetween 1998 and 2009, 229 patients were treated with HDR brachytherapy followed 3 weeks later by supplemental EBRT. The HDR brachytherapy boost consisted of three fractions of ¹⁹²Ir (5.5–7.5 Gy per fraction), and EBRT consisted of intensity-modulated radiotherapy delivering an additional 45.0–50.4 Gy directed to the prostate gland and seminal vesicles. Median follow-up was 61 months.ResultsSeven-year PSA relapse-free survival for low-, intermediate-, and high-risk patients were 95%, 90%, and 57%, respectively (p < 0.001). Among high-risk patients treated with biological equivalent doses in excess of 190 Gy, 7-year PSA relapse-free survival was 81%. In multivariate analysis, Gleason scores of ≥8 predicted for increased risk of biochemical failure, whereas the use of short-term neoadjuvant androgen deprivation therapy did not influence tumor-control outcomes even among intermediate- or high-risk patients. Seven-year incidence of distant metastases for low-, intermediate-, and high-risk patients were 5%, 3%, and 17%, respectively. Seven-year incidence of late Grade 2 and 3 genitourinary toxicities were 22.1% and 4.9%, respectively and the 7-year incidence of Grade 2 and 3 gastrointestinal toxicities were 1% and 0.4%, respectively.ConclusionHDR prostate brachytherapy in conjunction with supplemental EBRT results in excellent biochemical relapse-free survival rates with a low incidence of severe late genitourinary or gastrointestinal toxicities. The use of short-term neoadjuvant androgen deprivation did not influence long-term biochemical tumor control in this cohort.     

Risk factors for urethral stricture following external beam radiotherapy and HDR brachytherapy for prostate cancer

PurposeA potential late side effect of high-dose-rate (HDR) prostate brachytherapy combined with external beam radiotherapy (EBRT) is urethral stricture. The purpose of this study was to evaluate dosimetric parameters possibly contributing to stricture development, including dose to bladder base and D2cc(Gy) within 10 mm of prostatic urethra (D2cc _10 mm), which has, so far, not been reported in the literature.Methods and MaterialsPatients developing urethral stricture, and matched controls, were identified from a prospective database of those receiving 46 Gy in 23 fractions of EBRT, followed by a single 15 Gy HDR brachytherapy dose. Patients had locally advanced, high- and intermediate-risk prostate cancer. Brachytherapy treatment planning parameters (planning target volume (PTV) size (cm ³), V110(%) _{bladder base}, D2cc _10mm, number of HDR catheters, number of source dwell positions, and total source dwell time within 10 mm of the prostatic urethra) were analyzed to determine potential risk factors for urethral stricture.ResultsSeventy-two patients were treated, 22 of whom developed a urethral stricture. Univariate logistic regression performed on the planning parameters identified increased PTV size and D2cc _10 mm, with decreased V110(%) _{bladder base} as risk factors for stricture formation.ConclusionsIt is suggested that PTV size, V110(%) _{bladder base}, and D2cc _10mm are predictive of urethral stricture formation following EBRT and brachytherapy to the prostate. This study demonstrates the importance of minimizing high dwell times and hot spots close to organs at risk and also the correction of any craniocaudal movement of catheters to avoid potential hot spots in the bulbomembranous urethra where there may be increased dose sensitivity.     

Reporting of dose–volume specifications for “Martinez Universal Perineal Interstitial Template–based interstitial high-dose-rate brachytherapy for gynecological cancers” according to International Commission on Radiation Units and Measurements 58 with early clinical outcomes

PurposeThe study is an audit of reporting dose and volume specifications as per the ICRU 58 for MUPIT-based interstitial brachytherapy in gynecological cancers. Correlation between total reference air kerma (TRAK) and isodose surface was also evaluated to understand the intensity of treatment in interstitial brachytherapy.Methods and MaterialsForty-two patients underwent HDR MUPIT-based interstitial brachytherapy 20 Gy in five fractions after EBRT during 2017–2019. Treated volume, high and low-dose regions, mean central dose, Dose Homogeneity Index (DHI), organ at risk doses, and TRAK values were computed.ResultsHigh-dose regions V150 mean was 12.4 cc and V200 was 4.58 cc; and low-dose region was 75.92 cc. The mean treated volume was 59.8 cc. The mean central dose was 3.7 Gy. DHI was 79%. The mean D2cm³ bladder and rectum were 2.9 Gy and 2.8 Gy. The mean TRAK was 0.16 cGy per fraction per hour at 1 m. TRAK values showed significant correlation with various isodose volumes (TRAK and V100: r = 0.943 p < 0.0005; and TRAK and V50: r = 0.953; p < 0.0005). A positive correlation was observed between TRAK and the number of needles (r = 0.746; p < 0.0005). At a median followup of 16 months, 4 of 42 patients (9.5%) had local recurrences.ConclusionsOur study shows compliance with ICRU 58 recommendations along with certain deviations. Local recurrence rate is acceptable. TRAK shows correlation with surface isodose in MUPIT-based brachytherapy and should to be evaluated in future studies.     

Electronic brachytherapy for postsurgical adjuvant vaginal cuff irradiation therapy in endometrial and cervical cancer: A retrospective study

PurposeA new platform for brachytherapy called electronic brachytherapy (EBT) has been developed, which uses a miniature X-ray source to generate low-energy radiation. A retrospective study of adverse events and clinical outcomes in patients treated with EBT to the vaginal cuff, either as monotherapy or in combination with external beam radiation therapy (EBRT), was conducted.Methods and MaterialsMedical records were reviewed from 16 patients treated with postoperative EBT for endometrial (n = 13) or cervical cancer (n = 3) between February 2009 and November 2010. Patients received either intracavitary vaginal EBT alone or EBT in combination with EBRT. The radiobiologic effectiveness of EBT was assumed to be one.ResultsMedian follow-up was 20.5 months (range, 7–36 months). When EBT was used alone (n = 5), the median dose per fraction, number of fractions, and total dose delivered were: 6 Gy (range, 5.5–6.2 Gy), 5 fractions (range, 5–6), and 30 Gy (range, 30–34 Gy), respectively. When EBT was combined with EBRT, the EBT component median dose per fraction, number of fractions, and total dose delivered were: 5 Gy (range, 4.5–7 Gy), 2 fractions (range, 2–4), and 14 Gy (range, 9–20 Gy), respectively. The median EBRT dose was 45 Gy (range, 45–49.2 Gy). Our local control rate, locoregional (pelvic) control rate, and overall survival rate were 94%, 94%, and 88%, respectively. Of the 16 patients, 4 patients reported Grade 2 or greater toxicity (25%); however, there were no Grade 4–5 adverse events. Gynecologic, genitourinary, and gastrointestinal adverse events accounted for 57% (n = 4), 43% (n = 3), and 0% (n = 0) of all Grade 2 or greater side effects. No Grade 2 or higher toxicities were noted in patients treated with EBT alone.ConclusionEBT is an acceptable means of delivering postoperative vaginal brachytherapy and appears comparable with other methods; as the sole method of treatment, the toxicity rates of EBT are low.     

Efficacy of high-dose-rate interstitial brachytherapy in patients with oral tongue carcinoma

PurposeTo evaluate the results of high-dose-rate (HDR)-interstitial brachytherapy (ISBT) in oral tongue carcinomas.Methods and MaterialsBetween September 1999 and August 2007, 50 patients were treated for oral tongue carcinoma with HDR-ISBT. The patient's mean age was 58 years. Forty-two patients were in T1–2 stage and 8 patients were in T3 stage; 16 patients were in N+ stage and 34 patients in N0 stage. Exclusive ISBT was given to 17 patients (34%) in T1–2 N0 stage and complementary to external beam radiotherapy (EBRT) to 33 patients (66%). A perioperative technique was performed on 14 patients. The median total dose was 44 Gy when HDR was used alone (4 Gy per fraction) and 18 Gy when complementary to 50 Gy EBRT (3 Gy per fraction).ResultsThe median followup was 44 months. Actuarial disease-free survival rates at 3 and 5 years were 81% and 74%, respectively. Local failure developed in 7 patients. Actuarial local control (LC) rates were 87% and 79% at 3 and 5 years in T1–2 stage 94.5% and 91% and T3 stage 43% and 43% (with salvage surgery). Exclusive HDR cases showed LC in 100% of the cases, and the combined group (EBRT + HDR) showed LC in 80% and 69% of the cases at 3 and 5 years (p = 0.044). Soft-tissue necrosis developed in 16% and bone necrosis in 4% of the cases.ConclusionsHDR brachytherapy is an effective method for the treatment of oral tongue carcinoma in low-risk cases. Doses per fraction between 3 and 4 Gy yield LC and complication rates similar to low-dose rate. The perioperative technique promises encouraging results.     

A precise and simple isodose-volume-based verification method for HDR and LDR brachytherapy plans

PURPOSEThe American Association of Physicists in Medicine (AAPM) code of practice for brachytherapy physics recommends performing an independent treatment time calculation. For this we implemented an easy to use isodose-based verification method for HDR (high-dose-rate) and LDR (low-dose-rate) brachytherapy plans.MATERIAL AND METHODSDose-volume-based methods have been developed for Ir-192-based high-dose-rate (HDR) and I-125 prostate low-dose-rate (LDR) brachytherapy. They allow checking the integral dwell time or activity when the volume of a suitable isodose is known. The verification method was validated for 55 clinical HDR and 243 clinical LDR plans.RESULTSFor HDR brachytherapy, the mean absolute difference between the estimated and calculated integral dwell time was 0.8% ± 1.0% (n = 30) with a single-source path and 2.7% ± 1.1% (n = 25) for multiple source paths. The corresponding value for LDR brachytherapy was 1.8% ± 2.0% (n = 243). In HDR brachytherapy, the verification method depends slightly on the plan class when considering one or more than one source paths. Good agreement between the estimated and calculated integral dwell times was obtained based on the 2 Gy isodose. Unlike HDR brachytherapy, the parameters used in the verification method for LDR brachytherapy plan verification strongly depend on the type of seed distribution. So, we recommend using an isodose at the prescribed dose for prostate HDR therapy.CONCLUSIONSIsodose-based verification methods are precise, do not presuppose dedicated tools, and are simple to implement in clinical practice.     

High-dose-rate brachytherapy boost for carcinoma of external auditory canal

PurposeTo report dosimetry and outcome in a case of early stage carcinoma of external ear (T1N0M0) treated with radical radiotherapy alone using a combination of external beam radiotherapy (EBRT) and intracavitary irradiation with a high-dose-rate (HDR) ¹⁹²Ir remote afterloading system.Methods and MethodsA 64-year-old gentleman who was diagnosed as T1N0M0 carcinoma of external ear was treated with combination of external beam radiation therapy followed by brachytherapy (BRT). A total dose of 40 Gy was delivered by EBRT, following which a 6-Fr catheter for the HDR ¹⁹²Ir remote afterloader, fixed by a customized acrylic mold, was inserted into the external auditory canal (EAC) and a total intracavitary radiation dose of 22.5 Gy (4.5 Gy/F) was given.ResultsEvaluation at the completion of treatment and at the end of 4-year followup revealed no evidence of the disease.ConclusionsIn the radical treatment of early stage EAC carcinoma, combination of external beam radiation therapy and BRT may be a modality of choice for its efficacy, less severe side effects, and better cosmetic results.     

Postoperative management of keloids: Low-dose-rate and high-dose-rate brachytherapy

PurposeWe report the experience of the Radiation Oncology Department of the European Institute of Oncology in Milan, Italy, on the adjuvant low-dose-rate (LDR) and high-dose-rate (HDR) interstitial brachytherapy. Brachytherapy might be useful to improve keloids recurrence rate or reduce keloids treatment side effects instead of external beam radiotherapy.Methods and MaterialsData on 70 consecutive patients treated after complete keloid surgical excision were retrospectively analyzed. First 38 patients and 46 keloids were treated with adjuvant LDR brachytherapy and the following 39 patients and 50 keloids underwent HDR treatment. Median delivered dose of LDR therapy was 16 Gy; HDR median dose was 12 Gy. Sixty-four keloids (66.7%) were symptomatic at diagnosis with pain, itching, or stress.ResultsFourteen relapses over 46 treated keloids (30.4%) were observed in the LDR group and 19 of 50 keloids (38%) in the HDR group (p = 0.521). Recurrence rate was significantly higher in males (p = 0.009), in patients younger than 44 years (p < 0.0001), for arms, neck, and chest wall anatomic sites (p = 0.0001) and for symptomatic keloids (p = 0.017). Aesthetic outcome was better in case of larger keloids (>8 cm) (p = 0.064). Symptomatic relief was achieved in 92% of HDR patients and only 68% of LDR patients (p = 0.032).ConclusionsPostoperative brachytherapy is an effective treatment for keloids. In our study, LDR and HDR treatments resulted in similar recurrence rate. Better symptomatic relief was reported in case of HDR treatment compared with the LDR regimen.