The American Brachytherapy Society recommendations for low-dose-rate brachytherapy for carcinoma of the cervix

High-Dose-Rate Brachytherapy in Cervical and Endometrial Cancer Patients: A Retrospective Study From a Tertiary Cancer Center in the UAE

Purpose This study evaluates the therapeutic outcomes and practical application of high-dose-rate (HDR) brachytherapy in managing cervical and endometrial cancers at a tertiary hospital in the UAE, focusing on treatment efficacy, safety, and patient-reported outcomes. Methods A retrospective analysis was conducted on 368 female patients treated between January 2008 and January 2022. Data included demographic information, cancer type, histopathology, treatment details, and survival outcomes. Statistical analyses were performed using descriptive and inferential statistics. Results The cohort comprised 275 cervical cancer patients (74.73%) and 93 endometrial cancer patients (25.27%). The majority were non-nationals (79.62%). The mean age was 57 years. Squamous cell carcinoma was the most common histopathological type (63.59%). HDR brachytherapy was administered to 290 patients (79.89%). The 12-month survival probability was significantly higher in the HDR-Brachy group (75%, 95% CI: 60% to 85%) compared to the noHDR-Brachy group (50%, 95% CI: 35% to 65%), with a hazard ratio of 0.953 (p=0.0035). At the last review, 86.68% of patients were alive, and disease progression was observed in 37.88% of patients. Conclusion HDR brachytherapy significantly improves survival outcomes in cervical and endometrial cancer patients. Continued efforts to enhance access and standardize brachytherapy protocols are essential to optimize treatment efficacy and patient outcomes in similar healthcare settings.

Dosimetry investigation of a prototype of 169Yb seed brachytherapy for use in circular stapler

This study aims to investigate dosimetry parameters for the new design of ¹⁶⁹Yb seed in the form of a surgical staple for circular staplers commonly used in the abdominal incision and the esophageal and gastric surgery, which facilitates the precise placement. This seed includes a titanium tube with the inner diameter and outer diameter 0.68 mm and 2.2 mm, respectively, and length of 0.8 mm. Both sides of the tube are closed by titanium wires with the thickness of 0.65 mm by the laser. Natural ytterbium oxide is used after the thermal neutron activation; it is necessary for cooling time of 40 days. The dosimetry parameters were calculated based on the TG-43U1 using Monte Carlo MCNP5 code. The experimental dosimetry was performed by EBT3 radiochromic film to determine 2D dosimetry at near distance of the source and validate the MC code. The dose rate constant of MC calculation was obtained at 1.39cGyh^-1U^-1 ± 4% with the difference of 5% compared to another study. The dose distribution was symmetrical along the Z-axis and Y-axis (around the seed) and there was a uniform activity inside the tube. The distinction of dose rate was not noticeable at the 90 and 270 degrees on the Z-axis, which indicated a slight effect on staple legs in the matter of delivery dose. However, to understand dose distribution and introduce this source in a pre-clinical study, 3D dosimetry as well as further studying the heterogeneous function is required.

Vaginal dose-surface maps in cervical cancer brachytherapy: Methodology and preliminary results on correlation with morbidity

PURPOSE

The purpose of the study was to develop a methodology for vaginal dose-surface maps (DSMs) in patients with cervix cancer and to investigate dose-surface histogram metrics as predictors for vaginal stenosis (St) and mucositis (Muc).

METHODS AND MATERIALS

Thirty-one patients with locally advanced cervix cancer with no vaginal St/Muc (CTCAE-v3) G ≥ 2 at baseline were analyzed. Patients were divided in four morbidity groups: 15 with St/Muc G0/1, 6 with St G ≥ 2, 4 with St/Muc G ≥ 2, and 6 with Muc G ≥ 2. Patients received external beam radiotherapy and 4-fraction intracavitary/interstitial high-dose-rate brachytherapy using tandem and ovoids. DSMs were generated from inner/outer vaginal surfaces. DSMs of external beam radiotherapy and brachytherapy (Gy EQD2₃) were added based on a system of homologous points, to generate cumulative DSMs. Dose-surface histogram/dose-volume histogram parameters, location of high/intermediate-dose regions, rectovaginal reference point, vaginal lateral 5 mm point doses, and vagina/implant dimensions were investigated for St and Muc prediction. Average/difference DSMs and one-way analysis of variance were used to compare between groups.

RESULTS

Best predictors of stenosis were D_15-25cm2 and upper-vagina S_65-120Gy(%). Cutoffs of ∼90 Gy EQD2₃ for D_20cm2 and ∼80% for S_65Gy to top 3 cm inner vaginal surface suitably discriminated for stenosis. Spatial dose location on average/difference DSMs showed significantly higher doses (by > 20 Gy, p < 0.001) over longer parts of the dorsolateral vagina and higher rectovaginal reference point doses for any G ≥ 2 morbidity, over the whole circumference of the upper vagina for G ≥ 2 stenosis. Dose-volume histogram parameters were dependent on vaginal wall thickness. An increase of wall thickness from 2 to 4 mm resulted in an increase of D_2cm3 (D_4cm3) of 16% (32%).

CONCLUSIONS

A novel method was developed to generate vaginal DSMs and spatial-dose metrics. DSMs were found to correlate with vaginal stenosis. The findings of this study are promising and should be further validated on a larger patient cohort, treated with different applicators.

Outcomes of patients with cervical cancer treated with low- or high-dose rate brachytherapy after concurrent chemoradiation

OBJECTIVE

The majority of patients with cervical cancer in Ghana present with locally advanced disease. In October 2014, high-dose rate (HDR) brachytherapy was introduced at the National Center for Radiotherapy, Accra after years of using low-dose rate (LDR) brachytherapy. The aim of this study was to compare the treatment outcomes of patients treated with LDR versus HDR brachytherapy.

METHODS

Patients with cervical cancer treated from January 2008 to December 2017 were reviewed. Those with stage IB-IIIB who received chemoradiation plus brachytherapy were included in the study. Post-operative patients and those with stage IV were excluded. The study end points were local control, disease-free survival, and overall survival at 2 years. Endpoints were estimated using the Kaplan-Meier method. Comparisons between treatment groups were performed using the log-rank test and Cox proportional hazards model.

RESULTS

We included 284 LDR and 136 HDR brachytherapy patients. For stages IB, IIA, IIB, IIIA and IIIB disease, the 2-year local control for LDR versus HDR brachytherapy was 63% and 61% (p=0.35), 86% and 90% (p=0.68), 86% and 88% (p=0.83), 66% and 60% (p=0.56), and 77% and 40% (p=0.005), respectively. The 2-year disease-free survival for LDR versus HDR brachytherapy was 64% and 61% (p=0.50), 81% and 69% (p=0.18), 81% and 80% (p=0.54), 62% and 33% (p=0.82), and 71% and 30% (p=0.001) for stages IB, IIA, IIB, IIIA, and IIIB, respectively. The 2-year overall survival for LDR versus HDR brachytherapy was 94% and 93% (p=0.92), 98% and 68% (p=0.21), 89% and 88% (p=0.60), and 88% and 82% (p=0.34) for stages IB, IIA, IIB, and IIIB disease, respectively.

CONCLUSION

There was no difference between LDR and HDR brachytherapy in local control and disease-free survival for all stages of disease, except in stage IIIB. These findings highlight the need to refine this brachytherapy technique for this group of patients.

The 100 most cited articles in cervical cancer brachytherapy

PURPOSE

This study aimed to identify the 100 most cited research articles on cervical cancer brachytherapy.

METHODS AND MATERIALS

The Institute for Scientific Information Web of Science was used to identify the 100 most cited articles in cervical cancer brachytherapy as of July 5, 2019. The following important information was extracted: journal, year and month, country of region, author, type of article, type of dose rate, type of radionuclide, and image modality for brachytherapy planning.

RESULTS

The 100 most cited articles in cervical cancer brachytherapy were published between 1981 and 2016, and the citations ranged from 858 to 49, which collectively had been cited 11,372 times at the time of searching. The index of citations per year ranged from 63.56 to 1.43. These articles were from 16 countries or regions, with most publications being from the United States (n = 27), followed by Austria (n = 26), Japan (n = 10), France (n = 7), and the Netherlands (n = 7). The International Journal of Radiation Oncology, Biology, Physics produced the most articles (n = 46), followed by Radiotherapy and Oncology (n = 39) and Gynecologic Oncology (n = 5). These articles were categorized as original studies (n = 75), reviews (n = 2), editorials (n = 2), surveys (n = 2), guidelines (n = 3), and recommendations (n = 6). A high dose rate (n = 69) was the most widely used, dose rate followed by a low dose rate (n = 20) and pulsed dose rate (n = 16).

CONCLUSIONS

The bibliometric analysis presents a detailed list of the 100 most cited articles in cervical cancer brachytherapy. This analysis provides an insight into historical developments and enables the important advances in this field to be recognized.

Comparative study to evaluate dosimetric differences in patients of locally advanced carcinoma cervix undergoing intracavitary brachytherapy under two different anaesthesia techniques: an audit from a tertiary cancer centre in India

BACKGROUND

Carcinoma cervix is amongst the leading causes of mortality and morbidity in women population worldwide. High-dose-rate intracavitary brachytherapy (HDR-ICBT) post external beam radiation therapy (EBRT) is the standard of care in managing locally advanced stage cervical cancer patients. HDR-ICBT is generally performed under general anaesthesia (GA) in operation theatre (OT), but due to logistic reasons, sometimes, it becomes difficult to accommodate all patients under GA. Since prolonged overall treatment time (OTT) makes the results inferior, taking patients in day care setup under procedural sedation (PS) can be an effective alternative. In this audit, we tried to retrospectively analyse the dosimetric difference, if any, in patients who underwent ICBT at our centre, under either GA in OT or PS in day care.

RESULTS

Thirty five patients were analysed 16/35 (45.71%) patients underwent HDR-ICBT under GA while 19/35 (54.28%) patients under PS. In both groups, a statistically significant difference was observed between the dose received by 0.1 cc as well as 2 cc of rectum (p < 0.05), while the bladder and sigmoid colon had comparable dosages.

CONCLUSION

Though our dosimetric analysis highlighted better rectal sparing in patients undergoing HDR-ICBT under GA when compared to patients under PS, PS can still be considered an effective alternative, especially in centres dealing with significant patient load. Further studies are required for firm conclusion.

Is economic status the main determinant of radiation therapy availability? The Arab world as an example of developing countries

BACKGROUND AND PURPOSE

Arab countries share a common location, history, language and culture with different economic characteristics. In this study, we analyze the availability and factors influencing radiotherapy services and cancer mortality incidence ratio (MIR) in Arabic countries.

MATERIALS AND METHODS

Data were collected from GLOBOCAN report, World Health Organization, World Bank, United Nation and Directory of Radiotherapy Centre databases.

RESULTS

The average number of megavoltage machines (MVM) in Arab countries is 0.84 machine per 1000 cancer patients. The number of MVM per 1000 cancer patients was found to be significantly correlated with gross domestic product (GDP) per capita (r = 0.583, P = 0.006). In addition, it was found to be significantly more in politically stable countries compared to unstable ones (P = 0.004) and more in high and upper-middle income countries (median 0.94 ± 1.0) compared to lower-middle and low income countries (median 0.3 ± 0.51) (P = 0.013). MIR was found to be significantly correlated with GDP per capita, physicians per 1000 population, MVM per 1000 cancer patients and absolute MVM deficit (r = -0.555, -0.625, -0.42, -0.436 and P = 0.009, 0.006, 0.047, 0.043, respectively). On multivariate regression analysis, the number of physicians per 1000 population had the strongest prediction of MIR in Arabic countries (P = 0.01).

CONCLUSION

Although the economic status is of paramount importance, it is not the only factor determining the quantity and quality of radiotherapy services in the Arab world. More efforts are urgently needed to improve the status of radiation oncology and fill its gap in the Arab countries.

Treatment of cervical cancer with electronic brachytherapy

PURPOSE

We report the first cervical cancer cases treated with interstitial electronic brachytherapy (eBT) at our hospital and compare them with plans made with high-dose-rate interstitial brachytherapy based on Ir192 (HDR-BT).

MATERIALS AND METHODS

Eight patients with cervical cancer were treated with the Axxent eBT device (Xoft, Inc.). Planning was with magnetic resonance imaging and computed tomography following the recommendations of the EMBRACE protocol. The dosimetry parameters of organs at risk (OAR) were evaluated for the bladder, rectum, and sigmoid colon (D2cc, D1cc, and D0.1cc). In addition, the V150 and V200 of irradiated tissue were compared for both eBT and HDR-BT. All patients received intensity-modulated external beam radiation therapy with a regimen of 23 sessions of 2 Gy followed by four sessions of 7 Gy of eBT performed over 2 weeks (two sessions followed by another two sessions a week later) following the EMBRACE recommendations. Each of the eight patients was followed to assess acute toxicity associated with treatment.

RESULTS

The doses reaching OAR for eBT plans were lower than for HDR-BT plans. As for acute toxicity associated with eBT, very few cases of mucositis were detected. No cases of rectal toxicity and one case with grade 1 urinary toxicity were detected. The results at 1 month are equally good, and no relapses have occurred to date.

CONCLUSIONS

The first results of treatment with the Axxent eBT device are promising, as no recurrences have been observed and toxicity is very low. eBT is a good alternative for treating cervical cancer in centers without access to conventional HDR.

Radiobiological considerations in combining doses from external beam radiotherapy and brachytherapy for cervical cancer

The recommended radio-therapeutic treatment for cervix cancer consists of a first phase of external beam radiotherapy (EBRT) plus a second phase of brachytherapy (BT), the combined treatment being delivered within 8 weeks. In order to assess a comprehensive dosimetry of the whole treatment, it is necessary to take into account that these two phases are characterized by different spatial and temporal dosimetric distributions, which complicates the task of the summation of the two contributions, EBRT and BT. Radiobiology allows to tackle this issue pragmatically by means of the LQ model and, in fact, this is the usual tool currently in use for this matter. In this work, we describe the rationale behind the summation of the dosimetric contributions of the two phases of the treatment, EBRT and BT, for cervix cancer, as carried out with the LQ model. Besides, we address, from a radiobiological point of view, several important considerations regarding the use of the LQ model for this task. One of them is the analysis of the effect of the overall treatment time in the result of the global treatment. Another important question considered is related to the fact that the capacity of LQ to predict the treatment outcomes is deteriorated when the dose per fraction of the radiotherapic scheme exceeds 6-10 Gy, which is a typical brachytherapy fractionation. Finally, we analyze the influence of the uncertainty and the variability of the main parameters utilized in the LQ model formulation in the assessment of the global dosimetry.

Neoadjuvant brachytherapy and chemotherapy followed by radical surgery for stage IB2 and IIA cervical cancer: A retrospective comparison with chemoirradiation

The aim of the present study was to assess the immediate and long-term results of preoperative brachytherapy and chemotherapy followed by radical surgery compared with those of standard chemoirradiation in patients with stage IB2-IIA cervical cancer. The medical records of 70 patients with stage IB2 and IIA cervical cancer who were treated between June 2006 and June 2010 were reviewed. The patients received either standard chemoirradiation (CRT) treatment (n=20) or neoadjuvant brachytherapy with one cycle of chemotherapy followed by radical hysterectomy [operation (OT) group; n=50]. Further adjuvant chemoirradiation was administered to patients with high-risk disease. Early and late complications as well as survival were compared between the two groups. No serious operative complications occurred in the OT group. In the CRT group, the incidence of symptomatic vaginal stenosis, as well as that of proctitis and cystitis, was higher compared with that in the OT group (35 vs. 4% and 20 vs. 2%, repectively). The median follow-up period was 52 months (range, 11-84 months). In the CRT group, the 3-year overall and disease-free survival rates were 95% [95% confidence interval (CI): 76.14-86.46] and 90% (95% CI: 59.94-73.66), respectively, whereas in the OT group, the respective rates were 90% (95% CI: 72.93-83.07) and 90% (95% CI: 71.84-82.96). In conclusion, the survival of patients with stage IB2-IIA cervical cancer treated with preoperative brachytherapy and chemotherapy followed by radical surgery was similar to that of patients treated with chemoirradiation, but with a more favorable side effect profile. Thus, this tri-modal treatment option requires further evaluation in prospective randomized studies.

Simultaneously integrated boost (SIB) spares OAR and reduces treatment time in locally advanced cervical cancer

We performed a dosimetric comparison of sequential IMRT (sIMRT) and simultaneously integrated boost (SIB) IMRT to boost PET‐avid lymph nodes while concurrently treating pelvic targets to determine the potential of SIB IMRT to reduce overall treatment duration in locally advanced cervical cancer. Ten patients receiving definitive radiation therapy were identified retrospectively. RTOG consensus guidelines were followed to delineate the clinical target volume and organs at risk (OAR), which were then expanded per IMRT consortium guidelines to yield the planning target volume (PTV). Dosimetric parameters for PTVs and OAR including conformity (CI95%) were collected and compared using Wilcoxon signed‐rank tests with Bonferroni correction. The median PTV volume was 1843 cc (1088–2225 cc) and the median boost volume was 43 cc (15–129 cc). Comparable target volume coverage was achieved with sIMRT and SIB plans, while hot spots were significantly reduced using SIB. SIB plans improved sparing for all OAR, though only rectum and small bowel doses were statistically significant. Comparing sIMRT and SIB plans averaged over all patients, rectal doses were V45: 70.8% vs. 64.5%(p=0.002) and 0.1 cc: 50.7 Gy vs. 48.7 Gy (p=0.006). For small bowel, sIMRT and SIB IMRT plans yielded V45: 13.4% vs. 11.4%(p=0.006) and 1 cc: 54.4 Gy vs. 52.6 Gy (p=0.006), respectively. Doses to femoral heads and bladder trended towards significance in favor of SIB plans. The mean treatment time was 25 versus 29 days for SIB and sIMRT plans, respectively. When compared to sIMRT, SIB for treatment of nodal targets provides a significant, but small, dose reduction (3.8%–4.4%) to OAR, which leads to comparable biological dose despite higher fractional doses. Furthermore, SIB IMRT reduces overall treatment time and simplifies the planning process, and should be considered for targeting PET‐positive nodal disease in patients with locally advanced cervical cancer.

PACS number(s): 87.19.xj cancer

Vaginal dose de-escalation in image guided adaptive brachytherapy for locally advanced cervical cancer

PURPOSE

Vaginal stenosis is a major problem following radiotherapy in cervical cancer. We investigated a new dose planning strategy for vaginal dose de-escalation (VDD).

MATERIALS AND METHODS

Fifty consecutive locally advanced cervical cancer patients without lower or middle vaginal involvement at diagnosis from 3 institutions were analysed. External beam radiotherapy was combined with MRI-guided brachytherapy. VDD was obtained by decreasing dwell times in ovoid/ring and increasing dwell times in tandem/needles. The aim was to maintain the target dose (D90 of HR-CTV⩾85Gy EQD2) while reducing the dose to the surface of the vagina to <140% of the physical fractional brachytherapy dose corresponding to a total EQD2 of 85Gy.

RESULTS

The mean vaginal loading (ovoid/ring) was reduced from 51% to 33% of the total loading with VDD, which significantly reduced the dose to the vaginal dose points (p<0.001) without compromising the target dose. The dose to the ICRU recto-vaginal point was reduced by a mean of 4±4Gy EQD2 (p<0.001), while doses to bladder and rectum (D_2cm³) were reduced by 2±2Gy and 3±2Gy, respectively (p<0.001).

CONCLUSIONS

VDD significantly reduces dose to the upper vagina which is expected to result in reduction of vaginal stenosis.

Imaging across the life span: innovations in imaging and therapy for gynecologic cancer

The focus of this article is radiation therapy for gynecologic cancers, with emphasis on imaging-based treatment planning and delivery. For the various gynecologic cancers, radiation oncologists rely on essential clinical information to triage treatment options, and various imaging studies are performed for treatment planning and radiation therapy delivery. A practical approach is provided to help radiologists tailor their reports for the needs of their radiation oncology and gynecologic oncology colleagues, to optimize multidisciplinary care for patients with gynecologic cancer. Template radiology reports are proposed to address the specific information needs of oncologists at each phase-before, during, and after treatment. Fueled by the rapid progress in engineering and computer sciences during the past 2 decades, remarkable advances have been made in anatomic, functional, and molecular imaging and in radiation treatment planning and delivery in patients with gynecologic cancer. Radiation therapy has evolved from a nontargeted approach to a precisely targeted, highly conformal treatment modality, to further improve treatment outcomes and reduce morbidity. High-quality imaging has become essential for staging of the disease, delineation of tumor extent for treatment planning and delivery, and monitoring therapy response. Anatomic and functional imaging has also been shown to provide prognostic information that allows clinicians to tailor therapy on the basis of personalized patient information. This field is an area of active research, and future clinical trials are warranted to validate preliminary results in the field.

Image-Based Brachytherapy for the Treatment of Cervical Cancer

Cervical cancer is a disease that requires considerable multidisciplinary coordination of care and labor in order to maximize tumor control and survival while minimizing treatment-related toxicity. As with external beam radiation therapy, the use of advanced imaging and 3-dimensional treatment planning has generated a paradigm shift in the delivery of brachytherapy for the treatment of cervical cancer. The use of image-based brachytherapy, most commonly with magnetic resonance imaging (MRI), requires additional attention and effort by the treating physician to prescribe dose to the proper volume and account for adjacent organs at risk. This represents a dramatic change from the classic Manchester approach of orthogonal radiographic images and prescribing dose to point A. We reviewed the history and currently evolving data and recommendations for the clinical use of image-based brachytherapy with an emphasis on MRI-based brachytherapy.

A study of high-dose-rate intracavitary brachytherapy boost for curative treatment of uterine cervical cancer

PURPOSE

This study assessed the trial of boost intracavitary brachytherapy (ICBT) for the patients of uterine cervical cancer with residual malignant cells detected at the final stage of ICBT.

MATERIAL AND METHODS

This is a retrospective analysis of 75 patients with cervical cancer treated radically with external beam radiotherapy and high-dose-rate intracavitary brachytherapy between August 2004 and December 2008. Eighteen patients (24%) out of 75 received one additional ICBT and five patients (7%) had two additional ICBT. All 75 patients were retrospectively analyzed. The median follow-up time was 30 months. The median age was 59 years (range 28-85 years). There were 12 patients (16%) in stage IB, 27 (36%) stage II, 22 (29%) stage III, and 14 (19%) stage IV.

RESULTS

The 5-year overall survival rate was 65%. Non-hematological toxicities greater than grade 2 occurred in 12 patients (16%). Of these, only two patients received on additional ICBT. No significant difference was found in grade 3 toxicity between patients who did and did not receive additional ICBT (p = 0.8).

CONCLUSIONS

The method to perform dose escalation should be examined depending on the treatment response.

Comparison of high-dose-rate intracavitary brachytherapy dosimetry with and without anesthesia in patients with cervical carcinoma

This study compares the dosimetry of high‐dose‐rate intracavitary brachytherapy (HDR‐ICBT) performed with and without general anesthesia/spinal anesthesia (GA/SA) in patients with cervical carcinoma. We retrospectively retrieved the records of 138 HDR‐ICBT applicator insertions performed in 46 patients: 69 performed with GA/SA (anesthesia group known as AG) in 23 patients, and 69 performed without GA/SA (nonanesthesia group known as NAG) in 23 patients. The intracavitary brachytherapy (ICBT) application was done with central tandem and two vaginal ovoids. For each ICBT plan, a high‐dose‐rate (HDR) dose of 7 Gy was prescribed to point A. From each plan, the doses to Point B right (BR), Point B left (BL), bladder and rectal reference points (Bladderref and Rectalref) were recorded and compared in the two groups. Student's t‐test was applied to find out the significance of difference. The two groups were comparable in terms of demography and clinical characteristics. Mean Point BL doses in AG and NAG were 1.89 Gy (27% of Point A dose) and 1.82 Gy (26% of Point A dose), respectively. Mean Point BR doses in AG and NAG were 1.91 Gy (27% of Point A dose) and 1.85 Gy (26% of point A), respectively (p‐value 0.7). The mean dose to Bladderref in AG and NAG was 5.03 Gy and 4.90 Gy, respectively (p‐value 0.6). The mean dose to Rectalref was significantly higher in AG than NAG (5.09 Gy vs. 4.49 Gy, p‐value 0.01). Although based on conventional 2D dosimetry planning, our study has demonstrated that avoiding GA/SA does not result in inferior HDR‐ICBT dosimetry.

PACS number: 87.53.Jw, 87.50.cm

Patterns of care study of brachytherapy in New South Wales: cervical cancer treatment quality depends on caseload

PURPOSE

We previously conducted modelling and a patterns of care study (POCS) that showed gynaecological brachytherapy (BT) was underutilized in New South Wales (NSW), the USA and Western Europe. The aim of the current study was to assess the quality of cervical BT in NSW, and to determine if caseload affects quality of treatment delivery.

MATERIAL AND METHODS

All nine NSW radiation oncology departments that treated patients with cervical BT in 2003 were visited. Patient, tumour and treatment related data were collected. Quality of BT was assessed using published quality benchmarks. Higher and lower caseload departments were compared.

RESULTS

The four higher cervical BT caseload departments treated 11-15 NSW residents in 2003, compared to 1-8 patients for the lower caseload departments. Cervix cancer patients treated at the higher caseload departments were more likely to be treated to a point A dose ≥ 80 Gy (58% vs. 14%, p = 0.001), and to have treatment completed within 8 weeks (66% vs. 35%, p = 0.02). Despite higher point A doses, there was no significant difference in proportions achieving lower than recommended rectal or bladder doses, implying better BT insertions in higher caseload departments.

CONCLUSIONS

Cervical BT in NSW was dispersed amongst a large number of departments and was frequently of sub-optimal quality. Higher quality BT was achieved in departments treating at least 10 patients per year. It is likely that improved outcomes will be achievable if at least 10 patients are treated per department per year.

Comparison of carboplatin- and cisplatin-based concurrent chemoradiotherapy in locally advanced cervical cancer patients with morbidity risks

BACKGROUND

The aim of this study was to assess the activity and toxicity of primary carboplatin-based chemoradiotherapy (CarboRT) and to compare CarboRT with cisplatin-based chemoradiotherapy (CisRT) in patients with locally advanced cervical cancer and poor general condition.

PATIENTS AND METHODS

Fifty-one locally advanced cervical cancer patients with morbidity risks were prospectively enrolled between January 2007 and April 2010. Eligible patients received weekly intravenous CarboRT with carboplatin 100 mg/m2, and a comparison was made with a historical patient group that received weekly CisRT with cisplatin 40 mg/m2.

RESULTS

Median follow-up was 36 months (range: 4-66 months) in the CarboRT group and 53 months (range: 4-121 months) in the CisRT group. Compared with the historical CisRT group, the CarboRT group showed no statistically significant differences in recurrence (hazard ratio [HR], 1.21; 95% confidence interval [CI], 0.52-2.81) and survival (HR, 1.80; 95% CI, 0.49-6.54). The mean numbers of received cycles of CarboRT and CisRT were 7.5 ± 1.4 and 6.0 ± 1.8, respectively (p < .001). The rates of grade 3-4 toxicity were similar in the two groups.

CONCLUSIONS

CarboRT was better tolerated than CisRT without compromising tumor response and survival in patients with locally advanced cervical cancer and poor general condition.

Vaginal dose point reporting in cervical cancer patients treated with combined 2D/3D external beam radiotherapy and 2D/3D brachytherapy

BACKGROUND AND PURPOSE

Traditionally, vaginal dose points have been defined at the vaginal source level, thus not providing dose information for the entire vagina. Since reliable vaginal dose volume/surface histograms are unavailable, a strategy for comprehensive vaginal dose reporting for combined EBRT and BT was established and investigated.

MATERIAL AND METHODS

An anatomical vaginal reference point was defined at the level of the Posterior-Inferior Border of Symphysis (PIBS), plus two points ±2 cm (mid/introitus vagina). For BT extra points were selected for the upper vagina at 12/3/6/9 o'clock, at the vaginal surface and 5 mm depth. A vaginal reference length (VRL) was defined from ring centre to PIBS. Fifty-nine patients treated for cervical cancer were included in this retrospective feasibility study.

RESULTS

The method was applicable to all patients. Total EQD2 doses at PIBS and ±2 cm were 36.7 Gy (3.1-68.2), 49.6 Gy (32.1-89.6) and 4.3 Gy (1.0-46.6). At the vaginal surface at ring level doses were respectively 266.1 Gy (67.6-814.5)/225.9 Gy (61.5-610.5) at 3/9 o'clock, and 85.1 Gy (55.4-140.3)/72.0 Gy (49.1-108.9) at 12/6 o'clock. Mean VRL on MRI was 5.6 cm (2.0-9.4).

CONCLUSIONS

With this novel system, a comprehensive reporting of vaginal doses is feasible. The present study has demonstrated large dose variations between patients observed in all parts of the vagina, resulting from different contributions from EBRT and BT.

Primary surgery versus primary radiotherapy with or without chemotherapy for early adenocarcinoma of the uterine cervix

BACKGROUND

For early squamous cell carcinoma of the uterine cervix, the outcome is similar after either primary surgery or primary radiotherapy. There are reports that this is not the case for early adenocarcinoma (AC) of the uterine cervix: some studies have reported that the outcome is better after primary surgery. There are no systematic reviews about surgery versus chemoradiation in the treatment of cervical cancer. This is an updated version of the original Cochrane review published in Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD006248. DOI: 10.1002/14651858.CD006248.

OBJECTIVES

The objectives of this review were to compare the effectiveness and safety of primary surgery for early stage AC of the uterine cervix with primary radiotherapy or chemoradiation.

SEARCH METHODS

We searched Cochrane Central Register of Controlled Trials (CENTRAL) Issue 3, 2009, MEDLINE (1950 to July week 5, 2009), EMBASE (1980 to week 32, 2009) and we also searched the related articles feature of PubMed and the Web of Science. We also checked the reference lists of articles. For this update, the searches were re-run in June 2012: MEDLINE 2009 to June week 2, 2012, EMBASE 2009 to 2012 week 24, CENTRAL Issue 6, 2012, Cochrane Gynaecological Specialised Register June 2012.

SELECTION CRITERIA

Studies of treatment of patients with early AC of the uterine cervix were included. Treatment included surgery, surgery followed by radiotherapy, radiotherapy and chemoradiation.

DATA COLLECTION AND ANALYSIS

Forty-three studies were selected by the search strategy and 30 studies were excluded. Twelve studies were considered for inclusion. Except for one randomised controlled trial (RCT), all other studies were retrospective cohort studies with variable methodological quality and had limitations of a retrospective study. Comparing the results from these retrospective studies was not possible due to diverging treatment strategies.

MAIN RESULTS

Analysis of a subgroup of one RCT showed that surgery for early cervical AC was better than radiotherapy. However, the majority of operated patients required adjuvant radiotherapy, which is associated with greater morbidity. Furthermore, the radiotherapy in this study was not optimal, and surgery was not compared to chemoradiation, which is currently recommended in most centres. Finally, modern imaging techniques (i.e. magnetic resonance imaging (MRI) and positive emission tomography - computed tomography (PET-CT) scanning) allow better selection of patients and node-negative patients can now be more easily identified for surgery, thereby reducing the risk of 'double trouble' caused by surgery and adjuvant radiotherapy.  

AUTHORS' CONCLUSIONS

We recommend surgery for early-stage AC of the uterine cervix in carefully staged patients. Primary chemoradiation remains a second best alternative for patients unfit for surgery; chemoradiation is probably first choice in patients with (MRI or PET-CT-suspected) positive lymph nodes. Since the last version of this review no new studies were found.

A proposed protocol on HDR cylinder treatments: proof of avoidance of re-planning of CT based fractionated treatment, using a critical, statistical and graphical analysis of clinical data

Purpose

An evaluation of CT plan data, using cylinder applicators, in fractionated HDR treatments of cervical cancers has been investigated in this clinical study. Critical and statistical analysis of the data, for each patient and fraction, for plan dose, doses for bladder and rectum have been enumerated and reported. Plans were done for each patient, following CT scans after insertion of the applicator in the respective cases. This process involved time for CT-scan and re-plan, in each fraction, adding cost of treatments for the poor patients.

Material and methods

This study on HDR brachytherapy for cervical cancer patients has applied the Co-60 BEBIG Multisource Unit. Cylinder applicators have been applied for treatments. A selection of twenty nine patients, out of a few hundred representative female patients, in the age group of 40-70 years, has been analyzed and presented in this paper. Radiation oncologists inserted the applicator and fixed it in more than 600 treatments. This study, therefore, aimed at their insertion technique, CT-planning by radiation oncology physicists and the delivery of the treatments. Details of set up and technique has been explained, where bladder and rectum doses has been assessed within the tolerance limit [1].

Results

Statistical analysis of data from the treatment plans, substantiates the conclusion of the argument that there is no need to do CT-plans for each subsequently prescribed number of fractions as the doses in plan, bladder and rectum are restricted within the limits of tolerance. Data in Table 1 are analyzed in various graphs. This utilized the Empirical Null Distribution of Group Differences. A graphic study of dose distribution is reported to assure the expected variation of dose from the central tandem. This analysis proves to substantiate a protocol that no re-plan for fractionated delivery is essential following the approval of the first plan.

Conclusions

The goal of this study was to critically evaluate the outcome of fractionated cylinder treatments of cervical cancers. This resulted in the set up technique for insertion of applicators and treatment plan, following a CT-scan and the assertion of the argument that re-plans are not necessary for multiple HDR cylinder treatments for the same patient [2, 3].

Impact of point A asymmetry on local control and survival for low dose-rate (LDR) brachytherapy in cervical cancer

Purpose

To evaluate whether Point A asymmetry in low dose-rate (LDR) brachytherapy is associated with local control (LC), disease-free survival (DFS) and/or overall survival (OS).

Material and methods

A retrospective analysis of disease control and survival outcomes was conducted for patients who underwent LDR brachytherapy for advanced cervical cancer. Institutional protocol entailed concurrent chemotherapy and whole pelvis radiotherapy (WPRT) over 5 weeks, followed by placement of Fletcher-Suit tandem and colpostat applicators at weeks 6 and 8. Objective Point A doses, 80-85 Gy, were accomplished by placement of Cesium-137 (Cs-137) sources. Cox proportional hazards regression models were used to assess associations between disease control and survival endpoints with variables of interest.

Results

The records of 50 patients with FIGO stage IB1-IVA cervical cancer undergoing LDR brachytherapy at our institution were identified. Thirty of these patients had asymmetry > 2.5%, and 11 patients had asymmetry > 5%. At a median survivor follow-up of 20.25 months, 15 patients had experienced disease failure (including 5 cervical/vaginal apex only failures and 2 failures encompassing the local site). Right/left dose asymmetry at Point A was associated with statistically significantly inferior LC (p = 0.035) and inferior DFS (p = 0.011) for patients with mean Point A dose of > 80 Gy. Insufficient evidence existed to conclude an association with OS.

Conclusions

LDR brachytherapy may be associated with clinically significant dose asymmetry. The present study demonstrates that patients with Point A asymmetry have a higher risk of failure for DFS and LC.

The quality of cervical cancer brachytherapy implantation and the impact on local recurrence and disease-free survival in radiation therapy oncology group prospective trials 0116 and 0128

PURPOSE

The objective of the study was to determine the impact of brachytherapy implant quality on outcome among cervical cancer patients treated on Radiation Therapy Oncology Group prospective trials 0116 and 0128.

METHODS

All enrolled patients received concurrent chemoradiation followed by brachytherapy. Individual brachytherapy parameters, including the symmetry of ovoids in relation to the tandem, displacement of ovoids in relation to the cervical os, tandem bisecting the ovoids, tandem in the midpelvis, and appropriateness of packing, were scored for each implant. Multivariate Cox proportional hazards models were constructed for each parameter for local recurrence (LR), regional recurrence, distant recurrence, disease-free survival (DFS), and overall survival.

RESULTS

Records for 103 patients were analyzed. The median follow-up time was 24.5 months. Patients with unacceptable symmetry of ovoids to the tandem had a significantly higher risk of LR than patients in the acceptable group (hazard ratio [HR], 2.67; 95% confidence interval [CI], 1.11-6.45; P = 0.03). Patients with displacement of ovoids in relation to the cervical os had a significantly increased risk of LR (HR, 2.50; 95% CI, 1.05-5.93; P = 0.04) and a lower DFS rate (HR, 2.28; 95% CI, 1.18-4.41; P = 0.01). Inappropriate placement of packing resulted in a lower DFS rate (HR, 2.06; 95% CI, 1.08-3.92; P = 0.03).

CONCLUSIONS

Assessment of the quality of a brachytherapy implant is imperative, as proper placement has an impact on patient DFS. If feasible, inappropriate placements should be corrected before treatment initiation. Brachytherapy applicators for cervical cancer should preferably be placed and assessed by experienced practitioners.

Simultaneous nonrigid registration, segmentation, and tumor detection in MRI guided cervical cancer radiation therapy

External beam radiation therapy (EBRT) for the treatment of cancer enables accurate placement of radiation dose on the cancerous region. However, the deformation of soft tissue during the course of treatment, such as in cervical cancer, presents significant challenges for the delineation of the target volume and other structures of interest. Furthermore, the presence and regression of pathologies such as tumors may violate registration constraints and cause registration errors. In this paper, automatic segmentation, nonrigid registration and tumor detection in cervical magnetic resonance (MR) data are addressed simultaneously using a unified Bayesian framework. The proposed novel method can generate a tumor probability map while progressively identifying the boundary of an organ of interest based on the achieved nonrigid transformation. The method is able to handle the challenges of significant tumor regression and its effect on surrounding tissues. The new method was compared to various currently existing algorithms on a set of 36 MR data from six patients, each patient has six T2-weighted MR cervical images. The results show that the proposed approach achieves an accuracy comparable to manual segmentation and it significantly outperforms the existing registration algorithms. In addition, the tumor detection result generated by the proposed method has a high agreement with manual delineation by a qualified clinician.

American Brachytherapy Society consensus guidelines for locally advanced carcinoma of the cervix. Part III: low-dose-rate and pulsed-dose-rate brachytherapy

PURPOSE

To develop a guideline for quality practice of low-dose-rate (LDR) and pulsed-dose-rate (PDR) brachytherapy for locally advanced cervical cancer.

METHODS

Members of the American Brachytherapy Society (ABS) with expertise in cervical cancer brachytherapy formulated updated guidelines for LDR and PDR brachytherapy for locally advanced (International Federation of Gynecology and Obstetrics [FIGO] Stages IB2-IVA) cervical cancer based on literature review and clinical experience.

RESULTS

The ABS strongly recommends the use of brachytherapy as a component of the definitive treatment of locally advanced cervical carcinoma. Precise applicator placement is necessary to maximize the probability of achieving local control without major side effects. The ABS recommends a cumulative delivered dose of approximately 80-90Gy for definitive treatment. Dosimetry must be performed after each insertion before treatment delivery. The dose delivered to point A should be reported for all intracavitary brachytherapy applications regardless of treatment planning technique. The ABS also recommends adoption of the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology guidelines for contouring, image-based treatment planning and dose reporting. Interstitial brachytherapy may be considered for a small proportion of patients whose disease cannot be adequately encompassed by intracavitary application and should be performed by practitioners with special expertise in these procedures. Quality management measures must be performed, and follow-up information should also be obtained.

CONCLUSIONS

Updated ABS guidelines are provided for LDR and PDR brachytherapy for locally advanced cervical cancer. Practitioners and cooperative groups are encouraged to use these guidelines to formulate their clinical practices and to adopt dose-reporting policies that are critical for outcome analysis.

American Brachytherapy Society consensus guidelines for locally advanced carcinoma of the cervix. Part I: general principles

PURPOSE

To develop brachytherapy recommendations covering aspects of pretreatment evaluation, treatment, and dosimetric issues for locally advanced cervical cancer.

METHODS

Members of the American Brachytherapy Society (ABS) with expertise in cervical cancer brachytherapy formulated updated recommendations for locally advanced (Federation of Gynecology and Obstetrics Stages IB2-IVA) cervical cancer based on literature review and clinical experience.

RESULTS

The ABS recommends the use of brachytherapy as a component of the definitive treatment of locally advanced cervical carcinoma. Precise applicator placement is necessary to maximize the probability of achieving local control without major side effects. The ABS recommends a cumulative delivered dose of approximately 80-90Gy for definitive treatment. The dose delivered to point A should be reported for all brachytherapy applications regardless of treatment-planning technique. The ABS also recommends adoption of the Groupe Européen Curiethérapie-European Society of Therapeutic Radiation Oncology (GEC-ESTRO) guidelines for contouring, image-based treatment planning, and dose reporting. Interstitial brachytherapy may be considered for a small proportion of patients whose disease cannot be adequately encompassed by intracavitary application. It should be performed by practitioners with special expertise in these procedures.

CONCLUSIONS

Updated ABS recommendations are provided for brachytherapy for locally advanced cervical cancer. Practitioners and cooperative groups are encouraged to use these recommendations to formulate their clinical practices and to adopt dose-reporting policies that are critical for outcome analysis.

Inverse-planned gynecologic high-dose-rate interstitial brachytherapy: clinical outcomes and dose--volume histogram analysis

PURPOSE

To present clinical outcomes and dose-volume histogram parameters of three-dimensional image-based high-dose-rate interstitial brachytherapy (HDR-ISBT) in patients with primary or recurrent gynecologic cancer unsuitable for intracavitary brachytherapy (ICB).

METHODS AND MATERIALS

Records of 43 women treated between 2001 and 2009 with iridium-192 gynecologic HDR-ISBT boost, using a Syed-Neblett template and inverse planning simulated annealing dose optimization, were reviewed. Median HDR-ISBT dose was 30Gy, delivered in 4-6Gy/fraction. Dose-volume histogram parameters recommended by the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology for image-based ICB were analyzed. Total doses were normalized to 2Gy fractions (biologically equivalent dose in 2Gy fractions). Local control (LC) and survival were calculated using Kaplan-Meier method. Toxicities were defined according to Common Terminology Criteria for Adverse Events v3.0.

RESULTS

There were 34 primary malignancies (cervix=12, vagina=15, Bartholin's gland=5, and vulva=2) and 9 recurrences. International Federation of Gynecology and Obstetrics stage distribution for primary cancers was I=2, II=13, III=15, and IV=4. Median followup was 19.3 months (range, 0-92.2). Two-year LC was 87% for primary cancers, and 45% for recurrent cancers, respectively (p=0.0175). Median V(100), D(90), and D(100) for clinical target volume were 97.6%, 90.2, and 68.7Gy(10), respectively. Median bladder and rectal D(2)(cc) were 76.6 and 79.5Gy(3), respectively. Median urethral D(10) was 80.6Gy(3). Twelve patients experienced Grades 3 and 4 late morbidity, but toxicities were transient. Only 2 patients had persistent severe toxicities. A trend toward increased risk for vaginal necrosis was observed with a clinical target volume >84cc.

CONCLUSIONS

HDR-ISBT may achieve good LC in gynecologic cancer unsuitable for ICB, especially in primary malignancies with a 2-year LC rate higher than 85%. Delivery of such high doses has potential advantages but may predispose to adverse effects, reversible in most cases.

Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model

Purpose

The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009.

Material and methods

In the first phase we studied the influence of the pulse dose and the pulse time in the biological equivalence between LDR and PDR treatments using the Linear Quadratic Model (LQM). In the second phase, the equivalent dose in 2 Gy/fraction (EQD₂) for the tumor, rectum and bladder in treatments performed with both techniques was evaluated and statistically compared. All evaluated patients had stage IIB cervical cancer and were treated with External Beam Radiotherapy (EBRT) plus two Brachytherapy (BT) applications. Data were collected from 48 patients (26 patients treated with LDR and 22 patients with PDR).

Results

In the analyses of the influence of PDR parameters in the biological equivalence between LDR and PDR treatments (Phase 1), it was calculated that if the pulse dose in PDR was kept equal to the LDR dose rate, a small the-rapeutic loss was expected. If the pulse dose was decreased, the therapeutic window became larger, but a correction in the prescribed dose was necessary. In PDR schemes with 1 hour interval between pulses, the pulse time did not influence significantly the equivalent dose. In the comparison between the groups treated with LDR and PDR (Phase 2) we concluded that they were not equivalent, because in the PDR group the total EQD₂ for the tumor, rectum and bladder was smaller than in the LDR group; the LQM estimated that a correction in the prescribed dose of 6% to 10% was ne-cessary to avoid therapeutic loss.

Conclusions

A correction in the prescribed dose was necessary; this correction should be achieved by calculating the PDR dose equivalent to the desired LDR total dose.

A unified framework for joint segmentation, nonrigid registration and tumor detection: application to MR-guided radiotherapy

Image guided external beam radiation therapy (EBRT) for the treatment of cancer enables accurate placement of radiation dose to the cancerous region. However, the deformation of soft tissue during the course of treatment, such as in cervical cancer, presents significant challenges. Furthermore, the presence of pathologies such as tumors may violate registration constraints and cause registration errors. In this paper, we present a unified MAP framework that performs automatic segmentation, nonrigid registration and tumor detection simultaneously. It can generate a tumor probability map while progressively identifing the boundary of an organ of interest based on the achieved transformation. We demonstrate the approach on a set of 30 T2-weighted MR images, and the results show that the approach performs better than similar methods which separate the registration and segmentation problems. In addition, the detection result generated by the proposed method has a high agreement with the manual delineation by a qualified clinician.

An integrated approach to segmentation and nonrigid registration for application in image-guided pelvic radiotherapy

External beam radiotherapy (EBRT) has become the preferred options for nonsurgical treatment of prostate cancer and cervix cancer. In order to deliver higher doses to cancerous regions within these pelvic structures (i.e. prostate or cervix) while maintaining or lowering the doses to surrounding non-cancerous regions, it is critical to account for setup variation, organ motion, anatomical changes due to treatment and intra-fraction motion. In previous work, manual segmentation of the soft tissues is performed and then images are registered based on the manual segmentation. In this paper, we present an integrated automatic approach to multiple organ segmentation and nonrigid constrained registration, which can achieve these two aims simultaneously. The segmentation and registration steps are both formulated using a Bayesian framework, and they constrain each other using an iterative conditional model strategy. We also propose a new strategy to assess cumulative actual dose for this novel integrated algorithm, in order to both determine whether the intended treatment is being delivered and, potentially, whether or not a plan should be adjusted for future treatment fractions. Quantitative results show that the automatic segmentation produced results that have an accuracy comparable to manual segmentation, while the registration part significantly outperforms both rigid and nonrigid registration. Clinical application and evaluation of dose delivery show the superiority of proposed method to the procedure currently used in clinical practice, i.e. manual segmentation followed by rigid registration.

Impact of the vaginal applicator and dummy pellets on the dosimetry parameters of Cs-137 brachytherapy source

In this study, dose rate distribution around a spherical 137Cs pellet source, from a low‐dose‐rate (LDR) Selectron remote afterloading system used in gynecological brachytherapy, has been determined using experimental and Monte Carlo simulation techniques. Monte Carlo simulations were performed using MCNP4C code, for a single pellet source in water medium and Plexiglas, and measurements were performed in Plexiglas phantom material using LiF TLD chips. Absolute dose rate distribution and the dosimetric parameters, such as dose rate constant, radial dose functions, and anisotropy functions, were obtained for a single pellet source. In order to investigate the effect of the applicator and surrounding pellets on dosimetric parameters of the source, the simulations were repeated for six different arrangements with a single active source and five non‐active pellets inside central metallic tubing of a vaginal cylindrical applicator. In commercial treatment planning systems (TPS), the attenuation effects of the applicator and inactive spacers on total dose are neglected. The results indicate that this effect could lead to overestimation of the calculated F(r,θ), by up to 7% along the longitudinal axis of the applicator, especially beyond the applicator tip. According to the results obtained in this study, in a real situation in treatment of patients using cylindrical vaginal applicator and using several active pellets, there will be a large discrepancy between the result of superposition and Monte Carlo simulations.

PACS number: 87.53.Jw

Localizing intracavitary brachytherapy applicators from cone-beam CT x-ray projections via a novel iterative forward projection matching algorithm

PURPOSE

To present a novel method for reconstructing the 3D pose (position and orientation) of radio-opaque applicators of known but arbitrary shape from a small set of 2D x-ray projections in support of intraoperative brachytherapy planning.

METHODS

The generalized iterative forward projection matching (gIFPM) algorithm finds the six degree-of-freedom pose of an arbitrary rigid object by minimizing the sum-of-squared-intensity differences (SSQD) between the computed and experimentally acquired autosegmented projection of the objects. Starting with an initial estimate of the object's pose, gIFPM iteratively refines the pose parameters (3D position and three Euler angles) until the SSQD converges. The object, here specialized to a Fletcher-Weeks intracavitary brachytherapy (ICB) applicator, is represented by a fine mesh of discrete points derived from complex combinatorial geometric models of the actual applicators. Three pairs of computed and measured projection images with known imaging geometry are used. Projection images of an intrauterine tandem and colpostats were acquired from an ACUITY cone-beam CT digital simulator. An image postprocessing step was performed to create blurred binary applicators only images. To quantify gIFPM accuracy, the reconstructed 3D pose of the applicator model was forward projected and overlaid with the measured images and empirically calculated the nearest-neighbor applicator positional difference for each image pair.

RESULTS

In the numerical simulations, the tandem and colpostats positions (x,y,z) and orientations (alpha, beta, gamma) were estimated with accuracies of 0.6 mm and 2 degrees, respectively. For experimentally acquired images of actual applicators, the residual 2D registration error was less than 1.8 mm for each image pair, corresponding to about 1 mm positioning accuracy at isocenter, with a total computation time of less than 1.5 min on a 1 GHz processor.

CONCLUSIONS

This work describes a novel, accurate, fast, and completely automatic method to localize radio-opaque applicators of arbitrary shape from measured 2D x-ray projections. The results demonstrate approximately 1 mm accuracy while compared against the measured applicator projections. No lateral film is needed. By localizing the applicator internal structure as well as radioactive sources, the effect of intra-applicator and interapplicator attenuation can be included in the resultant dose calculations. Further validation tests using clinically acquired tandem and colpostats images will be performed for the accurate and robust applicator/sources localization in ICB patients.

Hypofractionated extracranial stereotactic radiotherapy boost for gynecologic tumors: a promising alternative to high-dose rate brachytherapy

The purpose of this study is to report toxicity and outcome results in patients with gynaecological tumours treated with a final boost using extra-cranial stereotactic radiotherapy (SRT) with a linac-based micro-multileaf collimator technique as an alternative to high-dose rate brachytherapy (HDR-BT). Since January 2002, 26 patients with either endometrial (n = 17) or cervical (n = 9) cancer were treated according to this protocol: 45-50.4 Gy external radiotherapy (RT) to the pelvic +/- para-aortic regions followed by a final SRT boost of 2 x 7 Gy to the vaginal vault (4-7 day interval between fractions). Median age was 62 years (37-74 range). Fifteen patients were diagnosed with adenocarcinoma, 7 with squamous-cell carcinoma, and 4 with sarcoma. FIGO stage I (n = 17), stage II (n = 7), and stage III (n = 2). Toxicity was scored according to RTOG/EORTC criteria. No severe (> grade-3) acute urinary or low-gastrointestinal (GI) toxicity was observed during treatment and up to 3 months after treatment completion. Moderate (grade < or = 3) acute urinary or low-GI toxicity was observed in 23% and 35% of patients, respectively. After a median follow-up of 47 months (4-77, range), late urinary, low-GI, and sexual > or = grade-2 (worst score) has been reported in 4%, 12% and 29.4% of patients, respectively. The 3-year loco-regional failure-free and overall survival rates were 96% and 95%, respectively. Preliminary results on feasibility, tolerance, and outcome with SRT are encouraging and may be considered a sound alternative to HDR-BT for gynecologic tumors.

Positional variation of applicators during low dose rate intracavitary brachytherapy for cervical cancer: a prospective study

Purpose

In order to know the effect of variation in position of applicators to the dose received by the tumor volume, critical organs such as rectum and bladder and the correlation of variation on the clinical outcome.

Material and methods

36 patients with histologically proven cervical cancer, undergoing intracavitary brachytherapy (ICBT) from October 2005 to December 2006 were the subjects of the study. Two pairs of orthogonal X-ray films were taken: one prior to loading of sources and the other after removal of sources. These patients were followed up as per the RTOG criteria.

Results

The median duration of insertion was 25 hours with a median follow up period of 6.7 months. The translational variation of the applicator position for all patients was 3 mm and 1 mm (2 SD), respectively, in the patient’s lateral and antero-posterior direction. The rotational variation was 3 and 4 degrees (2 SD) in the patient’s transverse and sagittal planes. Detailed analysis of source movement showed following changes in median dose: point A: 14%, point B: 2%, point P: 1%, Rectum 1: 3.5%, Rectum 2: 4% and Bladder: 9.1%. The incidence of rectal toxicity was 6/36 (16.7%) and that of bladder was 1/36 (2.8%). When the variables were grouped to evaluate the relationship, our study showed statistically significant relationship between: R2 and rectal toxicity (p value: 0.002), point A and rectal toxicity (Pearson: 0.792), lateral displacement/anteroposterior displacement and rectal toxicity (p value: 0.012/0.003), beta angle and R2 (p value: 0.002).

Conclusions

The geometric relationships between the ICBT applicators and the critical structures vary during the course of low dose rate brachytherapy. Source movement does result in significant dose alterations in terms of increased rate of complications, but its impact on cure rates needs to be studied in the future.