Correlation of dose-volume parameters, endoscopic and clinical rectal side effects in cervix cancer patients treated with definitive radiotherapy including MRI-based brachytherapy

A Japanese prospective multi-institutional feasibility study on accelerated partial breast irradiation using multicatheter interstitial brachytherapy: clinical results with a median follow-up of 60 months

BACKGROUND

We carried out the first multi-institutional prospective study on accelerated partial breast irradiation (APBI) via multicatheter interstitial brachytherapy in a shorter period for early breast cancer in Japan.

METHODS

Patient eligibility criteria included positive hormone receptors, tumors ≤ 3 cm and TNM stage pN0M0. After breast-conserving surgery (Japanese cylindrical resection) and histological confirmation of negative surgical margins and the absence of lymph node metastasis, applicator implantation was performed either postoperatively or intraoperatively. High-dose-rate brachytherapy of 36 Gy in 6 fractions was delivered.

RESULTS

Forty-six patients from six institutions received this treatment regimen, and the median follow-up time was 60 months (range 57-67 months). The median resected breast tissue volume was 81 cm³ (range 28-260 cm³). No Grade 4 late sequela, local recurrence nor death due to breast cancer were observed. Grade 2-3 sequelae such as rib fracture (2%), soft tissue necrosis (9%), fibrosis (20%), and breast pain (9%) were observed. The resected breast tissue volumes of the patients who had Grade ≥ 2 fibrosis and Grade < 2 fibrosis were 105.9 ± 32.3 cm³ and 76.3 ± 45.6 cm³, respectively, p = 0.02. The overall cosmetic outcome score of Excellent/Good was 74% at 60 months after APBI. Grade ≥ 1 fibrosis was observed in 44% and 92% of patients who scored Excellent/Good and Fair/Poor, respectively, p = 0.004.

CONCLUSIONS

This study showed excellent local control and survival results with minimal late sequelae.

The Relationship Between Late Morbidity and Dose-Volume Parameter of Rectum in Combined Intracavitary/Interstitial Cervix Cancer Brachytherapy: A Mono-Institutional Experience

Purpose

To establish a dose volume–effect relationship for predicting late rectal complication (LRC) in locally advanced cervical cancer patients treated with external beam radiotherapy (EBRT) followed by combined intracavitary/interstitial brachytherapy (IC/IS-BT).

Materials and Methods

A retrospective analysis was performed in 110 patients with locally advanced cervical cancer who underwent definitive radiotherapy combined with IC/IS-BT from July 2010 to September 2018. We report the 90% of the target volume receiving the minimum dose for high risk clinical target volume (HR-CTV D₉₀) and intermediate risk clinical target volume (IR-CTV D₉₀), and the minimum doses to the most exposed 0.1, 1, and 2 cm³ D0.1cm3,D1cm3,D2cm3 doses at the International Commission on Radiation Units and Measurements (D_ICRU) for organs at risk (OARs). The total dose of EBRT plus brachytherapy was transformed to the biologically equivalent dose in 2 Gy fractions (EQD2) with α/β value of 10 Gy for target, 3 Gy for organs at risk using the linear quadratic model. The morbidity was scored according to the Radiation Therapy Oncology Group (RTOG) criteria. The Probit model was used to establish a prediction model on rectum between the organs at risk for dose and LRC. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of dose volume parameters for LRC.

Results

The median follow-up time was 72.3 months. The mean ( ± standard deviation) D2cm3,D1cm3,D0.1cm3, and D_ICRU values of rectum were 64.72 ± 7.47 Gy_EQD2, 70.18 ± 5.92 Gy_EQD2, 79.32 ± 7.86 Gy_EQD2, and 67.22 ± 7.87 Gy_EQD2, respectively. The Probit model showed significant relationships between D1cm3 or D0.1cm3, and the probability of grade1–4, grade 2–4 rectal events at 1 year, and between D1cm3and the probability of grade2–4 rectal events at 3 and 5 years. The dose values for 10% complication rates (ED10) of D1cm3were 74.18 (70.42–76.71) Gy_EQD2, 67.80 (59.91, 71.08) Gy_EQD2, 66.37 (52.00, 70.27) Gy_EQD2 for grade 2–4 with rectal morbidity at 1, 3, and 5 years, respectively.

Conclusion

Our study proved that D1cm3 andD0.1cm3were considered as useful dosimetric parameters for predicting the risk of grade1–4 and grade2–4 LRC at 1-year, and D1cm3might be an indicator for predicting grade2-4 LRC at 3/5years. The patients with rectal D1cm3>66.37–74.18 Gy_EQD2 should be closely observed for grade2–4 LRC.

Correlation analysis of CT-based rectal planning dosimetric parameters with in vivo dosimetry of MOSkin and PTW 9112 detectors in Co-60 source HDR intracavitary cervix brachytherapy

Intracavitary cervical brachytherapy delivers high doses of radiation to the target tissue and a portion of these doses will also hit the rectal organs due to their close proximity. Rectal dose can be evaluated from dosimetric parameters in the treatment planning system (TPS) and in vivo (IV) dose measurement. This study analyzed the correlation between IV rectal dose with selected volume and point dose parameters from TPS. A total of 48 insertions were performed and IV dose was measured using the commercial PTW 9112 semiconductor diode probe. In 18 of 48 insertions, a single MOSkin detector was attached on the probe surface at 50 mm from the tip. Four rectal dosimetric parameters were retrospectively collected from TPS; (a) PTW 9112 diode maximum reported dose (RP_max) and MOSkin detector, (b) minimum dose to 2 cc (D_2cc), (c) ICRU reference point (ICRU_r), and (d) maximum dose from additional points (R_max). The IV doses from both detectors were analyzed for correlation with these dosimetric parameters. This study found a significantly high correlation between IV measured dose from RP_max (r = 0.916) and MOSkin (r = 0.959) with TPS planned dose. The correlation between measured RP_max with both D_2cc and R_max revealed high correlation of r > 0.7, whereas moderate correlation (r = 0.525) was observed with ICRUr. There was no significant correlation between MOSkin IV measured dose with D_2cc, ICRU_r and R_max. The non-significant correlation between parameters was ascribable to differences in both detector position within patients, and dosimetric volume and point location determined on TPS, rather than detector uncertainties.

Analysis of Radiation Dose/Volume Effect Relationship for Anorectal Morbidity in Children Treated for Pelvic Malignancies

PURPOSE

To examine dose-volume effect relationships for anorectal morbidity in children treated with image-guided brachytherapy for pelvic tumors.

METHODS AND MATERIALS

Medical records of all consecutive children with pelvic tumors treated in our center and receiving image-guided pulsed-dose-rate brachytherapy with or without external beam radiation therapy (EBRT) between 2005 and 2019 were reviewed. The effect of the minimal doses to the most exposed 0.5 cm³, 1 cm³, and 2 cm³ of the anorectum (respectively: D_0.5cm³, D_1cm³, and D_2cm³), total reference air kerma (TRAK), and volume of 100% isodose was examined for anorectal toxicities.

RESULTS

Seventy-eight consecutive children were included. Median age was 2.9 years (range, 0.8-14.9 years). Most of the tumors were bladder or prostate (67%) or vaginal (22%) rhabdomyosarcoma. Six patients received EBRT in addition to brachytherapy. Median follow-up was 21.3 months. At last follow-up, 30 children (38%) had experienced Common Terminology Criteria for Adverse Events version 5 grade ≥1 acute or late anorectal events: 24% had grade 1 events, 7.7% had grade 2 events, and 6.4% had grade 3 events. No toxicity greater than grade 3 was observed (eg, fistula or stricture). In univariate analysis, the D_0.5cm³ and D_1cm³ were significant for probability of grade 1 to 3 (P = .009 and P = .017, respectively) and grade 2 to 3 anorectal morbidity (P = .007 and P = .049, respectively). There was no significant correlation for D_2cm³ (P = .057 for grade 1-3; P = .407 for grade 2-3). A 10% probability (95% confidence interval, 4%-20%) for anorectal toxicity of grade 2 or greater was reached for a D_0.5cm³ = 52 Gy. The age, EBRT use, TRAK, and treated volume values were not significant.

CONCLUSIONS

To our knowledge, this study is the first to show a significant dose-volume effect relationships for anorectal morbidity in children undergoing treatment with brachytherapy. Integrating these data into brachytherapy treatment planning could help to optimize the therapeutic index in these young patients.

Plan-Optimization Method for Central-shielding Pelvic Volumetric-modulated Arc Therapy for Cervical Cancer

AIM

To establish a method of plan optimization in pelvic volumetric-modulated arc therapy (VMAT) for cervical cancer using the central-shielding (CS) principle.

PATIENTS AND METHODS

We created external beam VMAT plans for eight cases with non-bulky stage I-IIb using the CS principle based on the Japanese standard guideline. Clinical target volumes (CTVs) for whole-pelvis (WP) irradiation were created using published guidelines, and CTVs for CS irradiation were created by subtracting the uterus corpus and 4 cm-wide regions centered at the cervix and vagina from the CTVs for WP irradiation. For plan optimization of CS irradiation, a 4-cm diameter cylindrical volume centered in the cervix and vagina was created as the volume receiving a high dose in brachytherapy, and the volume overlapping with the rectum was defined as the Ant-Rectum. Dose-volume histogram (DVH) parameters of two CS VMAT plans with and without (VMAT_OPT/VMAT_NO) dose optimization to the Ant-Rectum were compared.

RESULTS

VMAT_OPT plans resulted in significantly lower DVH parameters of the Ant-Rectum and rectum compared to VMAT_NO plans. These were comparable to the DVH parameters of three-dimensional conformal radiotherapy (3DCRT) plans. Both VMAT plans resulted in significantly better coverage of planning target volumes than did the 3DCRT plans.

CONCLUSION

In the implementation of IMRT/VMAT as the standard treatment for cervical cancer in Japan, our optimization method may be an essential step toward fully benefitting from the CS principle.

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.

Dosimetric comparison of inverse optimisation methods versus forward optimisation in HDR brachytherapy of breast, cervical and prostate cancer

Objective

Dosimetric comparison of HIPO (hybrid inverse planning optimisation) and IPSA (inverse planning simulated annealing) inverse and forward optimisation (FO) methods in brachytherapy (BT) of breast, cervical and prostate cancer.

Methods

At our institute 38 breast, 47 cervical and 50 prostate cancer patients treated with image-guided interstitial high-dose-rate BT were selected. Treatment plans were created using HIPO and IPSA inverse optimisation methods as well as FO. The dose–volume parameters of different treatment plans were compared with Friedman ANOVA and the LSD post-hoc test.

Results

IPSA creates less dose coverage to the target volume than HIPO or FO: V100 was 91.7%, 91% and 91.9% for HIPO, IPSA and FO plans (p = 0.1784) in breast BT; 90.4%, 89.2% and 91% (p = 0.0045) in cervical BT; and 97.1%, 96.2% and 97.7% (p = 0.0005) in prostate BT, respectively. HIPO results in more conformal plans: COIN was 0.72, 0.71 and 0.69 (p = 0.0306) in breast BT; 0.6, 0.47 and 0.58 (p < 0.001) in cervical BT; and 0.8, 0.7 and 0.7 (p < 0.001) in prostate BT, respectively. In breast BT, dose to the skin and lung was smaller with HIPO and FO than with IPSA. In cervical BT, dose to the rectum, sigmoid and bowel was larger using IPSA than with HIPO or FO. In prostate BT, dose to the urethra was higher and the rectal dose was smaller using FO than with inverse methods.

Conclusion

In interstitial breast and prostate BT, HIPO results in comparable dose–volume parameters to FO, but HIPO plans are more conformal. In cervical BT, HIPO produces dosimetrically acceptable plans only when more needles are used. The dosimetric quality of IPSA plans is suboptimal and results in unnecessary larger active lengths.

Importance of Technique, Target Selection, Contouring, Dose Prescription, and Dose-Planning in External Beam Radiation Therapy for Cervical Cancer: Evolution of Practice From EMBRACE-I to II

PURPOSE

To describe the evolution of external beam radiation therapy (EBRT) from EMBRACE-I (general guidelines for EBRT) to the initial phase of the EMBRACE-II study (detailed protocol for EBRT).

METHODS AND MATERIALS

EMBRACE-I enrolled 1416 locally advanced cervical cancer patients treated with chemoradiation including image-guided adaptive brachytherapy during 2008 to 2015. From March 2016 until March 2018, 153 patients were enrolled in the ongoing EMBRACE-II study, which involves a comprehensive detailed strategy and accreditation procedure for EBRT target contouring, treatment planning, and image guidance. EBRT planning target volumes (PTVs), treated volumes (V43 Gy), and conformity index (CI; V43 Gy/PTV) were evaluated in both studies and compared.

RESULTS

For EMBRACE-I, conformal radiation therapy (60% of patients) or intensity-modulated radiation therapy (IMRT) and volumetric arc therapy (VMAT; 40%) was applied with 45 to 50 Gy over 25 to 30 fractions to the elective clinical target volume (CTV). For pelvic CTVs (82%), median PTV and V43 Gy volumes were 1549 and 2390 mL, respectively, and CI was 1.54. For pelvic plus paraortic nodal (PAN) CTVs (15%), median PTV and V43 Gy volumes were 1921 and 2895 mL, and CI was 1.51. For pelvic CTVs treated with 45 to 46 Gy, the use of conformal radiation therapy was associated with a median V43 Gy volume that was 546 mL larger than with IMRT/VMAT. For pelvic CTVs treated with IMRT, the use of a dose prescription ≥48 Gy was associated with a median V43 Gy volumes that was 428 mL larger than with a dose prescription of 45 to 46 Gy. For EMBRACE-II, all patients were treated with: IMRT/VMAT, daily IGRT, 45 Gy over 25 fractions for the elective CTV, and simultaneously integrated boost for pathologic lymph nodes. For pelvic CTVs (61%), median PTV and V43 Gy volumes were 1388 and 1418 mL, and CI was 1.02. For pelvic plus PAN CTVs (32%), median PTV and V43 Gy volumes were 1720 and 1765 mL, and CI was 1.03. From EMBRACE-I to initial II, median V43 Gy was decreased by 972 mL (41%) and 1130 mL (39%), and median CI decreased from 1.54 to 1.02 and 1.51 to 1.03 for pelvic and pelvic plus PAN irradiation, respectively.

CONCLUSIONS

Application of IMRT/VMAT, IGRT, and a 45-Gy dose provides the potential of higher conformality inducing significant reduction of treated volume. Adherence to a detailed protocol including comprehensive accreditation, as in EMBRACE-II, reduces considerably V43 Gy and V50 Gy and improves conformality and interinstitutional consistency.

Comparative analysis of image-guided adaptive interstitial brachytherapy and intensity-modulated arc therapy versus conventional treatment techniques in cervical cancer using biological dose summation

Purpose

To compare image-guided adaptive interstitial brachytherapy (BT) and intensity-modulated arc therapy (IMAT) with conventional treatment techniques in cervical cancer using an alternative biological dose summation method.

Material and methods

Initially, 21 interstitial BT and IMAT plans of patients with cervical cancer were included and additional plans were created (inverse optimized interstitial, optimized intracavitary, non-optimized intracavitary BT plans, and conformal external beam radiotherapy [EBRT]). The most exposed volume of critical organs in BT were identified manually on EBRT CT images. Biological total doses (EQD2) were calculated and compared between each combination of BT and EBRT plans. This method was compared with uniform dose conception (UDC) in IMAT and conformal EBRT plans.

Results

The D₉₀ of high-risk CTV and D₂ of bladder and sigmoid were different in BT techniques only: p = 0.0149, < 0.001, < 0.001, respectively. The most advantageous values were obtained in the interstitial treatment plans and inverse optimized interstitial plans did not differ dosimetrically from these, while optimized intracavitary plans resulted in worse dose-volume parameters, and the worst of all were intracavitary plans without optimization. The D₂ of rectum was significantly lower with IMAT than with conformal EBRT plans (p = 0.037) and showed the same trend in BT plans as the other parameters (p < 0.001). The UDC dose summation method overestimated D₂ of bladder, rectum, and sigmoid (p < 0.001 for all).

Conclusions

Although optimization improves the quality of conventional BT plans, interstitial plans produce significantly higher dose coverage of high-risk clinical target volume (HR-CTV) and lower doses to organs at risk (OARs). IMAT plans decrease the dose to the rectum. UDC overestimates OARs doses.

Characterization of MOSkin detector for in vivo dose verification during Cobalt-60 high dose-rate intracavitary brachytherapy

In vivo dosimetry in high dose-rate (HDR) intracavitary brachytherapy (ICBT) is important for assessing the true dose received by surrounding organs at risk during treatment. It also serves as part of the treatment delivery quality assurance and verification program with the use of a suitable dosimeter. Such a dosimeter should be characterized under brachytherapy conditions before clinical application to ensure the accuracy of in vivo measurement. In this study, a MOSFET-based detector, MOSkin, was calibrated and characterized under HDR Cobalt-60 (Co-60) brachytherapy source. MOSkin possessed the major advantages of having small physical and dosimetric sizes of 4.8 × 10^-6 mm³ with the ability to provide real-time measurements. Using solid water and polymethyl methacrylate (PMMA) phantom, the detectors' reproducibility, linearity, angular and distance dependency was tested for its suitability as an in vivo detector. Correction factors to account for differences in depth measurements were determined. The MOSkin detector showed a reliable response when tested under Co-60 brachytherapy range of doses with an excellent linearity of R² = 0.9997 and acceptable reproducibility. A phantom verification study was also conducted to verify the differences between MOSkin responses and treatment planning (TPS) calculated doses. By taking into account several correction factors, deviations ranging between 0.01 and 0.4 Gy were found between MOSkin measured and TPS doses at measurement distance of 20-55 mm. The use of MOSkin as the dosimeter of choice for in vivo dosimetry under Co-60 brachytherapy condition is feasible.

Dosimetric research into target regions and organs at risk in three-dimensional intracavitary brachytherapy techniques for Chinese patients with cervical carcinoma

The present study aimed to compare the dosages of target regions and organs at risk (OARs) in 3D intracavitary brachytherapy (ICBT) and conventional 2D ICBT for Chinese patients with cervical carcinoma. ICBT was performed in a total of 66 patients with Stage IB to IVA cervical carcinoma who had not received surgery but who had received whole-pelvic external-beam radiotherapy (EBRT). Plans for the 3D-ICBT and the conventional 2D-ICBT were individually designed for every patient. The dosages differences between the target regions and the OARs in patients with each of the various stages of cervical carcinoma were compared between the two ICBT plans. There was no significant difference in the dose at Point A between the two ICBT plans. However, the CTVhr-D90, CTVhr-D100 and CTVir-D90 in 3D-ICBT were much higher than in 2D-ICBT, especially in Stage IIB (P < 0.05). As compared with conventional 2D-ICBT, the dosages of DICRU and D2.0cm3 in the rectum/bladder, and D2.0cm3 in the sigmoid/small bowel were decreased significantly in 3D-ICBT (P < 0.05). For patients with Stage IIA, IIB and IIIB, the D2.0cm3 in the rectum/bladder was significantly reduced in 3D-ICBT (P < 0.05). It was demonstrated that, in Chinese patients, 3D-ICBT for cervical carcinoma could optimize the target coverage and reduce the dosages to the OARs compared with conventional 2D-ICBT.

The role of endoscopic evaluation for radiation proctitis in patients receiving intermediate-dose postoperative radiotherapy for rectal cancer

Objectives

High-dose pelvic radiotherapy (RT) is known to be associated with chronic radiation proctitis (RP). However, the effects of intermediate radiation doses are unknown. We assessed the incidence of late clinical RP among patients with rectal cancer receiving intermediate-dose postoperative RT, as well as the role of early endoscopic abnormalities in predicting RP development.

Methods

We retrospectively reviewed 153 patients with rectal cancer who received postoperative RT at a median dose of 54 Gy between 2005 and 2009 and who underwent endoscopic examination within 12 months thereafter. Endoscopic RP was assessed using the Vienna rectoscopy score (VRS). Late clinical RP toxicity was evaluated, as was its correlation with endoscopic RP.

Results

All patients underwent an endoscopic examination at a median of 9 months after postoperative pelvic RT. Endoscopic RP was detected in 45 patients (29.4%); the predominant patterns were telangiectasia and congested mucosa. During the median 88-month follow-up period, 29 patients (19.0%) experienced late clinical RP; only 3 (2.0%) had Grade 3 or above. The VRS predicted the development of late clinical RP as well as its cumulative incidence (P < 0.001). Endoscopic evidence of telangiectasia was significantly associated with the development of late clinical RP (P < 0.001).

Conclusions

Early endoscopic findings using VRS are useful for predicting the possibility of late clinical RP, although the incidences of severe cases were low. Patients with endoscopic abnormalities should be followed closely owing to their susceptibility to clinical RP.

Evaluation of offline adaptive planning techniques in image-guided brachytherapy of cervical cancer

Modern three‐dimensional image‐guided intracavitary high dose rate (HDR) brachytherapy is often used in combination with external beam radiotherapy (EBRT) to manage cervical cancer. Intrafraction motion of critical organs relative to the HDR applicator in the time between the planning CT and treatment delivery can cause marked deviations between the planned and delivered doses. This study examines offline adaptive planning techniques that may reduce intrafraction uncertainties by shortening the time between the planning CT and treatment delivery. Eight patients who received EBRT followed by HDR boosts were retrospectively reviewed. A CT scan was obtained for each insertion. Four strategies were simulated: (A) plans based on the current treatment day CT; (B) plans based on the first fraction CT; (C) plans based on the CT from the immediately preceding fraction; (D) plans based on the closest anatomically matched previous CT, using all prior plans as a library. Strategies B, C, and D allow plans to be created prior to the treatment day insertion, and then rapidly compared with the new CT. Equivalent doses in 2 Gy for combined EBRT and HDR were compared with online adaptive plans (strategy A) at D₉₀ and D₉₈ for the high‐risk CTV (HR‐CTV), and D_2 cc for the bladder, rectum, sigmoid, and bowel. Compared to strategy A, D₉₀ deviations for the HR‐CTV were −0.5 ± 2.8 Gy, −0.9 ± 1.0 Gy, and −0.7 ± 1.0 Gy for Strategies B, C, and D, respectively. D_2 cc changes for rectum were 2.7 ± 5.6 Gy, 0.6 ± 1.7 Gy, and 1.1 ± 2.4 Gy for Strategies B, C, and D. With the exception of one patient using strategy B, no notable variations for bladder, sigmoid, and bowel were found. Offline adaptive planning techniques can shorten time between CT and treatment delivery from hours to minutes, with minimal loss of dosimetric accuracy, greatly reducing the chance of intrafraction motion.

Assessment of cartesian co-ordinates-based bladder and rectal dose and variability with tandem-ring angles first Nigerian experience in high-dose-rate brachytherapy

OBJECTIVE:

This study assessed bladder and rectal dose based on Cartesian-coordinates in intracavitary brachytherapy and examined the variations resulting from use of tandem-ring (T-R) of different angles.

METHODS:

Cartesian-co-ordinates of bladder and rectum points were derived on orthogonal-radiographs of 90 patients who had high-dose-rate brachytherapy for cervical cancer at the Department of Radiation Oncology, University College Hospital, Ibadan, Nigeria. The patients were classified in three groups of 30, based on T-R angles 30°, 45° and 60° used, bearing same lengths and diameters across sets. The measured co-ordinates and the related percentage doses to points of interest in the two organs were analysed using EViews and SPSS statistical softwares.

RESULTS:

The mean rectal point dose (RPD) obtained was 68.97 ± 13.57 % of the prescribed doses as against 56.57 ± 11.83% for bladder point dose. While the maximums of the mean RPD were 95.7, 90.5 and 82.5% for T-R angles 30°, 45° and 60° respectively; corresponding values for the bladder point were 72.8, 87.8 and 62.3%.

CONCLUSION:

The baseline data obtained in this study served as guidelines for subsequently achieving acceptable values of bladder point dose and RPD at University College Hospital, Nigeria. Special attention should be paid to the application of 2 cm-tandems in relation to the RPD.

ADVANCES IN KNOWLEDGE:

This is one of the few studies assessing the influence of T-R angles on organs-at-risk. The increase in RPD with the use of intrauterine tandem-2 cm is found to be most pronounced with T-R 30⁰, and this trend reduced with larger angles.

Bowel morbidity following radiochemotherapy and image-guided adaptive brachytherapy for cervical cancer: Physician- and patient reported outcome from the EMBRACE study

BACKGROUND/PURPOSE

This study describes late bowel morbidity prospectively assessed in the multi-institutional EMBRACE study on MRI-guided adaptive brachytherapy in locally advanced cervical cancer (LACC).

MATERIALS/METHODS

A total of 1176 patients were analyzed. Physician reported morbidity (CTCAE v.3.0) and patient reported outcome (PRO) (EORTC QLQ C30/CX24) were assessed at baseline and at regular follow-up.

RESULTS

At 3/5 years the actuarial incidence of bowel morbidity grade 3-4 was 5.0%/5.9%, including incidence of stenosis/stricture/fistula of 2.0%/2.6%. Grade 1-2 morbidity was pronounced with prevalence rates of 28-33% during follow-up. Diarrhea and flatulence were most frequently reported, significantly increased after 3 months and remained elevated during follow-up. Incontinence gradually worsened with time. PRO revealed high prevalence rates. Diarrhea ≥"a little" increased from 26% to 37% at baseline to 3 months and remained elevated, difficulty in controlling bowel increased from 11% to 26% at baseline to 3 months gradually worsening with time. Constipation and abdominal cramps improved after treatment.

CONCLUSION

Bowel morbidity reported in this large cohort of LACC patients was limited regarding severe/life-threatening events. Mild-moderate diarrhea, flatulence and incontinence were prevalent after treatment with PROs indicating a considerable and clinically relevant burden. Critical knowledge based on the extent and manifestation pattern of treatment-related morbidity will serve future patient management.

Predictive Factors of Late-onset Rectal Mucosal Changes After Radiotherapy of Prostate Cancer

BACKGROUND/AIM

The Vienna Rectoscopy Score (VRS; from 0, absence of rectal mucosal changes, to 5) assessed 1 year after radiotherapy is a surrogate end-point of late rectal toxicity. The aim of this study was to investigate the association between treatment-related factors and 1-year VRS.

PATIENTS AND METHODS

We performed a retrospective analysis of prospectively collected data. Patients with prostate adenocarcinoma treated with definitive or postoperative radiotherapy (RT) underwent endoscopy 1 year after RT. Relationships between VRS of 2 or more and treatment parameters were investigated by univariate and multivariate logistic analyses.

RESULTS

One hundred and ninety-five patients (mean age=69 years; range=43-81 years) were considered eligible for the study. At univariate analysis, patients treated with hypofractionation plus radiosurgery boost (p<0.001) and an equivalent dose in 2 Gy per fraction (EQD2) (α/β=3) ≥75 Gy (p<0.001) was associated with a significantly higher incidence of VRS ≥2 after 1 year of follow-up. At multivariate analysis, radiosurgery boost was an independent risk factor for developing rectal mucosal lesions (VRS ≥2), yielding an odds ratio (OR) of 4.14 (95% confidence interval (CI)=1.2-13.8), while pelvic surgery was inversely associated with VRS ≥2 (OR=0.39; 95% CI=0.17-0.94).

CONCLUSION

Hypofractionation followed by radiosurgery boost significantly increased the risk of developing late-onset rectal mucosal changes. Therefore, special care and preventative treatment strategies are needed when using radiosurgery boost after hypofractionated RT.

Clinical analysis of speculum-based vaginal packing for high-dose-rate intracavitary tandem and ovoid brachytherapy in cervical cancer

Purpose

Intra-vaginal packing is used to fix the applicator and displace organs at risk (OAR) during high-dose-rate intracavitary tandem and ovoid brachytherapy (HDR-ICB). We retain the speculum from applicator placement as a dual-function bladder and rectum retractor during treatment. Our objective is to review salient techniques for OAR displacement, share our packing technique, and determine the reduction in dose to OAR and inter-fraction variability of dose to OAR, associated with speculum-based vaginal packing (SBVP) in comparison to conventional gauze packing during HDR-ICB.

Material and methods

We reviewed HDR-ICB treatment plans for 45 patients, including 10 who underwent both conventional gauze packing and SBVP. Due to institutional inter-provider practice differences, patients non-selectively received either packing procedure. Packing was performed under conscious sedation, followed by cone beam computed tomography used for dosimetric planning. Maximum absolute and percent-of-prescription dose to the International Commission of Radiation Units bladder and rectal points in addition to D_0.1cc, D_1.0cc, and D_2.0cc volumes of the bladder and rectum were analyzed and compared for each packing method using an independent sample t-test.

Results

Of the 179 fractions included, 73% and 27% used SBVP and gauze packing, respectively. For patients prescribed 6 Gy to point A, SBVP was associated with reduced mean D_0.1cc bladder dose, inter-fraction variability in D_0.1cc bladder dose by 9.3% (p = 0.026) and 9.0%, respectively, and statistically equivalent rectal D_0.1cc, D_1.0cc, and D_2.0cc. Patients prescribed 5.5 Gy or 5 Gy to point A after dose optimization, were less likely to benefit from SBVP. In the intra-patient comparison, 80% of patients had reduction in at least one rectum or bladder parameter.

Conclusions

In patients with conducive anatomy, SBVP is a cost-efficient packing method that is associated with improved bladder sparing and comparable rectal sparing relative to gauze packing during HDR-ICB without general anesthesia.

Effects of vaginal cylinder position on dose distribution in patients with endometrial carcinoma in treatment of vaginal cuff brachytherapy

PURPOSE

To investigate the impact of different cylinder positions on dosimetry of critical structures in patients with endometrial carcinoma undergoing three-dimensional image-based vaginal cuff brachytherapy (VCB).

MATERIAL AND METHODS

We delivered VCB at a dose of 4 Gy to a depth of 5 mm in the vaginal cuff of 15 patients using three different cylinder positions (neutral [N], parallel [P], and angled [A]) according to the longitudinal axis of the patient. We analyzed the dose-volume distribution and volumetric variability of the rectum and bladder. We converted the total doses to equivalent doses in 2 Gy (EQD₂) using a linear-quadratic model (a/b = 3 Gy).

RESULTS

The mean rectum volume for the N, P, and A positions was 68.2 ± 22.7 cc, 79.3 ± 33.7 cc, and 74.2 ± 29.6 cc, respectively. The mean rectum volume for the P position was significantly larger than that for the N position (p = 0.03). Relative to the N position, the A position resulted in a lower total EQD₂ in the highest irradiated 2 cc (D_2cc; p = 0.001), 1 cc (D_1cc; p = 0.004), and 0.1 cc (D_0.1cc; p = 0.047) of the rectum. Similarly, the P position resulted in a lower EQD₂ in the D_2cc (p = 0.018) and D_1cc (p = 0.024) of the rectum relative to the N position. In the bladder, the P position resulted in a higher EQD₂ in the D_2cc relative to the N position (p = 0.02). There was no dosimetric difference between the P and A positions in either the rectum or the bladder.

CONCLUSIONS

Vaginal cuff brachytherapy in the P and A positions is significantly superior to that in the N position in terms of rectum dosimetry. The bladder dose in the N position is considerably lower than that in the other positions.

The usefulness of fleet rectal enemas on high-dose-rate intracavitary cervical cancer brachytherapy. A prospective trial

Purpose

To evaluate the effects of rectal enemas on rectal doses during radical high-dose-rate (HDR) intracavitary cervical brachytherapy (BT).

Material and methods

Twenty patients suffering from cervical cancer and treated with external beam radiotherapy and HDR-BT were included in a prospective trial. The first brachytherapy fraction was considered the basal status, and patients were instructed to self-administer two rectal cleansing enemas before the second fraction. Dose-volume histogram (DVH) values were generated for the rectum and correlated with rectal volume variation. Brachytherapy was carried out with a Fletcher or Utrecht applicator.

Results

No significant rectal volume differences were observed between fractions with or without rectal enemas (without, 52.64 ± 15.92 cc; with, 53.16 ± 19.28 cc). There was a significant correlation between both rectal volumes (r = 0.722, p = 0.001). No significant differences were observed in analyzed DVH parameters (median values: ΔD_0.1cc, 4.17 vs. 3.61 Gy; ΔD_1cc, 3.23 vs. 2.87 Gy; ΔD_2cc, 2.9 vs. 2.54 Gy; ΔD_5cc, 2.35 vs. 2.05 Gy, for no enema and enema fraction, respectively). No significant rectal volume differences nor DVH parameter differences were observed according the applicator type.

Conclusions

Our rectal enemas protocol prior to HDR-BT was ineffective in significantly modifying rectal DVH parameters. No differences were observed according to the type of applicator used.

Model assessment of individual tumor control rate and adverse effects in comparing locally advanced cervical cancer treatment using intracavitary with and without interstitial brachytherapy

Purpose

This study assessed the modeled probability of tumor control and organ at risk toxicities in locally advanced cervical cancer in patients treated by external beam radiation plus brachytherapy using intracavitary combined with interstitial brachytherapy (IC/IS) vs. intracavitary brachytherapy (IC) alone.

Material and methods

Twenty cervical cancer patients with a mean HR-CTV volume of 47.4 cm³ and a mean width of 54 mm were planned with both IC/IS and IC brachytherapy alone. A probit model was utilized to model 3-year (3-yr) local control rate (LC), 3-yr cancer specific survival rate (CSS), and the adverse effect (AE) of the organ at risk by using a modeled data set from multiple institutions. Modeling results were used to estimate the LC, CSS, and AE of the treatments in this study.

Results

Using the IC/IS technique, an EQD₂ increase of 12.3 Gy to D₉₀ (from 76.1 Gy to 88.3 Gy) of HR-CTV is expected to increase 3-yr LC and 3-yr CSS by 12.5%, and 11.0%, respectively. Comparing IC/IS to IC alone, the expected G2⁺ AE were 7.7% vs. 7.9% for the bladder, and 5.9% vs. 6.8% for the rectum.

Conclusions

The IC/IS technique improved dose coverage to the HR-CTV without significantly increasing dose to 2 cm³ of the organ at risk (OAR) surrounding it. With different regimens of EBRT combined with BT, IC/IS can be used to increase the probability of LC and CSS, or decrease the risk of AE.

Feasibility study of toxicity outcomes using GEC-ESTRO contouring guidelines on CT based instead of MRI-based planning in locally advanced cervical cancer patients

PURPOSE

To report late rectal and bladder toxicity outcomes of a CT-based image-guided brachytherapy (IGBT) technique for treatment of cervical cancer.

METHODS AND MATERIALS

Between 2008 and 2014, 95 women with International Federation of Gynecology and Obstetrics stage IB to IVA cervical carcinoma treated with definitive concurrent cisplatin-based chemotherapy and external beam radiation therapy 50.4 Gy in 28 fractions followed by planned prescription dose of 7 Gy × 4 fractions of high-dose-rate IGBT was retrospectively reviewed. At each implantation, all patients had a urinary catheter in situ and received bowel enema before undergoing planning CT simulation. A high-risk clinical target volume (HRCTV) as per GEC-ESTRO guidelines and the entire cervix, rectum, and bladder was contoured on the simulation CT according to Radiation Therapy Oncology Group Gynaecology Contouring Atlas. Reported doses to HRCTV and organs at risk were recorded. Toxicities were recorded using National Cancer Institute Common Terminology Criteria for Adverse Events version 3.

RESULTS

The median followup time was 29 months. The mean HRCTV equivalent dose in 2 Gy fractions (EQD2) of external beam radiation therapy combined with brachytherapy was 80 Gy (standard deviation [SD], 11), and the rectal doses to 2 cm³ (D2cc) EQD2 and bladder D2cc EQD2 were 74 Gy (SD, 6) and 79 Gy (SD, 15), respectively. Twenty-two patients (23%) had grade 2 proctitis and 10 patients (11%) had grade 3 proctitis. Four patients (4%) had grade 2 cystitis and two patients (2%) had grade 3 cystitis. No patients had ≥ grade 4 toxicity.

CONCLUSIONS

Despite CT-based brachytherapy planning, reported organ at risk toxicity was still significant compared with reported MRI-based planning series. Coimplementation of interstitial IGBT using the European Study on MRI-guided Brachytherapy in Locally Advanced Cervical Cancer (EMBRACE) protocol or using intensity-modulated radiation therapy during the external beam phase treatment might help to limit these late toxicities.

Rectal separation using hydroxypropyl methylcellulose in intracavitary brachytherapy of cervical cancer: an innovative approach

PURPOSE

This study was initiated to prove feasibility of hydrogel application in recto-vaginal space in intracavitary brachytherapy (ICBT) of cervical cancer in order to reduce rectal toxicity.

MATERIAL AND METHODS

In a case of stage IIB cervical cancer, after external beam radiotherapy (EBRT), we planned ICBT 7 Gy × 3 fractions. In 1^st fraction (Plan 1), due to narrow separation between rectum and cervix (0.18 cm), only 5 Gy was delivered at point A (with high-risk clinical target volume [HR-CTV] D₉₀ 5.94 Gy, intermediate risk clinical target volume [IR-CTV] D₉₀ 4.54 Gy, rectum D_2cc 5.72 Gy, bladder D_2cc 5.52 Gy, and sigmoid colon 5.82 Gy). In 2^nd fraction (Plan 2), interstitial brachytherapy (ISBT) was attempted. For the prescription of 5 Gy, we get dose levels almost similar to the 1^st insertion: HR-CTV D₉₀ (6.7 Gy), IR-CTV D₉₀ (3.06 Gy), bladder D_2cc (5.7 Gy), rectum D_2cc (4.8 Gy), sigmoid colon D_2cc (1.3 Gy) (separation = 0.23 cm). During 3^rd fraction (Plan 3), prior doing interstitial insertion, we instilled 50 cc of hydroxypropyl methylcellulose (Viscomet^®) up to the tip of recto-vaginal septum. A repeat computed tomography (CT) scan was done 4 hours after Plan 3 treatment and it was re-planned (Plan 4) to find out migration of hydrogel if any and its dosimetric impact.

RESULTS

9 Gy was delivered to point A with a separation of 1.1 cm in Plan 3 (with HR-CTV D₉₀ 16.4 Gy, IR-CTV D₉₀ 11.3 Gy, rectum D_2cc 3.6 Gy, bladder D_2cc 6.9 Gy, and sigmoid colon 2.2 Gy). We achieved an optimum cumulative EQD₂ dose (HR-CTV D₉₀ 98.4 Gy, IR-CTV D₉₀ 76.1 Gy, rectum D_2cc 67.7 Gy, bladder D_2cc 73.2 Gy, and sigmoid colon 59.3 Gy). Hydrogel volume was decreased in Plan 4 without a major dosimetric changes.

CONCLUSIONS

Hydrogel instillation is a useful tool for recto-vaginal separation during cervical cancer brachytherapy. It increases therapeutic ratio without any adverse event.

Dose-volume effect relationships for late rectal morbidity in patients treated with chemoradiation and MRI-guided adaptive brachytherapy for locally advanced cervical cancer: Results from the prospective multicenter EMBRACE study

PURPOSE

To establish dose volume-effect relationships predicting late rectal morbidity in cervix cancer patients treated with concomitant chemoradiation and MRI-guided adaptive brachytherapy (IBABT) within the prospective EMBRACE study.

MATERIAL AND METHOD

All patients were treated with curative intent according to institutional protocols with chemoradiation and IGABT. Reporting followed the GEC-ESTRO recommendations ( [Formula: see text] , [Formula: see text] ), applying bioeffect modeling (linear quadratic model) with equieffective doses (EQD2₃). Morbidity was scored according to the CTC-AE 3.0. Dose-effect relationships were assessed using comparisons of mean doses, the probit model and log rank tests on event-free periods.

RESULTS

960 patients were included. The median follow-up was 25.4months. Twenty point one percent of the patients had grade 1 events, 6.0% grade 2, 1.6% grade 3 and 0.1%, grade 4. The mean D_ICRU, [Formula: see text] , and [Formula: see text] were respectively: 66.2±9.1Gy, 72.9±11.9Gy, and 62.8±7.6Gy. Increase of dose was associated with increase in severity of single endpoints and overall rectal morbidity (grade 1-4) (p<0.001-0.026), except for stenosis (p=0.24-0.31). The probit model showed significant relationships between the [Formula: see text] , [Formula: see text] , and D_ICRU and the probability of grade 1-4, 2-4, and 3-4 rectal events. The equieffective [Formula: see text] for a 10% probability for overall rectal grade⩾2 morbidity was 69.5Gy (p<0.0001). After sorting patients according to 6 [Formula: see text] levels, less favorable outcome was observed in the high dose subgroups, for bleeding, proctitis, fistula, and overall rectal morbidity. A [Formula: see text] ⩾75Gy was associated with a 12.5% risk of fistula at 3years versus 0-2.7% for lower doses (p>0.001). A [Formula: see text] <65Gy was associated with a two times lower risk of proctitis than [Formula: see text] ⩾65Gy.

CONCLUSIONS

Significant correlations were established between late rectal morbidity, overall and single endpoints, and dose-volume ( [Formula: see text] , [Formula: see text] ) and dose-point (D_ICRU) parameters. A [Formula: see text] ⩽65Gy is associated with more minor and less frequent rectal morbidity, whereas a [Formula: see text] ⩾75Gy is associated with more major and more frequent rectal morbidity.

Dose reconstruction technique using non-rigid registration to evaluate spatial correspondence between high-dose region and late radiation toxicity: a case of tracheobronchial stenosis after external beam radiotherapy combined with endotracheal brachytherapy for tracheal cancer

Purpose

Small organ subvolume irradiated by a high-dose has been emphasized to be associated with late complication after radiotherapy. Here, we demonstrate a potential use of surface-based, non-rigid registration to investigate how high-dose volume topographically correlates with the location of late radiation morbidity in a case of tracheobronchial radiation stenosis.

Material and methods

An algorithm of point set registration was implemented to handle non-rigid registration between contour points on the organ surfaces. The framework estimated the global correspondence between the dose distribution and the varying anatomical structure. We applied it to an 80-year-old man who developed tracheobronchial stenosis 2 years after high-dose-rate endobronchial brachytherapy (HDR-EBT) (24 Gy in 6 Gy fractions) and external beam radiotherapy (EBRT) (40 Gy in 2 Gy fractions) for early-stage tracheal cancer.

Results and conclusions

Based on the transformation function computed by the non-rigid registration, irradiated dose distribution was reconstructed on the surface of post-treatment tracheobronchial stenosis. For expressing the equivalent dose in a fractional dose of 2 Gy in HDR-EBT, α/β of linear quadratic model was assumed as 3 Gy for the tracheal bronchus. The tracheobronchial surface irradiated by more than 100 Gy_αβ3 tended to develop severe stenosis, which attributed to a more than 50% decrease in the luminal area. The proposed dose reconstruction technique can be a powerful tool to predict late radiation toxicity with spatial consideration.

Prospective comparison of rectal dose reduction during intracavitary brachytherapy for cervical cancer using three rectal retraction techniques

PURPOSE

To compare three rectal retraction methods on dose to organs at risk, focusing on rectal dose, in cervix cancer patients treated with high-dose-rate intracavitary brachytherapy.

METHODS AND MATERIALS

A prospective study was conducted on patients with cervical carcinoma treated with chemoradiotherapy, including external beam radiation and four fractions of high-dose-rate intracavitary brachytherapy prescribed to Point A using a ring and tandem applicator under conscious sedation. Rectal retraction methods included: a rectal retractor blade (RR), vaginal gauze packing (VP), and a tandem Foley balloon (FB). All three methods were used in all patients. The RR was used first, and the following applications were randomly assigned to VP or FB. CT planning was used to calculate D2cc for rectum, sigmoid, small bowel, and bladder. The Wilcoxon signed rank test was used to determine if the median dose differences between methods were statistically significant.

RESULTS

In these 11 patients, median dose (min, max) in cGy to the rectum using RR, FB, and VP was 131 (102, 165), 199 (124, 243), and 218 (149, 299), respectively. The RR demonstrated lower median intrapatient doses to rectum compared with FB and VP (-55 cGy; p = 0.014 and -76 cGy; p = 0.004, respectively). The RR also resulted in lower sigmoid doses. No differences in dose were observed between the VP and FB methods.

CONCLUSION

The rectal retractor significantly reduced the dose to rectum and sigmoid compared with FP and VP. In patients treated under conscious sedation, the RR method provides the best rectal sparing. There were no significant differences in dose observed between the FB and VP techniques.

Vaginal Dose Is Associated With Toxicity in Image Guided Tandem Ring or Ovoid-Based Brachytherapy

PURPOSE

To calculate vaginal doses during image guided brachytherapy with volume-based metrics and correlate with long-term vaginal toxicity.

METHODS AND MATERIALS

In this institutional review board-approved study, institutional databases were searched to identify women undergoing computed tomography and/or magnetic resonance-guided brachytherapy at the Duke Cancer Center from 2009 to 2015. All insertions were contoured to include the vagina as a 3-dimensional structure. All contouring was performed on computed tomography or magnetic resonance imaging and used a 0.4-cm fixed brush to outline the applicator and/or packing, expanded to include any grossly visible vagina. The surface of the cervix was specifically excluded from the contour. High-dose-rate (HDR) and low-dose-rate (LDR) doses were converted to the equivalent dose in 2-Gy fractions using an α/β of 3 for late effects. The parameters D0.1cc, D1cc, and D2cc were calculated for all insertions and summed with prior external beam therapy. Late and subacute toxicity to the vagina were determined by the Common Terminology Criteria for Adverse Events version 4.0 and compared by the median and 4th quartile doses, via the log-rank test. Univariate and multivariate hazard ratios were calculated via Cox regression.

RESULTS

A total of 258 insertions in 62 women who underwent definitive radiation therapy including brachytherapy for cervical (n=48) and uterine cancer (n=14) were identified. Twenty HDR tandem and ovoid, 32 HDR tandem and ring, and 10 LDR tandem and ovoid insertions were contoured. The median values (interquartile ranges) for vaginal D0.1cc, D1cc, and D2cc were 157.9 (134.4-196.53) Gy, 112.6 (96.7-124.6) Gy, and 100.5 (86.8-108.4) Gy, respectively. At the 4th quartile cutoff of 108 Gy for D2cc, the rate of late grade 1 toxicity at 2 years was 61.2% (95% confidence interval [CI] 43.0%-79.4%) below 108 Gy and 83.9% (63.9%-100%) above (P=.018); grade 2 or greater toxicity was 36.2% (95% CI 15.8%-56.6%) below 108 Gy and 70.7% (95% CI 45.2%-96.2%) above (P=.004); and grade 3 or worse toxicity was 9.9% (95% CI 0.0%-23.6%) below 108 Gy and 30.0% (95% CI 4.7%-55.3%) above (P=.025). This association was maintained on multivariate analysis, independent of covariates such as applicator type, age, and dose rate.

CONCLUSIONS

Vaginal dose was associated with all grades of vaginal toxicity. Confirmation at other sites using this methodology will be necessary to establish reproducibility; however, the integration of routine calculation of vaginal dose may be warranted.

Image Guided Cervical Brachytherapy: 2014 Survey of the American Brachytherapy Society

PURPOSE

To provide an update of the 2007 American brachytherapy survey on image-based brachytherapy, which showed that in the setting of treatment planning for gynecologic brachytherapy, although computed tomography (CT) was often used for treatment planning, most brachytherapists used point A for dose specification.

METHODS AND MATERIALS

A 45-question electronic survey on cervical cancer brachytherapy practice patterns was sent to all American Brachytherapy Society members and additional radiation oncologists and physicists based in the United States between January and September 2014. Responses from the 2007 survey and the present survey were compared using the χ(2) test.

RESULTS

There were 370 respondents. Of those, only respondents, not in training, who treat more than 1 cervical cancer patient per year and practice in the United States, were included in the analysis (219). For dose specification to the target (cervix and tumor), 95% always use CT, and 34% always use MRI. However, 46% use point A only for dose specification to the target. There was a lot of variation in parameters used for dose evaluation of target volume and normal tissues. Compared with the 2007 survey, use of MRI has increased from 2% to 34% (P<.0001) for dose specification to the target. Use of volume-based dose delineation to the target has increased from 14% to 52% (P<.0001).

CONCLUSION

Although use of image-based brachytherapy has increased in the United States since the 2007 survey, there is room for further growth, particularly with the use of MRI. This increase may be in part due to educational initiatives. However, there is still significant heterogeneity in brachytherapy practice in the United States, and future efforts should be geared toward standardizing treatment.

Evaluation of planning aims and dose prescription in image-guided adaptive brachytherapy and radiochemotherapy for cervical cancer: Vienna clinical experience in 225 patients from 1998 to 2008

BACKGROUND

To assess planning aims (PAs) and dose prescription in image-guided adaptive brachytherapy (IGABT) of cervical cancer and investigate potential impact on clinical outcome.

MATERIAL AND METHODS

Our study population consists of 225 consecutive cervical cancer patients (FIGO stages IB-IVA) treated between 1998 and 2008 at the Medical University of Vienna by external beam radiotherapy (EBRT) ± chemotherapy and IGABT. For this retrospective study, patients were stratified into two treatment groups: PA+ group, all dose constraints fulfilled for prescription; PA-, one or more dose constraints not fulfilled for prescription. The following dose constraints (EBRT+ IGABT) were applied: clinical target volume (CTV)HR D90 ≥ 85 Gy, D2cm3 Rectum < 70 Gy, D2cm3 Bladder < 90 Gy. Differences in patient, tumor and treatment characteristics and clinical outcome (event: local failure or grade 3 + 4 toxicity) were compared between Group 1 and 2. Further, the impact of learning period (1998-2000) and protocol period (2001-2008) on the fulfillment of PAs for dose prescription and clinical outcome was analyzed.

RESULTS

In the PA+ group there were 77 (34%) and in the PA- group 148 (66%) patients. In the PA- group, CTVHR D90 < 85 Gy was prescribed in 82 patients, D2cm3 bladder > 90 Gy was prescribed in 80 patients and D2cm3 Rectum > 70 Gy in 60 patients. Fulfillment of the PA for dose prescription improved from 4% in the learning period to 48% in the protocol period. The five-year event-free interval was 64% in the learning period and 84% in the protocol period (p = 0.008).

CONCLUSION

Fulfillment of all PAs for dose prescription is challenging - especially in patients with more advanced tumors. However, with growing experience fulfillment of PA for dose prescription can be significantly increased (learning and protocol period). Such increase in fulfilling PA for dose prescription is followed by a significant improvement in clinical outcome.

Three-dimensional dose accumulation in pseudo-split-field IMRT and brachytherapy for locally advanced cervical cancer

PURPOSE

Dose accumulation of split-field external beam radiotherapy (EBRT) and brachytherapy (BT) is challenging because of significant EBRT and BT dose gradients in the central pelvic region. We developed a method to determine biologically effective dose parameters for combined split-field intensity-modulated radiation therapy (IMRT) and image-guided BT in locally advanced cervical cancer.

METHODS AND MATERIALS

Thirty-three patients treated with split-field-IMRT to 45.0-51.2 Gy in 1.6-1.8 Gy per fraction to the elective pelvic lymph nodes and to 20 Gy to the central pelvis region were included in this study. Patients received six weekly fractions of high-dose rate BT to 6.5-7.3 Gy per fraction. A dose tracker software was developed to compute the equivalent dose in 2-Gy fractions (EQD2) to gross tumor volume (GTV), organs-at-risk and point A. Total dose-volume histogram parameters were computed on the 3D combined EQD2 dose based on rigid image registration. The dose accumulation uncertainty introduced by organ deformations between IMRT and BT was evaluated.

RESULTS

According to International Commission on Radiation Unit and Measurement and GEC European Society for Therapeutic Radiology and Oncology recommendations, D98, D90, D50, and D2cm3 EQD2 dose-volume histogram parameters were computed. GTV D98 was 84.0 ± 26.5 Gy and D2cc was 99.6 ± 13.9 Gy, 67.4 ± 12.2 Gy, 75.0 ± 10.1 Gy, for bladder, rectum, and sigmoid, respectively. The uncertainties induced by organ deformation were estimated to be -1 ± 4 Gy, -3 ± 5 Gy, 2 ± 3 Gy, and -3 ± 5 Gy for bladder, rectum, sigmoid, and GTV, respectively.

CONCLUSIONS

It is feasible to perform 3D EQD2 dose accumulation to assess high and intermediate dose regions for combined split-field IMRT and BT.

Image-based brachytherapy for cervical cancer

Cervical cancer is the third most common cancer in women worldwide; definitive radiation therapy and concurrent chemotherapy is the accepted standard of care for patients with node positive or locally advanced tumors > 4 cm. Brachytherapy is an important part of definitive radiotherapy shown to improve overall survival. While results for two-dimensional X-ray based brachytherapy have been good in terms of local control especially for early stage disease, unexplained toxicities and treatment failures remain. Improvements in brachytherapy planning have more recently paved the way for three-dimensional image-based brachytherapy with volumetric optimization which increases tumor control, reduces toxicity, and helps predict outcomes. Advantages of image-based brachytherapy include: improved tumor coverage (especially for large volume disease), decreased dose to critical organs (especially for small cervix), confirmation of applicator placement, and accounting for sigmoid colon dose. A number of modalities for image-based brachytherapy have emerged including: magnetic resonance imaging (MRI), computed tomography (CT), CT-MRI hybrid, and ultrasound with respective benefits and outcomes data. For practical application of image-based brachytherapy the Groupe Europeen de Curietherapie-European Society for Therapeutic Radiology and Oncology Working Group and American Brachytherapy Society working group guideline serve as invaluable tools, additionally here-in we outline our institutional clinical integration of these guidelines. While the body of literature supporting image-based brachytherapy continues to evolve a number of uncertainties and challenges remain including: applicator reconstruction, increasing resource/cost demands, mobile four-dimensional targets and organs-at-risk, and accurate contouring of “grey zones” to avoid marginal miss. Ongoing studies, including the prospective EMBRACE (an international study of MRI-guided brachytherapy in locally advanced cervical cancer) trial, along with continued improvements in imaging, contouring, quality assurance, physics, and brachytherapy delivery promise to perpetuate the advancement of image-based brachytherapy to optimize outcomes for cervical cancer patients.

Severe gastrointestinal complications in the era of image-guided high-dose-rate intracavitary brachytherapy for cervical cancer

PURPOSE

The purposes of this analysis are to report a modern series of severe gastrointestinal toxic effects after definitive chemoradiotherapy in the treatment of locally advanced cervical cancer at our institution and to review the existing literature on factors that contribute to toxic effects and preventive strategies and management.

METHODS

Our institution's cervical cancer cohort was evaluated for patients with late grade 3 to 4 gastrointestinal toxic effects who were retrospectively reviewed for clinical or dosimetric parameters that could have contributed to late toxic effects. A review of the published literature was performed to identify factors associated with late toxic effects, prophylactic agents, and corrective therapy.

FINDINGS

Five of 85 patients were identified as having late grade 3 to 4 gastrointestinal toxic effects with a median follow-up of 13.3 months. Two of 5 patients developed late grade 3 toxic effects, and 3 of 5 developed late grade 4 toxic effects. Three of the 5 patients reviewed ultimately required permanent colostomies. Cumulative median dose (in equivalent dose in 2-Gy fractions) of clinical target volume to the hottest 90% was 107.2 Gy, rectal dose to the hottest 2 cc (D2cc) was 81.7 Gy, sigmoid D2cc was 61.7 Gy, and bladder D2cc was 79.5 Gy. No patient had evidence of disease recurrence in the pelvis. One patient developed oligometastatic disease in the suprarenal gland and was successfully salvaged with adrenalectomy.

IMPLICATIONS

Despite its risk of toxic effects, intracavitary brachytherapy remains a critical component of the treatment of locally advanced cervical cancer. Even with modern radiotherapy planning and delivery techniques, extra attention is warranted to continue to strive for optimal outcomes.

Inter-application displacement of brachytherapy dose received by the bladder and rectum of the patients with inoperable cervical cancer

BACKGROUND

The aim of the study was to examine on the CT basis the inter-application displacement of the positions D0.1cc, D1cc and D2cc of the brachytherapy dose applied to the bladder and rectum of the patients with inoperable cervical cancer.

PATIENTS AND METHODS

This prospective study included 30 patients with cervical cancer who were treated by concomitant chemo-radiotherapy. HDR intracavitary brachytherapy was made by the applicators type Fletcher tandem and ovoids. For each brachytherapy application the position D0.1cc was determined of the bladder and rectum that receive a brachytherapty dose. Then, based on the X, Y, and Z axis displacement, inter-application mean X, Y, and Z axis displacements were calculated as well as their displacement vectors (R). It has been analyzed whether there is statistically significant difference in inter-application displacement of the position of the brachytherapy dose D0.1cc, D1cc and D2cc of the bladder and rectum. The ANOVA test and post-hoc analysis by Tukey method were used for testing statistical importance of differences among the groups analyzed. The difference among the groups analyzed was considered significant if p < 0.05.

RESULTS

There are significant inter-application displacements of the position of the brachytherapy dose D0,1cc, D1cc and D2cc of the bladder and rectum.

CONCLUSIONS

When we calculate the cumulative brachytherapy dose by summing up D0,1cc, D1cc and D2cc of the organs at risk for all the applications, we must bear in mind their inter-application displacement, and the fact that it is less likely that the worst scenario would indeed happen.

Mapping of dose distribution from IMRT onto MRI-guided high dose rate brachytherapy using deformable image registration for cervical cancer treatments: preliminary study with commercially available software

PURPOSE

For patients undergoing external beam radiation therapy (EBRT) and brachytherapy, recommendations for target doses and constraints are based on calculation of the equivalent dose in 2 Gy fractions (EQD2) from each phase. At present, the EBRT dose distribution is assumed to be uniform throughout the pelvis. We performed a preliminary study to determine whether deformable dose distribution mapping from the EBRT onto magnetic resonance (MR) images for the brachytherapy would yield differences in doses for organs at risk (OARs) and high-risk clinical target volume (HR-CTV).

MATERIAL AND METHODS

Nine cervical cancer patients were treated to a total dose of 45 Gy in 25 fractions using intensity-modulated radiation therapy (IMRT), followed by MRI-based 3D high dose rate (HDR) brachytherapy. Retrospectively, the IMRT planning CT images were fused with the MR image for each fraction of brachytherapy using deformable image registration. The deformed IMRT dose onto MR images were converted to EQD2 and compared to the uniform dose assumption.

RESULTS

For all patients, the EQD2 from the EBRT phase was significantly higher with deformable registration than with the conventional uniform dose distribution assumption. The mean EQD2 ± SD for HR-CTV D90 was 45.7 ± 0.7 Gy vs. 44.3 Gy for deformable vs. uniform dose distribution, respectively (p < 0.001). The dose to 2 cc of the bladder, rectum, and sigmoid was 46.4 ± 1.2 Gy, 46.2 ± 1.0 Gy, and 48.0 ± 2.5 Gy, respectively with deformable dose distribution, and was significantly higher than with uniform dose distribution (43.2 Gy for all OAR, p < 0.001).

CONCLUSIONS

This study reveals that deformed EBRT dose distribution to HR-CTV and OARs in MR images for brachytherapy is technically feasible, and achieves differences compared to a uniform dose distribution. Therefore, the assumption that EBRT contributes the same dose value may need to be carefully investigated further based on deformable image registration.

Brachytherapy in the treatment of cervical cancer: a review

Dramatic advances have been made in brachytherapy for cervical cancer. Radiation treatment planning has evolved from two-dimensional to three-dimensional, incorporating magnetic resonance imaging and/or computed tomography into the treatment paradigm. This allows for better delineation and coverage of the tumor, as well as improved avoidance of surrounding organs. Consequently, advanced brachytherapy can achieve very high rates of local control with a reduction in morbidity, compared with historic approaches. This review provides an overview of state-of-the-art gynecologic brachytherapy, with a focus on recent advances and their implications for women with cervical cancer.