High Dose Rate Brachytherapy Technique Research Articles

Selection criteria for high-dose-rate surface brachytherapy and electron beam therapy in cutaneous oncology

PurposeHigh-dose-rate (HDR) brachytherapy is an alternative treatment to electron external beam radiation therapy (EBRT) of superficial skin lesions. The purpose of this study was to establish the selection criteria for HDR brachytherapy technique (HDR-BT) and EBRT in cutaneous oncology for various clinical scenarios.Material and methodsThe study consists of two parts: a) EBRT and HDR-BT treatment plans comparison analyzing clinical target volumes (CTVs) with different geometries, field sizes, and topologies, and b) development of a prediction model capable of characterization of dose distributions in HDR surface brachytherapy for various geometries of treatment sites.ResultsA loss of CTV coverage for the electron plans (D90, D95) was recorded up to 45%, when curvature of the applicator increased over 30°. Values for D2 cm3 for both plans were comparable, and they were in range of ±8% of prescription dose. An increase in higher doses (D0.5 cm3 and D0.1 cm3) was observed in HDR-BT plans, and it was greater for larger lesions. The average increase was 3.8% for D0.5 cm3 and 12.3% for D0.1 cm3. When CTV was approximately flat, electron plans were comparable with HDR-BT plans, having lower average D2 cm3, D0.5 cm3, and D0.1 cm3 of 7.7%. Degradation of quality of electron plans was found to be more dependent on target curvature than on CTV size.ConclusionsBoth EBRT and HDR-BT could be used in treatments of superficial lesions. HDR-BT revealed superior CTV coverage when the surface was very large, complex, curvy, or rounded, and when the topology was complicated. The prediction model can be used for an approximate calculation and quick assessment of radiation dose to organs-at-risk (OARs), at a depth or at a lateral distance from CTV.

Optimized penile surface mold brachytherapy using latest stereolithography techniques: A single-institution experience

PurposeTo describe a technique of penile surface mold high-dose-rate (HDR) brachytherapy and early outcomes. Methods and MaterialsFive patients diagnosed with a T1aN0 squamous cell carcinoma of the penis were treated using a penile surface mold HDR brachytherapy technique. A negative impression of the penis was obtained using dental alginate. CT images were acquired of the penile impression; subsequently, a virtual model of the patient's penis was generated. The positive model was imported into a computer-assisted design program where catheter paths were planned such that an optimized offset of 5 mm from the penile surface was achieved. The virtual model was converted into a custom applicator. A total dose of 40 Gy was delivered in 10 fractions. Patients were followed at 1, 3, 6, and 12 months after treatment and then every 6 months thereafter. Toxicities were reported using Common Terminology Criteria for Adverse Events v4.0. ResultsAll patients tolerated treatment well. Acute Grade 2 skin reactions were observed within the first month after treatment. Median followup was 35 months. Late Grade 1 skin toxicities were observed. One patient experienced a urethral stricture requiring dilatation. Two patients developed local recurrence. ConclusionThis technique allows the delivery of penile HDR brachytherapy as an outpatient procedure with minimal discomfort to the patient during each application and is a repeatable and accurate setup. This technique warrants validation in larger series with longer followup.

Initial experience with high dose rate brachytherapy of periorbital sarcoids in the horse

SummaryPeriorbital sarcoids are a common condition in the horse and are difficult to treat due to their location and invasive nature. Radiotherapy is considered the gold standard treatment, and high dose rate brachytherapy (HDRB) may represent a safer and more effective method of delivering radiotherapy in the standing sedated horse. The objective of this retrospective clinical case series study was to describe the response rate and safety of HDRB for the treatment of periorbital sarcoids in the horse. Horses and ponies referred for HDRB treatment of confirmed periorbital sarcoids were eligible for inclusion in the study. Sarcoids were confirmed via clinical diagnosis and biopsy. Horses were given 2 fractions of 12.5 Gy per fraction, delivered a week apart, under standing sedation via a novel HDRB technique. Eight horses with periorbital sarcoids were treated with HDRB under standing sedation. A complete response occurred in all cases. No significant acute adverse effects were noted after treatment and the cosmetic result was excellent, with permanent epilation and leucotrichia the only long‐term sequelae. Follow‐up was available for between 10 and 12 months after treatment. The major limitation of this study is the lack of long‐term follow‐up and the small case numbers. It was concluded that HDRB appears to be an effective and safe method of treating periorbital sarcoids in the horse. Long‐term follow‐up is required to determine the risk of recurrence of treated lesions.

Freiburg Flap from 2D to 3D: A Novel Peri-Operative High Dose Rate Brachytherapy Approach

A 16 year old patient with a second recurrence of Wilms tumour within a previously irradiated field presented a technically challenging case to treat. Due to the close proximity of previously irradiated organs at risk including the single remaining ureter, a high dose rate brachytherapy technique allowing for steep dose drop off surrounding the target volume and minimal low dose wash was considered the most suitable option. We report the novel use of the Freiburg flap applicator to form a modified 3-dimensional catheter arrangement in order to treat the tumour bed immediately following surgical excision. Following excision of the tumour and temporary transposition of the right ureter away from the treatment volume, the brachytherapy team assessed the dimensions of the tumour bed to be treated. Under sterile conditions, the Freiburg flap was carefully cut down and reshaped, undergoing several iterations before an optimal shape was achieved. By curving the modified flap and suturing the edges together, a bespoke 3-dimensional applicator designed to custom fit the surgical cavity was formed. Gauze packing filled the central space in the applicator and 13 catheters with fixation buttons were threaded through the channels. The modified flap was inserted and sutured into the surgical cavity and the small bowel packed away from the treatment volume. A vacuum dressing was used to temporarily seal the surgical site with care taken to minimise curvature of the catheters. The patient remained intubated and sedated throughout treatment. The post-implant CT demonstrated good conformity of the modified Freiburg flap to the surgical cavity. Each channel could be easily visualised and accurately identified. A highly conformal plan was produced delivering a D90 dose of 32.9Gy in 5 bi-daily fractions to the tumour bed CTV and achieving organ at risk doses below set thresholds. Acceptable stability and consistency of the implant and organs at risk were verified daily via CT scan. All HDR brachytherapy treatments were delivered as planned, free from catheter obstructions, radiation or medical emergencies. The Freiburg flap has been successfully converted from a flat 2-dimensional sheet to a customised 3-dimensional applicator. This modified flap maintained good conformity to the surgical cavity and stability over the course of treatment. A highly conformal dose to the tumour bed CTV was planned and delivered without incident.

Long-term outcome for prostate cancer using pseudo pulse–dosed rate brachytherapy, external beam radiotherapy, and hormones

We report the long-term outcomes of pulse-dose rate (PDR) brachytherapy used in a nonstandard style (pseudo-PDR) with an high-dose rate brachytherapy technique in conjunction with external beam radiotherapy (EBRT) and hormonal manipulation on prostate cancer (PC). We treated 253 patients with Stage T1-T3 N0M0 PC, between December 1999 and March 2006. All patients received neoadjuvant androgen deprivation for a median 6 months. Treatment consisted of three pulses of pseudo-PDR brachytherapy to a median dose of 18Gy with 50.4Gy in 28 fractions of EBRT. At a median 6 years followup, (range, 1-11 years), 5-year overall survival was 92%, and PC-specific survival was 96%. The 5-year biochemical control (biochemical no evidence of disease) by the Phoenix definition for low-, intermediate-, and high-risk groups was 95%, 90%, and 71%, respectively (p<0.00001). At 6 years, the incidence of Radiotherapy Oncology Group Grade 2 and 3 genitourinary toxicity was 1% and 6%; Radiotherapy Oncology Group Grade 2 and 3 gastrointestinal toxicity was 4% and 0%. Erectile preservation at 3 years was 58%. The Phoenix definition best predicted clinical failure with a high specificity (94%). Pseudo-PDR brachytherapy plus EBRT with limited neoadjuvant hormonal manipulation is an effective treatment option in localized PC, with minimal and tolerable morbidity and provides excellent control. This technique of a modified PDR-delivery technique appears as effective as high-dose rate therapy.

Quelle modalité de curiethérapie prostatique ?

Brachytherapy techniques by permanent implant of radioactive sources or by temporary high-dose-rate (HDR) fractions are nowadays extensively used for the treatment of prostatic carcinoma. Long-term results (at 20 years) concerning large amount of patients have been published by major centers confirming both in terms of efficacy and toxicities that permanent implant of radioactive iodine-125 seeds yields at least the same good results of surgery and of external beam irradiation when proposed to patients affected by low-risk disease. For intermediate to high-risk tumors, HDR temporary implants are proposed as a boost for dose escalation. For both techniques, several topics still need to be clarified dealing with a recent enlargement of indications (HDR alone for low-risk, iodine-125 seeds boost for intermediate-high-risk cancers), or with technical aspects (loose seeds versus linked ones, number of fractions and dose for HDR protocols), while dosimetric issues have only recently been addressed by cooperatives groups. Last but not least, there is a real need to address and clearly characterize the correct definition of biochemical disease control both for iodine permanent implant and for HDR implant. New challenges are facing the prostate-brachytherapy community in the near future: local relapse after external beam radiotherapy are currently managed by several salvage treatments (prostatectomy, cryo, high intensity focused ultrasounds [HIFU]) but the role of reirradiation by brachytherapy is also actively investigated. Focal therapy has gained considerable interest in the last 5 years aiming at treating only the area of cancer foci inside the prostate and preserving nearby healthy tissues. Encouraging results have been obtained with the so-called “minimally invasive” approaches and both permanent seed implantation and HDR brachytherapy techniques may be worthwhile testing in this setting because of their capability of exactly sculpting the dose inside the prostatic gland.

Values of biologically equivalent doses in healthy tissues: Comparison of PDR and HDR brachytherapy techniques

Purpose The aim of this work was to compare the values of doses measured in healthy tissues in chosen pulsed-dose-rate (PDR) brachytherapy (PDRBT) and high-dose-rate (HDR) brachytherapy (HDRBT) fractionation schemas. Methods and Materials Fifty-one patients treated with PDRBT were qualified for calculations. This group included patients with head and neck cancer, brain tumor, breast cancer, sarcoma, penile cancer, and rectal cancer. The doses were calculated in chosen points in surrounded organs at risk (OaR). The biologically equivalent dose (BED) formula was used to compare doses in PDRBT and HDRBT. Results One ascertained that in biologically equivalent (to PDR) HDRBT, the increase of fractional dose from 4 to 10 Gy caused the necessity to decrease the total dose in treatment target ( p < 0.001). The use of HDR instead of PDR essentially caused lower physical and biologic doses in examined OaR. In many examined critical points in OaR where BED in the treatment area was the same, one ascertained the decrease of total physical HDR dose according to the growth of the fractional dose. Similar dependences were observed for BED. Conclusions The use of biologically equivalent HDRBT instead of PDRBT caused the decrease of physical doses in the treatment target and the decrease of physical doses and BEDs in OaR. Prolongation of intervals between pulses in PDRBT was connected with lower values of BED doses in healthy tissues.

Clinical Impact of Computed Tomography-based Image-guided Brachytherapy for Cervix Cancer using the Tandem-ring Applicator — the Addenbrooke's Experience

Aims We report our initial 3-year experience of chemoradiotherapy for cervical cancer with computed tomography-based image-guided high dose rate (HDR) brachytherapy using the tandem-ring applicator. Materials and methods Twenty-eight patients were treated between February 2005 and December 2007. All patients received initial external beam radiotherapy (EBRT) followed by HDR brachytherapy (planned dose 21 Gy to point A in three fractions over 8 days). For each insertion, a computed tomography scan was obtained with the brachytherapy applicator in situ. The cervix, uterus and organs at risk (OAR) were contoured on the computed tomography images to create an individualised dosimetry plan. The D 90 (the dose delivered to 90% of the tumour target), V 100 (the percentage of tumour target volume receiving 100% of the prescribed dose) and the minimum dose in the most exposed 2 cm 3 volume ( D 2cc) of rectum, bladder and bowel were recorded. The equivalent dose in 2 Gy fractions delivered by EBRT and brachytherapy was calculated. Results The 3-year cancer-specific survival was 81%, with a pelvic control rate of 96%. In 24 patients, a D 90 ≥74 Gy α/β10 was achieved. The only patient with local recurrence had a D 90 of 63.8 Gy α/β10. The overall actuarial risk of serious late morbidity was 14%. Seventeen patients had satisfactory OAR doses using the standard loading pattern. Seven patients had modifications to reduce the risk of toxicity, whereas two had modifications to improve the tumour dose. Comparison with a previous cohort of patients treated with chemoradiotherapy and a conventionally planned low dose rate triple source brachytherapy technique showed an improvement in local pelvic control of 20% ( P = 0.04). Conclusions The implementation of a computed tomography-based tandem-ring HDR brachytherapy technique in conjunction with individual dose adaptation has resulted in a significant improvement in local control at Addenbrooke's without increasing the risk of serious toxicity, and with little effect on radiotherapy resources.

Partial breast irradiation: revolution or evolution?

It is well established that there is no significant difference in terms of overall survival between mastectomy and radio-surgical conservative treatment (RSCT). Ten to fifteen years have been needed to change from the "standard" to the "new" breast cancer treatment. At the end of the 1990s, a few authors published preliminary results of phase II trials using partial breast irradiation (PBI) as sole post-operative treatment based on interstitial low or high dose rate brachytherapy techniques. Currently, phase III randomized trials comparing whole breast irradiation versus PBI are ongoing in the USA and in EU. The authors reviewed the literature regarding issues in the irradiation of breast cancer and the potential role of PBI to prevent local recurrence in the ipsilateral breast. Furthermore, potential advantages of PBI were discussed as well as the limits of such a procedure. Finally, we tried to determine the characteristics of a subgroup of patients who would receive benefit from this radiation technique. Phase II and III trials have been analyzed concerning feasibility, efficacy and toxicity. PBI may be delivered through low or high dose rate brachytherapy or intraoperative/external beam radiation therapy. PBI satisfies the control quality criteria. The majority of the teams provide PBI recurrence rates lower than 5% (0-4.4%) with a median follow-up varying between 8 and 72 months, and associated with cosmetic results comparable to those achieved with conventional external beam. RSCT does not replace mastectomy; mastectomy and RSCT are used together to treat different subgroups of patients. PBI furnished encouraging preliminary results in terms of local control and cosmetic results. However, caution in interpreting the results is required along with longer follow-up. PBI should not replace CT, but could be considered as a new therapeutic strategy for breast cancer dedicated to a very well defined subgroup of patients with a low risk of local recurrence.

High-dose-rate brachytherapy for vaginal cancer: Learning from treatment complications

Abstract.Tyree WC, Cardenes H, Randall M, Papiez L. High-dose-rate brachytherapy for vaginal cancer: learning from treatment complications.Historically, early stage vaginal cancer has been treated with low-dose-rate (LDR) brachytherapy with or without external beam radiation therapy (EBRT). Complication rates have been low and treatment efficacious. Although high-dose-rate (HDR) brachytherapy has been used for cervical cancer in many countries for over a decade, only more recently has it been integrated into treatment plans for vaginal cancer. This paper describes three patients treated with HDR brachytherapy who experienced significant late effects. Given the very limited amount of literature regarding the use of HDR brachytherapy in vaginal cancer, this analysis potentially contributes to an understanding of treatment-related risk factors for complications among patients treated with this modality.A focused review of hospital and departmental treatment records was done on three patients treated with HDR brachytherapy. Abstracted information included clinical data, treatment parameters (technique, doses, volume, combinations with other treatments) and outcomes (local control, survival, early and late effects). A review of the available literature was also undertaken.All patients had significant complications. Although statistical correlations between treatment parameters and complications are impossible given the limited number of patients, this descriptive analysis suggests that vaginal length treated with HDR brachytherapy is a risk factor for early and late effects, that the distal vagina has a lower radiation tolerance than the upper vagina with HDR as in LDR, and that combining HDR with LDR as done in our experience carries a high risk of late toxicity.Integration of HDR brachytherapy techniques into treatment plans for early stage vaginal cancers must be done cautiously. The etiology of the significant side effects seen here is likely to be multifactorial. For users of HDR brachytherapy in vaginal cancer, there is a need to further refine and standardize treatment concepts and treatment delivery. Ideally this will be based on continued careful observation and reporting of both favorable and unfavorable outcomes and experiences.

Optimizing brachytherapy for locally advanced cervical cancer

Purpose : No adequate high dose rate brachytherapy technique exists to cover all known tumor volume by using one type of applicator in patients presenting with a cervix carcinoma extending to the vaginal wall and the parametria. Methods and Materials : We adapted the existing high dose rate applicator, existing of two ovoids and one intrauterine tube, to achieve adequate irradiation of the uterus, the parametria, and the vaginal wall in these patients. Using the optimization program of the Nucletron Planning System, isodose curves were obtained to apply a specified dose of 8.5 Gy at point A and at 5 mm depth of the vaginal wall by using a single applicator for both fractions. Results : Fractionated high dose rate brachytherapy can be given with both higher dosimetric accuracy and more adequate irradiation of the vaginal and the parametrial tumor component after adapting the existing high dose rate applicator for brachytherapy in cervical cancer.