High-dose-rate interstitial brachytherapy for mucinous adenocarcinoma endocervical-type – a case study

Background: Adenocarcinoma in cervical cancer has poorer response rate to treatment and requires longer time to achieve complete remission than squamous cell carcinoma [1]. Lower response to chemotherapy and radiotherapy is observed [2,3,4,5] and the optimal management remains undefined [1,4,6,7]. Case: We report a case of a 58-year-old woman with bulky mucinous adenocarcinoma endocervical-type G1, treated previously with radiochemotherapy with no visible response. After subsequent interstitial HDR brachytherapy (iHDR-BT) complete local remission was achieved. Conclusion: Interstitial HDR brachytherapy in bulky mucinous adenocarcinoma endocervical-type may be the best treatment choice that allows to receive a complete local response

Real-time brachytherapy for prostate cancer – implant analysis

SummaryBackgroundIn HDR brachytherapy precision of catheter implantation is crucial for conformal treatment planning as a starting point for better optimization process.AimThe aim was to investigate differences between virtual and real needle position and the effect of needle displacement on dosimetric parameters as a function of prostate volume for better evaluation of “real” implant with respect to final dose distribution.Materials/MethodsThirty treatment plans calculated by Nucletron SWIFT™ were randomly selected. Dosimetric data including V100 for prostate gland and D10 for urethra were analyzed as a function of prostate volume and needle displacement.Needle displacement was determined by measuring the distance between virtual and real positions of respective needles in three sectional images: at the base, apex of the prostate gland and reference image. Dosimetric parameters were determined for consecutive computer plans: virtual (before implantation), live (after implantation and renewed optimization). For the purpose of this study a new parameter, VD (Volume-Dose), was created.ResultsVD indicates the quality of “real” dose distribution with respect to “virtual” treatment plan. In order to realize the assumption of virtual plan (VD<1) for a given prostate volume, mean values of needle displacement r should not exceed racceptable according to the formula: racceptable (Vp) ∝ Vp2. For larger glands (above 30cc) final dose distribution is less dependent on needle displacement than smaller ones.ConclusionsThe experiment determined maximum values of needle displacement for a given Vp parameter, allowing one to take advantage of optimization algorithms and to improve the final dose distribution

Radiation Planning Index for dose distribution evaluation in stereotactic radiotherapy

AimThe aim of this study was to provide a parameter for treatment plan comparisons in clinical practice.Materials and Methods21 patients with brain tumours were selected for analysis. Two alternative treatment plans were calculated for each patient. One of the alternative plans was approved while the second one was rejected by the physician. Alternative plans were compared with the parameter RPI. The computer program RPIWin® was prepared to facilitate the calculation process.ResultsCalculations showed that 80% of approved treatment plans had higher RPI than rejected ones. Only 4 cases of approved treatment plans were characterized by lower RPI values than rejected ones.ConclusionThe experiment demonstrated that the Radiation Planning Index formula takes into account the relation between dose distributions calculated for planning treatment volumes and organs at risk and is a convenient tool for treatment plan comparisons in routine clinical practice

Clinical examples of 3D dose distribution reconstruction, based on the actual MLC leaves movement, for dynamic treatment techniques

AbstractAimTo present practical examples of our new algorithm for reconstruction of 3D dose distribution, based on the actual MLC leaf movement.BackgroundDynaLog and RTplan files were used by DDcon software to prepare a new RTplan file for dose distribution reconstruction.Materials and methodsFour different clinically relevant scenarios were used to assess the feasibility of the proposed new approach: (1) Reconstruction of whole treatment sessions for prostate cancer; (2) Reconstruction of IMRT verification treatment plan; (3) Dose reconstruction in breast cancer; (4) Reconstruction of interrupted arc and complementary plan for an interrupted VMAT treatment session of prostate cancer. The applied reconstruction method was validated by comparing reconstructed and measured fluence maps. For all statistical analysis, the U Mann–Whitney test was used.ResultsIn the first two and the fourth cases, there were no statistically significant differences between the planned and reconstructed dose distribution (p=0.910, p=0.975, p=0.893, respectively). In the third case the differences were statistically significant (p=0.015). Treatment plan had to be reconstructed.ConclusionDeveloped dose distribution reconstruction algorithm presents a very useful QA tool. It provides means for 3D dose distribution verification in patient volume and allows to evaluate the influence of actual MLC leaf motion on the dose distribution

Interstitial high-dose-rate brachytherapy in locally advanced and recurrent vulvar cancer

Purpose: The aim of the study was to report our experience with high-dose-rate interstitial brachytherapy (HDR-ISBT) in locally advanced and recurrent vulvar cancer. Material and methods: Between 2004 and 2014, fourteen women with locally advanced or recurrent vulvar cancer were treated using HDR-ISBT in our Centre. High-dose-rate interstitial brachytherapy was performed as a separate treatment or in combination with external beam radiotherapy (EBRT) (given prior to brachytherapy). Results: Patients were divided into: group I (n = 6) with locally advanced tumors, stages III-IVA after an incisional biopsy only, and group II (n = 8) with recurrent vulvar cancer after previous radical surgery. In group I, median follow up was 12 months (range 7-18 months); 1-year overall survival (OS) was 83%. Transient arrest of cancer growth or tumor regression was noticed in all patients but 4/6 developed relapse. Median time to failure was 6.3 months (range 3-11 months). The 1-year progression-free survival (PFS) was 33%. In group II, median follow up was 28 months (range 13-90 months). The 1-year and 3-year OS was 100% and 80%, respectively. The arrest of cancer growth or tumor regression was achieved in all patients. In 4/8 patients neither clinical nor histological symptoms of relapse were observed but 4/8 women experienced relapse. Median time to failure was 31 months (range 13-76 months). The 1-year and 3-year PFS was 100% and 62.5%, respectively. Two patients (14.3%) in group II had severe late toxicity (G3). Conclusions: High-dose-rate interstitial brachytherapy is a well-tolerated treatment option in selected patients with advanced or recurrent vulvar cancer. It is a safe and effective treatment modality for advanced and recurrent vulvar cancer, yielding good local control with acceptable late treatment related side effects. In our study, patients with recurrent vulvar cancer had better results in HDR-ISBT treatment, probably because of the smaller tumor volume. This hypothesis should be verified in a larger group of patients

Real-time brachytherapy for prostate cancer – implant analysis

BackgroundIn HDR brachytherapy precision of catheter implantation is crucial for conformal treatment planning as a starting point for better optimization process.AimThe aim was to investigate differences between virtual and real needle position and the effect of needle displacement on dosimetric parameters as a function of prostate volume for better evaluation of “real” implant with respect to final dose distribution.Materials/MethodsThirty treatment plans calculated by Nucletron SWIFT™ were randomly selected. Dosimetric data including V100 for prostate gland and D10 for urethra were analyzed as a function of prostate volume and needle displacement.Needle displacement was determined by measuring the distance between virtual and real positions of respective needles in three sectional images: at the base, apex of the prostate gland and reference image. Dosimetric parameters were determined for consecutive computer plans: virtual (before implantation), live (after implantation and renewed optimization). For the purpose of this study a new parameter, VD (Volume-Dose), was created.ResultsVD indicates the quality of “real” dose distribution with respect to “virtual” treatment plan. In order to realize the assumption of virtual plan (V

Physical parameters in thermal imaging of basal cell cancer patients treated with high-dose-rate brachytherapy — first study

Background: The basal cell carcinoma (BCC) is often treated by surgery or radiotherapy using ionizing radiation. While there is an established diagnostic path before treatment and also for the follow-up there are no good noninvasive methods objectifying irradiated area evolution during treatment. The main goal of preliminary studies was to try to answer if there are any useful information that can be derived from temperature effects of high-dose-rate (HDR) brachytherapy in treatment of BCC. Moreover, the temperature gradient was introduced as a physical parameter characterizing the thermal map of the lesion, its surroundings and reference area, which provided information about cancer tissue thermal reaction to brachytherapy. Materials and methods: Thirty-three patients suffering from BCC were monitored with thermovision during the brachytherapy treatment. All lesions were diagnosed as superficial and were confirmed with histopathology examination. Results: Results of the study showed two groups of patients characterized with two thermal maps and temperature gradient describing the lesion and surrounding area of BCC. The first group was characterized by higher temperature of the lesion than the surrounding tissue temperature (mean dT = 0,41°) whereas the other one, with lower lesion temperature (mean dT = –0.42°). It seems that the temperature changes observed in designated areas before and after therapy may provide physicians with additional information which could be useful in planning the treatment process, especially when considering temperature gradient changes during therapy. Conclusions:Although the data obtained indicate the possibilities of temperature distribution in pre-irradiation cases, further research is required for estimation of clinical effects of treatment

Pre-operative high-dose-rate brachytherapy in early-stage cervical cancer: long-term single-center results

Purpose: The aim of the study was to report the outcomes of pre-operative high-dose-rate brachytherapy (pHDRBT), followed by hysterectomy in patients with early cervical cancer. Material and methods: From January, 1998 to December, 2003, 113 women with IB1, IB2, and IIA1 cervical cancer (according to International Federation of Gynecology and Obstetrics [FIGO] 2018) were treated with pHDR-BT, and 6 to 8 weeks later followed by radical hysterectomy. Patients found to have positive lymph nodes, residual cervical cancer, involved parametria, or lymphovascular space invasion (LVSI) received post-operative adjuvant therapy. Results: Post-operatively, 81.4% of patients had a complete response to pHDR-BT in the cervix, and 18.6% had residual cervical cancer. Failures occurred in 11/113 (9.7%) patients (all were stage IIA1), with pelvic recurrences in 5/113 (4.4%) and distant metastasis (DM) in 6/113 (5.3%). The 5- and 10-year disease-free survival (DFS) rates were 100% for IB1 and IB2, and 86.4% and 81.3% for IIA1, respectively. Lymph node involvement and/or residual cervical cancer correlated with worse DFS. Two vesicovaginal fistulas were observed (one in a patient treated only with pHDRBT and one in a woman, who underwent adjuvant external-beam radiotherapy [EBRT]). Two rectovaginal fistulas and one case of proctitis were observed in patients treated with adjuvant EBRT. Conclusions: pHDR-BT in early cervical cancer is well-tolerated and effective in sterilizing tumor cells in the cervix. The growing number of publications in this area may help define an optimal therapeutic scheme, but randomized trials are required to determine the best candidates for this treatment modality. In our opinion, cervical cancer patients with FIGO stage IIA1 are not good candidates for pHDR-BT, and could be given this treatment only after rigorous selection, including assessment with state-of-the-art imaging, due to higher probability of treatment failure

Comparison of dose distribution in IMRT and RapidArc technique in prostate radiotherapy

AimThe aim was to provide a dosimetric comparison between IMRT and RapidArc treatment plans with RPI index with simultaneous comparison of the treatment delivery time.BackgroundIMRT and RapidArc provide highly conformal dose distribution with good sparing of normal tissues. However, a complex spatial dosimetry of IMRT and RapidArc plans hampers the evaluation and comparison between plans calculated for the two modalities. RPI was used in this paper for treatment plan comparisons. The duration of the therapeutic session in RapidArc is reported to be shorter in comparison to therapeutic time of the other dynamic techniques. For this reasons, total treatment delivery time in both techniques was compared and discussed.Materials and methods15 patients with prostate carcinoma were randomly selected for the analysis. Two competitive treatment plans using respectively the IMRT and RapidArc techniques were computed for each patient in Eclipse planning system v. 8.6.15. RPIwin® application was used for RPI calculations for each treatment plan.Additionally, total treatment time was compared between IMRT and RapidArc plans. Total treatment time was a sum of monitor units (MU) for each treated field.ResultsThe mean values of the RPI indices were insignificantly higher for IMRT plans in comparison to rotational therapy. Comparison of the mean numbers of monitor units confirmed that the use of rotational technique instead of conventional static field IMRT can significantly reduce the treatment time.ConclusionAnalysis presented in this paper, demonstrated that RapidArc can compete with the IMRT technique in the field of treatment plan dosimetry reducing the time required for dose delivery

EPID in vivo dosimetry in RapidArc technique

AbstractAimThe aim of the study was to estimate the dose at the reference point applying an aSi-EPID device in the course of patient treatment.Materials and methodsThe method assumes direct proportionality between EPID signal and dose delivered to the patient reference point during the treatment session. The procedure consists of treatment plan calculation for the actual patient in the arc technique. The plan was realized with an elliptic water-equivalent phantom. An ionization chamber inside the phantom measured the dose delivered to the reference point. Simultaneously, the EPID matrix measured the CU distribution. EPID signal was also registered during patient irradiation with the same treatment plan. The formula for in vivo dose calculation was based on the CU(g) function, EPID signal registered during therapy and the relation between the dose and EPID signal level measured for the phantom. In vivo dose was compared with dose planned with the treatment planning system.Irradiation was performed with a Clinac accelerator by Varian Medical Systems in the RapidArc technique. The Clinac was equipped with an EPID matrix (electronic portal image device) of aSi-1000. Treatment plans were calculated with the Eclipse/Helios system. The phantom was a Scanditronix/Wellhöfer Slab phantom, and the ionization chamber was a 0.6ccm PTW chamber.ResultsIn vivo dose calculations were performed for five patients. Planned dose at the reference point was 2Gy for each treatment plan. Mean in vivo dose was in the range of 1.96–2.09.ConclusionsOur method was shown to be appropriate for in vivo dose evaluation in the RapidArc technique