Comparison of image registration methods in patients with non-melanoma skin cancer treated with superficial brachytherapy.

The accumulated dose from sequential treatments of metachronous non-melanoma skin cancer can be assessed using image registration, although guidelines for selecting the appropriate algorithm are lacking. This study shows the impact of rigid (RIR), deformable (DIR) and deformable structure-based (SDIR) algorithms on the skin dose. DIR increased: the maximum dose (39.2 Gy vs 9.4 Gy), the dose to 0.1 cm3 (16.4 Gy vs 7.8 Gy) and the dose to 2 cm3 (7.6 Gy vs 5.7 Gy). RIR only affected the maximum dose, which increased to 17.0 Gy. SDIR correctly translated the dose maps, as none of the parameters changed significantly.

HDR brachytherapy versus robotic-based and linac-based stereotactic ablative body radiotherapy in the treatment of liver metastases - A dosimetric comparison study of three radioablative techniques.

Purpose: The aim of our study was to compare dosimetric aspects of three radioablation modalities - direct high-dose-rate brachytherapy (HDR-BT) and virtually planned stereotactic body radiation therapy performed on CyberKnife (SBRTck) and Elekta Versa HD LINAC (SBRTe) applied in patients with liver metastases. Material and methods: We selected 30 patients with liver metastases, who received liver interstitial HDR-BT and virtually prepared plans for SBRTck and SBRTe. In all the cases, the prescribed dose was a single fraction of 25 Gy. Treatment delivery time, doses delivered to PTV and organs at risk, as well as conformity indices, were calculated and compared. Results: The longest median treatment delivery time was observed in SBRTck in contrast to HDR-BT and SBRTe which were significantly shorter and comparable. HDR-BT plans achieved better coverage of PTV (except for D98%) in contrast to SBRT modalities. Between both SBRT modalities, SBRTck plans resulted in better dose coverage in Dmean, D50%, and D90% values compared to SBRTe without difference in D98%. The SBRTe was the most advantageous considering the PCI and R100%. SBRTck plans achieved the best HI, while R50% value was comparable between SBRTe and SBRTck. The lowest median doses delivered to uninvolved liver volume (V5Gy, V9.1Gy) were achieved with HDR-BT, while the difference between SBRT modalities was insignificant. SBRT plans were better regarding more favourable dose distribution in the duodenum and right kidney, while HDR-BT achieved lower doses in the stomach, heart, great vessels, ribs, skin and spinal cord. There were no significant differences in bowel and biliary tract dose distribution between all selected modalities. Conclusions: HDR-BT resulted in more favourable dose distribution within PTVs and lower doses in organs at risk, which suggests that this treatment modality could be regarded as an alternative to other local ablative therapies in carefully selected patients' with liver malignancies. Future studies should further address the issue of comparing treatment modalities in different liver locations and clinical scenarios.

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 (pHDR-BT), 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 pHDR-BT 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.

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.

Advanced dose calculation algorithm in superficial brachytherapy - the impact of tissue inhomogeneity on treatment plan dosimetry.

PURPOSE: Given tissue inhomogeneity and lack of backscatter media, superficial brachytherapy necessitates more accurate dosimetry than TG-43 formalism. However, the introduction of modern model-based dose calculation algorithms into clinical practice should be carefully evaluated. The aim of this work was to compare dose distributions calculated with TG-43 and advanced collapsed cone engine (ACE) algorithms for individual multi-catheter moulds, and investigate the impact of target size and the lack of bolus to differences between plans. MATERIAL AND METHODS: Eleven treatment plans for individual mould multi-catheter high-dose-rate brachytherapy (IMM HDR) were selected for retrospective analysis. All treatment plans were initially calculated with TG-43 formula and re-calculated using ACE algorithm. Plan re-calculation with ACE was repeated for each plan in order to assess the impact of bolus. To evaluate differences between TG-43 and ACE dose distributions, dose-volume histogram (DVH) parameters for each ROI were compared. Dmax (maximal point dose), D0.1cc, and D2cc were calculated for each risk's organ (OARs) and for external contour. For clinical target volume (CTV), D98, D90, D50, CTV coverage (CTV-V100), and dose delivered to reference point were compared between the plans. RESULTS: A significantly lower values (p < 0.05) of CTV parameters were observed for treatment plans calculated with ACE algorithm comparing to TG-43. Further analysis showed that differences between CTV-V100 for ACE and TG-43 plans depended on CTV volume. Dosimetric parameters for OARs were significantly lower in ACE plans than those of TG-43. Only D2cc for external and D0.1cc for both eye lenses in ACE plans were insignificantly different comparing to TG-43 plans. CONCLUSIONS: Results show that differences between dosimetric parameters are statistically significant. However, their clinical relevance is still undetermined. Careful re-evaluation of the clinical results based on long-term research on TG-43 is necessary to safely introduce modern algorithms to clinical practice.

Individual multi-catheter mould technique in high-dose-rate brachytherapy - personalized approach in treating multifocal angiosarcoma of the face.

PURPOSE: The aim of this study was to report individual surface mould multi-catheter high-dose-rate (IMM HDR) application as a salvage treatment for a head and neck angiosarcoma patient, previously treated with surgery followed by external beam radiotherapy. MATERIAL AND METHODS: A 74-year-old male reported to our center with an uncommon malignant neoplasm of blood vessels. The patient was qualified for a wide local excision (WLE) of tumor with simultaneous reconstruction using a free-flap collected from the patient's thigh. After surgery, the patient was qualified for adjuvant external-beam radiotherapy (EBRT). Volumetric arc therapy (VMAT; RapidArc®, Varian Medical Systems) was used to deliver 52.8 Gy/1.6 Gy in 33 fractions. Overall treatment time was 51 days. Six months after radiotherapy, an incisional biopsy of non-healing ulcer of the nasal bridge revealed angiosarcoma. Wide local excision with skin graft reconstruction was planned. Due to multifocal disease and lack of possibility for further margin, the resection surgery was completed after skin graft reconstruction from the right thigh. Surface IMM HDR was considered as an alternative option for further treatment. Total dose of 48 Gy (12 fractions) was planned. RESULTS: One month after surface IMM HDR, healing process of the skin was observed in the treated regions and six months later, the irradiated areas recovered. General condition of the patient deteriorated two years after diagnosis and one year after HDR. He was hospitalized to receive palliative care. CONCLUSIONS: HDR brachytherapy may be a valuable option for angiosarcoma treatment. Difficult lesion location may yield non-radical surgery. Surface IMM HDR provides highly conformal plan and allow adjusting the dose to individual clinical situation.

Nineteen-year single-center experience in 76 patients with penile cancer treated with high-dose-rate brachytherapy.

PURPOSE: To report the outcomes for 76 patients with penile cancer treated with high-dose-rate brachytherapy (HDR-BT) at a single institution. METHODS: Seventy-six patients with penile cancer treated with HDR-BT in our department between October 1998 and September 2018 were analyzed. Seventy underwent interstitial HDR-BT (fractionation dose range of 3-3.5 Gy given twice a day with an interval of at least six hours between the fractions), and six underwent superficial treatment with mold applicators (fractionation dose range of 4-7 Gy given once or twice a week). RESULTS: Median follow-up was 76 months (7-204 months). In the whole group, 22/76 local failures (28.9%) were observed: 14/76 (18.4%) local recurrences and 8/76 (10.5%) cases of persistent disease. Median time to recurrence was 24 months (9-54 months). Inguinal lymph node metastases were observed in 18/76 cases (23.7%). Distant metastases occurred in 12/76 (15.8%) cases. Patients with local recurrence and persistent disease underwent salvage penectomies, except four who refused surgery and underwent a second course of interstitial HDR-BT. Five- and 10-year cause-specific survival were 85.0% and 77.8%, respectively. Local control at 5 and 10 years was 65.6%. Five- and 10-year penile preservation were 69.5% and 66.9%, respectively. There was no G3 or G4 acute toxicity. One urethral stenosis (1.3%) occurred in a patient with a T3 tumor and was treated successfully with dilatation. CONCLUSIONS: HDR-BT provides good local control of penile cancer and is a good option for penis preservation therapy and in our experience achieves a penile preservation rate at 10 years of 66.9%.

Salvage high-dose-rate brachytherapy for locally recurrent prostate cancer after primary radiotherapy failure.

BACKGROUND AND PURPOSE: To evaluate high-dose-rate brachytherapy (HDR BT) as a salvage modality for locally recurrent prostate cancer after primary radiotherapy failure. MATERIALS AND METHODS: Eighty-three prostate cancer patients, who locally relapsed after radiotherapy, were treated with salvage HDR BT. The schedule was three implantations, every two weeks, with 10Gy per implant, to a total dose of 30Gy. Acute and late toxicity rates were evaluated. Overall survival (OS) and biochemical control were calculated using Kaplan-Meier method. RESULTS: Median follow-up after salvage HDR was 41months. The 3-year and 5-year OS were 93% and 86%, respectively. The 3-year and 5-year biochemical disease-free survival (bDFS) were 76% and 67%, respectively. The single factor associated with biochemical control was time to achieve salvage PSA nadir (p-.006). OS was linked significantly with primary nadir level (p-.001) while primary biochemical relapse interval was of borderline significance (p-.07). CONCLUSIONS: Salvage HDR BT is a promising treatment option for patients with localized relapse of previously irradiated prostate cancer. Lower PSA nadir after primary radiotherapy and longer primary disease-free interval influence the outcome.

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.

Integral dose: Comparison between four techniques for prostate radiotherapy.

AIM: Comparisons of integral dose delivered to the treatment planning volume and to the whole patient body during stereotactic, helical and intensity modulated radiotherapy of prostate. BACKGROUND: Multifield techniques produce large volumes of low dose inside the patient body. Delivered dose could be the result of the cytotoxic injuries of the cells even away from the treatment field. We calculated the total dose absorbed in the patient body for four radiotherapy techniques to investigate whether some methods have a potential to reduce the exposure to the patient. MATERIALS AND METHODS: We analyzed CyberKnife plans for 10 patients with localized prostate cancer. Five alternative plans for each patient were calculated with the VMAT, IMRT and TomoTherapy techniques. Alternative dose distributions were calculated to achieve the same coverage for PTV. Integral Dose formula was used to calculate the total dose delivered to the PTV and whole patient body. RESULTS: Analysis showed that the same amount of dose was deposited to the treated volume despite different methods of treatment delivery. The mean values of total dose delivered to the whole patient body differed significantly for each treatment technique. The highest integral dose in the patient's body was at the TomoTherapy and CyberKnife treatment session. VMAT was characterized by the lowest integral dose deposited in the patient body. CONCLUSIONS: The highest total dose absorbed in normal tissue was observed with the use of a robotic radiosurgery system and TomoTherapy. These results demonstrate that the exposure of healthy tissue is a dosimetric factor which differentiates the dose delivery methods.

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

AIM: To present practical examples of our new algorithm for reconstruction of 3D dose distribution, based on the actual MLC leaf movement. BACKGROUND: DynaLog and RTplan files were used by DDcon software to prepare a new RTplan file for dose distribution reconstruction. MATERIALS AND METHODS: FOUR 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. RESULTS: In 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. CONCLUSION: Developed 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.

The importance of the implant quality in APBI - Gliwice experience. Dosimetric evaluation.

This study includes four years of our clinical trials to improve implant quality in multicatheter accelerated partial breast irradiation (APBI). The progress in dosimetric and volumetric parameters of the treatment plans was evaluated. One hundred and ninety-one women, for whom treatment plans were made based on three dimensional imaging, were selected for the study. To evaluate progress made in our APBI procedure, following parameters and indices were taken into account: percentage of the target volume receiving the reference dose (PTVref), minimum dose in the target volume expressed as a percentage of reference dose (PTVmin), dose homogeneity index (DHI), and conformity index (COIN). Additionally, the plan quality index was calculated for every group as the sum of mean values of four evaluated parameters. PTVref have increased from the mean value of 83.4% at the beginning to recent 94.8%. The maximum value equals to 95.4%. The same trend can be observed with PTVmin value, which has been improved from 51.7% to 70.1%, maximally. DHI and COIN mean values present similar progress. DHI value increased from 0.53 level to 0.68, and COIN from 0.58 in 2009 to 0.74. Plan quality index has increased from 2.46 in 2009 to 3.06, recently. The implant quality is crucial for the accurate dose distribution. This paper shows the progress that was made in APBI procedure to improve implant quality. Nowadays, our implant technique is based on three-dimensional CT imaging results in acceptable dose distributions.

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.

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

AIM: The aim was to provide a dosimetric comparison between IMRT and RapidArc treatment plans with RPI index with simultaneous comparison of the treatment delivery time. BACKGROUND: IMRT 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 METHODS: 15 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. RESULTS: The 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. CONCLUSION: Analysis 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.

Interstitial HDR brachytherapy (HDR-BT) in early stage mobile tongue cancers in young patients - Gliwice experience.

PURPOSE: In early stage mobile tongue cancer radical radiotherapy offers good local control and organ preservation, which is especially important in the group of young patients. In our department, for many years HDR-BT has been performed in mobile tongue cancers as a sole treatment or as a "boost" with EBRT. The aim of the study was to show our experience with HDR-BT in early stage mobile tongue cancers among young patients. MATERIAL AND METHODS: From 2001 to 2006 in Maria Sklodowska-Curie Memorial Cancer Centre and Institute of Oncology, Gliwice Branch, five patients under 45 years with mobile tongue cancer were treated with HDR brachytherapy (T1N0M0 - 3/5 and T2N0M0 - 2/5); 4 with HDR brachytherapy "boost" and 1 as a sole treatment. One woman was previously treated with tumour resection, but because of positive surgical margins was referred for radiotherapy. All patients had clinically negative lymph nodes, without dissection. They were treated with interstitial HDR-BT (3-8 catheters). In 4 patients treated with HDR-BT as a "boost", total doses ranged from 18 to 21 Gy given in 6-7 fractions (twice a day, 3 Gy per fraction). Total doses in EBRT (to local lymph nodes and tumour bed) ranged from 50 to 60 Gy (1.8-2 Gy per fraction 5 days/week). One patient, treated with radical HDR brachytherapy, received 45 Gy in 10 fractions and 50 Gy in EBRT to regional lymph nodes. RESULTS: We did not notice local recurrences or distant metastases in our group of patients. Median follow-up was 67 months (range 47-79 months). All patients preserved normal tongue function. A severe late complication occurred in 1 patient - fracture of the mandible. CONCLUSIONS: In the analysed group of young patients with mobile tongue cancer interstitial HDR brachytherapy in combination with EBRT was an effective and well tolerated treatment modality which allowed preservation of the tongue and its function.

EPID in vivo dosimetry in RapidArc technique.

AIM: The 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 METHODS: The 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 0.6 ccm PTW chamber. RESULTS: In vivo dose calculations were performed for five patients. Planned dose at the reference point was 2 Gy for each treatment plan. Mean in vivo dose was in the range of 1.96-2.09. CONCLUSIONS: Our method was shown to be appropriate for in vivo dose evaluation in the RapidArc technique.

Two-dimensional imaging of tumour control probabilities and normal tissue complication probabilities.

AIM: To create a presentation method of TCP and NTCP distributions calculated based on dose distribution for a selected CT slice. MATERIALS AND METHODS: Three 24-bit colour maps - of dose distribution, delineated structures and CT information - were converted into m-by-n-by-3 data arrays, containing intensities of red, green, and blue colour components for each pixel. All calculations were performed with Matlab v.6.5. The transformation function, which consists of five linear functions, was prepared to translate the colour map into a one-dimensional data array of dose values. A menu-driven application based on the transformation function and mathematical models of complication risk (NTCP) and treatment control probability (TCP) was designed to allow pixel-by-pixel translation of colour maps into one-dimensional arrays of TCP and NTCP values. RESULTS: The result of this work is an application created to visualize the TCP and NTCP distribution for a single CT scan based on the spatial dose distribution calculated in the treatment planning system. The application allows 10 targets (PTV) and 10 organs at risks (OaR) to be defined. The interface allows alpha/beta values to be inserted for each delineated structure. The application computes TCP and NTCP matrices, which are presented as colour maps superimposed on the corresponding CT slice. There is a set of parameters used for TCP/NTCP calculations which can be defined by the user. CONCLUSION: Our application is a prototype of an evaluation tool. Although limited to a single plane of the treatment plan, it is believed to be a starting point for further development.

Comparison of 2D- and 3D-guided implantation in accelerated partial breast irradiation (APBI).

PURPOSE: In this study two different pre-planning methods (2D vs. 3D) were compared in respect to the implant quality as judged by volumetric and dose parameters of the treatment plans. The aim of this work was to evaluate the influence of the imaging modalities used for pre-planning purpose to the treatment plan quality. MATERIAL AND METHODS: Twenty-four patients treated with HDR multicatheter implants were randomly selected for experiment. All patients underwent breast conserving surgery. Flexible catheters were implanted into the breast through the template. Inter-catheter distance, number of planes and catheters were adjusted, in respect to the size and location of the target. Pre-planning was used to evaluate the implant geometry in respect to the target. Needles number and position were modified if necessary. There were two experimental subgroups consisted of 12 patients each. Different pre-planning procedure was employed in each group. In the first group 2D X-ray imaging system was used. In the second one the 3D pre-planning method based on CT was performed. Treatment plans were evaluated with parameters calculated based on dose-volume histograms (DVHs). Volumetric and dose parameters were used for comparison of the dose distribution between the two experimental subgroups. RESULTS: The mean value of target coverage VPTV100 is higher for 3D pre-planning than for 2D (91.7% vs. 86.1%). The dose that covers 90% of the PTV (D90) is also higher for 3D pre-planning than for 2D (4.2 Gy vs. 3.6 Gy). Similar relation can be observed for the values of dose homogeneity index where DHI obtained for 3D pre-planning is 0.60 and 0.53 for 2D. All differences were statistically significant with p < 0.05. CONCLUSIONS: Analysis presented in this paper showed that 3D pre-planning method improves the geometrical quality of the implant.

Salvage brachytherapy for local recurrences of prostate cancer treated previously with radiotherapy.

PURPOSE: The aim of the study was to analyze early effects and toxicity of salvage high dose rate brachytherapy for local recurrences of adenocarcinoma of the prostate after external beam radiotherapy (EBRT). MATERIAL AND METHODS: In MCS Memorial Institute of Oncology in Gliwice a research programme on salvage HDR brachytherapy for local recurrences of prostate cancer treated previously with EBRT has been ongoing since February 2008. The treatment consisted of 3 fractions of 10 Gy each given every 14 days. Maximal urethral doses were constrained to be ≤ 120% of the prescribed dose. Maximal bladder and rectum doses were constrained to be ≤ 70% of the prescribed dose. RESULTS: Fifteen eligible patients were treated and analyzed from February 2008. All patients completed the treatment without major complications. The most common early complications were: macroscopic haematuria, pain in lower part of the abdomen, and transient dysuria. During the first week after the procedure a transient increase in IPSS score was noticed. The Foley catheter was removed on day 2 to 5. No complications after spinal anaesthesia were observed. Acute toxicity according to EORTC/RTOG was low. For bladder EORTC/RTOG score ranged from 0 to 2. Only in two patients grade 1 toxicity for rectum was observed. The follow-up ranged from 3 to 9 months. In one patient grade 2 rectal toxicity was observed, and one had urethral stricture. Other patients did not have any other significant late toxicity of the treatment. Two patients developed bone metastases. CONCLUSIONS: Salvage brachytherapy for localized prostate cancer (3 × 10 Gy every 14 days) seems to be a safe and well tolerated procedure. A significant decline in prostate-specific antigen (PSA) level is seen in patients with hormone-responsive cancer. Long-term efficiency and toxicity of the procedure are yet to be established.

Comparison of traditional and simultaneous IMRT boost technique basing on therapeutic gain calculation.

Two different radiotherapy techniques, a traditional one (CRT) - based on consecutive decreasing of irradiation fields during treatment, and intensity modulated radiation therapy technique (IMRT) with concomitant boost, deliver different doses to treated volumes, increasing the dose in regions of interest. The fractionation schedule differs depending on the applied technique of irradiation. The aim of this study was to compare different fractionation schedules considering tumor control and normal tissue complications. The analysis of tumor control probability (TCP) and normal tissue complication probability (NTCP) were based on the linear quadratic (LQ) model of biologically equivalent dose. A therapeutic gain (TG) formula that combines NTCP and TCP for selected irradiated volumes was introduced to compare CRT and simultaneous boost (SIB) methods. TG refers to the different doses per fraction, overall treatment time (OTT), and selected biological factors such as tumor cell and repopulation time. Therapeutic gain increases with the dose per fraction and reaches the maximum for the doses at about 3 Gy. Further increase in dose per fraction results in decrease of TG, mainly because of the escalation of NTCP. The presented TG formula allows the optimization of radiotherapy planning by comparing different treatment plans for individual patients and by selecting optimal fraction dose.