External beam boost for cancer of the cervix uteri when intracavitary therapy cannot be performed

PURPOSE: To assess the outcome of patients treated with radical radiotherapy for cervical cancer who received an external beam boost, in place of intracavitary brachytherapy (ICT), after irradiation to the whole pelvis. METHODS AND MATERIALS: Case notes were reviewed for all patients treated in this way in a single center between 1996 and 2004. Patient and tumor details, the reasons why ICT was not possible, and treatment outcome were documented. RESULTS: Forty-four patients were identified. The mean age was 56.4 years (range, 26-88 years). Clinical International Federation of Gynecology and Obstetrics or radiologic stage for Stages I, II, III, and IV, respectively, was 16%, 48%, 27%, and 7%. A total radiation dose of 54-70 Gy was given (75% received > or =60 Gy). Reasons for ICT not being performed were technical limitations in 73%, comorbidity or isolation limitations in 23%, and patient choice in 4%. The median follow-up was 2.3 years. Recurrent disease was seen in 48%, with a median time to recurrence of 2.3 years. Central recurrence was seen in 16 of the 21 patients with recurrent disease. The 5-year overall survival rate was 49.3%. The 3-year cancer-specific survival rate by stage was 100%, 70%, and 42% for Stages I, II, and III, respectively. Late Grades 1 and 2 bowel, bladder, and vaginal toxicity were seen in 41%. Late Grade 3 toxicity was seen in 2%. CONCLUSION: An external beam boost is a reasonable option after external beam radiotherapy to the pelvis when it is not possible to perform ICT.     

A CT based dosimetry system for intracavitary therapy in carcinoma of the cervix

The physical dose distribution from intracavitary sources used in the treatment of carcinoma of the cervix can be accurately calculated in three dimensions. However it is no simple matter to relate dose to critical tissues within, the pelvis. We have studied 10 patients and have used CT scanning with dummy sources to determine the dose to lymph nodes, bladder and rectum. This technique may be superior to the use of orthogonal radiographs and highlights the limitations of the use of the flexible rectal dose meter. Further work will required to determine whether or not the morbidity of radical radiotherapy can be reduced using such detailed dosimetry to adjust therapy and eliminate small areas of high dose to critical normal tissues. In one case, CT showed a spontaneous and unexplained uterine perforation by the intrauterine tube one day after check films had shown a satisfactory position.     

Patterns of failure using a conformal radiation therapy tumor bed boost for medulloblastoma.

PURPOSE: To assess the patterns of failure for patients with medulloblastoma receiving a conformal tumor bed boost rather than a boost to the entire posterior fossa. PATIENTS AND METHODS: From 1994 to 2002, 32 consecutive patients with newly diagnosed medulloblastoma treated at Memorial Sloan-Kettering Cancer Center (New York, NY) received a conformal boost to the tumor bed in conjunction with craniospinal radiation therapy. Twenty-eight patients also received chemotherapy. The median age was 9 years (range, 3 to 34 years), and the male to female ratio was 3:1. Twenty-seven patients had standard-risk disease, and five patients had high-risk disease. Craniospinal doses ranged from 23.4 to 39.6 Gy, and total tumor bed doses ranged from 54 to 59.4 Gy. RESULTS: With a median follow-up of 56 months, six patients have relapsed; five relapsed outside of the posterior fossa, and one failed within the posterior fossa, outside of the high-dose boost volume. Five-year actuarial disease-free and overall survival rates were 84% and 85%, respectively. Freedom from posterior fossa failure was 100% and 86% at 5 and 10 years, respectively. Freedom from distant failure was 84% at 5 years, with a trend for improvement when full-dose craniospinal radiation (36 to 39.6 Gy) was used compared with a reduced dose (23.4 Gy) of radiation (100% v 63%, respectively; P =.06). No other predictive variables were identified. CONCLUSION: Conformal treatment to the tumor bed allows for significant sparing of critical structures. The posterior fossa failure rate in this series is similar to that reported when the entire posterior fossa is treated. This approach should be investigated further in a phase III trial.     

Automated radiation therapy treatment plan workflow using a commercial application programming interface

PurposeThe objective of this study was to create a workflow for the automation and standardization of treatment plan generation and evaluation using an application programming interface (API) to access data from a commercial treatment planning system (Varian Medical Systems, Inc, Palo Alto, CA).Methods and materialsThe automation workflow begins with converting electronic patient-specific physician treatment planning orders that specify demographics, simulation instructions, and dosimetric objectives for targets and organs at risk into XML files. These XML files are used to generate standard contour names, beam, and patient-specific intensity modulated radiation therapy (IMRT) optimization templates to be executed in a commercial treatment planning system (TPS) by the user. A set of computer programs have been developed to provide quality control (QC) reports that verify demographic information in the TPS against the treatment planning orders, ensure the existence and proper naming of organs at risk, and generate patient-specific plan evaluation reports that provide real-time feedback on the concordance of an active treatment plan to the physician-specified treatment planning goals.ResultsA workflow for lung IMRT was chosen as a test scenario. Contour, beam, and patient-specific IMRT optimization templates were automatically generated from the physician treatment planning orders and loaded into the planning system. The QC reports were developed for lung IMRT, including the option of patient-specific modifications to the standard templates. The API QC reporting includes a dynamic program that runs in parallel to the TPS during the planning process, providing real-time feedback as to whether physician-specified treatment plan parameters have improved or worsened from previous iterations.ConclusionsUser-created computer programs to access information in the TPS database by means of a commercial TPS API enable automation and standardization of treatment plan generation and evaluation.     

An intracavitary cone system for electron beam therapy using a Therac 20 linear accelerator

The Therac 20 is an AECL medical linear accelerator that produces electron and photon beams. Electron fields are produced by a scanned beam; collimation is provided by two sets of primary collimators and further collimated by external electron trimmers located 11 cm above the plane of isocenter (100 cm). These collimators are not suitable for intracavitary treatment. To overcome this limitation, we have designed an intracavitary cone system that attaches to the electron trimmers. Since the trimmers do not have to be removed while this system is in use, there is no need to bypass the associated interlock system. The apparatus consists of a platform which slides onto the lower set of trimmers, onto which a lead insert is attached. Dosimetry measurements for 9, 13, and 17 MeV electron beams are reported for three different treatment cones.     

Four-week course of radiation for breast cancer using hypofractionated intensity modulated radiation therapy with an incorporated boost

PURPOSE: Standard radiation for early breast cancer requires daily treatment for 6 to 7 weeks. This is an inconvenience to many women, and for some a barrier for breast conservation. We present the acute toxicity of a 4-week course of hypofractionated radiation. METHODS AND MATERIALS: A total of 75 patients completed radiation on a Phase II trial approved by the hospital institutional review board. Eligibility criteria were broad to include any patient normally eligible for standard radiation: age >or=18 years, invasive or in situ cancer, American Joint Committee on Cancer Stage 0 to II, breast-conserving surgery, and any systemic therapy not given concurrently. The median age was 52 years (range, 31-81 years). Of the patients, 15% had ductal carcinoma in situ, 67% T1, and 19% T2; 71% were N0, 17% N1, and 12% NX. Chemotherapy was given before radiation in 44%. Using photon intensity-modulated radiation therapy and incorporated electron beam boost, the whole breast received 45 Gy and the lumpectomy bed 56 Gy in 20 treatments over 4 weeks. RESULTS: The maximum acute skin toxicity by the end of treatment was Grade 0 in 9 patients (12%), Grade 1 in 49 (65%) and Grade 2 in 17 (23%). There was no Grade 3 or higher skin toxicity. After radiation, all Grade 2 toxicity had resolved by 6 weeks. Hematologic toxicity was Grade 0 in most patients except for Grade 1 neutropenia in 2 patients, and Grade 1 anemia in 11 patients. There were no significant differences in baseline vs. 6-week posttreatment patient-reported or physician-reported cosmetic scores. CONCLUSIONS: This 4-week course of postoperative radiation using intensity-modulated radiation therapy is feasible and is associated with acceptable acute skin toxicity and quality of life. Long-term follow-up data are needed. This radiation schedule may represent an alternative both to longer 6-week to 7-week standard whole-breast radiation and more radically shortened 1-week, partial-breast treatment schedules.     

Phase i-ii study of hypofractionated simultaneous integrated boost using volumetric modulated arc therapy for adjuvant radiation therapy in breast cancer patients: a report of feasibility and early toxicity results in the first 50 treatments

ABSTRACT: BACKGROUND: : To report results in terms of feasibility and early toxicity of hypofractionated simultaneous integrated boost (SIB) approach with Volumetric Modulated Arc Therapy (VMAT) as adjuvant treatment after breast-conserving surgery. METHOD: S: Between September 2010 and May 2011, 50 consecutive patients presenting early-stage breast cancer were submitted to adjuvant radiotherapy with SIB-VMAT approach using RapidArc in our Institution (Humanitas). Three out of 50 patients were irradiated bilaterally (53 tumors in 50 patients). All patients were enrolled in a phase I-II trial approved by the ICH ethical committee. All 50 patients enrolled in the study underwent VMAT-SIB technique to irradiate the whole breast with concomitant boost irradiation of the tumor bed. Doses to whole breast and surgical bed were 40.5 Gy and 48 Gy respectively, delivered in 15 fractions over 3 weeks. Skin toxicities were recorded during and after treatment according to RTOG acute radiation morbidity scoring criteria with a median follow-up of 12 months (range 8-16). Cosmetic outcomes were assessed as excellent/good or fair/poor. RESULTS: : The median age of the population was 68 years (range 36-88). According to AJCC staging system, 38 breast lesions were classified as pT1, and 15 as pT2; 49 cases were assessed as N0 and 4 as N1. The maximum acute skin toxicity by the end of treatment was Grade 0 in 20/50 patients, Grade 1 in 32/50, Grade 2 in 0 and Grade 3 in 1/50 (one of the 3 cases of bilateral breast irradiation). No Grade 4 toxicities were observed. All Grade 1 toxicities had resolved within 3 weeks. No significant differences in cosmetic scores on baseline assessment vs. 3 months and 6 months after the treatment were observed: all patients were scored as excellent/good (50/50) compared with baseline; no fair/poor judgment was recorded. No other toxicities or local failures were recorded during follow-up. CONCLUSIONS: : The 3-week course of postoperative radiation using VMAT with SIB showed to be feasible and was associated with acceptable acute skin toxicity profile. Long-term follow-up data are needed to assess late toxicity and clinical outcomes.     

Endometrial carcinoma: Does the addition of intracavitary vault caesium to external beam therapy postoperatively result in improved control or increased morbidity?

A retrospective analysis of treatment for endometrial carcinoma is reported here. From 1987 to 1989, 138 patients were referred to the oncology department following total abdominal hysterectomy and bilateral salpingo-oophorectomy for endometrial cancer. Forty-seven patients were not prescribed postoperative radiotherapy; 31 had Stage I well differentiated adenocarcinoma with minimal myometrial invasion, while the remaining 16 patients were considered unfit for postoperative radiotherapy. There were no instances of local relapse amongst the 31 patients with minimal myometrial invasion.The remaining 91 patients all received external beam irradiation to the pelvis and, according to the preference of the individual therapist, 51 were prescribed additional intracavitary vault caesium-137. Patients receiving postoperative radiotherapy were analysed according to whether or not they received additional intracavitary vault caesium. The two groups were also analysed for incidence of vaginal vault recurrence and treatment related morbidity.In the group receiving additional intracavitary treatment more patients had Stage II or III disease (P<0.05), and had greater depth of myometrial invasion (P<0.05). Vaginal vault recurrence was not observed in patients receiving intracavitary therapy in addition to external beam therapy. Four patients (10%) receiving external beam therapy alone developed vaginal vault recurrence.The incidence of Kottmeier-Perez grade 2 or 3 bowel toxicity following treatment was significantly higher in those patients receiving combined treatment (18% vs. 2.5%; P<0.03). There was also a higher incidence of vaginal stenosis in the group receiving both external beam and intracavitary therapy (21% vs. 3%; P<0.05). There was only one instance of grade 2 bladder toxicity in the external beam and intracavitary treatment group and none in the external beam therapy alone group.In conclusion, postoperative radiotherapy for Stages I-III endometrial carcinoma was carried out in a non-randomized manner by two regimens; either external beam therapy alone or external beam therapy with additional intracavitary vaginal caesium. The combined therapy gave significantly better local control but resulted in significantly more late bowel and vaginal morbidity.     

Evaluation of a commercial diode monitor for mailed quality control of therapy units

A commercial diode dosimeter was evaluated for use in a mailed radiotherapy quality control package. The quality control package contained the commercial diode dosimeter and four thermoluminescent dosimeters to measure the given dose, and it also contained a photographic film to measure the light/radiation field coincidence. The film also served as a backup dosimeter. Twenty small Midwestern hospitals participated in field measurements; approximately half of the hospitals had a consulting physicist and the others had one full-time physicist. Each hospital was asked to deliver 1.5 Gy (150 rads) to the device, which was returned to our laboratory for evaluation. Reliable results were obtained from three measurements at each hospital at about 3-month intervals. The diode dosimeter was more precise than thermoluminescent dosimeters or film.     

A methodology for dosimetry audit of rotational radiotherapy using a commercial detector array

Purpose

To develop a methodology for the use of a commercial detector array in dosimetry audits of rotational radiotherapy.

Materials and methods

The methodology was developed as part of the development of a national audit of rotational radiotherapy. Ten cancer centres were asked to create a rotational radiotherapy treatment plan for a three-dimensional treatment-planning-system (3DTPS) test and audited. Phantom measurements using a commercial 2D ionisation chamber (IC) array were compared with measurements using 0.125 cm³ IC, Gafchromic film and alanine pellets in the same plane. Relative and absolute gamma index (γ) comparisons were made for Gafchromic film and 2D-Array planes, respectively.

Results

Comparisons between individual detectors within the 2D-Array against the corresponding IC and alanine measurement showed a statistically significant concordance correlation coefficient (both ρ_c > 0.998, p < 0.001) with mean difference of −1.1 ± 1.1% and −0.8 ± 1.1%, respectively, in a high dose PTV. In the γ comparison between the 2D-Array and film it was that the 2D-Array was more likely to fail planes where there was a dose discrepancy due to the absolute analysis performed.

Conclusions

It has been found that using a commercial detector array for a dosimetry audit of rotational radiotherapy is suitable in place of standard systems of dosimetry.     

Intraoperative radiation therapy at the National Cancer Institute: technical innovations and dosimetry

The technical complexity of intraoperative radiotherapy (IORT) requires modification of the standard physical and dosimetric methods used in external electron beam therapy. At the National Cancer Institute, a number of technical innovations have been integrated into ongoing clinical studies of IORT. These include: (1) an electron beam applicator system that is significantly different from other IORT systems and includes customized "squircle" applicators; (2) peripheral dose shields; (3) a modified surgical table replacing the standard radiation treatment couch; and (4) routine use of multiple IORT fields that necessitates field matching. The IORT applicator system and related devices and techniques are dosimetrically characterized in detail both for use in the IORT program and in order to illustrate many useful facets of electron dosimetry.     

二维半导体探测器阵列的方向性响应和在调强放射治疗合成剂量验证中的应用研究

Background and Objective:The planning dose distribution of intensity-modulated radiation therapy(IMRT) has to be verified before clinical implementation.The commonly used verification method is to measure the beam fluency at 0 degree(0°) gantry angle with a 2-dimensional(2D) detector array,but not the composite dose distribution of the real delivery in the planned gantry angles.This study was to investigate the angular dependence of a 2D diode array(2D array) and the feasibility of using it to verify the co...     

Definitive radiation therapy for invasive carcinoma of the vagina: impact of high-dose rate intracavitary brachytherapy

Background

This study was designed to evaluate the efficacy of definitive radiation therapy (RT) for invasive carcinoma of the vagina.

Methods

Twenty-six patients with invasive carcinoma of the vagina who received RT were studied retrospectively. The median age was 68 years. The pathologic subtype of vaginal carcinoma was squamous cell carcinoma in 24 patients, adenosquamous cell carcinoma in one patient, and adenocarcinoma in one patient. The distribution of clinical stage according to the International Federation of Gynecology and Obstetrics staging system was as follows: stage I, seven patients; stage II, 10 patients, stage III, seven patients; and stage IVA, two patients. Twenty patients received external beam radiation therapy (EBRT) combined with high-dose rate intracavitary brachytherapy (HDR-ICBT), and three received EBRT alone. The remaining three patients with stage I disease were given HDR-ICBT alone. The median dose was 50 Gy for EBRT, and 23 Gy for HDR-ICBT. Systemic chemotherapy was administered concurrently with RT to three patients.

Results

The median follow-up was 90 months. The initial rate of response to RT was 100%, and complete remission was attained in 21 patients (81%). The 5-year overall survival rate (OS) and the median survival time of the 26 patients were 57% and 97 months, respectively. The 5-year OS for the three patients who received HDR-ICBT alone was 100%. Severe toxicity occurred in three patients—grade 3 rectal hemorrhage in one, grade 3 cystitis in one, and grade 4 cystitis in one.

Conclusions

Our results demonstrated that definitive RT with HDR-ICBT is effective for invasive carcinoma of the vagina, with acceptable toxicity.     

External audits of electron beams using mailed TLD dosimetry: preliminary results.

AIM: A feasibility study has been performed to investigate the possibility of using mailed thermoluminescence dosimetry (TLD) for external audits of clinical electron beams in Europe. METHODS: In the frame of the EC Network Project for Quality Assurance in Radiotherapy, instruction sheets and mailing procedures have been defined for mailed TLD dosimetry using the dedicated holder developed by a panel of experts of the International Atomic Energy Agency (IAEA). Three hundred and thirty electron beam set-ups have been checked in the reference centres and some local centres of the EC Network Project and in addition through the centres participating to the EORTC Radiotherapy Group trial 22922. RESULTS: The mean ratio of measured dose to stated dose is 0.2% and the standard deviation of measured dose to stated dose is 3.2%. In seven beam set-ups, deviations greater than 10% were observed (max. 66%), showing the usefulness of these checks. CONCLUSION: The results of this feasibility study (instruction sheets, mailing procedures, holder) are presently endorsed by the EQUAL-ESTRO structure in order to offer in the future to all ESTRO members the possibility to request external audits of clinical electron beams.