Acceptance testing and clinical assessment of the in-vivo dose measurement EPIgray system / 中国医学装备

Objective:To assess the accuracy of dose reconstruction of the in-vivo dose verification EPIgray system in intensity-modulated radiation therapy(IMRT)and volumetric-modulated arc therapy(VMAT)through acceptance testing,and to explore the preliminarily clinical application of that.Methods:A total of 37 patients with cancer at various parts were selected for clinical testing.Referring to the suggestions of the acceptance manual of manufacturer and the American Association of Physicists in Medicine(AAPM)TG-119 report,the square field,strip field and intensity-modulated plan were adopted to test the precision of dose reconstruction of EPIgray system on phantom.The recognition ability of the system for error was researched through changed the thickness of homogeneous phantom and the skin distance of exposure source.A total of 37 patients with cancer at different parts who underwent VMAT were selected to conduct clinical test,and then,the consistence between the dose reconstruction of EPIgray system and the counted dose of treatment plan system were further analyzed.Results:In the tests of square field,EPIgray dose reconstruction demonstrated excellent linearity and higher accuracy.On the phantoms with different thicknesses of fields with different sizes,the highest precision of dose reconstruction of central axis of field was(0.10±0.39)%.The all precisions of dose reconstruction were within 3.0%besides the built region of dose and field edges.In the tests of IMRT and VMAT plan,the deviation of dose reconstruction was<5.0%.With the increasing of the complexity of plan and the heterogeneity of phantom,there was a slight decrease in the reconstruction precision,but all deviations of dose reconstruction were within the range of allowable deviations.In clinical testing of 37 patients,the average reconstruction deviation of the prescription dose point was(-0.6±4.8)%,and the average deviation of sampling points within the range of target area was(-2.1±2.7)%.The reconstruction deviations outside of field and that with large dose gradient were larger.Conclusion:The dose reconstructions of in-vivo dose verification system EPIgray has better consistency with treatment planning system in calculating dose,and the precision of dose reconstruction can meet the requirement of clinical application.

Xerostomia y radioterapia de cabeza y cuello: actualización / Radiation-induced xerostomia: update

Resumen En la radioterapia de cabeza y cuello las glándulas salivales suelen recibir una dosis elevada de radiación, lo que provoca una disminución progresiva y, a partir de determinada dosis, irreversible de la secreción salival, entre otros efectos. La xerostomía o sensación de boca seca es el efecto secundario más frecuente tras la radioterapia de cabeza y cuello, el cual disminuye la calidad de vida de los pacientes al dificultar funciones como la fonación y la deglución. Dada la complejidad y la temprana aparición de este síntoma, su prevención es la solución más eficaz. Los avances de las últimas décadas tienen un papel imprescindible: la radioterapia de intensidad modulada, la administración de sustancias citoprotectoras y el autotransplante de glándula submandibular parecen limitar en cierta medida el efecto de la radiación y disminuir así la sensación de sequedad bucal.

Abstract Radiation therapy is a key component in the multidisciplinary treatment of head-and-neck malignancies. In these cases, salivary glands are irradiated with high-level doses, which, among other side effects, results in a progressive and irreversible decrease in the salivary output. Radiation-induced xerostomia is the most common side effect of the head and neck region after radiotherapy treatment, and highly impairs the patients' long-term quality of life, threatening physiological functions, essentially speaking and swallowing. Given the complexity and early appearance of this symptom, its prevention is the most effective solution. In the past decades, the development of new radiation delivery techniques, such as intensity-modulated radiotherapy (IMRT), along with the administration of radioprotective drugs and autologous submandibular gland transplantation, seem to reduce the dose reaching the salivary glands, which in turn improves the patients' perception of dry mouth.

Dosimetric comparison of two arcs VMAT plan and IMRT plan for breast cancer post-mastectomy / 中华放射医学与防护杂志

Objective To analyze the biophysical dosimetric characteristics and clinical application ability of VMAT technology for breast cancer post-mastectomy.Methods 28 patients with breast cancer (10 at left side and the other at right side) were planned in different ways respectively.One was two 90 degree arc VMAT plan and the other were 5 beam IMRT plan.The dosimetric parameters of two different plans including tumor control probability (TCP),conformity index(CI),homogeneity index (HI),V95and V110 in target,normal tissue complication probability (NTCP),V5,V20,V30 for ipsilateral lung,NCTP,D V25 for heart,D for the contralateral breast in OARs,MU and times were compared.Results The average tumor control probability (TCP) in VMAT and IMRT group was(96 ±2)％ and (90 ±2)％ (t =-6.28,P ＜ 0.01),respectively.The PTV dose average homogeneity index (HI) of VMAT plans was better than that of IMRT plan (0.15 ±0.04 vs 0.22 ±0.02,t =13.29,P ＜0.01).For cancer position in left side,the mean dose of heart was decreased by 433.24 cGy in the VMAT plan.The NTCP of the hearts in VMAT plans had statistically significant difference compared with IMRT plans [(1.00±0.12)％ vs (1.70±0.13)％,t =2.14,P ＜0.05].For plans of right breast cancer,the average mean dose of hearts in two control group was (3.27 ± 0.26) Gy and (6.00 ± 0.47) Gy (t =9.21,P＜0.01).The total monitor unit (MU) was 530.7 in the VMAT arm and 693.9 in the IMRT arm (t =9.58,P ＜0.01).The treatment time was shorter in VMAT arm (t =8.40,P ＜0.05).Conclusions VMAT plans have better clinical value and more superior biophysical dosimetric characteristics for breast cancer post-mastectomy.

Curent advances and stretegies for reducing the side effects of radiation therapies used for various types of cancers.

Cancer originates from the abnormal expression or activation of positive regulators and functional suppression of negative regulators. The World Health Organization (WHO) estimates that 84 million people will die of cancer between 2005 and 2015 without intervention. Research suggests that one-third of cancer deaths can be avoided through prevention. Major cancer treatment modalities are surgery, radiation therapy and chemotherapy. Radiation therapy is an important cancer treatment method and is used for approximately 50% of all cancer patients with varying success. Therapy uses high-energy waves or particles to destroy cancer cells. It can be used basically for three main reasons: to achieve high radiation dose into tumors; minimizing dose into surrounding normal tissues; to avoid complications as far as possible. The recent advances in this treatment method have led to the improvement in cancer death statistics. It can also be combined with surgery or chemotherapy for better results. This review covers general applications, various side effects/agents and factors affecting to get rid of these effects and strategies to improve radiation therapy.

Comparison of Intensity Modulated Radiation Therapy Dose Calculations with a PBC and AAA Algorithms in the Lung Cancer / 의학물리

The pencil beam convolution (PBC) algorithms in radiation treatment planning system have been widely used to calculate the radiation dose. A new photon dose calculation algorithm, referred to as the anisotropic analytical algorithm (AAA), was released for use by the Varian medical system. The aim of this paper was to investigate the difference in dose calculation between the AAA and PBC algorithm using the intensity modulated radiation therapy (IMRT) plan for lung cancer cases that were inhomogeneous in the low density. We quantitatively analyzed the differences in dose using the eclipse planning system (Varian Medical System, Palo Alto, CA) and I'mRT matirxx (IBA, Schwarzenbruck, Germany) equipment to compare the gamma evaluation. 11 patients with lung cancer at various sites were used in this study. We also used the TLD-100 (LiF) to measure the differences in dose between the calculated dose and measured dose in the Alderson Rando phantom. The maximum, mean, minimum dose for the normal tissue did not change significantly. But the volume of the PTV covered by the 95% isodose curve was decreased by 6% in the lung due to the difference in the algorithms. The difference dose between the calculated dose by the PBC algorithms and AAA algorithms and the measured dose with TLD-100 (LiF) in the Alderson Rando phantom was -4.6% and -2.7% respectively. Based on the results of this study, the treatment plan calculated using the AAA algorithms is more accurate in lung sites with a low density when compared to the treatment plan calculated using the PBC algorithms.

Intensity Modulated Radiation Therapy Commissioning and Quality Assurance: Implementation of AAPM TG119 / 의학물리

The purpose of this study is to evaluate the accuracy of IMRT in our clinic from based on TG119 procedure and establish action level. Five IMRT test cases were described in TG119: multi-target, head&neck, prostate, and two C-shapes (easy&hard). There were used and delivered to water-equivalent solid phantom for IMRT. Absolute dose for points in target and OAR was measured by using an ion chamber (CC13, IBA). EBT2 film was utilized to compare the measured two-dimensional dose distribution with the calculated one by treatment planning system. All collected data were analyzed using the TG119 specifications to determine the confidence limit. The mean of relative error (%) between measured and calculated value was 1.2+/-1.1% and 1.2+/-0.7% for target and OAR, respectively. The resulting confidence limits were 3.4% and 2.6%. In EBT2 film dosimetry, the average percentage of points passing the gamma criteria (3%/3 mm) was 97.7+/-0.8%. Confidence limit values determined by EBT2 film analysis was 3.9%. This study has focused on IMRT commissioning and quality assurance based on TG119 guideline. It is concluded that action level were +/-4% and +/-3% for target and OAR and 97% for film measurement, respectively. It is expected that TG119-based procedure can be used as reference to evaluate the accuracy of IMRT for each institution.

Incidence and Prognostic Factors of Radiation Pneumonitisin NSCLC Treated with Intensity Modulated Radiation Therapy (IMRT) / 대한방사선종양학회지

PURPOSE: To evaluate the incidence and prognostic factors of treatment-related pneumonitis in non-small-cell lung cancer (NSCLC) patients treated with intensity modulated radiation therapy (IMRT). MATERIALS AND METHODS: One-hundred-five patients with NSCLC treated with IMRT between 1 August 2004 and 30 November 2006 were analyzed retrospectively. The mean age of patients was 62.9 years, and squamous carcinomas were confirmed in 81 patients (77%). Sixty-six patients (62.9%) were classified as stage III, and 59 patients had lesions in the right lung. Twenty-seven patients were treated with a dose of 3,060 cGy preoperatively, and 10 patients were given a dose of 5,040 cGy postoperatively. Sixty-eight patients received a dose of 7,020 cGy for curative intent. Sixty-eight patients were treated with the use of the CORVUS planning system and 37 patients were treated with the use of the ECLIPSE planning system. RESULTS: Of 105 patients, 21 patients (20%) had abnormal radiological findings, but only seven patients (6.7%) required treatment for radiation pneumonitis. Six of the seven patients had other serious lesions, including a bronchioesophageal fistula (one patient), recurrence in the treatment field (two patients), brain metastasis (one patient) and lung-to-lung metastasis (two patients); all of these patients died within 19 months after radiation treatment. Sixteen patients (23.5%) that received planning with the CORVUS system had abnormal lung findings. Five patients (13.5%) had abnormal lung findings with the use of the ECLIPSE planning system. Other prognostic factors such as perioperative radiation therapy, a volume over 10% of the V20 volume in the right lung, were also statistically significant. CONCLUSION: This retrospective analysis suggests that IMRT could be a beneficial treatment modality for the reduction of radiation pneumonitis in NSCLC patients. However, the higher incidence of abnormal radiological findings in perioperative patients treated with relatively lower doses (3,060~5,040 cGy) suggest the need for judicious treatment planning in preoperative or postoperative treatment.

Pioneering innovative radiation oncology technology in clinics

Pioneering and implementing new technology successfully in a radiation oncology clinic requires hard work, team effort and management support. Over the last 15 years, we have pioneered the clinical implementation of intensitymodulated radiation therapy (IMRT) as well as combined radio-gene-therapy in the treatment of cancer. The entire department including physicists, dosimetrists, therapists, nurses, managers, data managers, radiation oncologists and residents in training, other medical specialists e.g. neurosurgeons, urologists, pathologists, radiologists, molecular biologists and many others have joined forces and contributed to the success. IMRT has transitioned from an initial experimental approach to a standard of care approach now in various disease sites. We are entering a new era of imageguided radiation therapy (IGRT) and molecular-targeted therapy and we continue to strive to implement these new technologies in the clinics. Frameless stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) have now become a clinical reality. Again, all these require a tremendous amount of efficient management and cooperation among all departmental staff. Five fundamental principles which can help the successful pioneering and implementation of innovative radiation oncology approaches will be discussed. These include identifying a project champion(s), pursuing a multi-disciplinary approach, showing clinical efficacy and return on investment (ROI), ability to articulate the project and celebrating the successful implementation.

Comparison of intensity-modulated and three-dimensional conformal techniques for radiotherapy of esophageal carcinoma / 中国癌症杂志

Three-dimensional conformal radiation therapy(3D-CRT) and intensity-modulated radiation therapy(IMRT) are becoming important parts for research of treatment in esophageal carcinoma patients.The advances of dosimetric study in 3D-CRT,IMRT of esophageal carcinoma and the evaluation indices are reviewed.