Audit tool for external beam radiation therapy departments

PurposeDevelopment of a self-contained audit tool for external beam radiation therapy to assess compliance with the major recommendations from professional organizations and generally accepted standards of practice. Intensity modulated radiation therapy, stereotactic body radiation therapy, stereotactic radiosurgery, and volumetric modulated arc therapy were included in this review.Methods and MaterialsA physics quality working group developed a department vision, distinguished and summarized key references, and condensed important elements of good documentation practices. The results were then compiled in a checklist format and used to perform audits at 3 sites.ResultsThe final audit tool contains 65 items spanning a wide range of external beam radiation therapy practices. Several of the audit items address issues not commonly identified by other authoritative sources. A total of 48 process improvements were identified at the 3 sites audited.ConclusionsThe enclosed self-inspection list may be useful to a site as an annual review tool, as an aid in preparation for the American College of Radiology-American Society for Therapeutic Radiology and Oncology practice accreditation, or as a catalyst for general quality improvement. Sites can quickly identify opportunities for improvement by concentrating on high importance items and commonly identified areas of noncompliance.     

Anesthesia for pediatric external beam radiation therapy.

BACKGROUND: For very young patients, anesthesia is often required for radiotherapy. This results in multiple exposures to anesthetic agents over a short period of time. We report a consecutive series of children anesthetized for external beam radiation therapy (EBRT). METHODS: Five hundred twelve children < or = 16 years old received EBRT from January 1983 to February 1996. Patient demographics, diagnosis, anesthesia techniques, monitoring, airway management, complications, and outcome were recorded for the patients requiring anesthesia. RESULTS: One hundred twenty-three of the 512 children (24%) required 141 courses of EBRT with anesthesia. Anesthetized patients ranged in age from 20 days to 11 years (mean 2.6 +/- 1.8 ). The frequency of a child receiving EBRT and requiring anesthesia by age cohort was: < or = 1 year (96%), 1-2 years (93%), 2-3 years (80%), 3-4 years (51%), 4-5 years (36%), 5-6 years (13%), 6-7 years (11%), and 7-16 years (0.7%). Diagnoses included: primary CNS tumor (28%), retinoblastoma (27%), neuroblastoma (20%), acute leukemia (9%), rhabdomyosarcoma (6%), and Wilms' tumor (4%). Sixty-three percent of the patients had been exposed to chemotherapy prior to EBRT. The mean number of anesthesia sessions per patient was 22 +/- 16. Seventy-eight percent of the treatment courses were once daily and 22% were twice daily. Anesthesia techniques included: short-acting barbiturate induction + inhalation maintenance (21%), inhalation only (20%), ketamine (19%), propofol only (12%), propofol induction + inhalation maintenance (7%), ketamine induction + inhalation maintenance (6%), ketamine or short-acting barbiturate induction + inhalation maintenance (6%). Monitoring techniques included: EKG (95%), O2 saturation (93%), fraction of inspired O2 (57%), and end-tidal CO2 (55%). Sixty-four percent of patients had central venous access. Eleven of the 74 children with a central line developed sepsis (15%): 6 of the 11 were anesthetized with propofol (55%), 4 with a short-acting barbiturate induction plus inhalation maintenance (36%), and 1 with inhalation alone (9%). Eight of the 11 (73%) received prior chemotherapy. CONCLUSION: Anesthesia was generally necessary at < or = 3 years, and rarely required at > 5 years of age. Sepsis associated with frequent use of the central venous access line was seen in 15% of the patients with these lines.     

Coronary artery radiation therapy for the prevention of restenosis after percutaneous coronary angioplasty, II: Outcomes of clinical trials

Coronary artery radiation therapy (CART) has become the standard of care for the treatment of coronary in-stent restenosis after repeat angioplasty. More than 5,000 patients have been enrolled into various clinical trials using 3 major systems. Based on the results of GAMMA I and START trials, both the Checkmate system using (192)Ir and the Betacath system using (90)Sr/Y have been approved for routine clinical use in the treatment of in-stent restenosis. The Galileo system using (32)P with data from INHIBIT trial is pending premarketing approval. With a better understanding and application of radiation oncology concepts to vascular brachytherapy, problems such as geographic miss and/or edge failure should be overcome. The complication of late thrombosis should also become less notable by eliminating restenting at the brachytherapy procedure and the prolonged use of antiplatelet therapy. Although there are other competing modalities in the very early phases of clinical trials, the future of CART appears bright. The durability of results, lack of any important complications, and confirmation of the efficacy in other sites will further consolidate the role of CART in preventing vascular restenosis.     

Free-to-total prostate-specific antigen ratios 18-24 months following external beam radiation for adenocarcinoma of the prostate

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate free-to-total prostate-specific antigen (PSA) ratios after definitive external beam radiation therapy for men with adenocarcinoma of the prostate (CaP). METHODS: A prospective evaluation of percent free PSA in men following definitive external beam radiation therapy for CaP was compared to men with untreated CaP and men at very low risk for CaP. Statistical comparison of clinical and pathologic parameters was performed. RESULTS: There was no statistically significant difference in free-to-total PSA ratios for men with newly diagnosed CaP and men with detectable PSA who were treated with external beam radiation therapy. CONCLUSIONS: Free-to-total PSA ratios after definitive external beam radiation therapy for CaP are consistent with percent free PSA in patients with newly diagnosed CaP. This supports the theory that PSA from in situ prostate tissue following external beam radiation therapy is produced by malignant cells.     

前列腺癌近距离照射联合外照射与单纯外照射疗效与安全性Meta分析

目的 系统评价近距离照射(BT)联合外照射(EBRT)与单纯EBRT对前列腺癌的疗效和安全性。方法 通过计算机检索Pubmed、Web of science、Cochrane Library、CNKI、万方和维普数据库中EBRT联合BT与单纯EBRT治疗前列腺癌的比较实验,检索时间均从建库至2018年7月,按照纳入和排除标准对纳入研究进行资料提取、方法学质量评价后,采用RevMan5.3软件进行Meta分析。结果 共纳入10项研究(含6篇RCT,4篇非RCT),共23393例患者。中危3、5年无生化进展生存率(b-PFS)OR值分别为2.03(95%CI为1.11~3.73,P=0.02)、2.27(95%CI为1.49~3.45,P<0.01),EBRT+BT组优于EBRT组;高危3、5年b-PFS、5年总生存率和5年无转移生存率两组相近。泌尿生殖道≥2、≥3级急性和慢性不良反应OR值分别为1.44(95%CI为1.1~1.38,P<0.01)、3.06(95%CI为1.37~6.80,P<0.01)和1.75(95%CI为1.14~2.69,P=0.01)、3.41(95%CI为2.42~4.82,P<0.01),EBRT组均优于EBRT+BT组;胃肠道不良反应两组相近。结论 BT联合EBRT较单纯EBRT能改善中危前列腺癌患者3、5年b-PFS,但同时也增加了泌尿生殖道不良反应发生率。     

Integral radiation dose to normal structures with conformal external beam radiation

BACKGROUND: This study was designed to evaluate the integral dose (ID) received by normal tissue from intensity-modulated radiotherapy (IMRT) for prostate cancer. METHODS AND MATERIALS: Twenty-five radiation treatment plans including IMRT using a conventional linac with both 6 MV (6MV-IMRT) and 20 MV (20MV-IMRT), as well as three-dimensional conformal radiotherapy (3DCRT) using 6 MV (6MV-3DCRT) and 20 MV (20MV-3DCRT) and IMRT using tomotherapy (6MV) (Tomo-IMRT), were created for 5 patients with localized prostate cancer. The ID (mean dose x tissue volume) received by normal tissue (NTID) was calculated from dose-volume histograms. RESULTS: The 6MV-IMRT resulted in 5.0% lower NTID than 6MV-3DCRT; 20 MV beam plans resulted in 7.7%-11.2% lower NTID than 6MV-3DCRT. Tomo-IMRT NTID was comparable to 6MV-IMRT. Compared with 6MV-3DCRT, 6MV-IMRT reduced IDs to the rectal wall and penile bulb by 6.1% and 2.7%, respectively. Tomo-IMRT further reduced these IDs by 11.9% and 16.5%, respectively. The 20 MV did not reduce IDs to those structures. CONCLUSIONS: The difference in NTID between 3DCRT and IMRT is small. The 20 MV plans somewhat reduced NTID compared with 6 MV plans. The advantage of tomotherapy over conventional IMRT and 3DCRT for localized prostate cancer was demonstrated in regard to dose sparing of rectal wall and penile bulb while slightly decreasing NTID as compared with 6MV-3DCRT.     

Dosimetry and techniques for simultaneous hyperthermia and external beam radiation therapy

An increased biological effect is realized when hyperthermia and radiation therapy are combined simultaneously. To take advantage of this effect, techniques have been developed that combine existing hyperthermia devices with a linear accelerator. This allows concomitant delivery of either ultrasound or microwave hyperthermia with photon radiation therapy. Two techniques have been used clinically: the orthogonal technique, in which the microwave or ultrasound beam and the radiation beam are orthogonal to one another, and the en face technique, in which the ultrasound or microwave beam and the radiation beam travel into the tumour through the same treatment window. The en face technique has necessitated the development of special attachments so that the hyperthermia device can be mounted to the linear accelerator and so that non-uniform portions of the hyperthermia device can be removed from the radiation beam. For microwave therapy, applicators are mounted onto the linear accelerator using the compensating filter tray holder. For ultrasound, special reflector devices are mounted to a frame that is mounted onto the compensating filter tray holder of the linear accelerator. Because the linear accelerator is an isocentric device, the height of the radiation source is fixed, and this has necessitated specially designed devices so that the ultrasound support system is compatible with the linear accelerator. The treatment setups for both the en face technique and the orthogonal technique require the interaction of both hyperthermia and radiation therapy personnel and equipment. The dosimetry and day-to-day operations for each technique are unique. The simulation for the en face technique is much different from the simulation of a normal radiation treatment and requires the presence of a hyperthermia physicist. Also, for the en face technique, the attenuation of the microwave applicator and the thickness and attenuation of the ultrasound reflector system are taken into account for radiation dosimetry. This paper presents details of the dosimetry and logistics of the techniques for simultaneous thermoradiotherapy based on 7 years of experience treating more than 50 patients.     

Dosimetric comparison between high-precision external beam radiotherapy and endovascular brachytherapy for coronary artery in-stent restenosis

PURPOSE: Several drawbacks of endovascular brachytherapy for the treatment of coronary artery in-stent restenosis may be addressed by high-precision external beam radiotherapy (EBRT). The dosimetric characteristics of both treatment techniques were compared. METHODS AND MATERIALS: The traversed volume of 10 coronary artery stents during the cardiac cycle was determined by electrocardiographically gated multislice spiral CT in 10 patients. By use of this traversed volume, high-precision EBRT treatment plans were generated for stents in the left circumflex (LCx), left anterior descending (LAD), and right coronary artery (RCA). The maximum dose to the nontargeted major coronary arteries was determined and compared to similar data calculated for endovascular brachytherapy. RESULTS: High-precision EBRT targeted at LCx stents contributed a mean maximum dose (D(max)) of 83.5% (range: 71.6-95.3%) and 16.3% to the LAD and RCA, respectively. Targeted LAD stents contributed a mean D(max) of 39.3% (range: 14.5-94.8%) and 5.2% (range: 0-13.4%) to the LCx and RCA, respectively. Targeted RCA stents contributed a mean D(max) of 6.2% (range: 0-12.4%) and 5.8% (range: 0-11.5%) to the LCx and LAD, respectively. Endovascular brachytherapy targeted at LCx stents contributed a mean D(max) of 1.7% (range: 0.7-2.7%) and 1.0% (range: 0.6-1.4%) to the LAD and RCA, respectively. Targeted LAD stents contributed a mean D(max) of 5.2% (range: 0.5-11.4%) and 0.7% (range: 0.4-1.1%) to the LCx and RCA, respectively; targeted RCA stents contributed a mean D(max) of 0.3% (range: 0.2-0.5%) and 0.2% (range: 0.1-0.3%) to the LCx and LAD, respectively.CONCLUSIONS: Although the doses distributed throughout the heart were higher for high-precision EBRT compared to endovascular brachytherapy, they are expected to be clinically irrelevant when nontargeted major coronary arteries are not closely situated to the targeted vessel segment. These encouraging results warrant further investigation of high-precision EBRT as a potential alternative to endovascular brachytherapy for the treatment of coronary artery in-stent restenosis.     

The role of external beam radiation therapy after prostatectomy for prostate cancer

The role of radiation therapy as an adjuvant to prostatectomy is evaluated in 21 patients. Eleven were treated prior to clinical recurrence with 100% local control, no serious complications, and 86% long-term survival. Ten were treated after local recurrence with 80% local control, no serious complications, and 71% long-term survival. These data and the available literature indicate that the patient found to have capsular penetration, seminal vesicle involvement, or positive surgical margins at prostatectomy can be salvaged by postsurgical radiation therapy. When this is done after recovery from surgery, rather than waiting for clinical recurrence, a lower radiation dose can be used (6000 rad vs. 7000 rad), improved local control is obtained (94% vs. 79%), and fewer serious complications are observed.     

Dosimetry and techniques for simultaneous hyperthermia and external beam radiation therapy.

An increased biological effect is realized when hyperthermia and radiation therapy are combined simultaneously. To take advantage of this effect, techniques have been developed that combine existing hyperthermia devices with a linear accelerator. This allows concomitant delivery of either ultrasound or microwave hyperthermia with photon radiation therapy. Two techniques have been used clinically: the orthogonal technique, in which the microwave or ultrasound beam and the radiation beam are orthogonal to one another, and the en face technique, in which the ultrasound or microwave beam and the radiation beam travel into the tumour through the same treatment window. The en face technique has necessitated the development of special attachments so that the hyperthermia device can be mounted to the linear accelerator and so that non-uniform portions of the hyperthermia device can be removed from the radiation beam. For microwave therapy, applicators are mounted onto the linear accelerator using the compensating filter tray holder. For ultrasound, special reflector devices are mounted to a frame that is mounted onto the compensating filter tray holder of the linear accelerator. Because the linear accelerator is an isocentric device, the height of the radiation source is fixed, and this has necessitated specially designed devices so that the ultrasound support system is compatible with the linear accelerator. The treatment setups for both the en face technique and the orthogonal technique require the interaction of both hyperthermia and radiation therapy personnel and equipment. The dosimetry and day-to-day operations for each technique are unique. The simulation for the en face technique is much different from the simulation of a normal radiation treatment and requires the presence of a hyperthermia physicist. Also, for the en face technique, the attenuation of the microwave applicator and the thickness and attenuation of the ultrasound reflector system are taken into account for radiation dosimetry. This paper presents details of the dosimetry and logistics of the techniques for simultaneous thermoradiotherapy based on 7 years of experience treating more than 50 patients.     

Post-irradiation sarcoma after external beam radiation therapy for localized adenocarcinoma of the prostate

We report a case of postirradiation sarcoma that arose in the right inguinal region 8 years after completion of external beam radiation therapy for a localized adenocarcinoma of the prostate. The patient was treated in 1995 with a "mixed-beams" technique (18 MV photons and 65 MeV fast neutrons). Eight years after the end of treatment, he presented with a radio-induced, high-grade spindle-cell sarcoma. Cytogenetic analysis was performed to confirm the diagnosis. Although the use of external beam radiation therapy for the treatment of prostate cancer has been common practice for decades, postirradiation sarcomas have been reported to be rare sequelae of irradiation and, to our knowledge, only a few of them were cytogenetically investigated.     

External beam radiation for prevention of intimal hyperplasia in peripheral arterial bypasses

PURPOSE: Neointimal hyperplasia is one of the limiting factors in infrainguinal prosthetic vascular grafting. We conducted a pilot study to assess the possible role of radiotherapy for the prevention of this proliferating cellular process. METHODS AND MATERIALS: Ten patients (7 men, 3 women; median age: 73 years) suffering from critical leg ischemia were treated by infrainguinal revascularization using 6-mm polytetrafluoroethylene. Postoperative radiation therapy of the anastomotic sites started within 24 h. A dose of 20.4 Gy was delivered in 12 fractions in 2.5 weeks by external beam radiation with electrons. The target volume was defined as the clip-marked anastomotic region plus a 1.5-cm safety margin in each direction. RESULTS: Radiation therapy was technically feasible in all cases without radiation-related side effects. In one patient, radiotherapy had to be terminated prematurely, because of a hematoma at the distal anastomotic site with consequent skin necrosis. One patient developed an occlusion of a suprainguinal graft without anastomotic stenosis after 9 months; 2 other grafts occluded at 12-month intervals. At a median follow-up of 16 months, the remaining 6 patients had no signs of restenosis. CONCLUSIONS: The restenosis rate of peripheral vascular grafts after external beam radiation was lower than expected without additional treatment. The value of this approach will now be determined in a randomized prospective trial.     

Cervix cancer oxygenation measured following external radiation therapy

Purpose: Tumor hypoxia may be an important factor predicting relapse following radiation therapy. This study was designed to determine the relationship between the oxygenation parameters measured using a polarographic oxygen electrode, prior to and during treatment in patients with cervix cancer, and to assess these results with regard to patient survival.Materials and Methods: Forty-three patients had pretreatment oxygen assays performed and measurements repeated following external beam radiation to a median dose of 50 Gy (range 26–52 Gy). Stage distribution showed 15 patients in Stage IB, 17 in Stage II, and 11 in Stage III. The median tumor size was 5 cm (range 3–10 cm).Results: The median proportion of pO₂ values <5 mm Hg (the HP₅) was 41% following radiation, and the median pO₂ was 12 mm Hg. These results were not significantly different from the pretreatment HP₅ or pO₂ of 37% and 12 mm Hg, respectively. Disease-free survival at 2 years was 50% in patients with posttreatment HP₅ ≤50%, compared to 60% when posttreatment HP₅ was >50% (p = 0.35).Conclusions: Unlike pretreatment results, tumour oxygenation measured following external radiation does not appear to be a useful predictive assay in patients with cervical cancer.     

Fiducial markers implanted during prostate brachytherapy for guiding conformal external beam radiation therapy

Prostate movement imposes limits on safe dose-escalation with external beam radiation therapy. If the precise daily location of the prostate is known, dose escalation becomes more feasible. We have developed an approach to dose escalation using a combination of prostate brachytherapy followed by external beam radiation therapy in which fiducial markers are placed along with (125)I seeds during transperineal interstitial permanent prostate brachytherapy. These markers serve to verify daily prostate location during the subsequent external beam radiotherapy. Prior to implementing this approach, preliminary studies were performed to test visibility of the markers. Three different (125)I seed models, as well as gold and silver marker seeds were placed within tissue-equivalent phantoms. Images were obtained with conventional x-rays (75-85 kV) and 6 MV photons from a linear accelerator. All (125)I seed models were clearly visible on conventional x-rays but none were seen with 6 MV photons. The gold markers were visible with both energies. The silver markers were visible with conventional x-rays and 6 MV x-rays, but not as clearly as the gold seeds at 6 MV. Subsequently, conventional x-rays, CT scans, and 6 MV port films were obtained in 29 patients in whom fiducial gold marker seeds were implanted into the prostate during (125)I prostate brachytherapy. To address the possibility of "seed migration" within the prostate, CT scans were repeated 5 weeks apart in 14 patients and relative positions of the gold seeds were evaluated. The repeated CT scans showed no change in intraprostatic gold marker location, suggesting minimal migration. The gold seeds were visible with conventional x-rays, CT, and 6 MV port films in all patients. During the course of external beam radiation therapy, the gold markers were visible on routine 6 MV port films and were seen in different locations from film to film suggesting prostate motion. Mean daily displacement was 4-5 mm in the anterior-posterior, and 4-5 mm in superior-inferior dimensions. Left-right displacement appeared less, averaging 2-3 mm. We conclude that implantation of gold marker seeds during prostate brachytherapy represents an easily implemented and practical means of prostate localization during subsequent image-guided external beam radiotherapy. With such markers, conformality of the external beam component can be confidently improved without expensive new equipment.