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Abstract
A number of newly emerging clinical techniques involve non-conventional patterns of radiation delivery which require an appreciation of the role played by radiation repair phenomena. This review outlines the main models of radiation repair, focussing on those which are of greatest clinical usefulness and which may be incorporated into biologically effective dose assessments. The need to account for the apparent "slowing-down" of repair rates observed in some normal tissues is also examined, along with a comparison of the relative merits of the formulations which can be used to account for such phenomena. Jack Fowler brought valuable insight to the understanding of radiation repair processes and this article includes reference to his important contributions in this area.
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Affiliation(s)
- Roger G Dale
- Department of Surgery and Cancer, Faculty of Medicine, Imperial College, London, UK
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Millar WT, Hendry JH, Davidson SE. Biphasic and monophasic repair: comparative implications for biologically equivalent dose calculations in pulsed dose rate brachytherapy of cervical carcinoma. Br J Radiol 2013; 86:20130288. [DOI: 10.1259/bjr.20130288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Huang Z, Mayr NA, Lo SS, Wang JZ, Jia G, Yuh WTC, Johnke R. A generalized linear-quadratic model incorporating reciprocal time pattern of radiation damage repair. Med Phys 2011; 39:224-30. [DOI: 10.1118/1.3666760] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Influence of length of interval between pulses in PDR brachytherapy (PDRBT) on value of Biologically Equivalent Dose (BED) in healthy tissues. J Contemp Brachytherapy 2010; 2:64-70. [PMID: 27829847 PMCID: PMC5095263 DOI: 10.5114/jcb.2010.14404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 06/08/2010] [Indexed: 11/17/2022] Open
Abstract
Purpose Different PDR treatment schemas are used in clinical practice, however optimal length of interval between pulses still remains unclear. The aim of this work was to compare value of BED doses measured in surrounded healthy tissues according to different intervals between pulses in PDRBT. Influence of doses optimization on BED values was analyzed. Material and methods Fifty-one patients treated in Greater Poland Cancer Centre were qualified for calculations. Calculations of doses were made in 51 patients with head and neck cancer, brain tumor, breast cancer, sarcoma, penis cancer and rectal cancer. Doses were calculated with the use of PLATO planning system in chosen critical points in surrounded healthy tissues. For all treatment plans the doses were compared using Biologically Equivalent Dose formula. Three interval lengths (1, 2 and 4 hours) between pulses were chosen for calculations. For statistical analysis Friedman ANOVA test and Kendall ratio were used. Results The median value of BED in chosen critical points in healthy tissues was statistically related to the length of interval between PDR pulses and decreased exponentially with 1 hour interval to 4 hours (Kendall = from 0.48 to 1.0; p = from 0.002 to 0.00001). Conclusions Prolongation of intervals between pulses in PDR brachytherapy was connected with lower values of BED doses in healthy tissues. It seems that longer intervals between pulses reduced the risk of late complications, but also decreased the tumour control. Furthermore, optimization influenced the increase of doses in healthy tissues.
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Pulsed-dose-rate intracavitary brachytherapy for cervical carcinoma: the AIIMS experience. Am J Clin Oncol 2009; 33:238-41. [PMID: 19841576 DOI: 10.1097/coc.0b013e3181aaca5b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE The aim of present study was to analyze the results of pulsed-dose-rate (PDR) brachytherapy in patients with cervical carcinoma treated at our center. METHODS From September 2003 to September 2005, 48 patients with histopathologically proved cervical carcinoma, stages IB to IVA, were treated with PDR intracavitary radiotherapy (ICRT) and pelvic irradiation at our center. Radiotherapy consisted of whole pelvis external beam radiation therapy (EBRT) with a dose of 40 Gy in 22 fractions over 4.5 weeks followed by 10 Gy in 5 fractions over 1 week with midline shielding. Weekly chemotherapy (Cisplatin, 40 mg/m) was administered during the course of EBRT to suitable patients. After an interval of 1 to 2 weeks, a single session of standard ICRT application was done to deliver a dose of 27 Gy to point A by PDR (hourly pulse, 70 cGy). RESULTS Median age was 50 years (range: 30-65). FIGO stage distribution of the patients was as follows: stage IB, 6; stage IIA, 1; stage IIB, 15; stage IIIB, 25; and stage IVA, 1. Follow-up period ranged from 3 to 50 months (median: 15 months). Ten patients had disease recurrence (5 each in stage IIB and stage IIIB). Eight patients had pelvic failure, 1 had bone metastases, and 1 had supraclavicular node metastases. Overall grades III to IV late toxicity rate at 50 months was 6%. For the median follow-up period of 15 months, the actuarial recurrence-free survival in stages I to II was 82% and stages III to IV was 78%. CONCLUSION Our results reveal that PDR ICRT in combination with pelvic EBRT provides excellent pelvic disease control, survival, and low radiation related morbidity rate in the patients with cervical carcinoma.
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Davidson SE, Hendry JH, West CM. Point: Why choose pulsed-dose-rate brachytherapy for treating gynecologic cancers? Brachytherapy 2009; 8:269-72. [DOI: 10.1016/j.brachy.2009.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Dale R. Use of the linear-quadratic radiobiological model for quantifying kidney response in targeted radiotherapy. Cancer Biother Radiopharm 2005; 19:363-70. [PMID: 15285884 DOI: 10.1089/1084978041425070] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This paper reviews the generalized application of the linear quadratic (LQ) model of radiobiological effect to targeted radiotherapy. Special attention is given to formulations for normal tissue responses and these are applied, in particular, to the kidney. Because it is derived from self-consistent bio-physical principles, the LQ model currently remains the standard formalism for assessing biological responses for the whole range of radiotherapy treatments. A central feature of the model is the derivation of biologically effective doses (BEDs), which may be used to quantify the impact of a treatment on both tumors and normal tissues. BEDs are routinely derived for conventional external-beam treatments. The likely limits of targeted radiotherapy may, thus, be assessed by comparing the expected normal-tissue BEDs for such treatments with those known to be just tolerable in conventional therapy. The main parameters required in the model are defined, and data are provided which demonstrate the tentative link between targeted radiotherapy doses and those used in conventional radiotherapy. The extension of the LQ method to targeted radiotherapy involves using parameters for which the numerical values may not be accurately known at present. This places a restriction on the overall predictive accuracy of the model and the necessary caveats are, therefore, outlined.
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Affiliation(s)
- Roger Dale
- Radiation Physics and Radiobiology, Charing Cross Hospital, Faculty of Medicine, Imperial College, University of London, London W6 8RF, United Kingdom.
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Streszczenie. Rep Pract Oncol Radiother 2005. [DOI: 10.1016/s1507-1367(05)70954-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Pop LA, Millar WT, van der Plas M, van der Kogel AJ. Radiation tolerance of rat spinal cord to pulsed dose rate (PDR-) brachytherapy: the impact of differences in temporal dose distribution. Radiother Oncol 2000; 55:301-15. [PMID: 10869745 DOI: 10.1016/s0167-8140(00)00205-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
PURPOSE To investigate the impact of a time-variable dose rate during a high dose rate (HDR-) or pulsed dose rate (PDR-) brachytherapy fraction with the HDR-microSelectron and to compare this with the biological effect of a constant dose rate treatment with the same average dose rate (as in the case of (192)Ir-wires). Moreover, the kinetics of repair in rat spinal cord are investigated using a wide spectrum of temporal dose distributions. MATERIALS AND METHODS Two parallel catheters are inserted on each side of the vertebral bodies of the rat spinal column (Th(10)-L(4)) and connected to the HDR-microSelectron. Interstitial irradiation (IRT) is performed with a stepping (192)Ir-point source, varying the activity of the point source between 0.3 and 6.5 Ci. Three different groups of experiments are defined, varying the overall treatment time and average dose rates in the range of 3-8, 28-53 and 82-182 min and 312-489 Gy/h, 32-56 Gy/h and 13-15 Gy/h, respectively. Difference in temporal dose distribution (dose rate variation) during almost the same overall treatment time is obtained by varying the number of pulses per dwell position in either one or ten runs through the implant. For reasons of comparison, previously reported results of continuous irradiation at a constant dose rate obtained with two (192)Ir-wires in a fixed position are reanalyzed. Paralysis of the hindlegs after 5-6 months and histopathological examination of the spinal cord of each animal are used as experimental endpoints. RESULTS During one run of the (192)Ir-point source, the peak dose rate is at least 25 times higher as compared with the minimum local dose rate and almost four times higher as compared with the average dose rate. For the three different groups of varying overall treatment times and average dose rates there is a significant difference in biological effect, with an ED(50)-value of 23.1-23.6 Gy (average dose rate 312-489 Gy/h), 25.4-27.9 Gy (average dose rate 312-489 Gy/h) and 29.3-33 Gy (average dose rate 13-15 Gy/h). For these range of single doses, difference in temporal dose distribution with either one or ten runs is only significant for treatment times less then 1 h. For the prolonged treatment times at lower average dose rates, the difference between one or ten run is no longer significant. However, the results with the (192)Ir-point source at an average dose rate/run of 13-15 Gy/h are significantly different from the ED(50)-value of 33 Gy using (192)Ir-wires at the same but constant dose rate. Using different types of analysis to estimate the repair parameters, the best fit of the data is obtained assuming biphasic repair kinetics and a variable dose rate (geometrically dependent) for the (192)Ir-point source. On the basis of the incomplete repair LQ model, two repair processes with an alpha/beta ratio=2.47 Gy and repair halftimes of 0.19 and 2.16 h are detected. The partition coefficient for the longer repair process is 0.98. This results in the proportion of total damage associated with the longer repair halftime being 0.495 for short sharp fractions with complete repair in between. CONCLUSIONS Even in the range of high dose rates of 15-500 Gy/h, spinal cord radiation tolerance is significantly increased by a reduction in dose rate. For larger doses per fraction in PDR-brachytherapy dose rate variation is important, especially for tissues with very short repair half times (components). In rat spinal cord the repair of sublethal damage (SLD) is governed by a biphasic repair process with repair halftimes of 0.19 and 2.16 h.
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Affiliation(s)
- L A Pop
- Institute of Radiotherapy, University of Nijmegen, P.O. Box 9101, 6500 HB, The, Nijmegen, Netherlands
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Mollà M, Panés J, Casadevall M, Salas A, Conill C, Biete A, Anderson DC, Granger DN, Piqué JM. Influence of dose-rate on inflammatory damage and adhesion molecule expression after abdominal radiation in the rat. Int J Radiat Oncol Biol Phys 1999; 45:1011-8. [PMID: 10571210 DOI: 10.1016/s0360-3016(99)00286-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE The goal of this study was to assess the effects of two clinically relevant radiation dose-rates on endothelial adhesion molecule expression, inflammatory response, and microvascular dysfunction. METHODS AND MATERIALS Rats were irradiated with 10 Gy at low (0.9 Gy/min) or high (3 Gy/min) dose-rates. Control animals received sham irradiation. Leukocyte rolling, adhesion, emigration, and microvascular permeability were assessed in mesenteric venules by intravital microscopy 6 hours after irradiation. P-selectin and intercellular adhesion molecule-1 (ICAM-1) expression were measured using radiolabeled monoclonal antibodies. RESULTS Low dose-rate (LDR) abdominal irradiation increased leukocyte adhesion compared with sham-irradiated animals, whereas high dose-rate (HDR) irradiation resulted in enhanced leukocyte rolling, adhesion, and emigration, compared with the LDR or with sham-irradiated rats. Both dose-rates increased microvascular permeability, although this effect was significantly greater after radiation with the high (8-fold) than the low (5-fold) dose-rate. HDR radiation induced significantly larger increments in P-selectin expression in splanchnic organs than LDR, whereas in most organs ICAM-1 expression was only upregulated by the HDR. Blockade of ICAM-1, but not P-selectin, abrogated leukocyte adhesion at both dose-rates. CONCLUSIONS The magnitude of upregulation of endothelial adhesion molecules, leukocyte recruitment, and endothelial barrier dysfunction elicited by radiation therapy is dependent on the dose-rate at which the radiation is delivered.
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Affiliation(s)
- M Mollà
- Gastroenterology Department, Institut Clínic de Malalties Digestives, IDIBAPS, Hospital Clínic, Barcelona, Spain
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de Pree C, Popowski Y, Weber D, Nouet P, Rouzaud M, Kurtz JM. Feasibility and tolerance of pulsed dose rate interstitial brachytherapy. Int J Radiat Oncol Biol Phys 1999; 43:971-6. [PMID: 10192342 DOI: 10.1016/s0360-3016(98)00525-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE Pulsed dose rate (PDR) treatment is a new approach that associates the physical advantages of high-dose-rate (HDR) technology with the potential radiobiological advantages of low-dose-rate (LDR) brachytherapy. This retrospective study analyzes the feasibility, toxicity, and preliminary oncologic results in a series of 43 patients treated with PDR interstitial brachytherapy. METHODS AND MATERIALS Twenty-four patients with pelvic, 17 patients with head and neck, and 2 patients with breast cancers were treated. Twenty-eight patients had primary and 15 recurrent tumors; 14 had received prior external irradiation to the same site. The doses per pulse at the prescription isodose were 0.4-1 Gy (median 0.5 Gy), delivered using a single cable-driven 0.3-1.0 Ci 192-iridium source (PDR Nucletron Micro-Selectron). RESULTS The median treated volumes (at the prescribed isodose) were 28 cc for pelvic, 8.33 cc for head and neck, and 40 cc for breast malignancies. Of 14,499 source and 14,499 dummy source transfer procedures, 3 technical machine failure events were observed (0.02%). Grade 3 acute toxicities were seen in 5/43 patients (4 oral stomatitis, 1 vaginal mucositis) and grade 4 acute toxicity in one patient (rectovaginal fistula). Grade 3-4 late complications were observed in 4/41 (9.8%) patients: 1 pubic fracture, 1 rectovaginal fistula, 1 vesicovaginal fistula and 1 local necrosis. With a median follow-up of 18 months, 10/41 patients progressed locoregionally (6 pelvic, 4 head and neck), 3 developed local recurrence and distant metastasis (3 pelvic), 3 only distant metastasis (2 pelvic, 1 head and neck). Two patients are lost to follow-up. CONCLUSION PDR interstitial brachytherapy for pelvic, head and neck, and breast malignancies is feasible and the acute and late toxicities seem acceptable. Although the physical advantages of PDR are clear, further follow-up is required to determine how results compare with those obtained with standard LDR brachytherapy.
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Affiliation(s)
- C de Pree
- Division of Radiation Oncology, University Hospital, Geneva, Switzerland
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Abstract
Radiation myelitis has long been recognised as a sinister consequence of spinal irradiation and has limited the acceptable dose of therapeutic radiation to the cord. Over the past 10 years, the pathogenesis has been increasingly understood through the use of animal models. The importance of 'dose per fraction' and 'inter-fraction interval' have been incorporated into new mathematical models which suggest that, for small fractions, the cord may tolerate higher doses of radiation than was previously thought. Clinical recognition of the condition has improved through the description of characteristic magnetic resonance imaging changes. However little advance has been made in its treatment.
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Affiliation(s)
- R Rampling
- Beatson Oncology Centre, Western Infirmary, Glasgow, UK. uk
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Abstract
The unique geometrical features of brachytherapy, together with the wide variety of temporal patterns of dose delivery, result in important interactions between physics and radiobiology. These interactions exert a major influence on the way in which brachytherapy treatments should be evaluated, both in absolute and comparative terms. This article reviews the main physical and radiobiological aspects of brachytherapy and considers examples of their influence on specific types of treatment. The issues relating to the optimization of high dose rate brachytherapy are presented, together with the implications of multiphasic repair kinetics for low dose-rate and pulsed high dose rate brachytherapy. The opportunities for application of radiobiological principles to improve various brachytherapy techniques, together with the integration of brachytherapy with teletherapy, are also outlined. Equations for the numerical evaluation of brachytherapy treatments are presented in the Appendices.
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Affiliation(s)
- R G Dale
- Hammersmith Hospitals NHS Trust, London, UK
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Affiliation(s)
- E J Hall
- Center for Radiological Research, Columbia University, New York, NY 10032, USA
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